Abstract:
Implants or systems of implants and methods apply a selected force vector or a selected combination of force vectors within or across the right atrium, which allow tricuspid valve leaflets to better coapt. The implants or systems of implants and methods make possible rapid deployment, facile endovascular delivery, and full intra-atrial retrievability. The implants or systems of implants and methods also make use of strong fluoroscopic landmarks. The implants or systems of implants and methods make use of an adjustable implant. The implants or systems of implants and methods may utilize a bridge stop to secure the implant.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of co-pending U.S. Provisional Application Ser. No. 62/131,688 filed 11 Mar. 2015. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention is directed to devices, systems, and methods for improving the function of a heart valve, e.g., in the treatment of tricuspid valve regurgitation. 
       BACKGROUND OF THE INVENTION 
     I. The Anatomy of a Healthy Heart 
       [0003]    The heart (see  FIG. 1 ) is slightly larger than a clenched fist. It is a double (left and right side), self-adjusting muscular pump, the parts of which work in unison to propel blood to all parts of the body. The right side of the heart receives poorly oxygenated (“venous”) blood from the body from the superior vena cava and inferior vena cava and pumps it through the pulmonary artery to the lungs for oxygenation. The left side receives well-oxygenation (“arterial”) blood from the lungs through the pulmonary veins and pumps it into the aorta for distribution to the body. 
         [0004]    The heart has four chambers, two on each side—the right and left atria, and the right and left ventricles. The atriums are the blood-receiving chambers, which pump blood into the ventricles. The ventricles are the blood-discharging chambers. A wall composed of fibrous and muscular parts, called the interatrial septum separates the right and left atriums (see  FIGS. 2 to 4 ). The fibrous interatrial septum is, compared to the more friable muscle tissue of the heart, a more materially strong tissue structure in its own extent in the heart. 
         [0005]    An anatomic landmark on the interatrial septum is an oval, thumbprint sized depression called the oval fossa, or fossa ovalis (shown in  FIG. 4 ), which is a remnant of the oval foramen and its valve in the fetus. It is free of any vital structures such as valve structure, blood vessels and conduction pathways. Together with its inherent fibrous structure and surrounding fibrous ridge which makes it identifiable by angiographic techniques, the fossa ovalis is the favored site for trans-septal diagnostic and therapeutic procedures from the right into the left heart, and attachment of structure to heart tissue. Before birth, oxygenated blood from the placenta was directed through the oval foramen into the left atrium, and after birth the oval foramen closes. 
         [0006]    The synchronous pumping actions of the left and right sides of the heart constitute the cardiac cycle. The cycle begins with a period of ventricular relaxation, called ventricular diastole. The cycle ends with a period of ventricular contraction, called ventricular systole. 
         [0007]    The heart has four valves (see  FIGS. 2 and 3 ) that ensure that blood does not flow in the wrong direction during the cardiac cycle; that is, to ensure that the blood does not back flow from the ventricles into the corresponding atria, or back flow from the arteries into the corresponding ventricles. The valve between the right atrium and the right ventricle is the tricuspid valve. The valve between the left atrium and the left ventricle is the mitral valve. The pulmonary valve is at the opening of the pulmonary artery. The aortic valve is at the opening of the aorta. 
         [0008]    At the beginning of ventricular diastole (i.e., ventricular filling) (see  FIG. 2 ), the aortic and pulmonary valves are closed to prevent back flow from the arteries into the ventricles. Shortly thereafter, the tricuspid and mitral valves open (as  FIG. 2  shows), to allow flow from the atriums into the corresponding ventricles. Shortly after ventricular systole (i.e., ventricular emptying) begins, the tricuspid and mitral valves close (see  FIG. 3 )—to prevent back flow from the ventricles into the corresponding atriums—and the aortic and pulmonary valves open—to permit discharge of blood into the arteries from the corresponding ventricles. 
         [0009]    The opening and closing of heart valves occur primarily as a result of pressure differences. For example, the opening and closing of the tricuspid valve occurs as a result of the pressure differences between the right atrium and the right ventricle. During ventricular diastole, when ventricles are relaxed, the return of carbon dioxide rich blood from the superior and inferior vena cava into the right atrium causes the pressure in the atrium to exceed that in the ventricle. As a result, the tricuspid valve opens, allowing blood to enter the ventricle. As the ventricle contracts during ventricular systole, the intraventricular pressure rises above the pressure in the atrium and pushes the tricuspid valve shut. 
         [0010]    The tricuspid and mitral valves are defined by fibrous rings of collagen, each called an annulus, which forms a part of the fibrous skeleton of the heart. The annulus provides attachments for the three cusps or leaflets of the tricuspid valve (called the anterior, posterior, and septal leaflets) and the two cusps or leaflets of the mitral valve (called the anterior and posterior leaflets). The leaflets receive chordae tendineae from more than one papillary muscle. In a healthy heart, these muscles and their tendinous chords support the mitral and tricuspid valves, allowing the leaflets to resist the high pressure developed during contractions (pumping) of the left and right ventricles.  FIG. 5  shows the chordae tendineae and papillary muscles in the right ventricle that support the tricuspid valve. 
