Stentless bioprosthetic valves
Stentless bioprosthetic valves do not have supporting framework so that they can have a higher effective valve orifice area. This is an advantage in avoiding patient prosthesis mismatch, especially in aortic stenosis. In isolated aortic stenosis, the aortic annulus is not dilated and often only a small sized prosthesis can be implanted unless one goes for aortic root widening procedures with added morbidity and potential mortality. The relatively smaller size of aortic prosthesis leads to patient prosthesis mismatch and poor regression of transvalvar gradient and left ventricular hypertrophy. This can be avoided to some extent by using stentless bioprosthesis which has higher effective valve orifice area compared to stented bioprosthesis due to the absence of a supporting framework. But implanting stentless bioprosthetic valve is technically more demanding for the surgeon and can prolong operating times causing higher morbidity. Stentless bioprosthetic valves aim at maximizing the effective orifice area to tissue annulus ratio for better hemodynamic and clinical outcomes.
A meta analysis conducted by Babu Kunadian, Kunadian Vijayalakshmi, Andrew R Thornley, Mark A de Belder, Steven Hunter, Simon Kendall, Richard Graham, Michael Stewart, Jeetendra Thambyrajah and Joel Dunning  compared the regression of left ventricular mass between stented and stentless aortic prosthetic valves. After evaluating ten studies which involved a total of over nine hundred patients, they concluded that stentless aortic prosthesis give better regression of left ventricular mass, lower trans aortic gradients and better effective orifice index. But the aortic cross clamp times and cardiopulmonary bypass times were higher because of the complexity of the replacement process of stentless aortic bioprosthesis.
- Babu Kunadian, Kunadian Vijayalakshmi, Andrew R Thornley, Mark A de Belder, Steven Hunter, Simon Kendall, Richard Graham, Michael Stewart, Jeetendra Thambyrajah, Joel Dunning. Meta-analysis of valve hemodynamics and left ventricular mass regression for stentless versus stented aortic valves. Ann Thorac Surg. 2007 Jul;84(1):73-8.
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