Usefulness of Stress Exercise Echocardiography for Evaluation of Aortic Bioprostheses

Introduction: Transthoracic echocardiography (TTE) is the method of choice for evaluation of prosthetic aortic valve function. The majority of studies reporting early and late hemodynamic performances after aortic valve replacement (AVR) with a bioprosthetic device are mainly based on echocardiographic examination at rest. A more accurate appraisal of bioprosthetic valves can be achieved by transthoracic echocardiographic evaluation under stress or under exercise conditions (ETTE), since, as often happens, normally and abnormally functioning biological aortic prostheses give similar gradients at rest echocardiographic examination. Materials and Methods: With the aim of assessing the changes in hemodynamic behavior of a low-gradient bioprosthesis, we evaluated a consecutive series of 184 patients who received an aortic valve replacement using a stentless prosthesis at our institution between 2003 and 2010, a seven-year follow up. The assessment of transvalvular gradients, valve areas and left ventricular function was carried out by transthoracic echocardiography examination obtained at rest and under exercise at different steps, using a semi-supine exercise bicycle, managed by a single cardiologist. Results: Mean transvalvular gradient increased from rest to maximum exercise by 3,81mmHg without significant difference as regard to the implanted valve size. Interestingly, the indexed valve area increased during exercise from 1.05cm2 to 1.10cm2. Conclusions: Use of exercise echocardiography represents a very helpful tool in the decision process for the choice of the most appropriate aortic valve substitute. Notably, stentless aortic bioprostheses demonstrated to achieve excellent hemodynamic features at rest and under exercise over time.