         [0011]    As seen in  FIGS. 5 and 6 , the tricuspid valve complex consists of the three leaflets, chordae tendineae, two main papillary muscles, the tricuspid annulus, and the right atrial and right ventricular myocardium. Successful valve function depends on the integrity and coordination of these components. Of the three tricuspid valve leaflets, the anterior leaflet is generally the largest and the posterior leaflet is notable for the presence of multiple scallops. The anterior papillary muscle provides chordae to the anterior and posterior leaflets. The medial papillary muscle provides chordae to the posterior and septal leaflets. The septal wall gives chordae to the anterior and septal leaflets (note that there is no formal septal papillary muscle as with the anterior and posterior papillary muscles). The small septal wall leaflet is fairly fixed and there is little room for compensation/movement if the free wall of right ventricle/tricuspid annulus should dilate. 2  Dilation of the tricuspid annulus therefore primarily occurs in the anterior/posterior (mural) aspect (see  FIG. 7 ). 3    
         [0012]    Other important factors influencing the degree of tricuspid regurgitation include the right ventricular preload, afterload and right ventricular function. The tricuspid annulus is dynamic and there is approximately a nineteen percent reduction in annular circumference (approximately thirty percent reduction in annular area) with atrial systole. 4, 5    
         [0013]    A 3-dimensional (3D) echocardiographic study has shown that the tricuspid annulus has a complicated 3D geometry (see  FIG. 8 ), distinct from the simpler “saddle shape” of the mitral annulus. In patients with functional tricuspid regurgitation, the tricuspid annulus is generally more dilated in the septal-lateral direction, resulting in a more circular shape than in healthy subjects. 4    
         [0014]    As  FIGS. 2 and 3  show, the anterior portion of the mitral valve annulus is intimate with the non-coronary leaflet of the aortic valve. As  FIGS. 2 and 3  also show, the mitral valve annulus is also near other critical heart structures, such as the circumflex branch of the left coronary artery (which supplies the left atrium, a variable amount of the left ventricle, and in many people the SA node) and the AV node (which, with the SA node, coordinates the cardiac cycle). 
         [0015]    Also in the vicinity of the posterior mitral valve annulus is the coronary sinus and its tributaries. These vessels drain the areas of the heart supplied by the left coronary artery. The coronary sinus and its tributaries receive approximately 85% of coronary venous blood. The coronary sinus empties into the posterior of the right atrium, anterior and inferior to the fossa ovalis (see  FIG. 4 ). A tributary of the coronary sinus is called the great cardiac vein, which courses parallel to the majority of the posterior mitral valve annulus, and is superior to the posterior mitral valve annulus by an average distance of about 9.64+/−3.15 millimeters (Yamanouchi, Y, Pacing and Clinical Electrophysiology 21(11):2522-6; 1998). 
       II. Characteristics and Causes of Tricuspid Valve Dysfunction 
       [0016]    When the left ventricle contracts after filling with blood from the left atrium, the walls of the ventricle move inward and release some of the tension from the papillary muscle and chords. The blood pushed up against the under-surface of the mitral leaflets causes them to rise toward the annulus plane of the mitral valve. As they progress toward the annulus, the leading edges of the anterior and posterior leaflet come together forming a seal and closing the valve. In the healthy heart, leaflet coaptation occurs near the plane of the mitral annulus. The blood continues to be pressurized in the left ventricle until it is ejected into the aorta. Contraction of the papillary muscles is simultaneous with the contraction of the ventricle and serves to keep healthy valve leaflets tightly shut at peak contraction pressures exerted by the ventricle. 
         [0017]    In a healthy heart (see  FIG. 9 ), the dimensions of the tricuspid valve annulus create an anatomic shape and tension such that the leaflets coapt, forming a tight junction, at peak contraction pressures. Where the leaflets coapt at opposing sides of the annulus are called the leaflet commissures. 
         [0018]    Valve malfunction can result from the chordae tendineae (the chords) becoming stretched, and in some cases tearing. When a chord tears, the result is a leaflet that flails. Also, a normally structured valve may not function properly because of an enlargement of or shape change in the valve annulus, as shown in  FIG. 7 . This condition is referred to as a dilation of the annulus and generally results from heart muscle failure. In addition, the valve may be defective at birth or because of an acquired disease. 
         [0019]    Regardless of the cause, tricuspid valve dysfunction can occur when the leaflets do not coapt at peak contraction pressures (see  FIG. 10 ). As shown, the coaptation line of the three leaflets is not tight at ventricular systole. As a result, an undesired back flow of blood from the right ventricle into the right atrium can occur. 
         [0020]    The general causes of tricuspid valve pathology are secondary (74%), rheumatic (11%), congenital (9%), or other (endocarditis, leaflet tear/prolapse, chordal rupture, papillary muscle rupture [rare], or myxomatous degeneration of the tricuspid valve). 6  In North America, the most common cause of tricuspid valve disease is tricuspid regurgitation (TR) secondary to left heart pathology, such as mitral valve disease/regurgitation and left heart failure. 7  This is felt to result in right-sided pressure overload which results in right ventricular chamber enlargement, tricuspid annular dilation, and resultant TR. This mechanistic cascade led to the concept that treatment of the left-sided abnormality will result in secondary improvement or amelioration of TR. However, Dreyfus et al. have made the point that because this paradigm advocates treatment of proposed “primary” lesion only (i.e., mitral valve disease), this approach will not directly correct tricuspid annular dilation or right ventricular function, the major determinants of functional TR. 
         [0021]    Without treatment, TR may become worse over time leading to severe symptoms, biventricular heart failure and death. 8  It has been shown in a large retrospective echocardiographic analysis of 5223 subjects by Nath et al., that independent of echo-derived pulmonary artery systolic pressure, left ventricular ejection fraction, inferior vena cava size, and right ventricular size and function, survival is worse for patients with moderate and severe TR than for those with no TR (TR graded using Framingham Heart Study criteria). 9  In this series, the prevalence of TR in a Veterans Administration population was: no TR, 11.5%; mild TR, 68.8%; moderate TR, 11.8%; and severe TR, 3.8%. 
