Patent Publication Number: US-2022218328-A1

Title: Purse-string sutures

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Patent Application No. PCT/US2020/052398, filed Sep. 24, 2020, which claims the benefit of U.S. Patent Application No. 63/012,030, filed Apr. 17, 2020, and the benefit of U.S. Patent Application No. 62/909,197, filed Oct. 1, 2019, the entire disclosures all of which are incorporated by reference for all purposes. 
    
    
     BACKGROUND 
     Field 
     The present disclosure generally relates to the field of suturing tissue openings. 
     Description of Related Art 
     Purse-string sutures can be stitched or placed around openings formed in various types of tissues for managing the openings, including to seal the openings. For example, purse-string sutures can be formed in heart tissue. In some cases, purse-string sutures can be used to manage openings formed on the heart wall during procedures for treating heart conditions. 
     SUMMARY 
     Described herein are methods and devices relating to purse-string sutures stitched or placed into a target tissue to close and/or seal an opening in the target tissue. The purse-string sutures can be formed in a heart wall, such as to close an opening in the heart wall formed to deploy one or more tethers to the mitral valve leaflet for coupling the leaflet to the heart wall. The purse-string sutures can enable extension of the tethers through the opening for coupling the tethers to the heart wall, without or substantially without undesired damage to the tethers. 
     In some implementations, a method of suturing a tissue opening can comprise placing a tissue-facing surface of a first pad over a first tissue area adjacent to the tissue opening in a target tissue, the first pad being coupled to a suture, the suture forming a first stitch over an upper surface of the first pad oriented away from the target tissue; placing a tissue-facing surface of a second pad over a second tissue area adjacent to the tissue opening on a first side of the first pad, the second pad being coupled to the suture, and the suture forming a second stitch over the upper surface of the second pad; and placing a tissue-facing surface of a third pad over a third tissue area adjacent to the tissue opening on a second side of the first pad, the third pad being coupled to the suture. The method can include stitching the suture through an area of tissue between the first pad and the second pad, through an area of tissue between the second pad and the third pad, and through an area of tissue between the third pad and the first pad. A first distal portion and a second distal portion of the suture can be coupled to the third pad for forming a purse-string suture. 
     In some instances, placing the tissue-facing surface of the first pad comprises aligning the first pad with a posterior mitral leaflet direction. In some instances, the target tissue is heart tissue and wherein placing the tissue-facing surface of the first pad comprises placing the first pad over a pericardium. 
     In some instances, distal ends of the first stitch and the second stitch are less than about 2 millimeters (mm) from respective nearest edges of the first pad and the second pad. In some instances, coupling the first distal portion and the second distal portion of the suture to the third pad comprises coupling the first and second distal portions to positions less than about 2 millimeters (mm) from nearest respective edges of the third pad. 
     In some instances, placing the tissue-facing surface of the first pad, placing the tissue-facing surface of the second pad, and placing the tissue-facing surface of the third pad comprises evenly distributing the first pad, second pad and third pad around the tissue opening. 
     In some implementations, a method of suturing an opening in a target tissue can comprise positioning a first pad over a target tissue at a first position on a first path for forming a first purse-string suture around the opening in the target tissue, the first pad being coupled to a first suture, wherein a first corresponding portion of the first suture is over an upper surface of the first pad, and wherein the upper surface of the first pad is configured to be oriented away from the target tissue. A first distal portion of the first suture and a second distal portion of the first suture can be coupled to a second pad, and the second pad can be positioned at a second position on the first path. The method can include providing a second suture coupled to one of the first pad and the second pad, the second suture for forming a second purse-string suture in the target tissue along a second path around and concentric with the first path, wherein a first corresponding portion of the second suture is over an upper surface of the one of the first pad and the second pad, and wherein the upper surface of the one of the first pad and the second pad is configured to be oriented away from the target tissue. A first distal portion of the second suture and a second distal portion of the second suture can be coupled to the other of the first pad and the second pad. The first distal portion and second distal portion of the first suture can be tensioned to form the first purse-string suture, and the first distal portion of the second suture and second distal portion of the second suture can be tensioned to form the second purse-string suture. 
     In some instances, ends of the first corresponding portion of the first suture positioned over the upper surface of the first pad are less than about 2 millimeters (mm) from respective nearest edges of the first pad. In some instances, coupling the first distal portion and the second distal portion of the first suture to the second pad comprises coupling the first distal portion and the second distal portion to respective locations on the second pad which are less than about 2 millimeters (mm) from respective nearest edges of the second pad. In some instances, distal ends of the first corresponding portion of the second suture positioned over the upper surface of the one of the first pad and the second pad are less than about 2 millimeters (mm) from respective nearest edges of the one of the first pad and the second pad. In some instances, coupling the first distal portion and the second distal portion of the second suture to the other of the first pad and the second pad comprises coupling the first distal portion and the second distal portion to respective locations on the other of the first pad and the second pad which are less than about 2 millimeters (mm) from respective nearest edges the first pad or the second pad. 
     In some instances, the target tissue is heart tissue and wherein positioning the first pad comprises positioning the first pad over a pericardium and at an apex region of a heart and aligning the first pad with a posterior mitral leaflet direction. In some instances, the first pad and the second pad each comprise a pledget. 
     In some instances, positioning the second pad comprises positioning the second pad at an opposing location from that of the first pad along the first path. 
     In some instances, the method can further comprise positioning a third pad over the target tissue at a third position on the first path, the third pad being coupled to the first suture and a third corresponding portion of the first suture being over an upper surface of the third pad, wherein the upper surface of the third pad is configured to be oriented away from the target tissue. In some instances, positioning the third pad over the target tissue at the third position comprises positioning the third pad between the first pad and the second pad. In some instances, positioning the first pad, positioning the second pad, and positioning the third pad comprises evenly distributing the first pad, the second pad, and the third pad around the opening in the target tissue along the first path. In some instances, distal ends of the third corresponding portion of the first suture positioned over the third pad are less than about 2 millimeters (mm) from respective nearest edges of the third pad. 
     In some instances, the method can further comprise coupling the second suture to the third pad, the second suture comprising a third corresponding portion positioned over the third pad, and the third corresponding portion of the second suture being parallel to the third corresponding portion of the first suture. In some instances, distal ends of the third corresponding portion of the second suture positioned over the third pad are less than about 2 millimeters (mm) from respective nearest edges of the third pad. 
     In some instances, the method can further comprise positioning a fourth pad over the target tissue at a fourth position on the first path, the fourth pad being coupled to the first suture and a fourth corresponding portion of the first suture being over an upper surface of the fourth pad, wherein the upper surface of the fourth pad is configured to be oriented away from the target tissue. In some instances, positioning the fourth pad over the target tissue at the fourth position comprises positioning the fourth pad between the third pad and the second pad. 
     In some instances, positioning the first pad, positioning the second pad, positioning the third pad, and positioning the fourth pad comprises evenly distributing the first pad, the second pad, the third pad and the fourth pad around the opening in the target tissue along the first path. In some instances, distal ends of the fourth corresponding portion of the first suture positioned over the fourth pad are less than about 2 millimeters (mm) from respective nearest edges of the fourth pad. 
     In some instances, the method can further comprise coupling the second suture to the fourth pad, the second suture comprising a fourth corresponding portion over the fourth pad. In some instances, distal ends of the fourth corresponding portion of the second suture over the fourth pad are less than about 2 millimeters (mm) from respective nearest edges of the fourth pad. 
     In some implementations, a method of suturing an opening in a target tissue can comprise threading a first suture through a first location on a first pad from a lower surface to an upper surface of the first pad, and threading the first suture through a second location on the first pad from the upper surface to the lower surface of the first pad, to position a first corresponding portion of the first suture over the upper surface of the first pad, the upper surface being configured to be oriented away from the target tissue. The method can include positioning the first pad over the target tissue at a first position along a first path for forming a first purse-string suture around the opening in the target tissue; and threading the first suture through the target tissue along the first path from the first position on the first path to a second position on the first path. A first distal portion of the first suture can be threaded through a first location on a second pad from a lower surface of the second pad to an upper surface of the second pad, wherein the lower surface is configured to be oriented toward the target tissue and the upper surface is configured to be oriented away from the target tissue. A second distal portion of the first suture can be threaded through a second location on the second pad from the lower surface of the second pad to the upper surface of the second pad. The method can include positioning the second pad over the target tissue at the second position on the first path; and threading a second suture through a first location from a lower surface to an upper surface of one of the first pad and the second pad, and threading the second suture through a second location from the upper surface to the lower surface of the one of the first pad and the second pad to position a first corresponding portion of the second suture over the upper surface of the one of the first pad and the second pad for forming a second purse-string suture around and concentric with the first purse-string suture, wherein the upper surface of the one of the first pad and the second pad is configured to be oriented away from the target tissue. The method can include threading a first distal portion of the second suture through a first location from a lower surface to an upper surface of the other of the first pad and the second pad and threading a second distal portion of the second suture through a second location from the lower surface to the upper surface of the other of the first pad and the second pad; and tensioning the first distal portion and the second distal portion of the first suture to form the first purse-string suture along the first path, and tensioning the first distal portion of the second suture and second distal portion of the second suture to form the second purse-string suture. 
     In some instances, the target tissue is heart tissue and wherein positioning the first pad comprises positioning the first pad over a pericardium and at an apex region of a heart and aligning the first pad with a posterior mitral leaflet. In some instances, the first pad and second pad each comprise a pledget. 
     In some instances, positioning the second pad comprises positioning the second pad at an opposing location on the first path relative to that of the first pad. 
     In some instances, threading the first suture through the first location on a first pad and threading the first suture through the second location on the first pad comprise threading the first suture through locations less than about 2 millimeters (mm) from respective nearest edges of the first pad, and wherein threading the second suture through the first location on the one of the first pad and the second pad and threading the second suture through the second location on the one of the first pad and the second pad comprise threading the second suture through locations less than about 2 millimeters (mm) from respective nearest edges of the one of the first pad and the second pad. 
     In some instances, threading the first distal portion of the first suture and threading the second distal portion of the first suture comprise threading the first and the second distal portions of the first suture through locations less than about 2 millimeters from respective nearest edges of the second pad, and wherein threading the first distal portion of the second suture and threading the second distal portion of the second suture comprise threading the first and the second distal portions of the second suture through locations less than about 2 millimeters from respective nearest edges of the other of the first pad and the second pad. 
     In some instances, the method can further comprise positioning a third pad between the first pad and the second pad. Positioning the third pad can comprise threading the first suture through the target tissue from the first position to a third position on the first path; threading the first suture through a first location on a third pad from a lower surface to an upper surface of the third pad, and threading the first suture through a second location on the third pad from the upper surface to the lower surface of the third pad, to position a third corresponding portion of the first suture over the upper surface of the third pad, the upper surface being configured to be oriented away from the target tissue; and positioning the third pad over the target tissue at the third position on the first path. 
     In some instances, positioning the first pad, positioning the second pad and positioning the third pad comprise evenly distributing the first pad, the second pad and the third pad along the first path around the opening in the target tissue. 
     In some instances, threading the first suture through the first location on the third pad and threading the first suture through the second location on the third pad comprise threading the first suture through locations less than about 2 millimeters (mm) from respective nearest edges of the third pad. 
     In some instances, further comprising threading the second suture through a third location from the lower surface to the upper surface of the third pad, and threading the second suture through a fourth location from the upper surface to the lower surface of the third pad to position a corresponding portion of the second suture over the upper surface of the third pad. 
     In some instances, the method can further comprise positioning a fourth pad between the third pad and the second pad, wherein positioning the fourth pad comprises: threading the first suture through the target tissue from the third position to a fourth position on the first path; threading the first suture through a first location on a fourth pad from a lower surface to an upper surface of the fourth pad, and threading the first suture through a second location on the fourth pad from the upper surface to the lower surface of the fourth pad, to position a fourth corresponding portion of the first suture over the upper surface of the fourth pad, the upper surface being configured to be oriented away from the target tissue; and positioning the fourth pad over the target tissue at the fourth position on the first path. 
     In some instances, positioning the first pad, positioning the second pad, positioning the third pad and positioning the fourth pad comprise evenly distributing the first pad, the second pad, the third pad, and the fourth pad along the first path around the opening in the target tissue. 
     In some instances, threading the first suture through the first location on the fourth pad and threading the first suture through the second location on the fourth pad comprise threading the first suture through locations less than about 2 millimeters (mm) from respective nearest edges of the fourth pad. 
     In some instances, the method can further comprise threading the second suture through a third location from the lower surface to the upper surface of the fourth pad, and threading the second suture through a fourth location from the upper surface to the lower surface of the fourth pad to position a corresponding portion of the second suture over the upper surface of the fourth pad. 
     In some implementations, a purse-string suture structure can comprise a first pad and a second pad positioned around an opening in a target tissue, the first pad and second pad each comprising an upper surface oriented away from the target tissue and a lower surface oriented toward the target tissue. The purse-string suture structure can comprise a first purse-string suture positioned around the opening in the target tissue and coupled to the first pad and the second pad, wherein the first purse-string suture comprises: a portion of the first purse-string suture positioned over the first pad, and distal portions of the first purse-string suture coupled to the second pad. The purse-string suture structure can comprise a second purse-string suture positioned around and concentric with the first purse-string suture, wherein the second purse-string suture is coupled to the first pad and the second pad, and the second purse-string suture comprises: a portion of the second purse-string suture positioned over one of the first pad and the second pad, and distal portions of the second purse-string suture coupled to the other of the first pad and the second pad. 
     In some instances, respective ends of the portion of the first purse-string suture positioned over the first pad are less than about 2 millimeters (mm) from respective nearest edges of the first pad and respective ends of the portion of the second purse-string suture positioned over one of the first pad and the second pad are less than about 2 millimeters (mm) from respective nearest edges of one of the first pad and the second pad. In some instances, distal portions of the first purse-string suture are coupled at positions less than about 2 millimeters (mm) from respective nearest edges of the second pad and distal portions of the first purse-string suture are coupled at positions less than about 2 millimeters (mm) from respective nearest edges of the other of the first pad and the second pad. 
     In some instances, the target tissue is heart tissue and wherein the first pad is aligned with a posterior mitral leaflet direction. 
     In some instances, the first pad and the second pad are at opposing locations around the tissue opening. 
     In some instances, the purse-string suture structure can further comprise a third pad positioned between the first pad and the second pad, wherein the first and second purse-string sutures are coupled to the third pad. In some instances, the purse-string suture structure can further comprise a fourth pad positioned around the opening, wherein the first and second purse-string sutures are coupled to the fourth pad. 
