Transcatheter Aortic Valves
Transcatheter Aortic Valves
Aortic stenosis (AS), due to accumulation of calcium in the valve leaflets, is a major heart valve disease encountered in the elderly. Surgical aortic valve replacement (AVR) is still the gold standard to treat patients with severe AI or AS. AVR is performed with excellent results, including low mortality and good long-term survival. Recently, percutaneous aortic stent valves have been implanted clinically in select patients. However, they have not been rigorously evaluated with respect to their biomechanical interactions and effect on blood flow.
The first human percutaneous TAV implantation was performed in 2002 by Alain Cribier. Two TAV designs have since been investigated in clinical trials: Edwards Sapien, a balloon-expandable, stainless steel stent housing bovine pericardial valve leaflets; and CoreValve, a self-expanding nitinol stent with 21 mm pericardial valve. Overall, TAV has 73-100% implant success and procedural mortality of 2-14% in patients with predicted surgical mortalities of 12-31%.
Studies done on endovascular aortic grafts for abdominal aortic aneurysm on cadaveric aorta has provided insight into the properties and migration forces of various endovascular aortic grafts. Percutaneous valves may have a substantial impact on the care of patients clinically with aortic stenosis. These valves are being tested clinically in humans, but little research has been performed experimentally in pulse duplicators or with computational simulations to determine more long-term effects. In addition, these valves have been proposed to treat bioprosthetic degeneration.