         [0022]    The prevalence of TR from pacemaker leads is as yet poorly defined, but is likely more significant and prevalent than currently perceived. In a recent report by Kim et al., the effect of transtricuspid permanent pacemaker (PPM) or implantable cardiac defibrillator (ICD) leads on 248 subjects with echocardiograms before and after device placement was studied. The authors found that TR worsened by 1 grade or more after implant in 24.2% of subjects, and that TR worsening was more common with ICDs than PPMs with baseline mild TR or less. 10  Residual and recurrent TR after surgical tricuspid annuloplasty is common and occurs in 14% of patients early after operation for all types of annuloplasty. 8  Five years after successful TV repair, 42% of patients with a pacemaker had severe TR, almost double those without the device. This suggests removing the transtricuspid lead and replacing it with an epicardial lead at the time of TV surgery may reduce late repair failure. 1    
         [0023]    There are numerous reports describing the presence of TR in patients undergoing surgery for mitral regurgitation. The prevalence of TR in the postoperative period depends to some degree on the mechanism of MR. Matsuyama et al. reported in a study of 790 patients that only 16% of patients who underwent nonischemic (i.e., degenerative) mitral valve surgery without tricuspid valve surgery developed 3 to 4+ TR at 8 year follow-up. 11  Conversely, TR appears to be prevalent in patients undergoing mitral valve repair for functional ischemic mitral regurgitation. In the series by Matsunaga et al., of 70 patients undergoing MV repair for functional ischemic mitral regurgitation, 30% (21/70) of patients had at least moderate TR before surgery. In the postoperative period, the prevalence of at least moderate TR increased over time from 25% at less than one year, 53% at 1 to 3 year, and 74% at greater than 3 year follow-up. 12    
         [0024]    Significant tricuspid valve insufficiency may also contribute to a poor hemodynamic result even after successful mitral valve repair. In one early series by King et al., patients requiring subsequent tricuspid valve surgery after MV surgery had high early and late mortality. The authors encouraged a policy of liberal use of tricuspid annuloplasty at initial mitral valve surgery. 13  Accordingly, 50-67% of patients undergoing surgery for mitral valve disease have been reported to undergo concomitant surgical TV repair or replacement. 1, 6  Investigators have also attempted to identify specific patient subsets that should have TV repair/replacement at the time of MV repair/replacement. 
         [0025]    It has been proposed that at the time of MV repair, the presence of tricuspid annular dilation (≧70 mm measured intraoperatively) even in the absence of significant TR should be an indication for TV annuloplasty. This paper also showed that TR increased by at least 2 grades in 45% of the patients who received isolated MVR, supporting the notion that tricuspid dilation is an ongoing, progressive process that often warrants preemptive surgical treatment. 14    
         [0026]    In the series by Singh and colleagues, tricuspid valve repair appears to result in improved mid-term survival (up to 10 years after surgery, primarily due to higher perioperative mortality with replacement) as compared with TV replacement, although there was no difference in valve-related mortality or need for TV reoperation.) The authors hypothesized that the higher perioperative mortality with replacement may have been due to a rigid object (TV valve) in a deformable low-pressure cavity (right ventricle, RV), with resultant RV dysfunction and perioperative low output state. Although patients in this series had less recurrent TR with replacement vs. repair (95% vs. 62% had mild or less TR at most recent echocardiographic follow-up), there was no difference in functional class in either group. 
         [0027]    Other surgical series have shown that successful tricuspid valve repair (primarily when combined with other valve surgeries) resulted in a significant improvement in recurrent TR, survival, and event-free survival. 
       III. Prior Treatment Modalities 
       [0028]    Multiple percutaneous therapies are now available or under development for the treatment of aortic, mitral and pulmonic valve disease. In contrast, there has been little discussion regarding percutaneous approaches to tricuspid valve repair. Despite the fact that tricuspid regurgitation (TR) can result in significant symptoms, it is rare for patients to be referred for isolated surgical tricuspid valve repair given the morbidity and mortality of surgery. 
         [0029]    The presence of tricuspid regurgitation is often underdiagnosed and surgically ignored. Re-operations for recurrent TR are also felt to be high risk surgical procedures (˜37% in-hospital mortality) and are therefore not offered to many patients. 1  In this era of percutaneous valve repair and replacement, the relevance and potential need for the percutaneous treatment of TR should be considered. 
         [0030]    The need remains for a simple, cost effective, and less invasive devices, systems, and methods for treating dysfunction of a heart valve, e.g., in the treatment of tricuspid valve regurgitation. 
       SUMMARY OF THE INVENTION 
       [0031]    The invention comprises devices, systems, and methods for reshaping a heart valve annulus. 
         [0032]    One aspect of the invention provides a method of placing an implant within a heart chamber. The method can comprise deploying a guide wire in an intravascular path that extends from a first vascular access into a heart chamber and from the heart chamber to a second vascular access site different than the first vascular access site, the guide wire having a first end extending beyond the first vascular access site and a second end extending beyond the second vascular access site, coupling the implant to one end of the guide wire, and pulling on the other end of the guide wire to pull the implant along at least a portion of the intravascular path into the heart chamber. 
         [0033]    The method may include placing the implant in tension within the heart chamber. In one embodiment, the heart chamber can comprise the right atrium. The implant may comprise, for example, a metallic material or polymer material or a metallic wire form structure or a polymer wire form structure or suture material or equine pericardium or porcine pericardium or bovine pericardium or preserved mammalian tissue. 
         [0034]    Another aspect of the invention provides a system comprising an implant sized and configured for placement within a heart chamber, a guide wire sized and configured for deployment in an intravascular path that extends from a first vascular access into the heart chamber and from the heart chamber to a second vascular access site different than the first vascular access site, the guide wire having a first end extending beyond the first vascular access site and a second end extending beyond the second vascular access site, and a connector to connect an end of the implant to one end of the guide wire such that pulling on the other end of the guide wire pulls the implant along at least a portion of the intravascular path into the heart chamber. The bridge element may comprise, for example, a metallic material or polymer material or a metallic wire form structure or a polymer wire form structure or suture material or equine pericardium or porcine pericardium or bovine pericardium or preserved mammalian tissue. 