     Methods and structures disclosed herein for treating a patient also encompass analogous methods and structures performed on or placed on a simulated patient, which is useful, for example, for training; for demonstration; for procedure and/or device development; and the like. The simulated patient can be physical, virtual, or a combination of physical and virtual. A simulation can include a simulation of all or a portion of a patient, for example, an entire body, a portion of a body (e.g., thorax), a system (e.g., cardiovascular system), an organ (e.g., heart), or any combination thereof. Physical elements can be natural, including human or animal cadavers, or portions thereof; synthetic; or any combination of natural and synthetic. Virtual elements can be entirely in silica, or overlaid on one or more of the physical components. Virtual elements can be presented on any combination of screens, headsets, holographically, projected, loud speakers, headphones, pressure transducers, temperature transducers, or using any combination of suitable technologies. 
     For purposes of summarizing the disclosure, certain aspects, advantages and novel features have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular instance. Thus, the disclosed instances may be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various instances are depicted in the accompanying drawings for illustrative purposes and should in no way be interpreted as limiting the scope of the inventions. In addition, various features of different disclosed instances can be combined to form additional instances, which are part of this disclosure. Throughout the drawings, reference numbers may be reused to indicate correspondence between reference elements. However, it should be understood that the use of similar reference numbers in connection with multiple drawings does not necessarily imply similarity between respective instances associated therewith. Furthermore, it should be understood that the features of the respective drawings are not necessarily drawn to scale, and the illustrated sizes thereof are presented for the purpose of illustration of inventive aspects thereof. Generally, certain of the illustrated features may be relatively smaller than as illustrated in some instances or configurations. 
         FIG. 1  is a cross-sectional view of a human heart. 
         FIG. 2  is a cross-sectional view of the human heart and a tether coupling a mitral valve leaflet of the heart to a ventricular wall of the heart. 
         FIG. 3  is a cross-sectional view of the human heart and an introducer instrument configured to deploy the tether as described with reference to  FIG. 2 . 
         FIG. 4  is a plan view of an example of a traditional purse-string suture structure. 
         FIG. 5  is a plan view of an example of a purse-string suture structure, according to some instances, where the structure comprises two concentric purse-string sutures positioned around a target tissue opening and where two pads are coupled to the each of the sutures, according to some instances. 
         FIGS. 6A and 6B  are plan views of examples of purse-string suture structures, according to some instances, each structure comprising two concentric purse-string sutures positioned around a respective target tissue opening, where each of the sutures are coupled to three pads, according to some instances. 
         FIGS. 7A through 7C  show an example of a purse-string suture structure comprising two concentric purse-string sutures positioned around a target tissue opening, and where both sutures are coupled to four pads, according to some instances. 
         FIG. 8  shows a heart and a direction of a posterior mitral valve leaflet (PML) marked thereon, according to some instances. 
         FIGS. 9A through 9D  show an example of a process for forming the purse-string suture structure described with reference to  FIG. 6A , according to some instances. 
         FIG. 10  is a flow diagram of an example of a process for forming a purse-string suture around an opening in a target tissue, according to some instances. 
         FIG. 11  is a flow diagram of an example of a process for forming two purse-string sutures around an opening in a target tissue, according to some instances. 
         FIG. 12  is a flow diagram of another example of a process for forming two purse-string sutures around an opening in a target tissue, according to some instances. 
     
    
    
     DETAILED DESCRIPTION 
     The headings provided herein are for convenience only and do not necessarily affect the scope or meaning of the claimed invention. 
     The present disclosure relates to devices and methods related to improved purse-string sutures stitched around tissue openings, where the purse-string sutures can advantageously provide desired closure of the tissue openings while reducing or eliminating damage to any tethers extending through the closed opening. 
     Although certain preferred instances and examples are disclosed below, inventive subject matter extends beyond the specifically disclosed instances to other alternative instances and/or uses and to modifications and equivalents thereof. Thus, the scope of the claims that may arise herefrom is not limited by any of the particular instances described below. For example, in any method or process disclosed herein, the acts or operations of the method or process may be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding certain instances; however, the order of description should not be construed to imply that these operations are order dependent. Additionally, the structures, systems, and/or devices described herein may be embodied as integrated components or as separate components. For purposes of comparing various instances, certain aspects and advantages of these instances are described. Not necessarily all such aspects or advantages are achieved by any particular instance. Thus, for example, various instances may be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as may also be taught or suggested herein. 
     Certain standard anatomical terms of location are used herein to refer to the anatomy of animals, and namely humans, with respect to the preferred instances. Although certain spatially relative terms, such as “outer,” “inner,” “upper,” “lower,” “below,” “above,” “vertical,” “horizontal,” “top,” “bottom,” and similar terms, are used herein to describe a spatial relationship of one device/element or anatomical structure to another device/element or anatomical structure, it is understood that these terms are used herein for ease of description to describe the positional relationship between element(s)/structures(s), as illustrated in the drawings. It should be understood that spatially relative terms are intended to encompass different orientations of the element(s)/structures(s), in use or operation, in addition to the orientations depicted in the drawings. For example, an element/structure described as “above” another element/structure may represent a position that is below or beside such other element/structure with respect to alternate orientations of the subject patient or element/structure, and vice-versa. 
     Purse-string sutures can be used for managing openings formed in various types of tissues. For example, a suture can be stitched through a target tissue along a path around an opening in the target tissue. The suture can subsequently be tensioned to form the purse-string suture around the opening. The suture can be tensioned such that the purse-string suture closes or reduces the size of the opening in the target tissue. The suture can be tensioned to seal the opening, and/or to close the opening around any instrumentation and/or material positioned in the opening. In some cases, purse-string sutures can be formed in heart tissue. For example, purse-string sutures can be stitched in a heart wall to close an opening formed in the heart wall, such as an opening formed in the heart wall in order to deliver medical device and/or therapy to a target site within the heart. Openings can be formed in the heart wall to treat various heart conditions. For example, the openings can be formed in the heart wall for various heart valve surgeries to treat any number of heart valve abnormalities, including to perform heart valve repair and/or replacement. 
       FIG. 1  is a schematic diagram showing various features of a human heart  1 . The heart  1  includes four chambers, namely the left atrium  2 , the left ventricle  3 , the right ventricle  4 , and the right atrium  5 . A wall of muscle, referred to as the septum  10 , separates the left atrium  2  and right atrium  5 , and the left ventricle  3  and right ventricle  4 . Blood flow through the heart  1  is at least partially controlled by four valves, the mitral valve  6 , aortic valve  7 , tricuspid valve  8 , and pulmonary valve  9 . The mitral valve  6  separates the left atrium  2  and the left ventricle  3  and controls blood flow therebetween. The aortic valve  7  separates and controls blood flow between the left ventricle  3  and the aorta  12 . The tricuspid valve  8  separates the right atrium  5  and the right ventricle  4  and controls blood flow therebetween. The pulmonary valve  9  separates the right ventricle  4  and the pulmonary trunk or artery  11 , controlling blood flow therebetween. 
     In a healthy heart, the heart valves can properly open and close in response to a pressure gradient present during various stages of the cardiac cycle (e.g., relaxation and contraction) to at least partially control the flow of blood to a respective region of the heart and/or to blood vessels. Deoxygenated blood arriving from the rest of the body generally flows into the right side of the heart for transport to the lungs, and oxygenated blood from the lungs generally flows into the left side of the heart for transport to the rest of the body. During ventricular diastole, deoxygenated blood arrive in the right atrium  5  from the inferior vena cava  15  and superior vena cava  16  to flow into the right ventricle  4 , and oxygenated blood arrive in the left atrium  2  from the pulmonary veins to flow into the left ventricle  3 . During ventricular systole, deoxygenated blood from the right ventricle  4  can flow into the pulmonary trunk  11  for transport to the lungs (e.g., via the left  14  and right  13  pulmonary arteries), and oxygenated blood can flow from the left ventricle  3  to the aorta  12  for transport to the rest of the body. 
     A number of conditions can contribute to a higher than normal pressure in the left atrium. Dysfunction of the mitral valve can contribute to elevated left atrial pressure. Conditions such as mitral valve regurgitation and/or stenosis may result in difficulty in pumping blood from the left atrium to the left ventricle, contributing to elevated pressure in the left atrium. Valve stenosis can cause a valve to become narrowed or obstructed. Mitral valve stenosis can restrict blood flow from the left atrium to the left ventricle. Valve regurgitation occurs when a valve does not close properly. For example, regurgitation can occur due to improper coaptation of the valve leaflets, such as due to prolapse of one or more of the valve leaflets. Mitral valve regurgitation can result in blood flow leakage back into the left atrium  2  from the left ventricle  3  when the left ventricle  3  contracts. Restricted flow of blood from the left atrium  2  into the left ventricle  3 , and blood flow leakage from the left ventricle  3  back into the left atrium  2  can both contribute to elevated atrial pressure. Dysfunction in the left ventricle  3  can also contribute to elevated left atrial pressure. Elevated left atrial pressure may lead to left atrial enlargement, producing symptoms such as shortness of breath during exertion, fatigue, chest pain, fainting, abnormal heartbeat, and swelling of the legs and feet. 
     Forming an opening through the heart wall  17  can be used to access a heart valve for treating various heart valve irregularities. Heart valve repair and/or replacement procedures can be performed to improve or restore valve function. For example, mitral valve repair procedures can be performed to alleviate mitral valve dysfunction, including mitral valve prolapse. In some cases, a transapical approach can be used to gain access into the heart  1 . For example, mitral valve repair procedures can include accessing the mitral valve  6  from within the left ventricle  3 , where entry into the left ventricle  3  can be achieved through the apex region  19  of the heart  1 . The heart wall  17  can be punctured in the apex region  19  to form an opening so as to allow delivery of medical devices and/or therapy to the mitral valve  6 . The apex region  19  is schematically shown in  FIG. 1  as the area within the dashed circle. As used herein, the “apex region” can include the true apex  18  of the heart  1  and an area of the heart wall  17  covering up to about 5 centimeters (cm) around the true apex  18 . For example, the opening in the left ventricular portion of the heart wall  17  about 2 centimeters (cm) to about 4 centimeters (cm) from the true apex  18 . 
       FIG. 2  schematically shows a tether  20  coupling a leaflet of the mitral valve  6  to the heart wall  17 . Mitral valve repair surgeries can comprise deploying one or more tethers onto a mitral valve leaflet for tethering the leaflet to the heart wall  17 . Coupling the leaflet to the heart wall  17  can facilitate reshaping of the mitral valve  6 , such as to reduce or eliminate leaflet prolapse. The tether  20  can serve to improve coaptation of the leaflet. In some instances, the tether  20  can be configured to couple the leaflet to a left ventricular portion of the heart wall  17 . In some instances, more than one tether can be used to couple the leaflet to the heart wall  17 . These tethers can be made from a variety of materials. One or more of these tethers can comprise for example expanded polytetrafluoroethylene (ePTFE). For example, the tether  20  can be an ePTFE suture. 
     The tether  20  can comprise an elongate portion  22  which extends between a first end  24  and a second end  26 . The first end  24  of the tether  20  can be coupled to the heart wall  17 . The second end  26  of the tether  20  can be coupled to the leaflet of the mitral valve  6 . In some instances, the second end  26  can comprise a suture knot  28  to facilitate securing the tether  20  to the leaflet. The suture knot  28  can be positioned at least partially over an upper surface of the leaflet. For example, the suture knot  28  can be positioned over an atrial facing surface of the mitral valve leaflet. The first end  24  can be anchored to a portion of the heart wall  17  at or proximate to the apex  18  of the heart  1 , such as the apex region  19 . In some instances, a portion of the elongate portion  22  can extend through the heart wall  17  such that the first end  24  is anchored at a position external to the heart  1 . The first end  24  can be coupled to a pad  30  positioned on an exterior surface of the heart  1 . For example, the pad  30  can be positioned over a pericardium of the heart  1 . In some instances, the pad  30  can be positioned over an exterior surface of the heart  1  in the apex region  19 . An opening  40  can be formed in the heart wall  17  to allow extension therethrough of the tether  20  such that the first end  24  of the tether  20  can be anchored to the pad  30 . The opening  40  can be formed in the apex region  19  of the heart  1 . The tether  20  can couple the mitral valve leaflet to the pad  30 , extending from the leaflet through the left ventricle  3  and opening  40  in the heart wall  17  to the pad  30 . The pad  30  can comprise any number of anchoring mechanisms configured to facilitate maintaining the first end  24  of the tether  20  anchored to the heart wall  17 . In some instances, the pad  30  can comprise a pledget. 
       FIG. 3  shows a schematic diagram of an introducer instrument  50  positioned through the opening  40  formed in the heart wall  17  during a mitral valve repair procedure to facilitate deployment of the tether  20  to the mitral valve leaflet. The introducer instrument  50  can be configured to be positioned within and extending through the opening  40  during the procedure. The introducer instrument  50  can have a proximal portion  52  extending externally of the heart  1  to allow a user to control operation of the introducer instrument  50 , and a distal portion  54  configured to be positioned within the heart  1 . For example, the distal portion  54  can be positioned in the left ventricle  3  such that a distal end  56  of the introducer instrument  50  can be positioned proximate or adjacent to the mitral valve leaflet for deployment of the tether  20 . In some instances, the second end  26  of the tether  20  can be deployed from the distal end  56  of the introducer instrument  50  to be positioned onto the mitral valve leaflet, positioning at least a portion of the suture knot  28  over the atrial facing surface of the leaflet. In some instances, the distal end  56  of the introducer instrument  50  can be positioned in contact with the mitral valve leaflet to facilitate deployment of the suture knot  28 , including in contact with a ventricle facing surface of the leaflet. 
     One or more purse-string sutures can be stitched around the opening  40  formed in the heart wall  17 . A purse-string suture can be formed in the target tissue to surround the opening  40  such that the purse-string suture can be tensioned to reduce the size of the opening  40  and/or to seal the opening  40 . For example, a purse-string suture can be used to reduce the size of the opening  40  to close the opening  40  around any medical instruments extending through the opening  40  during a procedure, such as the introducer instrument  50 . The purse-string suture can be closed around one or more medical instruments during a procedure to provide hemostasis. As described herein, more than one tether can be deployed to the mitral valve leaflet. For example, the purse-string suture can be closed around the introducer instrument  50  and one or more deployed tethers during a procedure, while one or more additional tethers are deployed using the introducer instrument  50 . After completion of a procedure, the purse-string suture can be tensioned to seal the opening  40  in the heart wall  17 . In some instances, the purse-string suture can be closed around one or more tethers after completion of a mitral valve repair procedure such that the opening  40  can be sealed around the one or more tethers. 
