Off-pump transapical mitral valve-in-ring implantation

New expandable mitral annuloplasty ring facilitates transcatheter mitral valve implantation: proof of concept

AIMS

Transcatheter mitral valve-in-ring (TMVIR) implantation with transcatheter heart valve (THV) prostheses can be performed in patients with recurrent mitral regurgitation (MR) following annuloplasty. However, an oval configuration and sometimes the rigidity of surgical rings can often lead to suboptimal THV expansion, resulting in considerable paravalvular or central leakage. Therefore, our aim was to develop an annuloplasty ring that fully adjusts to THV implantation.

METHODS AND RESULTS

A three-dimensional annuloplasty ring was separated into four pieces at defined locations, the sections were reconnected with heat-shrinkable tubing and rearranged into the original shape. A non-tear stainless steel circular cord of defined length was inserted into the ring's sewing cuff to serve as a limiting structure for THV expansion. We implanted this ring in the mitral position into an isolated pig heart, deployed a THV into the ring, and investigated its function. Fluoroscopy showed that, upon THV deployment, the four breaking points of the ring separated as expected, and the ring expanded in a circular fashion to full expansion of the limiting cord. It securely anchored the THV to the ring, leaving no paravalvular gaps.

CONCLUSIONS

We developed an expandable mitral ring to which the THV attached without leakage. This may impact on the future design of annuloplasty rings. Further studies should evaluate the safety of increasing the perimeter of a mitral ring and its durability.

Successful first-in-man Melody transcatheter valve implant in a dehisced mitral annuloplasty ring transapical valve-in-ring implant

AIMS

A "valve-in-ring" (ViR) procedure involves the transcatheter implant of a valved stent in a prosthetic mitral ring. The presence of a partial dehiscence of the prosthetic ring is a major contraindication for a ViR due to inefficacious sealing. We describe an alternative method of ViR implant to achieve proper valve sealing in the case of ring dehiscence.

METHODS AND RESULTS

A 76-year-old male patient suffered from severe central mitral regurgitation due to annuloplasty ring dehiscence and leaflet tethering. ECG-gated multidetector computed tomography was used for preoperative planning. Standard transapical access was gained through a minimally invasive left thoracotomy in the 5th intercostal space. A customised Melody valve with two PTFE sutures fixed to the apex was used. The intervention was performed without complications, the patient recovered well, and transthoracic echo revealed no mitral regurgitation through the implanted valve with a transvalvular gradient of 4 mmHg.

CONCLUSIONS

The implantation of a long covered stent such as the Melody valve allows successful sealing following a ViR even in case of partially detached annuloplasty rings. This procedure is a proof of concept that proper sealing can be achieved at the leaflet level without the use of radial force at the annular level.

Development of off-pump mitral valve replacement in a porcine model

PURPOSE

We describe our initial experience with on-bypass and off-bypass (off-pump) mitral valve replacement with the modified version of our novel catheter-based sutureless mitral valve (SMV) technology, which was developed to atraumatically anchor and seal in the mitral position.

DESCRIPTION

The SMV is a self-expanding device consisting of a custom designed nitinol framework and a pericardial leaflet valve mechanism. For the current studies, our original device was modified (SMV2) to reduce the delivery profile and to allow for controlled deployment while still maintaining the key principles necessary for atraumatic anchoring and sealing in the mitral valve position.

EVALUATION

Ten Yorkshire pigs underwent successful SMV2 device implantation through a left atriotomy (on-pump, n = 6; off-pump, n = 4). Echocardiography and angiography revealed excellent left ventricular systolic function, no significant perivalvular leak, no mitral valve stenosis, no left ventricular outflow tract obstruction, and no aortic valve insufficiency. Postmortem examination demonstrated that the SMV2 devices were anchored securely.

CONCLUSIONS

This study demonstrates the feasibility and short-term success of off-pump mitral valve replacement using a novel, catheter-based device in a porcine model.

A Technical Review of Minimally Invasive Mitral Valve Replacements

Mitral regurgitation is one of the most common forms of heart valve disorder, which may result in heart failure. Due to the rapid ageing of the population, surgical repair and replacement treatments, which have represented an effective treatment in the past, are now unsuitable for about half of symptomatic patients, who are judged high-risk. Encouraged by the positive experience with transcatheter aortic valves and percutaneous reconstructive mitral treatments, a number of research groups are currently engaged in the development of minimally invasive approaches for the functional replacement of the mitral valve. The first experiences have clearly demonstrated that the approach is feasible and promising, though significant progress is still required in the prostheses design and implantation procedures before the treatment can establish as a safe and effective solution. This review analyses the devices currently at a most advanced stage of development, describing their main features and the technical solutions that they adopt in order to respond to the functional requirements of the most challenging of the heart valves.