         [0035]    Other features and advantages of the invention shall be apparent based upon the accompanying description, drawings, and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  is an anatomic anterior view of a human heart, with portions broken away and in section to view the interior heart chambers and adjacent structures. 
           [0037]      FIG. 2  is an anatomic superior view of a section of the human heart showing the tricuspid valve in the right atrium, the mitral valve in the left atrium, and the aortic valve in between, with the tricuspid and mitral valves open and the aortic and pulmonary valves closed during ventricular diastole (ventricular filling) of the cardiac cycle. 
           [0038]      FIG. 3  is an anatomic superior view of a section of the human heart shown in  FIG. 2 , with the tricuspid and mitral valves closed and the aortic and pulmonary valves opened during ventricular systole (ventricular emptying) of the cardiac cycle. 
           [0039]      FIG. 4  is an anatomic anterior perspective view of the left and right atriums, with portions broken away and in section to show the interior of the heart chambers and associated structures, such as the fossa ovalis, coronary sinus, and the superior and inferior vena cava. 
           [0040]      FIG. 5  is an anatomic anterior view of a human heart with portions broken away and in section to show the interior of the right atrium and right ventricle, and associated muscle and chord structures coupled to the tricuspid valve. 
           [0041]      FIG. 6  is a superior view of a healthy tricuspid valve, with the leaflets closed and coapting at peak contraction pressures during ventricular systole. 
           [0042]      FIG. 7  is a superior view of a dysfunctional tricuspid valve, and showing the common progression of an enlarged and/or dilated annulus, which causes the leaflets to fail to coapt during peak contraction pressures during ventricular systole, leading to tricuspid regurgitation. 
           [0043]      FIG. 8  is a three dimensional view of the tricuspid annulus showing its complicated shape. 
           [0044]      FIG. 9  is an anatomic superior view of a section of the human heart, with the normal tricuspid valve shown in  FIG. 6  closed during ventricular systole (ventricular emptying) of the cardiac cycle. 
           [0045]      FIG. 10  is a superior view of a dysfunctional tricuspid valve, with the leaflets failing to coapt during peak contraction pressures during ventricular systole, leading to tricuspid regurgitation. 
           [0046]      FIG. 11A  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an implant system that includes an inter-atrial bridging element that spans the tricuspid valve annulus, with a superior bridge stop positioned in the superior vena cava and an inferior bridge stop positioned in the inferior vena cava, the inter-atrial bridging element extending in an essentially straight path generally across the tricuspid valve. 
           [0047]      FIG. 11B  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an implant system that includes an inter-atrial bridging element that spans the tricuspid valve annulus, with a superior bridge stop positioned on the inter-atrial septum and an inferior bridge stop positioned in the inferior vena cava, the inter-atrial bridging element extending in an essentially straight path generally across the tricuspid valve. 
           [0048]      FIG. 11C  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an implant system that includes an inter-atrial bridging element that crosses through the base of the leaflet/annulus, with a superior bridge stop positioned on the ventricle side of the tricuspid valve and an inferior bridge stop positioned in the inferior vena cava, the inter-atrial bridging element extending in an essentially straight path through the base of the leaflet/annulus. 
           [0049]      FIG. 11D  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an implant system that includes an inter-atrial bridging element that crosses through the base of the leaflet/annulus, with a superior bridge stop positioned on the inter-atrial septum and an inferior bridge stop positioned on the ventricle side of the tricuspid valve, the inter-atrial bridging element extending in an essentially straight path generally through the base of the leaflet/annulus. 
           [0050]      FIG. 11E  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an implant system that includes an inter-atrial bridging element that spans the tricuspid valve annulus and crosses through the base of the leaflet/annulus, with a superior bridge stop positioned in the superior vena cava, an inferior bridge stop positioned in the inferior vena cava, and ventricle bridge stop positioned on the ventricle side of the tricuspid valve, the inter-atrial bridging element extending in a generally “V” path from the superior bridge stop to the inferior bridge stop, and from the inferior bridge stop to the ventricle bridge stop. 
           [0051]      FIG. 11F  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an implant system that includes an inter-atrial bridging element that twice crosses through the base of the leaflet/annulus, with a superior bridge stop positioned in the superior vena cava, an inferior bridge stop positioned in the inferior vena cava, and a ventricle bridge stop positioned on the ventricle side of the tricuspid valve, the inter-atrial bridging element extending in a generally “V” path from the superior bridge stop to the ventricle bridge stop, and from the ventricle bridge stop to the inferior bridge stop. 
           [0052]      FIG. 11G  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an implant system that includes two inter-atrial bridging element that spans the tricuspid valve annulus, with a superior bridge stop positioned in the superior vena cava and an inferior bridge stop positioned in the inferior vena cava, the first inter-atrial bridging element extending in an essentially straight path generally across the tricuspid valve, and a superior bridge stop positioned on the inter-atrial septum and an inferior bridge stop positioned on the ventricle side of the tricuspid valve, the inter-atrial bridging element extending in an essentially straight path generally through the base of the leaflet/annulus. 
           [0053]      FIG. 12A  is a side view of a bridge stop adapted for use in or on the inter-atrial septum, which may be used as part of the implant system of the type shown in  FIGS. 11A through 11G . 
           [0054]      FIG. 12B  is a side view of a deployed bridge stop of the type shown in  FIG. 12A , showing the bridge stop sandwiching portions of the septum through an existing hole. 
           [0055]      FIG. 13  is a perspective view of a bridge stop configuration adapted for use in the vena cava and/or the coronary sinus, the bridge stop including an attachment point to attach the bridging element to the bridge stop. 
