Evaluation of Prosthetic Aortic Valve Obstruction

Evaluation of Prosthetic Aortic Valve Obstruction This discussion will focus beyond the basic clinical evaluation, ECG, chest X-ray and hematological workup. Hematological workup is important in aortic valve obstruction because of likelihood of associated hemolytic anemia and acquired von Willebrand Syndrome. Former is due to destruction of red blood cells across the narrowed aortic valve, and latter due to loss of the largest multimers of von Willebrand factor. High shear stress across the narrowed aortic valve exposes a region of the von Willebrand factor which is susceptible to a specific von Willebrand protease. This can lead on to gastrointestinal angiodysplasia (Heyde’s syndrome) and bleeding complications. Obstruction of prosthetic aortic valve could be due to thrombosis or a fibrotic tissue overgrowth known as pannus formation. Another reason was “stent creep” in certain types of bioprosthesis due to inward bending of stent struts. Stent creep can cause increase in transvalvar gradient and the damage may not be evident on two dimensional echocardiography. Stent creep was due to ultrastructural deformity of polypropylene used in the valve stent. Newer stent materials resistant to such deformity were developed after this was noted in explanted Hancock bioprosthesis. Most commonly used methods for evaluation of prosthetic valve are echocardiography and fluoroscopy. But they may not identify morphological substrate or the extent of prosthetic valve patho...
Source: Cardiophile MD - Category: Cardiology Authors: Tags: General Cardiology Source Type: blogs