     Closing of openings sutured using traditional purse-string sutures can result in damage to portions of tethers extending therethrough. The traditional purse-string sutures can result in abrasive damage to and/or breakage of the tethers. Tensioning of traditional purse-string sutures, such as to close tissue openings around one or more tethers, can cause undesired folding of the tissue proximate and/or adjacent to the opening. The undesired folding of the tissue can in turn result in concentrated loading on portions of the tethers proximate to and/or extending through the opening, leading to damage and/or breakage of the tethers. A pattern of stitches used in traditional purse-string sutures can result in contact between the sutures and the one or more tethers, thereby contributing to damage and breakage of the tethers. 
     An example of a traditional purse-string suture structure  100  is shown schematically in  FIG. 4 . The traditional purse-string structure  100  can comprise a first purse-string suture  102  and a second purse-string suture  104 .  FIG. 4  shows the first purse-string suture  102  and the second purse-string suture  104  arranged around an opening in a target tissue. The opening is marked by “X” in  FIG. 4 . The first purse-string suture  102  can be coupled to a first pad  160  and a second pad  162 . The second purse-string suture  104  can be coupled to a third pad  164  and a fourth pad  166 . The first purse-string suture  102  and the second purse-string suture  104  can be arranged in a crisscross pattern. In some instances, the first purse-string suture  102  and the second purse-string suture  104  can be perpendicular or substantially perpendicular to one another. In some instances, the first pad  160  and the second pad  162  can be arranged in opposing fashion around the opening, and the third pad  164  and the fourth pad  166  can be arranged in opposing fashion around the opening. The first and second pads  160 ,  162  can be perpendicular or substantially perpendicular to the third and fourth pads  164 ,  166 . 
     Referring to  FIG. 4 , the first purse-string suture  102  can be configured to be stitched using a first suture  120 . The first suture  120  can comprise a first distal portion  122  coupled to the first pad  160 , a first portion  124  configured to be stitched through the target tissue and extend between the first pad  160  and the second pad  162 , a portion  126  configured to be positioned over the second pad  162 , a second portion  128  configured to be stitched through the target tissue and extend between the second pad  162  to the first pad  160 , and a second distal portion  130  coupled to the first pad  160 . A distal end  132  of the first distal portion  122  can be positioned at a first location on the first pad  160 . First and second distal ends  134 ,  136  of the portion  126  can be positioned at a first and second location on the second pad  162 , respectively. A distal end  138  of the second distal portion  130  can be positioned at a second location on the first pad  160 . The first portion  124  of the first suture  120  can extend alongside the fourth pad  166  and the second portion  128  of the first suture  120  can extend alongside the third pad  164 . 
     The second purse-string suture  104  can be configured to be stitched using a second suture  140 . The second suture  140  can comprise a first distal portion  142  coupled to the third pad  164 , a first portion  144  configured to be stitched through the target tissue and extend between the third pad  164  and the fourth pad  164 , a portion  146  configured to be positioned over the fourth pad  166 , a second portion  148  configured to be stitched through the target tissue and extend between the fourth pad  166  to the third pad  164 , and a second distal portion  150  coupled to the third pad  164 . A distal end  152  of the first distal portion  142  can be positioned at a first location on the third pad  164 . First and second distal ends  154 ,  156  of the portion  146  can be positioned at a first and second location on the fourth pad  166 , respectively. A distal end  158  of the second distal portion  150  can be positioned at a second location on the third pad  164 . The first portion  144  of the second suture  140  can extend alongside the first pad  160  and the second portion  148  of the second suture  140  can extend alongside the second pad  162  such that the first purse-string suture  102  and the second purse-string suture  104  can be arranged in a crisscross pattern. 
     The opening shown in  FIG. 4  can be formed on the heart wall, such as for performing a mitral valve repair procedure. One or more tethers coupled to a mitral valve leaflet can extend through the opening. The purse-string suture structure  100  as described with reference to  FIG. 4  can cause damage to the one or more tethers, which can lead to breakage of the tethers. Tensioning of purse-string sutures  102 ,  104  can cause undesired folding of the tissue proximate and/or adjacent to the opening, which can in turn result in concentrated loading on portions of the tethers. The pattern of stitching, such as the crisscross pattern, of the purse-string sutures  102 ,  104  can result in contact between the sutures and the one or more tethers, thereby contributing to damage and breakage of the tethers. 
     The disclosure herein provides one or more devices and methods related to improved purse-string sutures which can advantageously provide desired closure of an opening in a tissue while reducing or preventing damage to any tethers extending through the opening. One or more purse-string sutures described herein can facilitate desired closure of the openings so as to provide hemostasis while reducing or avoiding loading upon and/or abrasion of the tethers. The purse-string sutures described herein can maintain sufficient clearance around the tethers to reduce or eliminate contact between the sutures and the tethers. The purse-string sutures described herein can be used in various applications, including in heart surgeries as described herein. In some instances, the purse-string sutures can be used in beating-heart surgeries. In some instances, the purse-string sutures described herein can be used in heart valve surgeries, including in mitral valve repair surgeries, such as beating-heart mitral valve repair surgeries. In some instances, the purse-string sutures can be used to suture openings formed to perform beating-heart surgeries for deploying one or more tethers a mitral valve leaflet. The purse-string sutures can be used to reduce and/or seal openings formed in apex regions of heart walls. The purse-string sutures described herein can provide safe zones through which one or more tethers can be extended such that the tethers can avoid undesired damage. 
     A purse-string suture structure can comprise one or more purse-string sutures coupled to a plurality of pads. Respective sutures can be coupled to each of the plurality of pads to provide the one or more purse-string suture structures. Corresponding portions of each the one or more sutures, such as a suture stitch, can be positioned over an upper surface of each of the pads to raise the corresponding portions of each suture above the surface of the target tissue. As described herein, the purse-string suture structures can be formed in the heart wall. The plurality of pads can be positioned over the pericardium, including directly on and in contact with the pericardium. Raising portions of the sutures above the target tissue over a plurality of pads can facilitate providing respective safe zones beneath the pads through which tethers can extend without or substantially without the tethers becoming damaged. For example, raising portions of the sutures above the pericardium over the plurality of pads can provide corresponding safe zones which extend beneath the plurality of pads into the heart wall. A safe zone can comprise a volume beneath at least a portion of a corresponding pad. The safe zones under the pads can be maintained after the purse-string suture is tensioned, including to close the opening around any instrumentation and/or seal the opening. In some instances, the safe zones can comprise an orientation aligned with the path of one or more tethers coupled to a heart valve leaflet, such as a mitral valve leaflet. Inclusion of the pads around the opening can reduce or prevent abrasion of the tethers. The pads can provide corresponding safe zones through which one or more tethers can pass without or substantially without undesired damage. In some instances, the number of safe zones corresponds to the number of pads. In some instances, a purse-string suture structure can comprise two pads. In some instances, three pads can be included. In some instances, four pads can be included. For example, a purse-string suture structure comprising two pads, three pads and four pads can provide two safe zones, three safe zones and four safe zones, respectively. In some instances, the plurality of pads can be evenly distributed around the opening. The number and/or arrangement of pads around the opening can be selected based on a variety of factors, including for example, a size of the opening, a size of the pads, paths of the tethers and/or a number of tethers. 
     In some instances, a purse-string suture structure can comprise a plurality of purse-string sutures formed in a concentric pattern on a target tissue. More purse-string sutures can be formed around an opening to provide increased suture strength. In some instances, a purse-string suture structure can comprise a plurality of purse-string sutures each coupled to a plurality of pads. For example, a purse-string suture structure can comprise two concentric purse-string sutures configured to be positioned around a tissue opening, and a plurality of pads coupled to both of the purse-string sutures. The plurality of pads can be configured to be positioned at predetermined positions around the tissue opening. In some instances, the predetermined positions of the plurality of pads can be selected based on the paths of the tethers. In some instances, the concentric pattern can facilitate providing the safe zones as described herein. In some instances, forming a concentric pattern can facilitate providing desired clearance around the one or more tethers. Maintaining clearance between the one or more tethers and the purse-string sutures can prevent or eliminate damage to the tethers extending through the tissue opening. 
     In some instances, a method of forming a purse-string suture structure can comprise forming a first purse-string suture along a first path around an opening using a first suture and a second purse-string suture along a second path around and concentric with the first path using a second suture. A plurality of pads can be coupled to the first and second sutures. For example, three pads can be coupled to the first and second sutures such that corresponding portions of the first suture and second suture can be positioned over an upper surface of each of the three pads. The upper surface can be configured to be oriented away from the target tissue, while a lower surface can be configured to be oriented toward the target tissue. In some instances, the pads can be positioned on and in contact with the target tissue. The length of suture positioned over an upper surface of a pad can be selected to raise a desired portion of the suture over the pad so as to facilitate providing a desired safe zone, while allowing desired securing of the pad to the target tissue. In some instances, positions of distal ends of the length of suture positioned over a pad can be selected to prevent or reduce edges of the pad from flipping upward and more central portions of the pad from caving downward, including when the purse-string suture is tightened. Warping of the pads can induce irritation, inflammation and/or scarring in the target tissue, such as in the pericardium. In some instances, the distal ends can be up to about 2 millimeters (mm) from a nearest edge of the pad, including about 1 mm to about 2 mm from the nearest edge. 
     Although purse-string suture structures described herein primarily include two concentric purse-string sutures, purse-string suture structures can include more or fewer purse-string sutures. In some instances, a purse-string suture structure can comprise a single purse-string suture arranged around an opening in a target tissue. In some instances, a purse-string suture structure can comprise more than two purse-string sutures concentrically arranged around the opening in the target tissue. In some instances, a purse-string suture structure can comprise three purse-string sutures concentrically arranged around the opening. In some instances, a purse-string suture structure can comprise four purse-string sutures concentrically arranged around the opening. In some instances, a purse-string suture structure can comprise five purse-string sutures concentrically arranged around the opening. More purse-string sutures can be used to provide added strength for the purse-string suture structure. 
     As used herein, a “pad” can refer to any number of padding material configured to provide space between a suture portion and the target tissue. In some instances, a pad can be a pledget. The pads as described herein can have a number of different shapes. In some instances, one or more of the pads can have a rectangular shape comprising two opposing longer edges and two opposing shorter edges. The purse-string sutures can described herein can be formed using sutures made of a variety of materials. In some instances, one or more of the purse-string sutures can be stitched using a suture comprising polypropylene (e.g., Prolene® polypropylene sutures, including Ethicon® 3-0 Prolene® sutures). 
     The methods, operations, steps, etc. described herein can be performed on a living animal or on a non-living cadaver, cadaver heart, simulator (e.g. with the body parts, tissue, etc. being simulated), etc. 
       FIG. 5  is a schematic plan view of an example of a purse-string suture structure  200  comprising a first purse-string suture  202  and a second purse-string suture  204  positioned around an opening in a target tissue and both coupled to a first pad  270  and a second pad  272 . The first purse-string suture  202  can be formed along a first path around the opening and the second purse-string suture  204  can be formed around the opening along a second path. The first pad  270  and the second pad  272  can be positioned at a first position and a second position, respectively, along the first path and the second path. The second path can surround and be concentric with the first path such that the second purse-string suture  204  surrounds and is concentric with the first purse-string suture  202 . The opening in the target tissue is marked by the “X” shown in  FIG. 5 . The purse-string suture structure  200  can have one or more of a circular, oval and rectangular shape. For example, the purse-string suture structure  200  can have one or more of a concentric circular, oval and rectangular shape. In some instances, the first purse-string suture  202  and the second purse-string suture  204  can both have an oval or substantially oval shape. In some instances, the first purse-string suture  202  and the second purse-string suture  204  can both have a circular or substantially circular shape. 
     A first suture  210  can be configured to form the first purse-string suture  202 . A second suture  230  can be configured to form the second purse-string suture  204 . The first suture  210  can be used to stitch along the first path around the target opening. The second suture  230  can be used to stitch along the second path around the target opening. In some instances, the target opening can be on a heart wall. The target opening can be formed in the heart wall to obtain transapical access to a mitral valve leaflet, such as to perform a mitral valve repair procedure. As described herein, the opening can be formed in the apex region of the heart wall. One or more purse-string sutures as described herein can be used for suturing the openings formed in the heart wall. The first suture  210  and/or the second suture  230  can be threaded through the pericardium and one or more layers of the heart wall. In some instances, the first suture  210  and the second suture  230  can be threaded through at least a portion of the myocardium, for example to provide sufficient depth into the target tissue to hold the respective purse-string sutures. In some instances, the first suture  210  and the second suture  230  can be threaded through each of the pericardium, the epicardium and at least a portion of the myocardium. The first pad  270  and the second pad  272  can be positioned over the pericardium of the heart wall. For example, the first pad  270  and the second pad  272  can be positioned directly on and in contact with the pericardium, where a lower surface of each of the pads  270 ,  272  can be oriented towards the pericardium and an upper surface of each of the pads  270 ,  272  can be oriented in an opposing direction away from the pericardium. 
     The first pad  270  and the second pad  272  can be at respective positions around the target opening. In some instances, the positions of one or more of the pads  270 ,  272  can be predetermined based at least in part on a number of tethers and/or paths of the tethers. In some instances, the positions of the pads  270 ,  272  can be selected to facilitate providing desired orientations for the safe zones and/or number of safe zones. In some instances, the first pad  270  and the second pad  272  can be evenly distributed around the target opening. For example, the first pad  270  and the second pad  272  can be positioned around the target opening along the first path and the second path at opposing or substantially opposing positions. One or both of the first pad  270  or the second pad  272  can be aligned with a direction of a posterior mitral valve leaflet (PML). The direction of the posterior mitral valve leaflet (PML) can comprise a path extending between the opening in the target tissue and the posterior mitral valve leaflet. For example, as described in further detail herein, the posterior mitral valve leaflet (PML) direction can comprise a path on an exterior of a heart, such as on a pericardium, where the path extends between the tissue opening and the posterior mitral valve leaflet (PML). As shown in  FIG. 5 , in some instances, both the first pad  270  and the second pad  272  can be aligned with the direction of the posterior mitral valve leaflet (PML). For example, the first pad  270  and the second pad  272  can be at opposing positions relative to one another around the target opening such that both the first pad  270  and the second pad  272  can be aligned with the direction of the posterior mitral valve leaflet (PML). In some instances, the first pad  270  and the second pad  272  may not be positioned at opposing positions around the target opening. 
