EVALUATION OF THE HEMODYNAMIC PERFORMANCE OF SMALL CARBOMEDICS AORTICPROSTHESES USING DOBUTAMINE-STRESS DOPPLER-ECHOCARDIOGRAPHY

Background. The well-known correlation between prosthetic valve orific e area and transvalvular gradients has raised concerns about the prese nce of significant residual gradients when the size of the prosthesis that can be implanted is limited by the presence of a small aortic ann ulus. Methods. Dobutamine-stress Doppler echocardiography was used to evaluate the hemodynamic performance of small CarboMedics aortic prost heses (19 mm and 21 mm) in 18 patients (16 women; mean age, 64 years) who had undergone aortic valve replacement 23.5 +/- 19 months (standar d deviation) previously. Dobutamine infusion was started at a rate of 5 mu g . kg(-1). min(-2) and increased to 10 and 20 mu g . kg(-1). min (-2) at 15-minute intervals. Pulsed and continuous wave Doppler studie s were performed at rest and at the end of each stage. Effective orifi ce area, performance index, and discharge coefficient of both valves w ere calculated, and peak and mean velocity and pressure drop across th e prostheses were measured. Results. Heart rate and cardiac output inc reased by 74% and 94%, respectively, and mean arterial blood pressure decreased by 9% at maximum stress. Effective orifice area, discharge c oefficient, and performance index were comparable in both valve sizes at rest and maximum stress. Also, there was no significant difference in mean transvalvular pressure drop (gradient) for 19-mm and 21-mm pro stheses at rest (8.1 +/- 8.4 and 4.8 +/- 3.8 mm Hg) or maximum stress (15.1 +/- 14.2 and 8.8 +/- 5.8 mm Hg, respectively). No significant co rrelation could be demonstrated between transvalvular pressure drop an d patient's body surface area. Conclusions. These data show that 19-mm and 21-mm CarboMedics aortic prostheses exhibit equally favorable hem odynamic performance with minimal pressure gradient, both at rest and under stress conditions.