Patent Publication Number: US-2021162165-A1

Title: Heart Vent Catheter and Method of Use

Description:
PRIORITY CLAIM 
     The present application claims priority from, and incorporates by reference herein for all purposes:
         Nonprovisional application Ser. No. 15,729,035, entitled Left Heart Vent Catheter and Method of Use, filed Oct. 10, 2017 by Robert E. Michler and Albert N. Santilli; and   Nonprovisional application Ser. No. 15/591,325, entitled Left Heart Vent Catheter and Method of Use, filed May 10, 2017 by Robert E. Michler and Albert N. Santilli, now abandoned; and   Nonprovisional application Ser. No. 14/216,214, entitled Left Heart Vent Catheter, filed Mar. 17, 2014 by Robert E. Michler and Albert N. Santilli, now abandoned; and   provisional application Ser. No. 61/801,957, entitled Left Heart Vent Catheter, filed Mar. 15, 2013 by Robert E. Michler and Albert N. Santilli.       

     The present application is a continuation-in-part of the &#39;035 application, which is a continuation-in-part of the &#39;325 and &#39;214 applications. The &#39;325 application was a continuation of the &#39;214 application, which claimed the benefit of the &#39;957 application. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to heart vent catheters and methods for their use. 
     Description of the Prior Art 
     In the course of conducting coronary surgery, it sometimes is necessary to provide a direct or indirect vent of portions of the heart, such as the left ventricle. This is accomplished by inserting an elongate, narrow, hollow tube into the ventricle. The distal end of the tube has a plurality of openings that permit air and blood to enter the tube and be conveyed out of the body. 
     A commercially known left heart vent catheter is marketed by Medtronic, Inc. of Minneapolis, Minn. under the trademark DLP. A specification sheet can be found at http://www.medtronic.com/mics/documents/200805572_EN.pdf (page VII-5) and at http://www.medtronic.com/content/dam/medtronic-com-m/mdt/cardio/documents/2011-medtrnc-cannulae-catalog.pdf. The catheter in question and the specification sheet are incorporated herein by reference for all purposes. The catheter in question is provided with a so-called guidewire introducer that maintains the catheter in a desired shape as it is being pushed into place. The guidewire introducer is withdrawn after the distal end of the catheter has been properly positioned, leaving the hollow tube in place to receive and discharge air and blood. 
     A problem with the catheter in question is that it can shift or otherwise move during the course of a surgical procedure. In particular, the catheter can be withdrawn if care is not taken or it can migrate forward in an unsafe manner, possibly rupturing the heart wall. In order to prevent undesired movement or withdrawal of the catheter, it usually is manually held in place or is sutured in place. Both of these approaches to retaining the catheter in place have a number of drawbacks, such as the need to dedicate a person to carrying out the task or finding a suitable and safe place to suture the catheter to the heart or the additional time it requires to suture the catheter to an appropriate portion of the patient&#39;s body. 
     U.S. Pat. No. 6,117,105 to Bresnaham et al. (“Bresnaham”) discloses an aortic catheter and a method for inducing cardioplegic arrest that includes the step of perfusing the patient&#39;s aortic arch with fluid through an arch perfusion lumen extending through a catheter shaft. The Bresnaham patent is incorporated herein by reference for all purposes. An objective of Bresnaham is to maintain a perfusion catheter in a precise location within the aorta. Two spaced inflatable members engage the interior walls of the aorta. An upstream occlusion member is designed to block blood flow through the aorta. A downstream anchoring member is designed to hold the catheter shaft in place. Arch perfusion ports and a pressure port are disposed between the upstream occlusion member and the downstream anchoring member. 