     The first suture  210  and the second suture  230  can be stitched in the target tissue around the opening and coupled to each of the pads. For example, each of the sutures can be stitched to the pads such that corresponding suture stitches can be positioned over the pads. Referring again to  FIG. 5 , the first suture  210  can comprise a first distal portion  212 . The first distal portion  212  can be coupled to the first pad  270 . The first pad  270  can be at a first position along the first path and the second path. The first suture  210  can comprise a first tissue portion  214  configured to be stitched through the target tissue and extend between the first pad  270  and the second pad  270  along the first path. The first suture  210  can be coupled to the second pad  272 , the first suture  210  comprising a second pad portion  216 , such as a suture stitch, configured to be positioned over the second pad  272 , such as on and in contact with the second pad  272 . The second pad  272  can be at a second position along the first path and the second path. A second tissue portion  218  of the first suture  210  can be configured to be stitched through the target tissue and extend between the second pad  272  and the first pad  270  along the first path. A second distal portion  220  of the first suture  210  can be coupled to the first pad  270 , such that the first suture  210  can surround the target opening. 
     The second suture  230  can comprise a first distal portion  232 . The first distal portion  232  can be coupled to the second pad  272 . The second suture  230  can comprise a first tissue portion  234  configured to be stitched through the target tissue and extend between the second pad  272  and the first pad  270  along the second path. The second suture  230  can be coupled to the first pad  270 , the second suture  230  comprising a first pad portion  236 , such as a suture stitch, configured to be positioned over the first pad  270 , such as on and in contact with the first pad  270 . A second tissue portion  238  of the second suture  230  can be configured to be stitched through the target tissue and extend between the second pad  272  and the first pad  270  along the second path. A second distal portion  240  of the second suture  230  can be coupled to the second pad  272 , such that the second suture  230  can surround the target opening. The second suture  230  can be tensioned to form the second purse-string suture  204  around the target opening. The first suture  210  can be tensioned to form the first purse-string suture  202  around the target opening. For example, the first suture  210 , including the first distal portion  212  and the second distal portion  220  of the first suture  210 , can be tensioned to form the first purse-string suture  202 . The second suture  230 , including the first distal portion  232  and the second distal portion  240  of the second suture  230 , can be tensioned to form the second purse-string suture  204 . The first purse-string suture  202  and the second purse-string suture  204  can be formed around the target opening, such as to close the target opening around a medical instrument and/or a valve leaflet tether, and/or to seal the target opening. 
     A method of forming the first purse-string suture  202  can comprise coupling the second pad  272  to the first suture  210 . The second pad  272  can be stitched to the first suture  210  such that the second pad portion  216  can be positioned over the upper surface of the second pad  272 . For example, the first suture  210  can be threaded through the second pad  272  from the lower surface of the second pad  272  through to the upper surface of the second pad  272 . The first suture  210  can then be extended along the upper surface of the second pad  272  to position the second pad portion  216  over the upper surface. Alternatively, the first suture  210  can be threaded through from the upper surface through to the lower surface of the second pad  272  at predetermined locations on the second pad  272  to position the second pad portion  216  over the upper surface. The second pad  272  can be positioned at the second position over the target tissue. The first suture  210  can be stitched through the target tissue and extended from each of the two respective predetermined locations on the second pad  272 , such as locations proximate and/or adjacent to opposing sides of the second pad  272 , along the first path toward the first position such that the first tissue portion  214  and the second tissue portion  218  can be formed. The first suture  210  can subsequently be coupled to the first pad  270 . The first distal portion  212  and the second distal portion  220  of the first suture  210  can be threaded through the first pad  270  from the lower surface of the first pad  270  through to the upper surface of the first pad  270 . The first pad  270  can then be positioned at its position along the first path and second path. 
     A method of forming the second purse-string suture  204  can comprise coupling the second suture  230  to the first pad  270 . The second suture  230  can be stitched to the first pad  270  such that the second suture  230  can comprise the first pad portion  236  positioned over the upper surface of the first pad  270 . For example, the second suture  230  can be threaded through the first pad  270  from the lower surface through to the upper surface of the first pad  270  and extended along the upper surface of the first pad  270  to position the first pad portion  236  over the upper surface. Alternatively, the second suture  230  can be threaded through from the upper surface through to the lower surface of the first pad  270  at predetermined locations on the first pad  270  to position the first pad portion  236  over the upper surface. The second suture  230  can be stitched through the target tissue and extended from the respective predetermined locations on the first pad  270 , such as locations proximate and/or adjacent to each of two opposing sides of the first pad  270 , along the second path toward the second position such that the first tissue portion  234  and the second tissue portion  238  can be formed. The second suture  230  can then be coupled to the second pad  272 , for example comprising threading the first distal portion  232  and the second distal portion  240  of the second suture  230  through the second pad  272  from the lower surface through to the upper surface of the second pad  272 . 
     A suture can be coupled to a plurality of pads in a number of different sequences. In some instances, the first suture  210  can be coupled to the first pad  270  prior to being coupled to the second pad  272 . In some instances, the first suture  210  can be threaded through the first pad  270  such that the first distal portion  212  can be coupled to the first pad  270 . The first suture  210  can be stitched through the target tissue along the first path from the first position to the second position so as to form the first tissue portion  214 . The first suture  210  can then be coupled to the second pad  272  to position the second pad portion  216  over the second pad  272 . The first suture  210  can be subsequently stitched through the target tissue along the first path from the second position to the first position so as to form the second tissue portion  218 . The second distal portion  220  can then be coupled to the first pad  270 . In some instances, the second distal portion  220  can be coupled to the first pad  270  prior to coupling the first distal portion  212  to the first pad  270 . In some instances, the second tissue portion  218  can be formed prior to forming the first tissue portion  214 . 
     In some instances, the second suture  230  can be coupled to the second pad  272  prior to being coupled to the first pad  270 . For example, the first distal portion  232  can be coupled to the second pad  270 , and the second suture  230  can then be stitched through the target tissue along the second path from the second position to the first position so as to form the first tissue portion  234 . The second suture  230  can be coupled to the first pad  270  and the first pad portion  236  can be positioned over the first pad  270 . The second suture  230  can be stitched through the target tissue along the second path from the first position to the second position so as to form the second tissue portion  238 . The second distal portion  240  can then be coupled to the second pad  272 . In some instances, the second distal portion  240  can be coupled to the second pad  272  prior to coupling the first distal portion  232  to the second pad  272 . In some instances, the second tissue portion  238  can be formed prior to forming the first tissue portion  234 . 
     In some instances, a length of the corresponding portions of the first suture  210  and second suture  230  configured to be positioned over the second pad  272  and the first pad  270 , respectively, can be predetermined to reduce or avoid irritation of the target tissue. For example, locations of the distal ends  224 ,  226  of the second pad portion  216  on the second pad  272  and/or the distal ends  244 ,  246  of the first pad portion  236  on the first pad  270  can be selected to reduce or eliminate warping of the respective pad, including bending upward of the edges of the pad. In some instances, a length of the first pad portion  236  and/or second pad portion  216  can be selected to provide a desired size for the safe zones. In some instances, a length of the first pad portion  236  and second pad portion  216  can be selected to reduce or avoid tissue irritation, and/or provide desired safe zones, while ensuring a secure attachment of the pads to the sutures. In some instances, distal ends of a portion of the first suture  210  and/or second suture  230  configured to be positioned over the first pad  270  and/or second pad  272  can be less than about 2 millimeters (mm) from respective nearest edge(s) of the pad, including about 1 mm to about 2 mm from the respective nearest edge(s). Referring to  FIG. 5 , in some instances, the first pad portion  236  can comprise distal ends  244 ,  246  at less than about 2 millimeters (mm) from respective nearest edge(s) of the first pad  270 , including about 1 mm to about 2 mm from the respective nearest edge(s). In some instances, the second pad portion  216  of the first suture  210  can comprise distal ends  224 ,  226  at less than about 2 millimeters (mm) from respective nearest edge(s) of the second pad  272 , including about 1 mm to about 2 mm from the respective nearest edge(s). The first pad portion  236  and the second pad portion  216  can extend along paths which are less than about 2 millimeters (mm) from the nearest edge of the respective pad, including about 1 mm to about 2 mm from the nearest edge. In some instances, ends  222 ,  228  of the first distal portion  212  and second distal portion  220  of the first suture  210 , and/or the ends  242 ,  248  of the first distal portion  232  and/or second distal portion  240  of the second suture  230  can be positioned less than about 2 millimeters (mm) from the respective nearest edge(s) of the corresponding pad, including about 1 mm to about 2 mm from the respective nearest edge(s). In some instances, a length of a suture portion can be the same as or similar to a distance between distal ends of distal portions coupled to the same pad. 
     In some instances, the first pad  270  and the second pad  272  can each have a rectangular shape. For example, a longer edge of the rectangle can be oriented toward the opening in the target tissue, while an opposing longer edge can be oriented away from the opening. Shorter edges of the rectangle can extend between the longer edges. In some instances, the first pad portion  236  can extend along a path less than about 2 millimeters (mm) from a nearest longer edge of the first pad  270 , such as the longer edge oriented farther away from the opening. The distal ends  244 ,  246  of the first pad portion  236  can be less than about 2 millimeters (mm) from respective nearest shorter edges of the first pad  270 . In some instances, the second pad portion  216  can extend along a path less than about 2 millimeters (mm) from a nearest longer edge of the second pad  272 , such as the longer edge oriented closer to the opening. The distal ends  224 ,  226  of the second pad portion  216  can be less than about 2 millimeters (mm) from respective nearest shorter edges of the second pad  272 . Ends  222 ,  228  of the distal portions  212 ,  220  of the first suture  210  can be less than about 2 millimeters (mm) from one or both of the nearest longer edge (e.g., the longer edge closer to the opening) and shorter edge. Ends  242 ,  248  of the distal portions  232 ,  240  of the second suture  230  can be positioned less than about 2 millimeters (mm) from one or both of the nearest longer edge (e.g., the longer edge farther from the opening) and shorter edge. In some instances, a pad can have a rounded shape, for example comprising an arcuate edge, such that an end of a suture portion is positioned less than about 2 millimeters (mm) from one nearest edge. 
       FIG. 5  shows the respective distal portions of the first suture  210  and second suture  230  as being coupled to different pads. The distal portions of the first suture  210  is shown as being coupled to the first pad  270  and the distal portions of the second suture  230  is shown as being coupled to the second pad  272 . In some instances, the distal portions of both of the first suture  210  and the second suture  230  can be coupled to the same pad, such as both being coupled to the first pad  270  or both being coupled to the second pad  272 . 
     Referring again to  FIG. 5 , a first safe zone  280  can extend under the first pad  270  and a second safe zone  282  can extend under the second pad  272 . The safe zones  280 ,  282  can extend downward into the target tissue (into the page). One or more tethers can extend through each of the safe zones  280 ,  282  without or substantially without being damaged. For example, a tether can extend from a mitral valve leaflet, such as a posterior mitral valve leaflet, and through a safe zone such that a distal end of the tether can be extended through the opening to couple to an exterior of the heart wall. The purse-string sutures  202 ,  204  can be closed around the tether such that the tether is not or substantially not damaged. For example, tensioning of the purse-string sutures  202 ,  204  can result in closure of the opening around one or more tethers extending through the opening without or substantially without damaging the one or more tethers. 
     A height of each of the safe zones  280 ,  282  can be a distance into the target tissue which the respective safe zone extends. For example, the safe zones  280 ,  282  can have a height equal or similar to a thickness of the heart wall beneath the respective pad. The safe zones  280 ,  282  can have a width similar or equal to a length of a suture portion positioned over a pad. For example, a width of a safe zone can be similar or equal to a length of a corresponding portion of suture raised above the target tissue over a pad. In some instances, the first safe zone  280  can have a width similar or equal to a length of the first pad portion  236  and/or a distance between the ends  222 ,  228  of the distal portions  212 ,  220 . In some instances, the first safe zone  280  can have a width similar or equal to a shorter one of the length of the first pad portion  236  and the distance between the ends  222 ,  228 . In some instances, the second safe zone  282  can have a width similar or equal to a length of the second pad portion  216  and/or a distance between the ends  242 ,  248  of the distal portion  232 ,  240  of the second suture  230 . In some instances, the second safe zone  282  can have a width similar or equal to a shorter one of the length of the first pad portion  216  and the distance between the ends  242 ,  248 . A length of each of the safe zones  280 ,  282  can be a dimension perpendicular or substantially perpendicular to both the height and width of the respective safe zone. For example, the safe zones  280 ,  282  can extend across an entire width of each of the first pad  270  and second pad  272 , respectively. Each of the safe zones  280 ,  282  can have a length longer than a dimension extending between opposing longer edges of a corresponding rectangular pad as described herein. For example, the safe zones  280 ,  282  can have a length longer than a width of the corresponding pad. In some instances, the safe zones  280 ,  282  can extend from the opening in the target tissue to at least an outer edge of the purse-string suture structure  200 . 
     In some instances, a purse-string suture can be coupled to three pads.  FIGS. 6A and 6B  are schematic plan views of examples of purse-string suture structures  300 ,  400 , respectively. Each purse-string suture structure  300 ,  400  can comprise a first purse-string suture  302 ,  402  and a second purse-string suture  304 ,  404  positioned around a respective opening in a target tissue. Both sutures in each of the structures  300 ,  400  are coupled to a respective first pad  370 ,  470 , second pad  372 ,  472  and third pad  374 ,  474 . The respective openings are marked by “X” in  FIGS. 6A and 6B . Distal portions of the first purse-string suture  302  and the second purse-string suture  304  of the purse-string suture structure  300  shown in  FIG. 6A  can be coupled to different ones of the three pads. In  FIG. 6B , distal portions of the first purse-string suture  402  and the second purse-string suture  404  of the purse-string suture structure  400  can be coupled to the same one of the three pads. The distal portions of the sutures can be arranged in a number of different manners relative to the three pads. A selection can be made based on convenience and/or preference of an operator. 
     Referring to  FIGS. 6A and 6B , the second purse-string sutures  304 ,  404  can surround and be concentric with the first purse-string sutures  302 ,  402 . The first purse-string sutures  302 ,  402  and/or the second purse-string sutures  304 ,  404  can have one or more of a circular, oval and hexagonal shape. In some instances, each of the first purse-string sutures  302 ,  402  and the second purse-string sutures  304 ,  404  can have a circular or substantially circular shape. In some instances, each of the first purse-string sutures  302 ,  402  and the second purse-string sutures  304 ,  404  can have a hexagonal or substantially hexagonal shape. The purse-string suture structures  300 ,  400  can be positioned in the heart wall for reducing a size and/or sealing of an opening formed in the heart wall, such as that described with reference with  FIG. 5 . For example, the sutures of the purse-string suture structures  300 ,  400  can be threaded through the pericardium and one or more layers of the heart wall, including through at least a portion of the myocardium. In some instances, the first pads  370 ,  470 , second pads  372 ,  472  and third pads  374 ,  474  can be placed over the pericardium, including directly on and in contact with the pericardium. A lower surface of each of the pads  370 ,  372 ,  374 ,  470 ,  472 ,  474  can be oriented towards the pericardium and an upper surface of each of the pads  370 ,  372 ,  374 ,  470 ,  472 ,  474  can be oriented in an opposing direction away from the pericardium. A first suture  310 ,  410  can be used to stitch the first purse-string sutures  302 ,  402  along a respective first path and a second suture  340 ,  440  can be used to stitch the second purse-string sutures  304 ,  404  along a respective second path. 