           [0056]      FIG. 14A  is a perspective view of a bridge stop configuration adapted for use in the ventricular tissue at or near the tricuspid valve annulus, the bridge stop configuration comprising a cork screw tissue anchor. 
           [0057]      FIG. 14B  is a perspective view of an alternative embodiment of a bridge stop configuration adapted for use in the ventricular tissue at or near the tricuspid valve annulus. 
           [0058]      FIG. 15  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an alternative implant system that includes a supra-annular leaflet based device and associated inter-atrial bridging element, the leaflet based device spans the tricuspid valve and allows free passage of blood from the right atrium into the right ventricle during diastole but deflects/stops tricuspid regurgitant flow during systole, the leaflet based device being shown supported by a superior bridge stop positioned on the inter-atrial septum and an inferior bridge stop positioned in the inferior vena cava. 
           [0059]      FIG. 16A  is a perspective view of a leaflet based device as shown in  FIG. 15 . 
           [0060]      FIG. 16B  is a perspective view of an alternative non-leaflet based device that may be used with the system as shown in  FIG. 15 . 
           [0061]      FIG. 16C  is a perspective view of an alternative embodiment of a leaflet based device as shown in  FIG. 15 , the device including a skirt adapted to be coupled to the tricuspid valve annulus to provide a seal around the device. 
           [0062]      FIG. 17  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of an alternative implant system that includes an atrial-ventricle bridging element that crosses through the base of the leaflet/annulus, with at least two bridge stops positioned on the ventricle side of the tricuspid valve, the atrial-ventricle bridging element extending up through the base of the leaflet/annulus from one bridge stop and back down through the base of the leaflet/annulus to the other bridge stop. 
           [0063]      FIG. 18A  is an anatomic partial view of a patient depicting multiple access points available for use during implantation of an implant system, and also showing a loop guide wire accessible exterior the body at two locations. 
           [0064]      FIG. 18B  is an anatomic partial view of a patient depicting multiple access points available for use during implantation of an implant system similar to  FIG. 18A , and showing the use of a first catheter and a second catheter access through the left and right femoral veins. 
           [0065]      FIG. 19  is anatomic anterior perspective view of the right atrium and right ventricle, with portions broken away and in section to show the presence of representative catheter-based devices for implanting one or more systems of the types shown in  FIGS. 11A to 11G , and showing previously deployed bridge stops and a bridging element extending between a bridge stop in the superior vena cava and a bridge stop in the inferior vena cava. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0066]    Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
       I. Trans-Annular Implants for Direct Shortening of Selected Dimensions of a Heart Valve Annulus 
       [0067]    A. Implant Configurations 
         [0068]      FIGS. 11A to 11G  show various embodiments of an implant  10  that is sized and configured to extend across or through portions of the right atrium, thereby spanning and/or affecting the tricuspid valve annulus to allow shortening of selected trans-annular dimensions. 
         [0069]    The implant  10  comprises a spanning region or bridging element  12  having at least a first bridge stop region and a second bridge stop region, which can comprise a variety of locations. Tensioning the bridging element would result in a reduction of trans-annular dimensions and improved leaflet coaption with consequent tricuspid regurgitation reduction. 
         [0070]    1. Bridging Element 
         [0071]    In its most basic form, the bridge  12  is made from a biocompatible metallic or polymer material, or a metallic or polymer material that is suitably coated, impregnated, or otherwise treated with a material to impart biocompatibility, or a combination of such materials. The material is also desirably radio-opaque or incorporates radio-opaque features to facilitate fluoroscopic visualization. 
         [0072]    The bridge  12  can be formed by bending, shaping, joining, machining, molding, or extrusion of a metallic or polymer wire form structure, which can have flexible or rigid, or inelastic or elastic mechanical properties, or combinations thereof. Alternatively, the bridge  12  can be formed from metallic or polymer thread-like or suture material. Materials from which the bridge  12  can be formed include, but are not limited to, stainless steel, Nitinol, titanium, silicone, plated metals, Elgiloy™, NP55, and NP57. 
         [0073]    The bridge  12  can take various shapes and have various cross-sectional geometries. The bridge  12  can have, e.g., a generally curvilinear (i.e., round or oval) cross-section, or a generally rectilinear cross section (i.e., square or rectangular), or combinations thereof. Shapes that promote laminar flow and therefore reduce hemolysis are contemplated, with features such as smoother surfaces and longer and narrower leading and trailing edges in the direction of blood flow. 
         [0074]    In use, the spanning region or bridging element  12  can be placed into tension between two or more bridge stop regions. The implant  10  thereby serves to apply a direct mechanical force generally in an anterior to posterior direction across the right atrium, although other directions are also possible. The direct mechanical force can serve to shorten the minor axis (line A-P in  FIG. 10 ) of the annulus. In doing so, the implant  10  can also reactively reshape the annulus along its major axis (line S-L in  FIG. 10 ) and/or reactively reshape other surrounding anatomic structures. It should be appreciated, however, the presence of the implant  10  can serve to stabilize tissue adjacent the heart valve annulus, without affecting the length of the minor or major axes. 
         [0075]    It should also be appreciated that, when situated in other valve structures, the axes affected may not be the “major” and “minor” axes, due to the surrounding anatomy. In addition, in order to be therapeutic, the implant  10  may only need to reshape the annulus during a portion of the heart cycle, such as during late diastole and early systole when the heart is most full of blood at the onset of ventricular systolic contraction, when most of the tricuspid valve leakage occurs. For example, the implant  10  may be sized to restrict outward displacement of the annulus during late ventricular diastolic relaxation as the annulus dilates. 
         [0076]    The mechanical force applied by the implant  10  across the right atrium can restore to the heart valve annulus and leaflets a more normal anatomic shape and tension. The more normal anatomic shape and tension are conducive to coaptation of the leaflets during late ventricular diastole and early ventricular systole, which, in turn, reduces tricuspid regurgitation. 
