Dr Gillespie and colleagues in the Gorman Cardiovascular Research Group describe in this issue of The Annals of Thoracic Surgery [1Gillespie M.J. Aoki C. Satoshi T. et al.Development of off-pump mitral valve replacement in a porcine model.Ann Thorac Surg. 2015; 99: 1408-1413Abstract Full Text Full Text PDF Scopus (2) Google Scholar] the further modification and experimental deployment of their custom-designed transcatheter mitral valve replacement (MVR) prosthesis. This nitinol and porcine pericardial prosthesis is notable for its low-profile transatrial delivery and atraumatic dual mechanism anchoring by means of annular radial forces and leaflet/chordae grasping. In this study, the authors demonstrate the ability to implant the device in pigs by means of both on-pump arrested direct vision and off-pump fluoroscopic techniques. The implantation times are very short. The postimplantation hemodynamics, echocardiography, and ventriculography revealed excellent valve prosthesis function and absence of paravalvular leak, left ventricular outflow tract obstruction, systolic anterior motion, and mitral stenosis. At necropsy, the valve prostheses were found to be well seated, and the anterior leaflet of the mitral valve was appropriately grasped within the nitinol arms. This is an excellent demonstration of the feasibility and functionality of this novel device and delivery approach. Perhaps the only limitation of this report is the absence of longer functional and histologic data. Fibrous incorporation of the device into the annular and leaflet tissue would further confirm the likely long-term stable implantation of this device. The results of such studies are likely forthcoming. The field of transcatheter valve replacement and repair is evolving rapidly. With its relatively uniform, adynamic annulus, calcification to anchor the prosthesis, and coronary clearance as the only major positioning concern, senile aortic stenosis has provided an excellent target for therapy. The mitral valve may prove more challenging. Devices for MVR face several additional anatomic and physiologic barriers, which must be integrated into device design. These include a flexible D-shaped annulus that changes acutely in three dimensions with the cardiac cycle, and chronically with posterior ischemic ventricular remodeling. Asymmetric mitral annular calcification may impair anchoring. The anterior mitral leaflet, normally incised and repositioned or excised in standard surgical MVR, will tend to be pushed into the left ventricular outflow tract, risking obstruction. This may be exacerbated in the treatment of mitral stenosis, wherein the left ventricular cavity may be small. Extensive stent and valve material protruding into the left atrium are unlikely to endothelialize in the same manner as would the sewing ring of a standard MVR prosthesis flush against the left atrium. In the lower-pressure cavity prone to stasis, there may be an elevated risk of thrombus formation. Finally, designs must take into consideration the unique facets of the various potential delivery routes such as transseptal, transapical, trans–left atrial, and perhaps even transaortic valve. These and other intriguing issues are currently under active investigation and will be solved in time by creative research and development teams such as the Gorman group and others, in academia, in industry, and in novel collaborative partnerships. Development of Off-Pump Mitral Valve Replacement in a Porcine ModelThe Annals of Thoracic SurgeryVol. 99Issue 4PreviewWe 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. Full-Text PDF