     Each of the first pads  370 ,  470 , second pads  372 ,  472  and third pads  374 ,  474  can be at a corresponding first position, a second position and a third position around the target opening along the respective first path and second path. Positions of one or more of the pads can be predetermined based at least in part on a number of tethers and/or paths of the tethers, such as to facilitate providing desired orientations of the safe zones and/or number of safe zones for the tethers. In some instances, the first pads  370 ,  470 , second pads  372 ,  472  and third pads  374 ,  474  can be evenly distributed around the target opening. For example, the pads  370 ,  372 ,  374 ,  470 ,  472 ,  474  can be positioned equidistant from one another around the target opening along the first path and the second path. In some instances, the pads  370 ,  372 ,  374 ,  470 ,  472 ,  474  may not be evenly distributed around the target opening. One or more of the pads can be aligned with a direction of a posterior mitral valve leaflet (PML). In some instances, a pad not coupled to any distal portions of a suture can be aligned with the direction of the posterior mitral valve leaflet (PML).  FIGS. 6A and 6B  show the second pad  372  being aligned with the direction of the posterior mitral valve leaflet (PML). Referring to  FIG. 6B , in some instances, the third pad  474  can be aligned with the direction of the posterior mitral valve leaflet (PML). 
     Referring to  FIG. 6A , the first suture  310  can comprise: a first distal portion  312  coupled to the first pad  370 , a first tissue portion  314  stitched through the target tissue and extending between the first pad  370  and the second pad  372  along the first path, a second pad portion  316  positioned over the second pad  372 , including on and in contact with the second pad  372 , a second tissue portion  318  stitched through the target tissue and extending between the second pad  372  and the third pad  374  along the first path, a third pad portion  320  configured to be positioned over the third pad  374 , including on and in contact with the third pad  374 , a third tissue portion  322  stitched through the target tissue and extending between the third pad  374  and the first pad  370 , and a second distal portion  324  coupled to the first pad  370 . The second suture  340  can comprise: a first distal portion  342  coupled to the third pad  374 , a first tissue portion  344  stitched through the target tissue and extending between the third pad  374  and the first pad  370  along the second path, a first pad portion  346  positioned over the first pad  370 , including on and in contact with the first pad  370 , a second tissue portion  348  stitched through the target tissue and extending between the first pad  370  and the second pad  372  along the second path, a second pad portion  350  positioned over the second pad  372 , including on and in contact with the second pad  372 , a third tissue portion  352  stitched through the target tissue and extending between the second pad  372  and the third pad  374 , and a second distal portion  354  coupled to the third pad  374 . In some instances, the second pad portion  350  of the second suture  340  can be parallel or substantially parallel to the second pad portion  316  of the first suture  310 . 
     The first suture  310  and second suture  340  can be tensioned to form the first purse-string suture  302  and the second purse-string suture  304 , respectively, around the target opening. For example, the first suture  310  and second suture  340  can be tensioned to close the target opening around a medical instrument and/or valve leaflet tether, and/or to seal the target opening. 
     Referring to  FIG. 6B , the purse-string suture structure  400  can have the first suture  410  and the second suture  440  arranged around the target opening such that the first distal portions  412 ,  442  and the second distal portions  424 ,  454  are coupled to the same pad, for example the first pad  470 . Each of the first suture  410  and the second suture  440  can comprise: a respective first distal portion  412 ,  442  coupled to the first pad  470 , a respective first tissue portion  414 ,  444  stitched through the target tissue and extending between the first pad  470  and the second pad  472  along the first path and second path, a respective second pad portion  416 ,  446  positioned over the second pad  472 , including on and in contact with the second pad  472 , a respective second tissue portion  418 ,  448  stitched through the target tissue and extending between the second pad  472  and the third pad  474  along the first path and second path, a respective third pad portion  420 ,  450  positioned over the third pad  474 , including on and in contact with the third pad  474 , a respective third tissue portion  422 ,  452  stitched through the target tissue and extending between the third pad  474  and the first pad  470  along the first path and second path, and a respective second distal portion  424 ,  454  coupled to the first pad  470 . In some instances, the second pad portion  446  of the second suture  440  can be parallel or substantially parallel to the second pad portion  416  of the first suture  410 . In some instances, the third pad portion  450  of the second suture  440  can be parallel or substantially parallel to the third pad portion  420  of the first suture  410 . 
     In the purse-string suture structure  300  of  FIG. 6A , the distal portions  312 ,  324  of the first suture  310  can be coupled to the first pad  370  while the distal portions  342 ,  354  of the second suture  340  can be coupled to the third pad  374 . Meanwhile, the purse-string suture structure  400  of  FIG. 6B  can have both the distal portions  412 ,  424  of the first suture  410  and both the distal portions  442 ,  454  of the second suture  440  coupled to the first pad  470 . As described herein, the distal portions of the sutures can be arranged in a number of different manners relative to the three pads, and are not limited to the examples described with reference to  FIGS. 6A and 6B . 
     Each of the pads can provide a corresponding safe zone. For example, in  FIG. 6A , a first safe zone  380  can extend into the tissue under the first pad  370 , a second safe zone  382  can extend into the tissue under the second pad  372  and a third safe zone  384  can extend into the tissue under the third pad  374 . In  FIG. 6B , a first safe zone  480  can extend into the tissue under the first pad  470 , a second safe zone  482  can extend into the tissue under the second pad  472  and a third safe zone  484  can extend into the tissue under the third pad  474 . A height of each of the safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can be a distance into the target tissue which the respective safe zone extends. For example, the safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can have a height equal or similar to a thickness of the heart wall beneath the respective pad. The safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can each have a width similar or equal to a length of a suture portion positioned over a corresponding pad and/or a distance between positions at which ends of suture distal portions are located on the corresponding pad. In some instances, one or more of the safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can each have a width which is the shorter of the length of a suture portion positioned over a corresponding pad and the distance between positions at which ends of suture distal portions are located on the corresponding pad. In some instances, one or more of the safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can each have a width which is the shorter of the lengths of suture portions positioned over a corresponding pad. Referring to  FIG. 6A , the first safe zone  380  can have a width similar or equal to a shorter one of the length of the first pad portion  346  and the distance between the ends  326 ,  336 . The second safe zone  382  can have a width similar or equal to a shorter one of the length of the second pad portions  316 ,  350 . The third safe zone  384  can have a width similar or equal to a shorter one of the length of the third pad portion  320  and the distance between the ends  356 ,  366 . Referring to  FIG. 6B , the first safe zone  480  can have a width similar or equal to a shorter one of the distance between the ends  426 ,  436  and the distance between the ends  456 ,  466 . The second safe zone  482  can have a width similar or equal to a shorter one of the length of the second pad portions  416 ,  446 . The third safe zone  482  can have a width similar or equal to a shorter one of the length of the third pad portions  420 ,  450 . 
     The safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can extend across an entire width of a respective pad. For example, each of the safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can have a length, such as a dimension perpendicular or substantially perpendicular to the width and height of the respective safe zone, longer than a width of the corresponding rectangular pad as described herein. In some instances, the safe zones  380 ,  382 ,  384 ,  480 ,  482 ,  484  can extend from the opening in the target tissue to at least an outer edge of the purse-string suture structures  300 ,  400 . 
     In some instances, an orientation and/or length of the corresponding portions of the first sutures  310 ,  410  and second sutures  340 ,  440  configured to be positioned over the first pads  370 ,  470 , the second pads  372 ,  472  and the third pads  374 ,  474  can be predetermined to reduce or avoid irritation of the target tissue, provide a desired size for the safe zones, while ensuring a secure attachment of the pads to the sutures. In some instances, positions of the ends of distal portions of the first sutures  310 ,  410  and second sutures  340 ,  440  on a respective pad, can be predetermined to reduce or avoid irritation of the target tissue, and/or provide a desired size for the safe zones, while ensuring a secure attachment of the pads to the sutures. Referring to  FIG. 6A , the first pad portion  346  can comprise distal ends  358 ,  360  and/or the distal portions  312 ,  324  can comprise ends  326 ,  336  at less than about 2 millimeters (mm) from respective nearest edge(s) of the first pad  370 , including about 1 mm to about 2 mm from the respective nearest edge(s). The second pad portion  316  of the first suture  310  can comprise distal ends  328 ,  330  and the second pad portion  350  of the second suture  340  can comprise distal ends  362 ,  364  at less than about 2 millimeters (mm) from respective nearest edge(s) of the second pad  372 , including about 1 mm to about 2 mm from the respective nearest edge(s). The third pad portion  320  can comprise distal ends  332 ,  334  and/or the distal portions  342 ,  354  can comprise ends  356 ,  366  at less than about 2 millimeters (mm) from respective nearest edge(s) of the third pad  374 , including about 1 mm to about 2 mm from the respective nearest edge(s). Referring to  FIG. 6B , distal portions  412 ,  424  can comprise ends  426 ,  436  and/or the distal portions  442 ,  454  can comprise ends  456 ,  466  at less than about 2 millimeters (mm) from respective nearest edge(s) of the first pad  470 , including about 1 mm to about 2 mm from the respective nearest edge(s). The second pad portion  416  of the first suture  410  can comprise distal ends  428 ,  430  and the second pad portion  446  of the second suture  440  can comprise distal ends  458 ,  460  at less than about 2 millimeters (mm) from respective nearest edge(s) of the second pad  472 , including about 1 mm to about 2 mm from the respective nearest edge(s). The third pad portion  420  of the first suture  410  can comprise distal ends  432 ,  434  and the third pad portion  450  of the second suture  440  can comprise distal ends  462 ,  464  at less than about 2 millimeters (mm) from respective nearest edge(s) of the third pad  474 , including about 1 mm to about 2 mm from the respective nearest edge(s). In some instances, corresponding suture portions positioned over pads can extend along a path less than about 2 millimeters (mm) from a nearest edge of the respective pad, including about 1 mm to about 2 mm from the nearest edge. For example, the first pad portion  346 , second pad portions  316 ,  350 ,  416 ,  446  and third pad portions  320 ,  420 ,  450  can extend along paths which are less than about 2 millimeters (mm) from the nearest edge of the respective pad, including about 1 mm to about 2 mm from the nearest edge. In some instances, suture portions positioned over a same pad can have the same or similar length. In some instances, a length of a suture portion can be the same as or similar to a distance between distal ends of distal portions coupled to the same pad. In some instances, a distance between a first pair and a distance between a second pair of distal ends of distal portions coupled to the same pad can be the same or similar. 
     In some instances, the first pads  370 ,  470 , the second pads  372 ,  472  and the third pads  374 ,  474  can each have a rectangular shape. For example, a longer edge of the rectangles can be oriented toward the opening in the target tissue, while an opposing longer edge can be oriented away from the opening. Shorter edges of the rectangles can extend between the longer edges. In some instances, corresponding portions of the first sutures  310 ,  410  positioned over the pads can extend along a path less than about 2 millimeters (mm) from respective longer edges which are closer to the opening in the target tissue. In some instances, corresponding portions of the second sutures  340 ,  440  positioned over the pads can extend along a path less than about 2 millimeters (mm) from respective longer edges which are farther away from the opening in the target tissue. In some instances, distal ends of the suture portions positioned over the pads can be at locations on the pad less than about 2 millimeters (mm) from a respective nearest shorter edge of the corresponding pad. Distal ends of the distal portions of the first sutures  310 ,  410  and second sutures  340 ,  440  can be less than about 2 millimeters (mm) from one or both of the nearest longer edge (e.g., one of the longer edge closer to the opening and the longer edge farther away from the opening) and the nearest shorter edge of the respective pad. In some instances, a pad can have a rounded shape, for example comprising an arcuate edge, such that an end of a suture portion is positioned less than about 2 millimeters (mm) from one nearest edge. 
     Methods of forming the purse-string structures  300 ,  400  of  FIGS. 6A and 6B  are described in further detail herein. 
       FIGS. 7A through 7C  are a schematic plan view, perspective view and side view, respectively, of an example of a purse-string suture structure  500 . The purse-string suture structure  500  can comprise a first purse-string suture  502  and a second purse-string suture  504  positioned around an opening in a target tissue, where both sutures  502 ,  504  are coupled to a first pad  590 , a second pad  592 , a third pad  594  and a fourth pad  596 . The opening is marked by “X” in  FIG. 7A .  FIG. 7A  is a plan view of the purse-string suture structure  500 , while  FIG. 7B  is a perspective view and  FIG. 7C  is a side view. The second purse-string suture  504  can surround and be concentric with the first purse-string suture  502 . The first purse-string suture  502  and/or the second purse-string suture  504  can have one or more of a circular, oval, and octagonal shape. In some instances, each of the first purse-string suture  502  and the second purse-string suture  504  can have a circular or substantially circular shape. In some instances, each of the first purse-string suture  502  and the second purse-string suture  504  can have an octagonal or substantially octagonal shape. As described herein, the purse-string suture structure  500  can be positioned in the heart wall for reducing a size and/or closing of an opening formed in the heart wall, such as that described with reference with  FIG. 5 . For example, the first purse-string suture  502  and second purse-string suture  504  can be threaded through the pericardium and one or more layers of the heart wall, including through at least a portion of the myocardium. For example, the first pad  590 , second pad  592 , third pad  594  and fourth pad  596  can be placed over the pericardium, including directly on and in contact with the pericardium. A lower surface of each of the pads  590 ,  592 ,  594 ,  596  can be oriented towards the pericardium and an upper surface of each of the pads  590 ,  592 ,  594 ,  596  can be oriented in an opposing direction away from the pericardium. 
