Percutaneous Transvenous Mitral Annuloplasty

Multimodality imaging for patient selection, procedural guidance, and follow-up of transcatheter interventions for structural heart disease: a consensus document of the EACVI Task Force on Interventional Cardiovascular Imaging: part 1: access routes, transcatheter aortic valve implantation, and transcatheter mitral valve interventions

Transcatheter therapies for the treatment of structural heart diseases (SHD) have expanded dramatically over the last years, thanks to the developments and improvements of devices and imaging techniques, along with the increasing expertise of operators. Imaging, in particular echocardiography, is pivotal during patient selection, procedural monitoring, and follow-up. The imaging assessment of patients undergoing transcatheter interventions places demands on imagers that differ from those of the routine evaluation of patients with SHD, and there is a need for specific expertise for those working in the cath lab. In the context of the current rapid developments and growing use of SHD therapies, this document intends to update the previous consensus document and address new advancements in interventional imaging for access routes and treatment of patients with aortic stenosis and regurgitation, and mitral stenosis and regurgitation.

Over 15 years: the advancement of transcatheter mitral valve repair

Patients with severe symptomatic mitral regurgitation, if left untreated, have a poor prognosis. In those patients not eligible for mitral valve (MV) surgery, percutaneous repair may improve clinical outcomes. In the past 15 years several devices have been developed to address different MV lesions. This manuscript will review the advancement of transcatheter MV repair through the years, focusing on technologies for which consistent clinical data is available.

Indirect Annuloplasty to Treat Functional Mitral Regurgitation: Current Results and Future Perspectives

The incidence of mitral regurgitation (MR) is approximately 1.7% in the developed world, and this increases to more than 10% in patients aged over 75 years. Functional (or secondary) mitral regurgitation (FMR) is defined as poor leaflet coaptation and tethering secondary to either ischemic or non-ischemic left ventricular (LV) dysfunction and dilatation. FMR is more common than degenerative (or primary) MR and is associated with significantly worse outcomes in patients with heart failure, post myocardial infarction and following coronary artery bypass graft surgery. Patients with severe degenerative MR have excellent outcomes with surgical repair, however the benefits of surgery in FMR are less clear. Although annuloplasty is associated with a lower operative mortality compared to replacement, the recurrence rate of mitral regurgitation is high in patients with FMR and neither surgical repair or replacement have been shown to reduce hospitalisation or death in FMR. Furthermore, nearly half of patients are deemed too high risk for surgery and therefore most patients are managed conservatively and there remains an unmet clinical need. Transcatheter mitral valve interventions are an emerging alternative for those at high surgical risk. This mini review focuses on indirect mitral annuloplasty: anatomical considerations, patient selection, current devices, implantation techniques and the associated clinical outcome data.

Transcatheter valve interventions in heart failure: new answers to old questions

Heart failure (HF) is often associated with different valve diseases, predominantly functional mitral and tricuspid regurgitation. However, the association between HF and aortic stenosis, particularly low-flow low-gradient aortic stenosis, is not infrequent. Severe mitral and tricuspid regurgitations, as well as aortic stenosis, in HF patients worsen prognosis and left ventricular dilatation and induce further reduction in left ventricular ejection fraction. Transcatheter edge-to-edge mitral and tricuspid valve repair and transcatheter aortic valve implantation could be an important therapeutic option with a satisfactory long-term outcome in HF patients with comorbidities and even in patients with severely depressed ejection fraction.

Percutaneous Mitral Valve Interventions and Heart Failure

Mitral regurgitation (MR) is the most frequent Valvular Heart Disease (VHD) and is an important cause of heart failure. MR can be caused by primary valve abnormality (Degenerative MR/Primary MR) or it can be secondary to cardiomyopathy (Functional MR/Secondary MR). Medical management alleviates symptoms but does not alter the progression of the disease. Current guidelines recommend surgery for moderate-to-severe (Grade > 3) MR in patients with symptoms or evidence of left ventricular dysfunction. Despite current practice guidelines, the majority of patients with severe MR do not undergo surgery. The reasons include high surgical risk from advanced age or multiple comorbidities, and a lack of clear data supporting valve surgery for secondary MR with LV dysfunction. The recent emergence of percutaneous interventional approaches in treating MR has expanded therapeutic options for patients who are at high risk for conventional Mitral Valve (MV) surgery. In this chapter, we will review the novel advancements in the field of percutaneous MV interventions that could potentially become the standard of care for patients with MR and heart failure.