         [0077]    2. Bridge Stop Regions 
         [0078]    Bridge stop regions can vary depending on the desired affect on the tricuspid valve annulus. The interatrial septum (A), the inferior vena cava (B), the superior vena cava (C), the right ventricle (D), and the coronary sinus (E) provide practical sites for bridge stop regions, i.e., for the placement of a bridge stop. Each is further described below. 
         [0079]    Location of the implant  10  in a supra-annular level within the right atrium, e.g., in the septum and a vena cava, and possibly in the ventricle, not only provides freedom from key vital structure damage or local impingement—e.g., to the right coronary artery, AV node, and the right coronary and non-coronary cusps of the aortic valve—but the supra-annular focused sites are also not reliant on purchase between tissue and direct tension-loaded penetrating/biting/holding tissue attachment mechanisms. Instead, physical structures and force distribution mechanisms such as bridge stops including, for example, stents, T-shaped members, and septal members can be used, which better accommodate the attachment or abutment of mechanical levers and bridge locks, and through which potential tissue tearing forces can be better distributed. 
         [0080]    Further, the bridge stop sites do not require the operator to use complex imaging due to radio-opaque bridge stops and well demarcated fluoroscopic landmarks. Adjustment of implant position after or during implantation is also facilitated, free of these constraints. These bridge stop sites also make possible full intra-atrial retrieval of the implant  10 . 
         [0081]    i. Interatrial Septum 
         [0082]    One possible bridge stop region A comprises a posterior bridge stop region which may be adjacent or abutting a region of fibrous tissue in the interatrial septum. As shown, the bridge stop site A is desirably superior to the posterior tricuspid annulus. In the illustrated embodiment, the bridge stop region A is adjacent to or near the inferior rim of the fossa ovalis. Alternatively, the bridge stop region A can be located at a more superior position in the septum, e.g., at or near the superior rim of the fossa ovalis. The bridge stop region A can also be located in a more superior or inferior position in the septum, away from the fossa ovalis, provided that the bridge stop site does not harm the septal tissue region and surrounding structures. 
         [0083]    The fibrous tissue in this region provides superior mechanical strength and integrity compared with muscle and can better resist a device pulling through. The septum is the most fibrous tissue structure in its own extent in the heart. Surgically handled, it is usually one of the only heart tissues into which sutures actually can be placed and can be expected to hold without pledgets or deep grasps into muscle tissue, where the latter are required. 
         [0084]    ii. Inferior Vena Cava 
         [0085]    Another possible bridge stop region B comprises the inferior vena cava. The inferior vena cava B conveys blood to the heart received from the lower half of the body, and terminates near the lower posterior portion of the right atrium. The bridge stop region B provides percutaneous access and presents more tissue mass for obtaining purchase for a bridge stop site. 
         [0086]    iii. Superior Vena Cava 
         [0087]    Another possible bridge stop region C comprises the superior vena cava. The superior vena cava conveys blood to the heart received from the upper half of the body, and is a short trunk, ranging in length from about two plus inches to about three inches. As with the bridge stop region B, the bridge stop region C also provides percutaneous access and presents more tissue mass for obtaining purchase for a bridge stop site. 
         [0088]    iv. Right Ventricle 
         [0089]    Yet another possible bridge stop region D comprises the ventricular side of the base of the tricuspid leaflets. This area provides a site where tissue (please describe the type of tissue) can be readily augmented and consolidated for obtaining purchase for a bridge stop site. 
         [0090]    iv. Coronary Sinus 
         [0091]    Yet another possible bridge stop region E comprises the coronary sinus. The orifice of the coronary sinus is generally superior to the septal leaflet of the tricuspid valve. The coronary sinus runs transversely in a groove between the left atrium and ventricle on the posterior surface of the heart. The bridge stop region E also provides percutaneous access and presents more tissue mass for obtaining purchase for a bridge stop site. 
         [0092]    3. Bridge Stops 
         [0093]    It is to be appreciated that a bridge stop as described herein, including a bridge stop adapted for use at bridge stop sites A, B, C, D, and E describes an apparatus that may releasibly hold the bridging element  12  in a tensioned state. The bridge stop(s) may be adapted to allow the bridging element  12  to move independent of the bridge stop sites during a portion of the cardiac cycle when the tension force may be reduced or becomes zero. Alternative embodiments are also described, all of which may provide this function. It is also to be appreciated that the general descriptions of posterior, anterior, superior, and inferior are non-limiting to the bridge stop function or site, i.e., a posterior bridge stop may be used anterior, and an anterior bridge stop may be used posterior. 
         [0094]    Bridge stops may be symmetrically shaped or asymmetrically shaped. A symmetrically shaped or asymmetrically shaped bridge stop may be chosen for its use in selecting application of forces differentially and preferentially, i.e, forces or tension on different points along the tricuspid annulus to optimize treatment, such as in cases of malformed or asymmetrical tricuspid valves. 
         [0095]    i. Interatrial Septal Bridge Stop 
         [0096]    The purchase of the posterior bridge stop region A in fibrous interatrial septal tissue is desirably enhanced by one or more septal member(s)  30 .  FIGS. 11B, 11D, and 11G  show the posterior bridge stop region A including the septal member  30 . The septal member  30  may be a percutaneously placed expandable tissue and bridging element attachment device, and also may be a commercially available device such as a septal occluder, e.g., Amplatzer® PFO Occluder (see  FIGS. 12A and 12B ). The septal member  30  may have a small attachment point  31  for the bridge  12  to connect to or to pass through. 