     Bresnaham&#39;s device cannot vent portions of the heart. In part, this is because there are no ports or openings in the catheter toward the distal end, i.e., between the forwardmost portion of the upstream occlusion member and the distal end. 
     in view of the foregoing, there is a need for a heart vent catheter and method of use that can provide a fast, easily operated, effective way to vent desired portions of a patient&#39;s heart during surgical procedures. Any such technique preferably would maintain the desired position of the catheter during the course of a surgical procedure without the need to provide a surgical assistant for the purpose of holding the catheter in place or without the need to take the time and trouble to suture the catheter in place. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved heart vent catheter and a new and improved technique for holding heart vent catheters in place. In the preferred embodiment, an elongate, flexible tube (hereinafter “tube”) defines a first passageway. The tube has a distal (or tip) end, a central portion, and a proximal (or exit) end. The distal end preferably includes a rounded bullet nose or tip at its forwardmost portion. A circumferentially extending, inflatable balloon is included as part of the distal end. The distal end, including the balloon in uninflated condition, and the central portion each have an outer diameter sufficiently small that the tube is capable of extending through a desired portion of the patient&#39;s body such as the patient&#39;s inferior or superior vena cava or the right pulmonary vein. The distal end, with the balloon uninflated, is capable of extending into a desired portion of the patient&#39;s heart such as the left ventricle, right atrium, etc. 
     The proximal end of the tube includes a vented connector that is in fluid communication with the first passageway. The distal end of the tube is provided with a plurality of openings that establish fluid communication with the first passageway. In the preferred embodiment, openings are disposed on either side of the balloon, i.e., intermediate the forwardmost portion of the balloon and the rounded bullet nose and adjacent the balloon on the side of the balloon opposite the rounded bullet nose. The size, shape, number, and placement of the openings are chosen to permit air, blood, other fluid and preferably at least some debris to pass through the openings and into the first passageway. Desirably, a flow rate of 50 cc per minute or greater can be established under suction applied at the vented connector. 
     A second passageway extends along at least a portion of the length of the tube. The second passageway establishes fluid communication with the balloon. A branch connector projects from the side of the tube in the region of the proximal end. The branch connector is in fluid communication with the second passageway such that the balloon can be inflated, typically by injecting saline solution by means of a syringe attached to the branch connector. 
     An elongate stiffening member, or guidewire introducer, can be inserted into, and removed from, the first passageway through the vented connector. The guidewire introducer can be made of a rigid material but more preferably is made of a malleable material such as metal. If desired, a number of visual markers can be provided on the outside of the tube at predetermined locations. 
     In use, after the guidewire introducer is in place, and if it is made of a malleable material, the tube can be bent into a shape desired by the surgeon. Thereafter, the distal end can be inserted into the heart through an opening formed in the inferior or superior vena cava, the right pulmonary vein, or any other desired location in the heart for application of the device. The extent to which the distal end is inserted into the heart can be gauged by the surgeon through the use of the visual markers. 
     The distal end can be inserted into a desired part of a patient&#39;s heart such as the left ventricle or right atrium. Thereafter, the balloon can be inflated by injecting fluid through the branch connector. The guidewire introducer is removed from the first passageway, preferably after the balloon has been inflated. The inflated balloon will engage a desired part of the patient&#39;s heart such as the mitral valve, aortic valve, pulmonary valve or tricuspid valve and thereby prevent undesired withdrawal of the catheter. During the surgical procedure, air, blood, other fluid and debris can be removed from the heart under suction applied through the vented connector. After the surgical procedure has been completed, the balloon can be collapsed by opening the branch connector. After the balloon has been collapsed the catheter can be withdrawn. 