     One or more of the pads  590 ,  592 ,  594 ,  596  can be aligned with a direction of a posterior mitral valve leaflet (PML). As shown in  FIG. 7A , in some instances, the fourth pad  596  can be aligned with the direction of the posterior mitral valve leaflet (PML). In some instances, both the second pad  592  and the fourth pad  596  can be aligned with the direction of the posterior mitral valve leaflet (PML). For example, the second pad  592  and the fourth pad  596  can be at opposing positions relative to one another around the target opening such that both the second pad  592  and the fourth pad  596  can be aligned with the direction of the posterior mitral valve leaflet (PML). In some instances, the first pad  590  and the third pad  594  can be at opposing positions relative to one another. In some instances, the first pad  590  and the third pad  594  can be perpendicular or substantially perpendicular to the second pad  592  and the fourth pad  596 . In some instances, the pads  590 ,  592 ,  594 ,  596  can be evenly distributed around the target opening, for example being equidistant from one another around the target opening. In some instances, the pads  590 ,  592 ,  594 ,  596  may not be evenly distributed around the target opening. In some instances, the positions of one or more of the pads  590 ,  592 ,  594 ,  596  can be predetermined based at least in part on a number of tethers and/or paths of the tethers, for example to provide desired orientations of the safe zones and/or number of safe zones for the tethers. 
     Referring to  FIG. 7A , a first suture  510  can be used to stitch the first purse-string suture  502  along a first path around the opening and a second suture  550  can be used to stitch the second purse-string suture  504  along a second path around the opening. Each of the first pad  590 , second pad  592 , third pad  594  and fourth pad  596  can be at a first position, a second position, a third position and a fourth position around the target opening, respectively, along the first path and second path. 
     The first suture  510  can comprise: a first distal portion  512  coupled to the first pad  590 , a first tissue portion  514  stitched through the target tissue and extending between the first pad  590  and the second pad  592  along the first path, a second pad portion  516  positioned over the second pad  592 , including on and in contact with the second pad  592 , a second tissue portion  518  stitched through the target tissue and extending between the second pad  592  and the third pad  594  along the first path, a third pad portion  520  positioned over the third pad  594 , including on and in contact with the third pad  594 , a third tissue portion  522  stitched through the target tissue and extending between the third pad  594  and the fourth pad  596 , a fourth pad portion  524  positioned over the fourth pad  596 , including on and in contact with the fourth pad  596 , a fourth tissue portion  526  stitched through the target tissue and extending between the fourth pad  596  and the first pad  590 , and a second distal portion  528  coupled to the first pad  590 . The second suture  550  can comprise: a first distal portion  552  coupled to the third pad  594 , a first tissue portion  554  stitched through the target tissue and extending between the third pad  594  and the fourth pad  596  along the second path, a fourth pad portion  556  positioned over the fourth pad  596 , including on and in contact with the fourth pad  596 , a second tissue portion  558  stitched through the target tissue and extending between the fourth pad  596  and the first pad  590  along the second path, a first pad portion  56   o  positioned over the first pad  590 , including on and in contact with the first pad  590 , a third tissue portion  562  stitched through the target tissue and extending between the first pad  590  and the second pad  592 , a second pad portion  564  positioned over the second pad  592 , including on and in contact with the second pad  592 , a fourth tissue portion  566  stitched through the target tissue and extending between the second pad  592  and the third pad  594 , and a second distal portion  568  coupled to the third pad  594 . In some instances, the second pad portions  516 ,  564  can be parallel or substantially parallel to one another. In some instances, the fourth pad portions  524 ,  556  can be parallel or substantially parallel to one another. The first suture  510  and second suture  550  can be tensioned to form the first purse-string suture  502  and the second purse-string suture  504 , respectively, around the target opening, for example, sealing the target opening and/or closing the target opening around a medical instrument and/or valve leaflet tether. 
     Each of the pads can provide a corresponding safe zone. For example, in  FIG. 7A , a first safe zone  600  can extend into the tissue under the first pad  590 , a second safe zone  602  can extend into the tissue under the second pad  592 , a third safe zone  604  can extend into the tissue under the third pad  594 , and a fourth safe zone  606  can extend into the tissue under the fourth pad  596 . A height of each of the safe zones  600 ,  602 ,  604 ,  606  can be a distance into the target tissue which the respective safe zone extends. For example, the safe zones  600 ,  602 ,  604 ,  606  can have a height equal or similar to a thickness of the heart wall beneath the respective pad. The safe zones  600 ,  602 ,  604 ,  606  can each have a width similar or equal to a length of a suture portion positioned over a corresponding pad and/or a distance between positions at which distal ends of suture distal portions are located on the corresponding pad. In some instances, one or more of the safe zones  600 ,  602 ,  604 ,  606  can each have a width which is the shorter of the length of a suture portion positioned over a corresponding pad (e.g., a suture stitch) and the distance between positions at which distal ends of suture distal portions are located on the corresponding pad. In some instances, one or more of the safe zones  600 ,  602 ,  604 ,  606  can each have a width which is the shorter of the lengths of suture portions positioned over a corresponding pad. For example, the first safe zone  600  can have a width similar or equal to a shorter one of the length of the first pad portion  56   o  and the distance between the ends  532 ,  546 . The second safe zone  602  can have a width similar or equal to a shorter one of the length of the second pad portions  516 ,  564 . The third safe zone  604  can have a width similar or equal to a shorter one of the length of the third pad portion  520  and the distance between the ends  570 ,  584 . The fourth safe zone  606  can have a width similar or equal to a shorter one of the length of the fourth pad portions  524 ,  556 . The safe zones  600 ,  602 ,  604 ,  606  can extend across an entire width of a respective pad. For example, each of the safe zones  600 ,  602 ,  604 ,  606  can have a length, such as a dimension perpendicular or substantially perpendicular to the height and width of the respective safe zone, longer than a width of a corresponding rectangular pad as described herein. In some instances, the safe zones  600 ,  602 ,  604 ,  606  can extend from the opening in the target tissue to at least an outer edge of the purse-string suture structure  500 . 
     In some instances, an orientation and/or length of the corresponding suture portions, and/or positions of the distal ends of suture distal portions on a respective pad can be selected to reduce or avoid irritation of the target tissue, and/or provide a desired size for the safe zones, while ensuring a secure attachment of the pads to the sutures. Referring to  FIG. 7A , the first pad portion  560  can comprise distal ends  576 ,  578  and/or the distal portions  512 ,  528  can comprise distal ends  532 ,  546  at less than about 2 millimeters (mm) from respective nearest edge(s) of the first pad  590 , including about 1 mm to about 2 mm from the respective nearest edge(s). The second pad portion  516  can comprise distal ends  534 ,  536  and the second pad portion  564  can comprise distal ends  580 ,  582  at less than about 2 millimeters (mm) from respective nearest edge(s) of the second pad  592 , including about 1 mm to about 2 mm from the respective nearest edge(s). The third pad portion  520  can comprise distal ends  538 ,  540  and/or the distal portions  552 ,  568  can comprise distal ends  570 ,  584  at less than about 2 millimeters (mm) from respective nearest edge(s) of the third pad  594 , including about 1 mm to about 2 mm from the respective nearest edge(s). The fourth pad portion  524  can comprise distal ends  542 ,  544  and the fourth pad portion  556  can comprise distal ends  572 ,  574  at less than about 2 millimeters (mm) from respective nearest edge(s) of the fourth pad  596 , including about 1 mm to about 2 mm from the respective nearest edge(s). In some instances, suture portions positioned over the same pad can have the same or similar length. In some instances, a length of a suture portion can be the same as or similar to a distance between distal ends of distal portions coupled to the same pad. 
     In some instances, the four pads  590 ,  592 ,  594 ,  596  each can have a rectangular shape, where a longer edge of the rectangles can be oriented toward the opening in the target tissue, while an opposing longer edge can be oriented away from the opening. Shorter edges of the rectangles can extend between the longer edges. In some instances, corresponding portions of the first suture  510  positioned over the pads can extend along a path less than about 2 millimeters (mm) from a respective longer edge which is closer to the opening in the target tissue. In some instances, corresponding portions of the second suture  550  positioned over the pads can along a path less than about 2 millimeters (mm) from a respective longer edge which is farther away from the opening in the target tissue. In some instances, distal ends of the suture portions positioned over the pads can be at locations on the pad less than about 2 millimeters (mm) from a respective nearest shorter edge of the corresponding pad. In some instances, distal ends of the distal portions can be less than about 2 millimeters (mm) from one or both of the nearest longer edge (e.g., one of the longer edge closer to the opening and the longer edge farther away from the opening) and nearest shorter edge of the respective pad. In some instances, a pad can have a rounded shape, for example comprising an arcuate edge, such that an end of a suture portion is positioned less than about 2 millimeters (mm) from one nearest edge. 
     A method of forming the first purse-string suture  502  and second purse-string suture  504  can comprise coupling each of the pads  590 ,  592 ,  594 ,  596  to the first suture  510  and second suture  550 . In some instances, the first suture  510  can be stitched to each of the pads  590 ,  592 ,  594 ,  596  prior to coupling the second suture  550  to each of the pads  590 ,  592 ,  594 ,  596 . In some instances, the first suture  510  can be coupled to the fourth pad  596 . For example, the first suture  510  can be threaded through the fourth pad  594  to position a stitch, such as the fourth pad portion  524 , over the fourth pad  596 . Subsequently, the first suture  510  can be stitched through the target tissue from each of two sides, such as two opposing sides, of the fourth pad  594  along the first path toward the position for the third pad  594  and the position for the first pad  590  such that the third tissue portion  522  and the fourth tissue portion  526  can be formed, respectively. The first suture  510  can then be coupled to the third pad  594  and the first pad  590 . The first suture  510  can be threaded through the first pad  590  such that the second distal portion  528  can be coupled to the first pad  590 . The first suture  510  can be stitched to the third pad  594  to position the third pad portion  520  over the third pad  594 . Subsequently, the second tissue portion  518  can be formed in the target tissue by threading the first suture  510  through the target tissue from the position for the third pad  594  toward the position for the second pad  592  along the first path. The second pad  592  can be coupled to the first suture  510  to position the second pad portion  516  over the pad. The first suture  510  can be extended along the first path through the target tissue from the second pad  592  to the position for the first pad  590  to form the first tissue portion  514 . The first suture  510  can then be threaded through the first pad  590  to couple the first distal portion  512  to the first pad  590 . 
     A method of forming the second purse-string suture  504  can comprise coupling the second suture  550  to the fourth pad  596 . The second suture  550  can be threaded through the fourth pad  594  to position a stitch, such as the fourth pad portion  556 , over the fourth pad  596 . Subsequently, the second suture  550  can be stitched through the target tissue from each of two sides, such as opposing sides, of the fourth pad  594  along the second path toward the position for the third pad  594  and the position for the first pad  590  such that the first tissue portion  554  and the second tissue portion  558  can be formed, respectively. The second suture  550  can then be coupled to the third pad  594  and the first pad  590 . The second suture  550  can be threaded through the third pad  594  such that the first distal portion  552  can be coupled to the third pad  594 . The second suture  550  can be stitched to the first pad  590  to position the first pad portion  56   o  over the first pad  590 . Subsequently, the third tissue portion  562  can be formed in the target tissue by threading the second suture  550  through the target tissue from the position for the first pad  590  toward the position for the second pad  592  along the second path. The second pad  592  can be coupled to the second suture  550  to position the second pad portion  564  over the pad. The second suture  550  can be extended along the second path through the target tissue from the second pad  592  to the position for the third pad  594  to form the fourth tissue portion  566 . The second suture  550  can then be coupled to the third pad  594 . The second suture  550  can be threaded through the third pad  594  to couple the second distal portion  568  to the third pad  594 . 
     Referring to  FIG. 7B , a schematic perspective view of the purse-string suture structure  500  is shown. Portions of the first suture  510  and second suture  550  positioned over each of the pads  590 ,  592 ,  594 ,  596  are shown. As described herein, positioning portions of the sutures  510 ,  550  over the pads  590 ,  592 ,  594 ,  596  can facilitate providing safe zones beneath the pads. Referring to  FIG. 7C , a schematic side view of the purse-string suture structure  500  is shown. The first pad  590 , second pad  592  and third pad  594 , and the corresponding safe zones  600 ,  602  and  604  are shown in  FIG. 7C . The pads  590 ,  592 ,  594  can be positioned over the target tissue, such as directly on and in contact with the target tissue, such as the heart wall. As described herein, the safe zones below the first pad  590 , second pad  592  and third pad  594  can extend into the target tissue. In some instances, the safe zone  602  can have a width similar or equal to a length of the second pad portion  516  and/or the second pad portion  564  positioned over the second pad  592 . In some instances, the safe zone  602  can have a width which is the shorter of the length of the second pad portion  516  and the length of the second pad portion  564 . In some instances, the safe zones  600 ,  604  can have a length, such as a dimension perpendicular or substantially perpendicular to the width of the respective safe zone, longer than a width of the corresponding pad. For example, the safe zones  600 ,  604  can have a length at least as long as a width of the first pad  590  and third pad  594 , respectively. In  FIG. 7C , only the portions of the safe zones  600 ,  604  under the respective pads are shown. Note that, for simplicity, details of the stitching through the tissue between the pads is not shown in  FIGS. 7B and 7C . 
     As described herein, the distal portions of the sutures can be arranged in a number of different manners relative to the four pads, and are not limited to the example described with reference to  FIGS. 7A to 7C . Respective distal portions of the sutures can be coupled to the same one of the four pads, or to two of the four pads different from those described herein. The combination shown in  FIGS. 7A to 7C  is used for illustrative purposes only. 
     One or more purse-string sutures as described herein can be formed on the heart wall, including on an apex region of the heart wall. In some instances, the purse-string sutures can be formed on a heart wall to seal an opening used to access the mitral valve, such as to perform a mitral valve repair procedure. In some instances, the mitral valve repair procedure can comprise deploying a tether to a mitral valve leaflet to tether the leaflet to the heart wall. For example, the procedure can comprise deploying a tether to a posterior mitral valve leaflet and coupling the posterior mitral valve leaflet to the heart wall using the tether. In some instances, one or more purse-string sutures can be formed on an antero-lateral portion of the left ventricular heart wall. The purse-string sutures can be formed to seal the left ventricle from the external environment, such as one or more purse-string sutures as described herein. For example, the sutures can be stitched through the pericardium, epicardium and at least a portion of the myocardium. Access to the heart can be achieved transapically, such as by performing a left thoracotomy (e.g., between the fourth or fifth intercostal space). As described herein, a purse-string suture structure can comprise one or more purse-string sutures, including two, three or four concentric purse-string sutures. 