         [0097]    The septal member  30  preferably mechanically amplifies the hold or purchase of the posterior bridge stop region A in the fibrous tissue site. The septal member  30  also desirably increases reliance, at least partly, on neighboring anatomic structures of the septum to make firm the position of the implant  10 . In addition, the septal member  30  may also serve to plug or occlude a small aperture created in the fossa ovalis or surrounding area during the implantation procedure. 
         [0098]    Anticipating that pinpoint pulling forces will be applied by the posterior bridge stop region A to the septum, the forces acting on the septal member  30  should be spread over a moderate area, without causing impingement on valve, vessels or conduction tissues. With the pulling or tensioning forces being transmitted down to the annulus, shortening of the minor axis is achieved. 
         [0099]    A flexurally stiff septal member is preferred because it will tend to cause less focal narrowing in the direction of bridge element tension of the right atrium as tension on the bridging element is increased. The septal member  30  should also have a low profile configuration and highly washable surfaces to diminish thrombus formation for devices deployed inside the heart. The septal member may also have a collapsed configuration and a deployed configuration. 
         [0100]    ii. Vena Cava Bridge Stop 
         [0101]    One or more vena cava bridge stop(s)  40  may be included as part of the implant  10 , i.e., an inferior vena cava bridge stop  40  and a superior vena cava bridge stop  40 . Both the inferior vena cava bridge stop site B and the superior vena cava bridge stop site C provide a percutaneously accessible and stable site for the placement of a vena cava bridge stop  40 . The vena cava bridge stops  40  may be used independently, as seen in  FIG. 11A , or in combination with the septal member  30 , as seen in  FIGS. 11B and 11G . 
         [0102]    A vena cava bridge stop  40  may be a percutaneously placed expandable device and also may be a commercially available device such as a traditional stent  40 , as shown in  FIG. 13 , or it may be of a variety of other configurations or materials. The vena cava bridge stop  40  includes an attachment point  42  to attach the bridging element  12  to the bridge stop. 
         [0103]    iii. Ventricle Bridge Stop 
         [0104]    One or more ventricle bridge stop(s)  46  may also be included as part of the implant  10 , and may be adapted to be placed percutaneously. In this configuration, the implant  10  includes the bridging element  12  crossing through the base of the leaflet/annulus from the ventricular to atrial side, then being attached to one or more of the bridge stops  46  at the bridge stop sites described above. For example, see  FIGS. 11C through 11G . 
         [0105]    The ventricle bridge stop may include multiple configurations (see  FIGS. 14A and 14B ). As seen in  FIG. 14A , the bridge stop  46  comprises a cork screw type of configuration for securement in ventricular tissue at or near the tricuspid annulus. The ventricle bridge stop  46  includes an attachment point  48  to attach the bridging element  12  to the bridge stop.  FIG. 14B  shows an additional embodiment of a ventricle bridge stop  50  including an attachment point  52 . (If there are other options for ventricle bridge stops, please describe). 
         [0106]    D. Orientation of the Bridging Element 
         [0107]    In the embodiments shown in  FIGS. 11A, 11B , and  11 G, the implant  10  is shown to span the right atrium beginning at a superior point of focus in the septum or superior vena cava posterior to the approximate mid-point of the tricuspid valve annulus, and proceeding in an inferior direction in a generally straight path directly to the region of anterior focus in the inferior vena cava or right ventricle. 
         [0108]    The spanning region or bridging element  12  of the implant  10  may be preformed or otherwise configured to extend in this essentially straight path above the plane of the valve, without significant deviation in depth toward or away from the plane of the annulus, other than as dictated by any difference in depth between the superior and inferior regions of placement. 
         [0109]    Lateral or medial deviations and/or superior or inferior deviations in this path can be imparted, if desired, to affect the nature and direction of the force vector or vectors that the implant  10  applies. It should be appreciated that the spanning region or bridging element  12  can be preformed or otherwise configured with various medial/lateral and/or inferior/superior deviations to achieve targeted annulus and/or atrial structure remodeling, which takes into account the particular therapeutic needs and morphology of the patient. In addition, deviations in the path of the bridging element may also be imparted in order to avoid the high velocity blood path within a heart chamber, such as the left atrium. 
         [0110]    Regardless of the orientation, more than one implant  10  can be installed to form an implant system  22 . For example,  FIG. 11G  shows a system  22  comprising a lateral implant  10 L and a medial implant  10 M of a type consistent with the implant  10  as described.  FIG. 11G  shows the implants  10 L and  10 M being located at individual superior and inferior bridge stop regions. It should be appreciated that the implants  10 L and  10 M can also include a common superior or inferior bridge stop region. 
       II. Supra-Annular Leaflet Treatment of Tricuspid Regurgitation 
       [0111]    This technique would allow the placement of a leaflet-based device  60  directly above the tricuspid valve (see  FIG. 15 ), which would allow free passage of blood from the right atrium into the right ventricle during diastole but would deflect/stop tricuspid regurgitant flow during systole. 
         [0112]    This device  60  would not replace the existing tricuspid valve, and the native leaflets would remain essentially intact. The device  60  could have moving elements  62 , similar to a mechanical or bioprosthetic valve leaflet (see  FIG. 16A ). Alternately, a device  66  could comprise a generally non-mobile fixed component(s) that would specifically deflect an eccentric regurgitant jet. Either device  60 ,  66  could be anchored to the tricuspid annulus directly or to one or more bridge stop sites previously described. The supra-annular device  60  could also have a “skirt”  64  or other feature that would attach to the annulus via sutures, for example, and form a seal, making the device more of a true supra-annular valve replacement. 
