title: Percutaneous aortic valve replacement: an experimental study. I. Studies on implantation.
abstract: OBJECTIVE
  The purpose of this preliminary study was to devise a new surgical procedure for minimally invasive aortic valve implantation with a transluminal technique.
  
  
  METHODS
  The new collapsible heart valve was prepared by mounting a porcine aortic valve, taken from a freshly slaughtered pig, into a self-expandable nitinol stent by means of a suture technique. The outer diameter of the valved stent ranged from 15 to 23 mm, and the length ranged from 21 to 28 mm. Before implantation in vivo, these valved stents were tested in an in vitro circulatory system. Only in vitro-tested valved stents with a pressure gradient of less than 7 mm Hg and regurgitation of I degrees or less were used for transluminal aortic valve implantation in vivo. Six of these valved stents were implanted in the descending aorta and 8 in the ascending aorta of anesthetized pigs. The catheter delivery system (22F) was extraperitoneally inserted through the left iliac artery or the infrarenal aorta. Measurements for transvalvular gradient, valvular opening and closure, blood-flow characteristics, regurgitation, and macroscopic analysis were performed at baseline and after the observation period (164 +/- 48 minutes).
  
  
  RESULTS
  This preliminary study contained 14 animals. One animal died of ventricular fibrillation. Technical failure occurred in 2 pigs as a result of stent twisting. At the end of the observation period, the 11 successfully implanted valved stents demonstrated low transvalvular gradients (mean end-systolic Deltarho(max) of 5.4 +/- 3.3 mm Hg for the descending aorta group, 5.4 +/- 1.2 mm Hg for the supracoronary group, and 5.4 +/- 1.1 mm Hg for the subcoronary group), which did not differ from their in vitro gradients. Two-dimensional echocardiography demonstrated complete valvular closure and opening in 5 of 5 cases. Angiography indicated only a physiologic jet of regurgitation (0 degrees ) in 8 animals and mild (I degrees ) regurgitation in 3 animals. Color Doppler ultrasonography indicated no regurgitation in 5 of 5 cases and minor paravalvular leakage in 1 case.
  
  
  CONCLUSIONS
  Aortic valved stents can be successfully implanted without thoracotomy by using a transluminal catheter technique. Long-term function of the valves remains to be established.
authors: Divisions of Cardiovascular Surgery, Cardiology, and Radiology, School of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany. lutter@ch11.ukl.uni-freiburg.de
authors: Georg
authors: G
authors: Lutter
authors: Daniela
authors: D
authors: Kuklinski
authors: Georg
authors: G
authors: Berg
authors: Patrick
authors: P
authors: Von Samson
authors: Juergen
authors: J
authors: Martin
authors: Michael
authors: M
authors: Handke
authors: Peter
authors: P
authors: Uhrmeister
authors: Friedhelm
authors: F
authors: Beyersdorf
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000601:surgery*; D001022:Aortic Valve Insufficiency / Q000150:complications / Q000503:physiopathology; D001705:Bioprosthesis; D001783:Blood Flow Velocity / Q000502:physiology; D020878:Device Removal; D004452:Echocardiography; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D023421:Models, Animal; D011183:Postoperative Complications / Q000209:etiology / Q000401:mortality; D015607:Stents; D013552:Swine; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000401:mortality; D018615:Ultrasonography, Doppler, Color