     In some instances, a method for forming a purse-string suture structure can comprise identifying a direction of a posterior mitral valve leaflet (PML). Referring to  FIG. 8 , a schematic is shown of the heart  1  and a direction of a posterior mitral valve leaflet (PML) marked thereon. The direction of the posterior mitral valve leaflet (PML) is marked using a bold arrow in the figure. A process for forming a purse-string suture around an opening on the heart wall  17  can comprise identifying the posterior mitral valve leaflet (PML) direction and marking the direction on the exterior of the heart  1 . The posterior mitral valve leaflet (PML) direction can be marked based on the location of the opening formed in the target tissue. For example, the opening can be formed on the heart wall  17  for tethering a posterior mitral valve leaflet to the heart wall  17 . In some instances, the opening can be formed in the apex region  19 . In some instances, the opening can be formed about 2 centimeters (cm) lateral of the left anterior descending artery (LAD) and about 2 cm to about 3 cm basal from the apex  18  of the heart  1 . The mark for the posterior mitral valve leaflet (PML) direction can be selected at a location having a desired distance from the opening while in alignment with the direction of the leaflet. One or more of the plurality of pads of the purse-string suture structure can be aligned with the posterior mitral valve leaflet (PML) direction. In some instances, one of the plurality of pads can be aligned and positioned over the marked arrow indicating the posterior mitral valve leaflet (PML) direction. 
       FIGS. 9A through 9D  show portions of an example of a process for forming the purse-string suture structure  300  described with reference to  FIG. 6A . As shown in  FIGS. 9A through 9D , stitching for an inner purse-string suture, such as the first purse-string suture  302 , can be formed prior to stitching an outer purse-string suture, such as the second purse-string suture  304 . The first suture  310  and second suture  340  can comprise a variety of materials. In some instances, the first suture  310  and/or the second suture  340  can be a polypropylene suture (e.g., Prolene® sutures, including Ethicon® 3-0 Prolene® sutures). 
     Referring to  FIG. 9A , a first needle  900  and a second needle  910  can be provided for forming the first purse-string suture  302 . Each of the first needle  900  and second needle  910  can comprise a curvature. For example, the needles  900 ,  910  can be curved needles. Respective first ends  902 ,  912  of each of the first needle  900  and second needle  910  can be configured to be coupled to opposing ends of the first suture  310 . Respective second ends  904 ,  914  of the first needle  900  and second needle  910  can be sharp ends, for example being configured to pierce the target tissue and/or pads. In some instances, the first needle  900  and the second needle  910  can comprise a taper which tapers toward the respective second ends  904 ,  914  of the needles  900 ,  910 . In some instances, the curved needle can have a semi-circular shape (e.g., Ethicon® tapered SH 26 mm 1/2C). 
     The first suture  310  can be coupled to the second pad  372 . For example, the first suture  310  can be threaded through the second pad  372  such that a suture stitch, for example the second pad portion  316 , can be positioned over the second pad  372 . The first suture  310  can be threaded through a first location and a second location on the second pad  372  to position the second pad portion  316  over an upper surface of the second pad  372 . In some instances, the first needle  900  can be threaded from the upper surface through to the lower surface of the second pad  372  at the first location and the second needle  910  can be threaded from the upper surface through to the lower surface of the second pad  372  at the second location such that the second pad portion  316  can be positioned over the upper surface of the second pad  372 . The first and second locations can be selected such that the distal ends  328 ,  330  of the second pad portion  316  are positioned less than about 2 millimeters from nearest edges of the second pad  372 . In some instances, the second pad portion  316  can extend along a path which is less than about 2 millimeters (mm) from a nearest edge of the second pad  372 . For example, the second pad portion  316  can extend along a path less than about 2 mm from an edge of the second pad  372  configured to be positioned closer to the opening in the target tissue, such as an inner edge of the second pad  372 , including a longer edge of the second pad  372  configured to be oriented closer to the opening in the target tissue. In some instances, the distal ends  328 ,  330  can be positioned less than about 2 millimeters (mm) from opposing ends of the second pad  372 . In some instances, the distal ends  328 ,  330  can be positioned less than about 2 millimeters (mm) from a respective one of opposing shorter edges of the second pad  372 . In some instances, the distal ends  328 ,  330  can be positioned less than about 2 millimeters (mm) from the longer edge of the second pad  372  configured to be oriented closer to the opening. 
     Referring to  FIG. 9B , the second pad  372  can be positioned over a desired position over the target tissue. For example, the second pad  372  can be positioned at the second position along the first path around the opening. In some instances, the second pad  372  can be oriented such that it aligns with the posterior mitral valve leaflet (PML) direction. For example, the second pad  372  can be positioned over the marked line indicating the posterior mitral valve leaflet (PML) direction. The second pad  372  can then be stitched to the second position. The first needle  900  can subsequently be used to thread the first suture  310  from the second pad  372  to the position of the first pad  370 . The first suture  310  can be stitched through the target tissue to extend from the second pad  372  to the first pad  370  along the first path so as to form the first tissue portion  314 . In some instances, the first path between the second pad  372  and the first pad  372  can be parallel or substantially parallel the left anterior descending artery (LAD). In some instances, the first path between the second pad  372  and the first pad  372  can be selected to avoid anatomical elements, such as left anterior descending artery (LAD) branches. 
     The first suture  310  can then be coupled to the first pad  370 . For example, the first needle  900  can be used to thread the first suture  310  through a first location on the first pad  370  from a lower surface to an upper surface of the first pad  370 . The first suture  310  can be extended through the first pad  370  such that the first distal portion  312  can be coupled to the first pad  370 . The first location on the first pad  370  can be selected such that a distal end  326  of the first distal portion  312  is positioned less than about 2 millimeters (mm) from a nearest edge of the first pad  370 . In some instances, the distal end  326  can be positioned less than about 2 millimeters (mm) from a nearest shorter edge of the first pad  370  and/or less than about 2 millimeters (mm) from the longer edge of the first pad  370  configured to be oriented closer to the opening. 
     In  FIG. 9C , the second needle  910  can be used to thread the first suture  310  through the target tissue from the second pad  372  to the third pad  374 . The first suture  310  can be stitched through the target tissue from the second pad  372  to the third pad  374  along the first path, so as to form the second tissue portion  318 . The first suture  310  can then be coupled to the third pad  374 . For example, the first suture  310  can be threaded through the third pad  374  such that a third pad portion  320  of the first suture  310  can be positioned over the upper surface of the third pad  374 . The first suture  310  can be threaded through a first location on the third pad  374  from the lower surface through to the upper surface of the third pad  374 , and through a second location on the third pad  374  from the upper surface through to the lower surface, so as to position the third pad portion  320  over the upper surface of the third pad  374 . In some instances, the third pad portion  320  can extend along a path which is less than about 2 millimeters (mm) from a nearest edge of the third pad  374 , such as a longer edge of the third pad  374  configured to be positioned closer to the opening in the target tissue, including an inner longer edge of the third pad  374  oriented closer to the opening in the target tissue. In some instances, the distal ends  332 ,  334  of the third pad portion  320  can be positioned less than about 2 millimeters (mm) from respective nearest edges of the third pad  374 , including from opposing edges of the third pad  374 . For example, the distal ends  332 ,  334  can be positioned less than about 2 millimeters (mm) from a respective one of opposing shorter edges of the third pad  374 . In some instances, the distal ends  332 ,  334  can be positioned less than about 2 millimeters (mm) from the longer edge of the third pad  374  configured to be oriented closer to the opening. 
     The third pad  374  can be positioned at a predetermined position along the first path. In some instances, the third pad  374  can be positioned at a third position such that the first pad  370 , second pad  372  and third pad  374  are evenly distributed around the opening in the target tissue, for example evenly distributed around the first path surrounding the target opening. 
     The first suture  310  can subsequently be stitched using the second needle  910  through the target tissue from the third pad  374  to the position of the first pad  370 . The first suture  310  can be threaded through the target tissue to form the third tissue portion  322  along the first path. The first suture  310  can then be coupled to the first pad  370  to surround the opening in the target tissue. In some instances, the first suture  310  can be threaded through a second location on the first pad  370 , for example from the lower surface through to the upper surface of the first pad  370 , such that the second distal portion  324  of the first suture  310  can be coupled to the first pad  370 . The second location on the first pad  370  can be selected such that a distal end  336  of the second distal portion  324  is positioned less than about 2 millimeters (mm) from one or more edges of the first pad  370 . In some instances, the distal end  336  can be positioned less than about 2 millimeters (mm) from a nearest shorter edge of the first pad  370  and/or less than about 2 millimeters (mm) from the longer edge of the first pad  370  configured to be oriented closer to the opening. 
       FIG. 9D  shows the second purse-string suture  304  formed in the target tissue to be around and concentric with the first purse-string suture  302 . In some instances, the second purse-string suture  304  can be formed after stitching for the first purse-string suture  302  is completed. The second purse-string suture  304  can be formed around the first purse-string suture  302  such that the second purse-string suture  304  surrounds and is concentric with the first purse-string suture  302 . As shown in  FIG. 9D , the first distal portion  342  and second distal portion  354  of the second suture  340  can be coupled to the third pad  374 . As described herein, the first distal portion  312  and the second distal portion  324  of the first suture  310  can be coupled to the first pad  370 . 
     A third needle  920  and a fourth needle  930  can be coupled to opposing ends of the second suture  340 . The third needle  920  and/or the fourth needle  930  can comprise one or more characteristics of the first needle  900  and/or second needle  910 . For example, each of the third needle  920  and fourth needle  930  can be a curved needle comprising a taper which tapers toward respective second ends  924 ,  934 . Respective first ends  922 ,  932  of each of the third needle  920  and fourth needle  930  can be configured to be coupled to the opposing ends of the second suture  340 , and respective second ends  924 ,  934  of the third needle  920  and fourth needle  930  can be sharp ends. 
     In some instances, forming the second purse-string suture  304  can comprise coupling the second suture  340  to the first pad  370 . The third needle  920  and fourth needle  930  can be used to thread the second suture  340  through the first pad  370  to position a first pad portion  346 , such as a stitch, of the second suture  340  over the upper surface of the first pad  370 . For example, the second suture  340  can be threaded at a third location from the upper surface through to the lower surface of the first pad  370  using the third needle  920 , and at a fourth location from the upper surface through to the lower surface of the first pad  370  using the fourth needle  930 . The third and fourth locations can be selected such that the distal ends  358 ,  360  of the first pad portion  346  are positioned less than about 2 millimeters from respective nearest edges of the first pad  370 . In some instances, the distal ends  358 ,  360  can be positioned less than about 2 millimeters (mm) from opposing ends of the first pad  370 . In some instances, the first pad portion  346  can extend along a path which is less than about 2 millimeters (mm) from a nearest edge of the first pad  370 , such as from an edge of the first pad  370  configured to be positioned away from the opening in the target tissue, such as an outer edge of the first pad  370 . For example, the first pad portion  346  can be positioned along a path less than about 2 millimeters (mm) from a longer edge of the first pad  370  configured to be oriented away from the opening. In some instances, the distal ends  358 ,  360  can be positioned less than about 2 millimeters (mm) from a respective nearest shorter edge of the first pad  370 . 
     The third needle  920  can then be used to thread the second suture  340  through the target tissue from the first pad  370  to the position of the third pad  374  along the second path, so as to form the first tissue portion  344 . The second suture  340  can subsequently be coupled to the third pad  374 . In some instances, the second suture  340  can be threaded through a third location on the third pad  374 , for example from the lower surface through to the upper surface of the third pad  374 , such that the first distal portion  342  of the second suture  340  can be coupled to the third pad  374 . The third location on the third pad  374  can be selected such that a distal end  356  of the first distal portion  342  is positioned less than about 2 millimeters (mm) from one or more edges of the third pad  374 . In some instances, the distal end  356  can be positioned less than about 2 millimeters (mm) from a nearest shorter edge of the third pad  374  and/or less than about 2 millimeters (mm) from the longer edge of the third pad  374  configured to be oriented farther away from the opening. 
     In some instances, the second suture  340  can be threaded through the target tissue using the fourth needle  930  to extend from the first pad  370  to the position of the second pad  372  along the second path to form the second tissue portion  348 . The second suture  340  can be coupled to the second pad  372 . The second suture  340  can be threaded through a third location and a fourth location on the second pad  372  to position the second pad portion  350  over the upper surface of the second pad  372 . In some instances, the fourth needle  930  can be threaded from the lower surface through to the upper surface of the second pad  372  at the third location and from the upper surface through to the lower surface of the second pad  372  at the fourth location to position the second pad portion  350  over the upper surface of the second pad  372 . The third and fourth locations can be selected such that the distal ends  362 ,  364  of the second pad portion  350  are positioned less than about 2 millimeters from respective nearest edges of the second pad  372 , such as from opposing edges of the second pad  372 . In some instances, the second pad portion  350  can extend along a path which is less than about 2 millimeters (mm) from a nearest edge of the second pad  372 , such as an edge configured to be positioned away from the opening in the target tissue, including an outer edge of the second pad  372 . For example, the second pad portion  350  can be positioned along a path less than about 2 millimeters (mm) from a longer edge of the second pad  372  configured to be oriented away from the opening. The distal ends  362 ,  364  can be positioned less than about 2 millimeters (mm) from a respective nearest shorter edge of the second pad  372 . 
     The fourth needle  930  can then be used to stitch the second suture  340  through the target tissue from the second pad  372  to the position of the third pad  374  along the second path, so as to form the third tissue portion  352 . The second suture  340  can subsequently be coupled to the third pad  374 , such as by threading the second suture  340  through a fourth location on the third pad  374 . The second suture  340  can be threaded from the lower surface through to the upper surface of the third pad  374 , such that the second distal portion  354  of the second suture  340  can be coupled to the third pad  374 . The fourth location on the third pad  374  can be selected such that a distal end  366  of the second distal portion  354  is positioned less than about 2 millimeters (mm) from one or more edges of the third pad  374 . In some instances, the distal end  366  can be positioned less than about 2 millimeters (mm) from a nearest shorter edge of the third pad  374  and/or less than about 2 millimeters (mm) from the longer edge of the third pad  374  configured to be oriented farther away from the opening. 
     The order in which the first suture  310  and/or the second suture  340  are coupled to one or more of the pads and/or are stitched through the target tissue can be different from the sequence as described herein. In some instances, first suture  310  can be coupled to the first pad  370  or the third pad  374  prior to being coupled to the second pad  372 . In some instances, the second suture  340  can be coupled to the second pad  372  or the third pad  374  prior to being coupled to the first pad  370 . 
