title: Transapical aortic valve implantation: an animal feasibility study.
abstract: BACKGROUND
  Percutaneous aortic valve implantation has recently been performed in nonsurgical patients with severe aortic stenosis. Retrograde valve delivery has been problematic because of the size of the delivery system and concomitant peripheral vascular disease. We investigated a minimally invasive approach through the left ventricular apex for antegrade placement of a device-deliverable valve.
  
  
  METHODS
  Transapical aortic valve implantation was performed using a 23-mm equine valve mounted on a stainless steel stent in 24 swine (weight range, 35 to 45 kg). A limited or full sternotomy approach was used to access the apex of the heart. The crimped valve was introduced through a sheath in the left ventricular apex. Fluoroscopy and echocardiography were used for guidance. Deployments were performed on the beating heart either with ventricular unloading using femoral extracorporeal circulation or rapid ventricular pacing.
  
  
  RESULTS
  All valves were successfully delivered at the selected target site with acceptable visualization of the noncalcified aortic annulus. Valve migration occurred during eight deployments (two distal and six retrograde) secondary to persistent cardiac output, unfavorable annular anatomy, and dislodgement by the delivery catheter. Exact positioning of the nonmigrated valves at the aortic annulus was examined by necropsy of all animals at the end of the procedures. Paravalvular leak was noted in 14 of 18 (77.8%) valves remaining in situ.
  
  
  CONCLUSIONS
  The transapical approach was used for the successful antegrade placement of a stented valve, obviating the technical problems associated with a large delivery system transiting the peripheral vascular system. Stent design contributing to paravalvular leak remains problematic.
authors.affiliation: Cardiopulmonary Research Science and Technology Institute, Dallas, Texas, USA. tdewey@csant.com
authors.forename: Todd M
authors.initials: TM
authors.lastname: Dewey
authors.forename: Thomas
authors.initials: T
authors.lastname: Walther
authors.forename: Mirko
authors.initials: M
authors.lastname: Doss
authors.forename: David
authors.initials: D
authors.lastname: Brown
authors.forename: William H
authors.initials: WH
authors.lastname: Ryan
authors.forename: Lars
authors.initials: L
authors.lastname: Svensson
authors.forename: Tomislav
authors.initials: T
authors.lastname: Mihaljevic
authors.forename: Rainer
authors.initials: R
authors.lastname: Hambrecht
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schuler
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wimmer-Greinecker
authors.forename: Friedrich W
authors.initials: FW
authors.lastname: Mohr
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Mack
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000601:surgery*; D001022:Aortic Valve Insufficiency / Q000209:etiology; D001281:Atrial Fibrillation / Q000209:etiology; D001705:Bioprosthesis; D002404:Catheterization; D005240:Feasibility Studies; D005548:Foreign-Body Migration / Q000209:etiology; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D006352:Heart Ventricles; D006736:Horses; D020007:Implants, Experimental; D019060:Minimally Invasive Surgical Procedures; D011183:Postoperative Complications / Q000209:etiology; D015607:Stents; D034421:Sus scrofa; D014693:Ventricular Fibrillation / Q000209:etiology