TMVI procedure
Experimental pigs were anesthetized with 4-10mg propofol for induction and maintained with 4-12mg/kg/h propofol. A left anterolateral thoracotomy was performed minimally in the fifth intercostal space for access to the left ventricle (LV) apex. Echocardiography and fluoroscopy were utilized as intraoperative guidance. Heparin (200 IU/kg) was administered intravenously before apical catheterization. An LV apex incision was performed following the echocardiographic measurement and sutured with two box stitches (Polyprolene2-0). A 0.035-inch J-shaped guidewire was inserted into the LV and retrograded across the mitral valve into the left atrium under the guidance of epicardial echocardiography and fluoroscopy. Then it was manipulated into the left inferior pulmonary vein and exchanged with a super-stiff guidewire. After the LV apex incision was dilated, a delivery system with a crimped valve prosthesis and two recurrent strings was introduced into the LV. The prosthesis was rotated to fit the anatomical position (one anchor matched anterior leaflet and another matched and posterior leaflet) and deployed following the tri-step implantation process. If the stent deployment is found to be inappropriate, the mitral stent was retrieved and redeployed. After valve implantation, intraoperative echocardiography was performed to confirm and evaluate the position and function of the implanted valve. (Figure 4) The delivery system was subsequently removed and replaced with a pigtail catheter for fluoroscopy to identify valvular insufficiency, paravalvular leakage (PVL), and left ventricular outflow tract (LVOT) obstruction, and coronary artery obstruction. (Figure 3) Finally, the chest incision was processed routinely. After implantation, all experiment animals received standardized care. All surviving pigs were monitored clinically and then sacrificed for four weeks. All the hearts were explanted for macroscopic evaluation. (Figure 5)