Design, Analysis and Testing of a Novel Mitral Valve for Transcatheter Implantation

Mitral regurgitation is a common mitral valve dysfunction which may lead to heart failure. Because of the rapid aging of the population, conventional surgical repair and replacement of the pathological valve are often unsuitable for about half of symptomatic patients, who are judged high-risk. Transcatheter valve implantation could represent an effective solution. However, currently available aortic valve devices are inapt for the mitral position. This paper presents the design, development and hydrodynamic assessment of a novel bi-leaflet mitral valve suitable for transcatheter implantation. The device consists of two leaflets and a sealing component made from bovine pericardium, supported by a self-expanding wireframe made from superelastic NiTi alloy. A parametric design procedure based on numerical simulations was implemented to identify design parameters providing acceptable stress levels and maximum coaptation area for the leaflets. The wireframe was designed to host the leaflets and was optimised numerically to minimise the stresses for crimping in an 8 mm sheath for percutaneous delivery. Prototypes were built and their hydrodynamic performances were tested on a cardiac pulse duplicator, in compliance with the ISO5840-3:2013 standard. The numerical results and hydrodynamic tests show the feasibility of the device to be adopted as a transcatheter valve implant for treating mitral regurgitation.

Coronary Sinus-Based Approach to Mitral Regurgitation

Functional, or secondary, mitral regurgitation (FMR) is clinically important because patient with congestive heart failure with FMR have worse clinical outcomes and associated higher risks than patients without FMR. There is interest in finding repair techniques which may modify the mitral valve dysfunction and reduce the clinical impact. Although several devices have taken advantage of the close anatomical relationship between the coronary sinus and the posterior annulus of the mitral valve, in order to provide a cinching force on the mitral annulus, only the Carillon device is currently in use in humans. A double blind randomized trial is currently being done to evaluate the value of this therapy, building upon the favorable result of three prior safety and efficacy trials, which have led to European approval of the device.

Anatomical considerations of percutaneous transvenous mitral annuloplasty: a novel procedure for treatment of functional mitral regurgitation

Percutaneous transvenous mitral annuloplasty (PTMA) has evolved as a latest procedure for the treatment of functional mitral regurgitation. It reduces mitral valve annulus (MVA) size and increases valve leaflet coaptation via compression of coronary sinus (CS). Anatomical considerations for this procedure were elucidated in the present study. In 40 formalin fixed adult cadaveric human hearts, relation of the venous channel formed by CS and great cardiac vein (GCV) to MVA and the adjacent arteries was described, at 6 points by making longitudinal sections perpendicular to the plane of MVA, numbered 1-6 starting from CS ostium. CS/GCV formed a semicircular venous channel on the atrial side of MVA. Based on the distance of CS/GCV from MVA, two patterns were identified. In 37 hearts, the venous channel at point 2 was widely separated from the MVA compared to the two ends and in three hearts a nonconsistent pattern was observed. GCV crossed circumflex artery superficially. GCV or CS crossed the left marginal artery and ventricular branches of circumflex artery superficially in 17 and 23 hearts, respectively. As the venous channel was related more to the left atrial wall, PTMA devices probably exert an indirect traction on MVA. The arteries crossing deep to the venous channel may be compressed by PTMA device leading to myocardial ischemia. Knowledge of the spatial relations of MVA and a preoperative and postoperative angiogram may help to reduce such complications during PTMA.

Mitral valve anatomy: implications for transcatheter mitral valve interventions

Mitral regurgitation is a common valvular heart disease and its prevalence is expected to increase with population ageing. Percutaneous techniques for the treatment of mitral regurgitation are emerging as an alternative therapeutic option. However, the mitral valve is a complex structure, and a comprehensive understanding of the anatomy of the mitral valve apparatus and its surrounding structures is crucial for a correct selection of patients and the success of transcatheter mitral valve interventions.

