Background and aim of the study: The study aim was to compare the effects of dobutamine stress and exercise on prosthetic mitral valve hemodynamics.
Methods: Twenty-three patients who had recently (3 ± 1 months) undergone mechanical mitral valve implantation were studied. Hemodynamic variables, two-dimensional echocardiographic and Doppler mitral/aortic flows were recorded at rest, and then repeated during exercise and dobutamine stress. The investigations were randomized place to determine which stress would be performed first.
Results: Heart rates and pressure drops rose significantly from resting values. At maximum stress, exercise produced maximum and mean pressure drops which were statistically greater than with dobutamine (19.4 ± 6.0 versus 12.8 ± 4.7 mmHg (p <0.001) and 10.2 ± 3.5 versus 6.8 ± 2.8 (p <0.01),

respectively). Exercise was associated with statistically shorter diastolic filling times and higher transvalvular diastolic flow rates. Dobutamine produced a greater augmentation in mitral effective orifice area (EOA) (p <0.05). The slopes of pressure drop/cardiac flow were calculated for stress type and shown to be significantly lower during dobutamine administration (p = 0.03).
Conclusion: Normally functioning mitral prostheses can generate significant increases in valvular pressure drops under high flow conditions. Physiological differences exist between dobutamine stress and exercise when assessing diastolic filling. At a given flow rate, dobutamine produces a greater augmentation in the mitral EOA and a smaller drop in transvalvular pressure.
The Journal of Heart Valve Disease 2006;15:87-91