Patient – prosthesis mismatch in AVR

Patient – prosthesis mismatch in AVR

Patient – prosthesis mismatch in AVR: When the effective orifice of a prosthetic valve is quite small with respect to the body size of the subject, there is patient-  prosthesis mismatch (PPM). An effective orifice area less than 0.7 square centimeter per square meter of body surface area for the aortic valve is taken as PPM in case of aortic valve replacement. PPM is most likely to occur while replacing aortic valve in aortic stenosis. As the aortic annulus is not dilated in aortic stenosis, only smaller prosthesis may be considered at the time of implantation, leading to PPM. In aortic regurgitation, since the annulus is often dilated, the chance of this occurrence is lesser. Sometimes larger aortic prosthesis can be used after annulus widening techniques. But this is not done in most centers due to the potential for added surgical risk and morbidity with annular widening procedures. It is often said that aortic valve replacement only converts severe aortic stenosis to mild aortic stenosis, due to these considerations.

Patient – prosthesis mismatch manifests as higher transaortic gradient soon after surgery. Twenty to seventy percent occurrence of patient – prosthesis mismatch has been reported [1]and it can lead to poor hemodynamic function with more cardiac events and lower survival. Regression of left ventricular hypertrophy which occurs after a successful aortic valve replacement is also limited by this factor.

Reference

1. Pibarot P, Dumesnil JG. Prosthesis‐patient mismatch: definition, clinical impact, and prevention. Heart. 2006; 92: 1022–1029.