     The invention eliminates the need to provide a surgical assistant for the purpose of holding the catheter in place, and it avoids the need to take the time and trouble to suture the catheter in place. The invention provides a fast, easily operated, effective way to maintain the desired position of the catheter during the course of a surgical procedure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which like reference characters refer to like elements through the different figures and in which: 
         FIG. 1  is a perspective view of a heart vent catheter according to the invention; 
         FIG. 2  is a top plan view of the heart vent catheter of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the catheter of  FIG. 1  taken along a section indicated by line  3 - 3  in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the catheter of  FIG. 1  taken along a section indicated by line  4 - 4  in  FIG. 2 ; 
         FIG. 5  is a view of a stiffening member, or guidewire introducer, used with the invention; 
         FIG. 6  is an enlarged, cross-sectional view of the distal end of the heart vent catheter of  FIG. 1  with a retention balloon collapsed; 
         FIG. 7  is an enlarged, cross-sectional view of the distal end of the heart vent catheter of  FIG. 1  with the retention balloon inflated; 
         FIG. 8  is a schematic representation of a human heart, partly in section, with the catheter of  FIG. 1  being inserted into a patient&#39;s heart through an opening formed in one of the right pulmonary veins, the catheter having a guidewire introducer extending the length of the catheter; 
         FIG. 9  is a view similar to  FIG. 8 , with a distal end portion of the catheter inserted into the left ventricle by passing through the left atrium and the mitral valve; 
         FIG. 10  is a view similar to  FIG. 9 , with a balloon in the process of being inflated to engage the mitral valve; 
         FIG. 11  is a view similar to  FIG. 10 , with the guidewire introducer being removed and the balloon fully inflated and engaging the mitral valve; 
         FIG. 12  is a view similar to  FIG. 11 , with suction being applied to the catheter in order to remove blood, air, and/or debris from the left ventricle; 
         FIG. 13  is a view similar to  FIG. 8 , with the catheter being inserted into a patient&#39;s heart through an opening formed in the aorta; 
         FIG. 14  is a view similar to  FIG. 13 , with a distal end portion of the catheter inserted into the left ventricle by passing through the aortic valve; 
         FIG. 15  is a view similar to  FIG. 14 , with a balloon in the process of being inflated to engage the aortic valve; 
         FIG. 16  is a view similar to  FIG. 15 , with the guidewire introducer being removed and the balloon fully inflated and engaging the aortic valve; and 
         FIG. 17  is a view similar to  FIG. 16 , with suction being applied to the catheter in order to remove blood, air, and/or debris from the left ventricle. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, a heart vent catheter according to the invention is indicated by the reference numeral  10 . The heart vent catheter  10  includes an elongate, flexible tube  12  made of latex, vinyl, silicone, or similar material that defines a first, hollow passageway  14 . The tube  12  has a distal end  16 , a central portion  18 , and a proximal end  20 . The forwardmost portion of the distal end  16  is closed by a generally rounded bullet nose or tip  22 . 
     A thin, circumferentially extending, expansible balloon  24  is included as part of the distal end  16 . The balloon  24  is connected to the tube  12  by means of circumferential retainer bands  26 . The balloon  24  preferably is made of a high tensile strength silicone rubber such as MED-4027 commercially available from NuSil Technology LLC, Carpinteria, Calif. 93013. The balloon  24  can accommodate 10 cc of saline solution, and preferably has a maximum capacity of about 15 cc. When inflated with 10 cc of solution ( FIG. 4 ), the balloon  24  assumes the shape of relatively straight end walls  28  connected by an oval center portion  30 . When inflated as illustrated, the end walls  28  are spaced from each other approximately 0.95 inch and the outer diameter of the center portion  30  is approximately 1.0 inch. 
     A second passageway  32  is included as part of a wall  33  that defines the tube  12  (see  FIG. 3 ). Alternatively, the second passageway  32  can be part of a separate tube (not shown) that preferably is disposed within the passageway  14 . An opening  34  in the wall  33  provides fluid communication between the second passageway  32  and the interior of the balloon  24 . 
     A formation  36  is connected to the tube  12  and defines a portion of the proximal end  20 . The formation  36  includes an end portion  38  having a through opening  40  that communicates with the first passageway  14 . The formation  36  also includes a branch tube  42 , a check valve  44 , and a luer lock connector  46 . An opening in the wall  33  provides fluid communication between the second passageway  32  and the interior of the branch tube  42 . A small syringe (about 35 ml) (not shown) is adapted to be connected to the branch tube  42  by means of the luer lock connector  46 . A syringe, suction line, or drain tube (not shown) can be connected to the end portion  38  in order to drain blood, air or other fluid or debris from the passageway  14  through the opening  40 . 
     A plurality of small openings  48  are formed in the distal end  16 , between the tip  22  and the forwardmost end wall  28  of the balloon  24 . Preferably 10 openings  48  are provided, each approximately 2.5 mm in diameter. The openings  48  are provided in pairs that open through the tube  12  on opposite sides of the tube  12 . Each pair of the openings  48  is oriented approximately 90 degrees relative to adjacent pairs of the openings  48  as measured along a centerline extending through the center of the tube  12 . The size, shape and placement of the openings  48  are such that a large quantity of air, blood and debris can flow into the passageway  14  while preventing or minimizing clogging and while maintaining the structural integrity of the tube  12 . 
