HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Elaine E. Tseng Permission Requests Google Scholar Articles by Dwyer, H. A. Articles by Tseng, E. E. PubMed Articles by Dwyer, H. A. Articles by Tseng, E. E. Related Collections Minimally invasive surgery Valve disease

J Thorac Cardiovasc Surg 2009;138:1227-1233
© 2009 The American Association for Thoracic Surgery

Evolving Technology/Basic Science

Migration forces of transcatheter aortic valves in patients with noncalcific aortic insufficiency

^a Department of Mechanical and Aeronautic Engineering, University of California at Davis, Davis, Calif
^b Department of Surgery, University of California at San Francisco Medical Center and San Francisco Veterans Affairs Medical Center, San Francisco, Calif

Received for publication October 27, 2008; revisions received December 23, 2008; accepted for publication February 1, 2009.

^_* Address for reprints: Elaine E. Tseng, MD, UCSF Medical Center, Division of Cardiothoracic Surgery, 500 Parnassus Avenue, Suite W405, Box 0118, San Francisco, CA 94143-0118. (Email: elaine.tseng{at}ucsfmedctr.org).

Objective: Transcatheter aortic valves have been successfully implanted into the calcified leaflets of patients with severe aortic stenosis. However, their stability in patients with noncalcified aortic insufficiency is unknown. Similar to thoracic and abdominal aortic stent grafts, transcatheter aortic valves are subjected to antegrade ejection forces during systole. However, retrograde migration forces into the left ventricle are also generated by the diastolic pressure gradient across the closed valve. It has been suggested that leaflet calcification anchors the prosthesis, and measurements of migration forces should be considered before clinical trials in noncalcified aortic insufficiency. The objective of this study was to use computational fluid dynamics simulations to quantify forces that could potentially dislodge the prosthesis.

Methods: A computational fluid dynamics model was developed to simulate systolic flow through a geometric mesh of the aortic root and transcatheter aortic valves. Hemodynamic measurements were made at discrete moments during ejection. Unsteady control volume analysis was used for calculations of force on the mesh.

Results: Results of the simulation indicate that a total force of 0.602 N acts on the transcatheter aortic valves during systole, 99% of which is in the direction of axial flow. The largest contributor to force was the dynamic pressure gradient through the transcatheter aortic valves. This antegrade force is approximately 10 times smaller than the retrograde force (6.01 N) on the closed valve during diastole.

Conclusion: Our model simulated systolic flow through a transcatheter aortic valve and demonstrated migration into the left ventricle to be of greater concern than antegrade ejection.