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.

How to cite: Hobson NA, Wilkinson GA, Cooper GJ, Wheeldon NM, Lynch J. Hemodynamic assessment of mitral mechanical prostheses under high flow conditions: comparison between dynamic exercise and dobutamine stress. J Heart Valve Dis. 2006 Jan;15(1):87-91. PMID: 16480017.