The usefulness of dobutamine in the assessment of the severity of mitral stenosis.

Patients with mitral stenosis often require supine exercise in order to increase their heart rate and cardiac output to assess the severity of their valvular obstruction during cardiac catheterization. We substituted dobutamine for exercise in 14 patients with suspected mitral stenosis. The dobutamine infusion was started at 5 μg/kg/min and was increased to 10, 15, and 20 μg/kg/min every 3 minutes as tolerated. The heart rate increased from 84 ± 4 to 123 ± 7 bpm (p < 0.001), the cardiac index increased from 2.4 ± 0.2 to 3.4 ± 0.2 L/min/m2 (p < 0.001), and the mean pulmonary artery pressure increased from 27 ± 3 to 30 ± 2 mm Hg (p < 0.02). The pulmonary wedge pressure of 19 ± 2 mm Hg and the mitral valve index of 0.8 ± 0.1 cm2/m2 remained unchanged, but the left ventricular end-diastolic pressure decreased from 11 ± 2 to 6 ± 2 mm Hg (p < 0.02). The hemodynamic response during the infusion of dobutamine identified a subgroup of patients with more severe mitral stenosis. Thus, the administration of dobutamine is useful in the evaluation of the severity of mitral valve obstruction during catheterization.