         [0000]    III. Percutaneous Bicuspidalization with Combined Edge-to-Edge Approach 
         [0113]    This percutaneous bicuspidalization with combined edge-to-edge approach mimics a surgical technique of bicuspidalization tricuspid annuloplasty for the treatment of functional TR (Ghanta, et al). The surgical technique involves placement of a pledget-supported mattress suture from the anteroposterior commissure to the posteroseptal commissure along the posterior annulus. This technique is based on prior studies by DeLoche et al. that posterior annulus dilation occurs in functional TR and that a focal posterior tricuspid annuloplasty should be effective in most cases. 
         [0114]    The percutaneous approach to this technique involves placement of one or more percutaneously placed anchors  46 , for example, that are located on the ventricular side D of the base of the tricuspid leaflets. They will be positioned and placed using catheter techniques, with a connecting bridge  12  crossing through the base of the leaflet/annulus from the ventricular to atrial side. The bridge  12  can be coupled to the other subleaflet anchor and result in partial annuloplasty akin to the surgical procedure (see  FIG. 17 ). It may also be necessary to combine this technique or the aforementioned trans-annular shortening technique with an edge-to-edge leaflet repair, with the selected portions of the leaflets being apposed with suture, clips or other mechanisms (edge to edge for TR described surgically by Castedo et al.) In some cases, an edge-to edge repair approach without annuloplasty may also be effective. 
       IV. General Methods of System Implantation 
       [0115]    The implants  10  or implant systems  22  as just described lend themselves to implantation in a heart or heart chamber in various ways. The implants  10  or implant systems  22  can be implanted, e.g., in an open heart surgical procedure. Alternatively, the implants  10  or implant systems  22  can be implanted using catheter-based technology via a peripheral venous access site, such as in the femoral or jugular vein (via the inferior vena cava and/or superior vena cava) under image guidance (see  FIGS. 18A and 18B . 
         [0116]    Alternatively, the implants  10  or implant systems  22  can be implanted using thoracoscopic means through the chest, or by means of other surgical access to the right atrium, also under image guidance. Image guidance includes but is not limited to fluoroscopy, ultrasound, magnetic resonance, computed tomography, or combinations thereof. 
         [0117]    The implants  10  or implant systems  22  may comprise independent components that are assembled within the body to form an implant, or alternatively, independent components that are assembled exterior the body and implanted as a whole. 
         [0118]    Catheter access to the right atrium can be achieved through either a femoral vein to inferior vena cava or superior vena cava route or an upper extremity or neck vein to SVC or inferior vena cava route. In the case of the superior vena cava, the easiest access is from the upper extremity or neck venous system; however, the inferior vena cava can also be accessed by passing through the superior vena cava and right atrium. Similarly the easiest access to the inferior vena cava is through the femoral vein; however the superior vena cava can also be accessed by passing through the inferior vena cava and right atrium.  FIG. 18A  shows access through both a superior vena cava route and an inferior vena cava route, and includes a loop guide wire.  FIG. 18B  shows access through both the left femoral vein and the right femoral vein, without the loop guide wire. It is to be appreciated that other access configurations are possible. 
         [0119]    By way of example,  FIG. 18A  shows a representative embodiment of the deployment of an implant  10  of the type shown in  FIG. 11A  by a percutaneous, catheter-based procedure, under image guidance. Percutaneous vascular access is achieved by conventional methods into the femoral or jugular vein, or a combination of both (as shown). Under image guidance, a loop guide wire  74  is first passed through the vasculature and includes a distal end and a proximal end, both available external the body. A first catheter  70  and a second catheter  80  are then steered over the guide wire and through the vasculature into the right atrium. It may be a function of the first catheter  70  and second catheter  80  to establish the bridge stop regions. 
         [0120]    A first implantation step can be generally described as establishing the superior bridge stop region C and the inferior bridge stop region B. As can be seen in  FIG. 19 , the first catheter  70  is steered through the vasculature into the superior vena cava (or inferior vena cava). The second catheter  80  may also be steered through the vasculature and into the inferior vena cava (or superior vena cava). Once the first catheter  70  and the second catheter  80  are in their respective positions in the superior vena cava and the inferior vena cava, it is a function of the catheters  70 ,  80  to configure the bridge stop region C and B, i.e., deploy their respective bridge stops  40 . 
         [0121]    A second step can be generally described as establishing the bridging element  12 . In one embodiment, the deployment catheter  80  may be used to deploy the superior vena cava bridge stop  40 . Desirably, a pre-attached and predetermined length of bridging element  12  is coupled to the attachment point  42  of the bridge stop  40 . The predetermined length of bridging element  12 , e.g., two meters, extends from the superior bridge stop  40 , through the right atrium, through the inferior vena cava, through the vasculature, and preferably remains accessible exterior the body. The predetermined length of bridging element  12  may be cut or detached in a future step, leaving implanted the portion extending from the superior bridge stop  40  to the inferior bridge stop  40 . 
         [0122]    With this configuration, the bridging element  12  must be passed through or around the attachment point  42  of the inferior vena cava bridge stop  40  before the bridge stop is deployed. This is simply achieved with the portion of the bridging element  12  extending exterior the body. The inferior vena cava bridge stop is now ready to be deployed. Alternatively, the inferior vena cava bridge stop may first be implanted, and then the bridging element  12  passed through or around its attachment point  42 . 
         [0123]    A third step can be generally described as adjusting the bridging element  12  for proper therapeutic effects. With the superior vena cava bridge stop region C, bridging element  12 , and inferior vena cava bridge stop region B configured as previously described, a tension is placed on the bridging element  12 . The implant  10  and associated regions may be allowed to settle for a predetermined amount of time, e.g., five or more seconds. The tricuspid valve and tricuspid valve regurgitation are observed for desired therapeutic effects. The tension on the bridging element  12  may be adjusted until a desired result is achieved. A bridge lock (not shown) is then allowed to secure the bridging element  12  to the attachment point  42  when the desired tension or measured length or degree of tricuspid regurgitation reduction is achieved. 
         [0124]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.