Transcatheter mitral valve repair therapies for primary and secondary mitral regurgitation

Mitral regurgitation is one of the most prevalent valvular heart diseases and its prevalence is related to population aging. Elderly patients with age-associated co-morbidities have an increased risk for conventional mitral valve surgery. Transcatheter mitral valve repair has emerged as a feasible and safe alternative in patients with contraindications for surgery or high operative risk. Several transcatheter mitral repair technologies have been developed during the last decade. While the development of some devices was abandoned due to suboptimal results, others demonstrated to be safe and effective and have been included in current practice guidelines. Not all technologies are suitable for all mitral anatomies and regurgitation mechanisms. Therefore, accurate evaluation of mitral valve anatomy and function are pivotal to the success of these therapies. Cardiac imaging plays a central role in selecting patients, guiding the procedure and evaluating the durability of the repair at follow-up.

Therapeutic decision-making for patients with fluctuating mitral regurgitation

Mitral regurgitation (MR) is a common, progressive, and difficult-to-manage disease. MR is dynamic in nature, with physiological fluctuations occurring in response to various stimuli such as exercise and ischaemia, which can precipitate the development of symptoms and subsequent cardiac events. In both chronic primary and secondary MR, the dynamic behaviour of MR can be reliably examined during stress echocardiography. Dynamic fluctuation of MR can also have prognostic value; patients with a marked increase in regurgitant volume or who exhibit increased systolic pulmonary artery pressure during exercise have lower symptom-free survival than those who do not experience significant changes in MR and systolic pulmonary artery pressure during exercise. Identifying patients who have dynamic MR, and understanding the mechanisms underlying the condition, can potentially influence revascularization strategies (such as the surgical restoration of coronary blood flow) and interventional treatment (including cardiac resynchronization therapy and new approaches targeted to the mitral valve).

Advances in percutaneous treatment of mitral regurgitation

Percutaneous techniques for the treatment of mitral regurgitation have aroused much interest in recent years. Percutaneous mitral annuloplasty can be performed indirectly by using devices implanted in the coronary sinus or directly by using a retrograde approach. However, as yet, the results of these techniques are scarce and some devices have a high complications rate. The most frequent percutaneous mitral valve repair technique consists of mitral leaflet plication by implanting 1 or more percutaneous clips (MitraClip) in an imitation of the Alfieri surgical technique. Clinical experience with this device is broader than that with any other. The MitraClip device is associated with improved mitral regurgitation in a high percentage of carefully-selected patients. However, the single randomized study performed to date (EVEREST) showed its efficacy to be less than that of surgical repair and we await the results of new randomized studies that should clarify which patient-type can benefit most from this technique. Other left ventricular remodeling devices, tendinous cord implantation, and leaflet ablation are currently undergoing preclinical development or first-in-human experimentation. Finally, the development of biological prostheses for percutaneous mitral valve replacement is at an early stage. Many promising experiments at the preclinical phase and initial experiments in humans will very probably multiply in the near future. However, the true role of this technique in treating mitral valve disease will have to be evaluated in appropriately designed randomized controlled studies.

Tension to passively cinch the mitral annulus through coronary sinus access: an ex vivo study in ovine model

INTRODUCTION

The transcatheter mitral valve repair (TMVR) technique utilizes a stent to cinch a segment of the mitral annulus (MA) and reduces mitral regurgitation. The cinching mechanism results in reduction of the septal-lateral distance. However, the mechanism has not been characterized completely. In this study, a method was developed to quantify the relation between cinching tension and MA area in an ex vivo ovine model.

METHOD

The cinching tension was measured from a suture inserted within the coronary sinus (CS) vessel with one end tied to the distal end of the vessel and the other end exited to the CS ostium where it was attached to a force transducer on a linear stage. The cinching tension, MA area, septal-lateral (S-L) and commissure-commissure (C-C) diameters and leakage was simultaneously measured in normal and dilated condition, under a hydrostatic left ventricular pressure of 90 mm Hg.

RESULTS

The MA area was increased up to 22.8% after MA dilation. A mean tension of 2.1 ± 0.5 N reduced the MA area by 21.3 ± 5.6% and S-L diameter by 24.2 ± 5.3%. Thus, leakage was improved by 51.7 ± 16.2% following restoration of normal MA geometry.

CONCLUSION

The cinching tension generated by the suture acts as a compensation force in MA reduction, implying the maximum tension needed to be generated by annuloplasty device to restore normal annular size. The relationship between cinching tension and the corresponding MA geometry will contribute to the development of future TMVR devices and understanding of myocardial contraction function.

