Evaluation of Hemodynamic Behavior of a Stentless Aortic Bioprosthesis under Stress by Exercise Echocardiography

Background: Aim of this study was to evaluate by transthoracic echo the hemodynamic behaviour and the changes in dimensional data of a stentless aortic bioprosthesis between rest and exercise conditions. Methods: 254 patients affected by stenosis or stenoinsufficiency of the aortic valve received a Sorin Pericarbon Freedom (SPF) aortic bioprosthesis at our institution between 2003 and 2010. Out of the entire cohort, 184 patients, alive and capable of sustaining an exercise test 7 years after surgery, were selected and enrolled in the study (mean age: 69.7 ± 10.9 years, 51.6% male, mean EF: 53.0 ± 7.1). All patients were evaluated by transthoracic echocardiography in order to assess hemodynamics at the time of hospital discharge and after 7 years. Followup control consisted of clinical examination and rest and exercise echocardiographic evaluation using a semisupine bicycle with a workload of 25W every two minutes, increasing up to 100W. Results: Comparing rest to exercise, mean gradient increased from 7.8 ± 3.3 mmHg to 11.6 ± 4.0 mmHg (p < 0.05) and peak gradient from 14.9 ± 5.2 mmHg to 21.6 ± 6.5 mmHg (p < 0.05) at maximum stress, without significant differences between valve sizes. Concurrently EOA and EOAi raised from 1.86 ± 0.69 cm2 to 1.96 ± 0.71 cm2 (p < 0.0001), and from 1.05 ± 0.37 cm2 to 1.10 ± 0.38 cm2 (p < 0.0001) respectively, without significant differences between the implanted valve sizes. Intraaortic regurgitation was absent or trivial in 98% of patients, and did not change with exercise. Conclusions: Use of exercise echocardiography to assess changes in hemodynamics and function of aortic bioprostheses can be helpful in the choice of appropriate aortic valve substitutes. SPF pericardial stentless valve presents favourable and durable hemodynamic characteristics at rest and on exercise, similar to native aortic valve. This prosthesis maybe suitable for patients with small aortic annulus and large BSA to avoid mismatch.