     A plurality of small openings  50 , similar to the openings  48 , are formed in the distal end  16 . The openings  50  are adjacent to the balloon  24  but on the proximal side thereof. Preferably  10  openings  50  are provided, each approximately 2.5 mm in diameter. The openings  50  extend through the tube  12  and are arranged relative to each other in the same manner as the openings  48 . As with the openings  48 , the size, shape and placement of the openings  50  permits a large quantity of air, blood and debris to flow into the passageway  14  while preventing or minimizing clogging and while maintaining the structural integrity of the tube  12 . 
     An elongate stiffening member, or guidewire introducer  54  ( FIG. 5 ), can be used to provide stiffness to the tube  12  for purposes of easier and more accurate insertion of the distal end  16  into the patient&#39;s heart. The guidewire introducer  54  has a large formation  56  at the proximal end for gripping purposes and a tapered tip  58  at the distal end. The guidewire introducer  54  can be made of a rigid material but more preferably is made of a malleable material such as metal. In order to reduce the force required to insert and remove the guidewire introducer  54  from the first passageway  14 , the guidewire introducer  54  may be coated with an anti-friction material such as PTFE. 
     A number of visual markers  60 ,  62 ,  64  are provided for the outside of the tube  12 . The markers  60 ,  62 ,  64  are evenly spaced at 50 mm±0.51 mm intervals along the length of the central portion  18 . The first marker  60  preferably is located 100 mm±2 mm from the tip  22 , the second marker  62  preferably is located approximately 150 mm from the tip  22  and the third marker  64  preferably is located approximately 200 mm from the tip  22 . The marker  60  consists of a single line, the marker  62  consists of two spaced lines, and the marker  64  consists of three spaced lines. The 100 mm measurement for the first marker  60  is to the edge of the line closest to the tip  22 , the 150 mm measurement for the second marker  62  is to a position between the two spaced lines, and the 200 mm measurement for the third marker  64  is to the middle line. The use of one, two and three lines, respectively, for the markers  60 ,  62 , and  64 , will inform the surgeon that the markers are located at 100, 150 and 200 mm from the tip  22 . 
     The maximum diameter of the inflated balloon  24  should not exceed 1.0 inch±0.10 inch. The distal side of the balloon  24  should be spaced approximately 1.25 inches from the end of the rounded tip  22 . The maximum width of the balloon should be 0.95 inch+0.20 inch/−0.10 inch. The openings  48  should be disposed between the tip  22  and the distal side of the balloon  24 , but should be at least 0.8 mm±0.1 mm away from the distal side of the balloon  24 . Similarly, the openings  50  should be disposed close to the balloon  24  on the proximal side thereof, but should be at least 0.8 mm±0.1 mm away from the proximal side of the balloon  24 . 
     The length of the combined distal end portion  16  and the central portion  18  is approximately 15.0 inches, while the exit end portion  20  is approximately 2.2 inches long. The tube  12  has an outer diameter of about 0.213 inch and an inner diameter of about 0.105 inch. The second passageway  32  has a diameter of about 0.030 inch. 
     Because the invention is intended for use in coronary surgery, most of the foregoing dimensions are important or critical and not merely approximations. In particular, the size and shape of the openings  48 ,  50  and the location of the openings  48 ,  50  relative to each other and to the balloon  24  and the tip  22  are important to the successful operation of the invention. These openings  48 ,  50  are large enough to permit not only air and blood to be removed from the heart, but also at least some debris can be removed without clogging the openings  48 ,  50 . The size, shape and placement of the openings  48 ,  50  permit a flow rate of equal to or greater than 50 cc per minute under suction. This flow rate is believed to be important to the successful operation of the device. 
     Operation 
     It is expected that the catheter  10  will be a relatively inexpensive, disposable device suitable for one-time use. The catheter  10  will be provided to the customer in a sterile package with the balloon  24  uninflated. The catheter  10  can be provided to the customer with the guidewire introducer  54  already inserted into the hollow passageway  14 , or it can be provided to the customer with the guidewire introducer  54  as a separate component. 