Mitral transcatheter technologies

Mitral valve regurgitation (MR) is often diagnosed in patients with heart failure and is associated with worsening of symptoms and reduced survival. While surgery remains the gold standard treatment in low-risk patients with degenerative MR, in high-risk patients and in those with functional MR, transcatheter procedures are emerging as an alternative therapeutic option. MitraClip(®) is the device with which the largest clinical experience has been gained to date, as it offers sustained clinical benefit in selected patients. Further to MitraClip implantation, several additional approaches are developing, to better match with the extreme variability of mitral valve disease. Not only repair is evolving, initial steps towards percutaneous mitral valve implantation have already been undertaken, and initial clinical experience has just started.

Treatment of functional mitral valve regurgitation with the permanent percutaneous transvenous mitral annuloplasty system: results of the multicenter international Percutaneous Transvenous Mitral Annuloplasty System to Reduce Mitral Valve Regurgitation in Patients with Heart Failure trial

OBJECTIVES

PTOLEMY-2 was a prospective multicenter phase I single-arm feasibility trial to evaluate the second-generation permanent percutaneous transvenous mitral annuloplasty (PTMA) device in reducing functional mitral regurgitation (MR).

BACKGROUND

Percutaneous MR reduction has been performed through a direct method of clipping and securing the mitral leaflets together or an indirect approach of reducing mitral annular dimension via the coronary sinus. The PTMA device is the only coronary sinus mitral repair device without a static fixation element.

METHODS

Patients with at least moderate functional MR, New York Heart Association functional class II to IV, and left ventricular ejection fraction of 20% to 50% were enrolled at 14 centers in 5 countries. Device effects on patients were assessed by serial echocardiography, quality of life (QOL), and exercise capacity metrics.

RESULTS

A total of 43 patients were recruited, and 30 patients (70%) were implanted with a permanent PTMA device with a mean follow-up of 5.8 ± 3.8 months. The primary safety end point (freedom from death, myocardial infarction, stroke, or emergency surgery) at 30 days was met in 28 patients, whereas 2 patients died of device-related complications. The primary efficacy end point (MR reduction of at least 1.0 grade or reduction of regurgitant orifice area by 0.1 cm(2) or regurgitant volume by 15 mL or regurgitant fraction by 10% compared with baseline) was obtained in 13 patients. No significant changes were noted in MR parameters, ventricular volumes, or QOL. Distance walked on 6 minutes testing at 6-month follow-up increased from 331 ± 167 m to 417 ± 132 m (P = .65). Compared with nonresponders, responders had a higher baseline regurgitant orifice area >0.2 cm(2) (P = .001) and less prior history of myocardial infarction (P = .02), coronary artery bypass surgery (P = .03), and ischemic MR (P = .04).

CONCLUSIONS

Overall, PTMA had mild impact on MR reduction, left ventricular remodeling, QOL, and exercise capacity. During follow-up, the risk/benefit ratio remained suboptimal.

Finite element analysis of the biomechanical interaction between coronary sinus and proximal anchoring stent in coronary sinus annuloplasty

Recent clinical studies of the percutaneous transvenous mitral annuloplasty (PTMA) devices have shown a short-term reduction of mitral regurgitation after implantation. However, adverse events associated with the devices such as compression and perforation of vessel branches, device migration and fracture were reported. In this study, a finite element analysis was carried out to investigate the biomechanical interaction between the proximal anchor stent of a PTMA device and the coronary sinus (CS) vessel in three steps including: (i) the stent release and contact with the CS wall, (ii) the axial pull t the stent connector and (iii) the pressure inflation of the vessel wall. To investigate the impact of the material properties of tissues and stents on the interactive responses, the CS vessel was modelled with human and porcine material properties, and the proximal stent was modelled with two different Nitinol materials with one being stiffer than the other. The results indicated that the vessel wall stresses and contact forces imposed by the stents were much higher in the human model than the porcine model. However, the mechanical differences induced by the two stent types were relatively small. The softer stent exhibited a better fatigue safety factor when deployed in the human model than in the porcine model. These results underscored the importance of the CS tissue mechanical properties. Vessel wall stress and stent radial force obtained in the human model were higher than those obtained in the porcine model, which also brought up questions as to the validity of using the porcine model to assess device mechanical function. The quantification of these biomechanical interactions can offer scientific insight into the development and optimisation of the PTMA device design.