     As described herein, a purse-string suture structure can comprise one or more purse-string sutures. In some instances, a purse-string suture structure can comprise one purse-string suture. In some instances, the one purse-string suture can comprise a suture coupled to three or more pads.  FIG. 10  is flow diagram of an example of a process  1000  for forming a purse-string suture around an opening in a target tissue. At block  1002 , the process  1000  can involve placing a tissue-facing surface of a first pad over a first tissue area adjacent to the tissue opening. The first pad can be coupled to a suture. The suture can be used to stitch the purse-string suture around the opening. The suture can form a first stitch over the upper surface of the first pad. At block  1004 , the process  1000  can involve placing a tissue-facing surface of the second pad over a second tissue area adjacent to the tissue opening on a first side of the first pad. The second pad can be coupled to the suture, and the suture can form a second stitch over the upper surface of the second pad. At block  1006 , the process  1000  can involve placing a tissue-facing surface of a third pad over a third tissue area adjacent to the tissue opening on a second side of the first pad. The third pad can be coupled to the suture. In some instances, an orientation and/or length of the corresponding stitch portions positioned over the pads can be predetermined to reduce or avoid irritation of the target tissue, and/or provide a desired size for the safe zones, while ensuring a secure attachment of the pads to the suture. For example, one or more of the stitch portions can have distal ends positioned at less than about 2 millimeters (mm) from the nearest respective edges of the pad. In some instances, the suture can be coupled to the third pad at positions on the pad which are less than about 2 millimeters (mm) from the nearest edges of the pad. 
     At block  1008 , the process  1000  can involve stitching the suture through an area of tissue between the first pad and the second pad, through an area of tissue between the second pad and the third pad, and through an area of tissue between the third pad and the first pad. The suture can be threaded through the target tissue to connect the three pads. At block  1010 , the process  1000  can involve coupling a first distal portion and a second distal portion of the suture to the third pad for forming the purse-string suture. The distal portions can be tensioned to form the purse-string suture, including to close and/or seal the opening using the purse-string suture. 
     In some instances, the target tissue can be heart tissue. For example, placing the first pad, second pad and third pad over the respective tissue areas can comprise positioning the pads over a pericardium of the heart. In some instances, the pads can be positioned around an opening formed in an apex region of the heart. In some instances, one or more of the plurality of pads can be aligned with the posterior mitral leaflet. 
       FIGS. 11 and 12  are flow diagrams showing examples of processes for forming a first purse-string suture and a second purse-string suture around an opening in a target tissue. In the processes described with reference to  FIGS. 11 and 12 , a first suture can be used to stitch the first purse-string suture and a second suture can be used to stitch the second purse-string suture in the target tissue around the opening along a first path and a second path, respectively. The second path can surround and be concentric with the first path. A plurality of pads can be stitched to the first purse-string suture and second purse-string suture and positioned over the target tissue. For example, a lower surface of each of the plurality of pads can be configured to be oriented toward the target tissue and an upper surface of each of the plurality of pads can be configured to be oriented away from the target tissue. As described herein, the target tissue can be heart tissue. In some instances, positioning one or more of the plurality of pads can comprise positioning a pad over a pericardium of the heart. In some instances, one or more of the plurality of pads can be positioned around an opening formed in an apex region of the heart. For example, the plurality of pads can be positioned directly on and in contact with the pericardium around an opening formed in the apex region of the heart. In some instances, one or more of the plurality of pads can be aligned with the posterior mitral leaflet. 
     Referring to  FIG. 11 , an example of a process  1100  for forming the first and second purse-string sutures around an opening in a target tissue is shown. In block  1102 , the process  1100  can involve positioning a first pad over a target tissue at a first position on the first path for forming the first purse-string suture around the opening. In some instances, the first pad can be positioned such that it is aligned with a direction of the posterior mitral leaflet. The first pad can be coupled to the first suture. A first corresponding portion of the first suture can be positioned over an upper surface of the first pad. 
     In block  1104 , the process  1100  can involve coupling a first distal portion of the first suture and a second distal portion of the first suture to a second pad. In block  11   o   6 , the process  1100  can involve positioning the second pad at a second position on the first path. In some instances, the second pad can be positioned at an opposing location along the first path from that of the first pad. 
     In block  11   o   8 , the process  1100  can involve providing the second suture coupled to one of the first pad and the second pad, the second suture for forming a second purse-string suture in the target tissue along a second path around and concentric with the first path. A first corresponding portion of the second suture can be positioned over an upper surface of the one of the first pad and the second pad. 
     In block  1110 , the process  1100  can involve coupling a first distal portion of the second suture and a second distal portion of the second suture to the other of the first pad and the second pad. In block  1112 , the process  1100  can involve tensioning the first distal portion and second distal portion of the first suture to form the first purse-string suture, and tensioning the first distal portion of the second suture and second distal portion of the second suture to form the second purse-string suture. 
     In some instances, a third pad can be positioned over the target tissue at a third position on the first path. The third pad can be coupled to the first suture and a third corresponding portion of the first suture can be positioned over an upper surface of the third pad. In some instances, the third pad can be positioned between the first pad and the second pad. In some instances, the first pad, the second pad, and the third pad can be evenly distributed around the opening in the target tissue along the first path. 
     The second suture can be coupled to the third pad. The second suture can comprise a corresponding portion positioned over the third pad. In some instances, the corresponding portion of the second suture positioned over the third pad can be parallel or substantially parallel to the third corresponding portion of the first suture positioned over the third pad. 
     In some instances, a fourth pad can be coupled to the first suture. The fourth pad can be positioned over the target tissue at a fourth position on the first path. The fourth pad can be positioned between the third pad and the second pad. In some instances, the first pad, the second pad, the third pad and the fourth pad can be evenly distributed around the opening in the target tissue along the first path. A fourth corresponding portion of the first suture can be positioned over an upper surface of the fourth pad. The second suture can be coupled to the fourth pad. The second suture can comprise a corresponding portion positioned over the fourth pad. In some instances, the corresponding portion of the second suture positioned over the fourth pad can be parallel or substantially parallel to the fourth corresponding portion of the first suture positioned over the third pad. 
       FIG. 12  shows another example of process  1200  for suturing a first purse-string suture and a second purse-string suture around an opening in a target tissue. A first suture can be used to form the first purse-strong suture and a second suture can be used to form the second purse-string suture. At block  1202 , the process  1200  can involve threading the first suture through a first location on a first pad from an upper surface to a lower surface of the first pad, and threading the first suture through a second location on the first pad from the upper surface to the lower surface of the first pad. A first corresponding portion of the first suture can be positioned over the upper surface of the first pad. The first location and the second location on the first pad can be less than about 2 millimeters (mm) from respective nearest edges of the first pad. For example, the first location and the second location can be less than about 2 millimeters (mm) from a respective opposing edge of the first pad. The first suture can run along a path less than about 2 millimeters (mm) from a nearest edge of the first pad, such as an edge perpendicular or substantially perpendicular to the opposing edges. 
     At block  1204 , the process  1200  can involve positioning the first pad over the target tissue at a first position along the first path for forming the first purse-string suture around the opening in the target tissue. 
     At block  1206 , the process  1200  can involve threading the first suture through the target tissue along the first path from the first position on the first path to a second position on the first path. 
     At block  1208 , the process  1200  can involve threading a first distal portion of the first suture through a first location on a second pad from a lower surface of the second pad to an upper surface of the second pad. 
     At block  1210 , the process  1200  can involve threading a second distal portion of the first suture through a second location on the second pad from the lower surface of the second pad to the upper surface of the second pad. The first location and second location on the second pad can be less than about 2 millimeters from respective nearest edges of the second pad, including from a respective opposing edge of the second pad. In some instances, the first and second locations can be less than about 2 millimeters (mm) from a third edge of the second pad, such as an edge perpendicular or substantially perpendicular to the opposing edges. 
     At block  1212 , the process  1200  can involve positioning the second pad over the target tissue at the second position on the first path. 
     At block  1214 , the process  1200  can involve threading the second suture through a first location from an upper surface to a lower surface of one of the first pad and the second pad, and threading the second suture through a second location from the upper surface to the lower surface of the one of the first pad and the second pad. A first corresponding portion of the second suture can be positioned over the upper surface of the one of the first pad and the second pad. In some instances, the first location and the second location on the one of the first pad and the second pad can be less than about 2 millimeters (mm) from respective nearest edges of the pad, such as a respective opposing edge of the pad. The second suture can run along a path less than about 2 millimeters (mm) from a nearest edge of the one of the first pad and the second pad, such as an edge perpendicular or substantially perpendicular to the opposing edges. 
     At block  1216 , the process  1200  can involve threading a first distal portion of the second suture through a first location from a lower surface to an upper surface of the other of the first pad and the second pad and threading a second distal portion of the second suture through a second location from the lower surface to the upper surface of the other of the first pad and the second pad. The first and second locations on the other of the first pad and the second pad can be less than about 2 millimeters (mm) from respective nearest edges of the pad, including from a respective opposing edge. The first and second locations can be less than about 2 millimeters (mm) from an edge perpendicular or substantially perpendicular to the opposing edges. 
     At block  1218 , the process  1200  can involve tensioning the first suture to form the first purse-string suture and tensioning the second suture to form the second purse-string suture. In some instances, the first distal portion and the second distal portion of the first suture can be tensioned. In some instances, the first distal portion of the second suture and second distal portion of the second suture can be tensioned. 
     In some instances, the first pad and the second pad can be positioned at opposing locations around the opening. In some instances, the first purse-string suture and the second purse-string suture can be coupled to two pads such that the first and second pad are positioned at opposing locations along the first path and the second path. 
     In some instances, the first purse-string suture and the second purse-string suture can comprise more than two pads coupled thereto. For example, a third pad can be coupled to the first and second purse-string sutures. In some instances, the third pad can be positioned over the target tissue at a third position around the target opening. The first suture can be threaded through the target tissue from the first position to the third position on the first path. The third pad can be coupled to the third pad. For example, a third corresponding portion of the first suture, such as a third pad portion of the first suture, can be positioned over the upper surface of the third pad, where the upper surface of the third pad can be configured to be oriented away from the target tissue. The first suture can be threaded through a first location on the third pad from a lower surface to the upper surface of the third pad, and through a second location on the third pad from the upper surface to the lower surface of the third pad. The first and second locations can be less than about 2 millimeters (mm) from respective nearest edges of the third pad, such as a respective opposing edge of the third pad. The first suture can run along a path less than about 2 millimeters (mm) from a nearest edge of the third pad, such as an edge perpendicular or substantially perpendicular to the opposing edges. In some instances, the first pad, the second pad and the third pad can be evenly distributed around the opening in the target tissue, for example being positioned along the first path and second path at equal distances from the nearest two pads. 
     The second suture can be coupled to the third pad. A corresponding portion of the second suture can be positioned over the upper surface of the third pad. For example, the second suture can be threaded through a third location on the third pad from the lower surface to the upper surface of the third pad, and through a fourth location on the third pad from the upper surface to the lower surface of the third pad to position the corresponding portion of the second suture over the upper surface of the third pad. The third and fourth locations can be less than about 2 millimeters (mm) from respective nearest edges of the third pad, such as a respective opposing edge of the third pad. The second suture can run along a path less than about 2 millimeters (mm) from a nearest edge of the third pad, such as an edge perpendicular or substantially perpendicular to the opposing edges. 
     In some instances, a fourth pad can be coupled to the first purse-string suture and second purse-string suture. For example, the fourth pad can be positioned at predetermined position around the opening along the first path, such as at a fourth position between the third pad and the second pad. In some instances, coupling the fourth pad can comprise threading the first suture through the target tissue from the third position to a fourth position on the first path. In some instances, the first suture can be threaded through a first location on the fourth pad from a lower surface to an upper surface of the fourth pad, and through a second location on the fourth pad from the upper surface to the lower surface of the fourth pad, to position a fourth corresponding portion of the first suture over the upper surface of the fourth pad. 
     The second suture can be coupled to the fourth pad. In some instances, the second suture can be threaded through a third location from the lower surface to the upper surface of the fourth pad, and through a fourth location from the upper surface to the lower surface of the fourth pad to position a corresponding portion of the second suture over the upper surface of the fourth pad. The third and fourth locations can be less than about 2 millimeters (mm) from respective nearest edges of the fourth pad, such as a respective opposing edge of the fourth pad. The second suture can run along a path less than about 2 millimeters (mm) from a nearest edge of the fourth pad, such as an edge perpendicular or substantially perpendicular to the opposing edges. In some instances, the first pad, the second pad, the third pad, and the fourth pad can be evenly distributed around the opening along the first path. 
     Additional Instances 
     Depending on the instance, certain acts, events, or functions of any of the processes or algorithms described herein can be performed in a different sequence, may be added, merged, or left out altogether. Thus, in certain instances, not all described acts or events are necessary for the practice of the processes. 
     Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is intended in its ordinary sense and is generally intended to convey that certain instances include, while other instances do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more instances or that one or more instances necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular instance. The terms “comprising,” “including,” “having,” and the like are synonymous, are used in their ordinary sense, and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is understood with the context as used in general to convey that an item, term, element, etc. may be either X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain instances require at least one of X, at least one of Y and at least one of Z to each be present. 
     It should be appreciated that in the above description of instances, various features are sometimes grouped together in a single instance, Figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than are expressly recited in that claim. Moreover, any components, features, or steps illustrated and/or described in a particular instance herein can be applied to or used with any other instance(s). Further, no component, feature, step, or group of components, features, or steps are necessary or indispensable for each instance. Thus, it is intended that the scope of the inventions herein disclosed and claimed below should not be limited by the particular instances described above, but should be determined only by a fair reading of the claims that follow. 
     It should be understood that certain ordinal terms (e.g., “first” or “second”) may be provided for ease of reference and do not necessarily imply physical characteristics or ordering. Therefore, as used herein, an ordinal term (e.g., “first,” “second,” “third,” etc.) used to modify an element, such as a structure, a component, an operation, etc., does not necessarily indicate priority or order of the element with respect to any other element, but rather may generally distinguish the element from another element having a similar or identical name (but for use of the ordinal term). In addition, as used herein, indefinite articles (“a” and “an”) may indicate “one or more” rather than “one.” Further, an operation performed “based on” a condition or event may also be performed based on one or more other conditions or events not explicitly recited. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example instances belong. It be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     The spatially relative terms “outer,” “inner,” “upper,” “lower,” “below,” “above,” “vertical,” “horizontal,” and similar terms, may be used herein for ease of description to describe the relations between one element or component and another element or component as illustrated in the drawings. It be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, in the case where a device shown in the drawing is turned over, the device positioned “below” or “beneath” another device may be placed “above” another device. Accordingly, the illustrative term “below” may include both the lower and upper positions. The device may also be oriented in the other direction, and thus the spatially relative terms may be interpreted differently depending on the orientations. 
     Unless otherwise expressly stated, comparative and/or quantitative terms, such as “less,” “more,” “greater,” and the like, are intended to encompass the concepts of equality. For example, “less” can mean not only “less” in the strictest mathematical sense, but also, “less than or equal to.”