     In order to use the guidewire introducer  54  with the catheter  10 , the tapered tip  58  of the guidewire introducer  54  is inserted into the through opening  40 . The entire guidewire introducer  54  then is inserted into the passageway  14  by grasping and pushing the formation  56 . After the guidewire introducer  54  is in place, and if it is made of a malleable material, the tube  12  can be bent into a shape desired by the surgeon. 
     Referring particularly to  FIGS. 8-17 , a schematic representation of a human heart  70  is shown. The components are identified by reference numerals, as follows:
           72  pulmonary veins (from right lung to left atrium)     74  pulmonary veins (from left lung to left atrium)     76  pulmonary artery (right ventricle/pulmonic valve to right lung)     78  pulmonary artery (right ventricle/pulmonic valve to left lung)     80  pulmonic valve (right ventricle to pulmonary artery)     82  inferior vena cava (lower body to right atrium)     84  superior vena cava (upper body to right atrium)     86  right atrium     87  tricuspid valve     88  right ventricle     90  left atrium     92  mitral valve     94  left ventricle     96  aortic valve     98  aorta (to upper body)     100  aorta (to lower body)       

     The distal end portion  16  is inserted into the heart  70  through an opening formed in a member such as the inferior or superior vena cava  82 ,  84 , one of the right pulmonary veins  72  or any other desired location in the heart  70  for application of the device. The extent to which the rounded tip  22  is inserted into the heart  70  can be gauged by the surgeon through the use of the markers  60 ,  62 ,  64 . 
     In a typical situation (for example,  FIGS. 8-12 ), the distal end portion  16  will be inserted into and through the right superior pulmonary vein  72 , across the mitral valve  92 , and into the left ventricle  94 , or it can be introduced directly into the left ventricle  94  during the course of mitral valve surgery. The soft balloon  24  can be inflated in the left ventricle  94 , keeping the tip  22  of the distal end  16  below the mitral valve  92  to enable drainage of blood, air or debris from the left ventricle  94 . In addition, the openings  50  on the proximal side of the balloon  24  will enable drainage of blood, air or debris from areas above the mitral valve  92 , e.g., the left atrium  90 . 
     After the distal end  16  has been properly positioned, the balloon  24  is inflated with about 10 cc of saline solution by a syringe connected to the branch tube  42 . The check valve  44  will retain the saline solution in the catheter so that the syringe can be removed, if desired. In an alternative construction, the check valve  44  can be eliminated. Without a check valve, the syringe must be kept in place for the duration of the surgical procedure in order to retain the saline solution in the balloon  24  and thereby keep the balloon  24  inflated. 
     Regardless of the manner by which the balloon  24  is inflated, the balloon  24  will bear against the aortic valve  96 , tricuspid valve  87 , etc., thereby preventing the catheter  10  from being withdrawn from the heart  70  during the course of the surgical procedure. While the distal end portion  16  is in the heart  70 , debris or blood, air or other fluid can be drained or withdrawn under vacuum through the openings  48 ,  50  and the hollow passageway  14 . After there is no need for the catheter  10 , the check valve  44  can be opened and/or the syringe removed in order to drain fluid from the balloon  24 . This will cause the balloon  24  to be collapsed so as to permit the catheter  10  to be withdrawn from the heart  70 . 
     By using the catheter  10  according to the invention, there no longer is a need to provide a surgical assistant for the purpose of holding a catheter in place. The invention also avoids the need to take the time and trouble to suture a catheter in place. The invention provides a fast, easily operated, effective way to maintain the desired position of the catheter  10  during the course of a surgical procedure. The particular size, shape, and placement of the openings in the distal end of the tip ensure that blood, air, and at least some debris can be removed effectively from the heart under suction without clogging the openings. 
     Although the invention has been described in detail with reference to particular examples and embodiments, the examples and embodiments contained herein are merely illustrative and are not an exhaustive list. Variations and modifications of the present invention will readily occur to those skilled in the art. The present invention includes all such modifications and equivalents.