The clinical anatomy and pathology of the human atrioventricular valves: implications for repair or replacement

A critical understanding of cardiac anatomy is essential for design engineers and clinicians with the intent of developing and/or employing improved or novel technologies or therapies for treating an impaired atrioventricular valve. Likewise, such knowledge is required for directing translational research, including initiating preclinical research, assessing the feasibility of clinical trials, and performing first-in-man procedures. There are two atrioventricular valves in the human heart, namely the tricuspid and mitral valves. Both are complex structures whose normal anatomies can vary greatly amongst individuals, and also become modified by disease processes. In this review, we discuss the anatomy, pathology, and issues related to surgical and transcatheter repair of the atrioventricular valves in a translational manner. This article is part of a JCTR special issue on Cardiac Anatomy.

Percutaneous treatment of mitral regurgitation: current status and future directions

The burgeoning field of catheter-based, percutaneous valve intervention takes an interdisciplinary approach to mitral valve regurgitation with the goal of maximizing clinical outcomes and minimizing procedure-associated morbidity. This exciting field continues to push the boundaries of technological innovation as it expands the armamentarium available to treat valvular disease. Around the world teams are working to create a catheter-based approach that is practical and durable. Several technologies are in various stages of development and clinical application.

Percutanenous therapies for mitral regurgitation

Percutaneous therapies for the treatment of mitral regurgitation have emerged rapidly over the past several years. Most of the percutaneous approaches are modifications of existing surgical approaches to mitral annuloplasty or leaflet repair. Most of the percutaneous devices are based on surgical approaches. Catheter-based leaflet repair with the MitraClip is accomplished using an implantable clip to mimic the surgical edge-to-edge technique. Percutaneous annuloplasty can be achieved indirectly via the coronary sinus, or directly from retrograde left ventricular access. Several of these percutaneous approaches have been successfully used in trials or are in the early stages of use in practice.

Percutaneous Techniques for the Treatment of Patients with Functional Mitral Valve Regurgitation

Percutaneous approaches to mitral regurgitation remain largely investigational. In the last decade, novel percutaneous strategies have opened new options in the treatment of valvular heart disease. Several studies are currently underway to determine the benefits of transcatheter mitral valve repair therapy. Transcatheter chordal procedures are being developed, including chordal cutting and chordal implantation. Transcatheter valve implantation in the mitral position might offer a desirable alternative in selected patients and has been accomplished in a compassionate fashion on rare occasions in patients who are not candidates for surgical valve repair or replacement.

Impact of mitral regurgitation on the outcome of patients treated with CRT-D: data from the InSync ICD Italian Registry

BACKGROUND

We assessed the influence of clinically significant mitral regurgitation (MR) on clinical-echocardiographic response and outcome in heart failure (HF) patients treated with a biventricular defibrillator (cardiac resynchronization therapy defibrillator [CRT-D]).

METHODS AND RESULTS

A total of 659 HF patients underwent successful implantation of CRT-D and were enrolled in a multicenter prospective registry (median follow-up of 15 months). Following baseline echocardiographic evaluation, patients were stratified into two groups according to the severity of MR: 232 patients with more than mild MR (Group MR+: grade 2, 3, and 4 MR) versus 427 patients with mild (grade 1) or no functional MR (Group MR-). On 6- and 12-month echocardiographic evaluation, MR was seen to have improved in the vast majority of MR+ patients, while it remained unchanged in most MR- patients. On 12-month follow-up evaluation, a comparable response to CRT was observed in the two groups, in terms of the extent of left ventricular reverse remodeling and combined clinical and echocardiographic response. During long-term follow-up, event-free survival did not differ between MR+ and MR- patients, even when subpopulations of patients with ischemic heart disease and with dilated cardiomyopathy were analyzed separately. On multivariate analysis, the only independent predictor of death from any cause was the lack of β-blocker use.

CONCLUSIONS

This observational analysis supports the use of CRT-D in HF patients with clinically significant MR; MR had no major influence on patient outcome.