Beneficial effect of salbutamol on cardiac function in severe congestive cardiomyopathy. Effect on systolic and diastolic function of the left ventricle.

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Abstract
The effects of salbutamol (a selective .beta.2 agonist) were studied in 12 patients with congestive cardiomyopathy in a dose of 0.5 .mu.g/min per kg. In study A (n = 6), pressures and cardiac index (CI) were measured at rest and during supine exercise. Study B (n = 6) was specifically designed to observe the effects of salbutamol on the indices of left ventricular performance and diastolic pressure-volume relationships. Study A revealed salbutamol infusion significantly (P < 0.001) increases CI from 1.8-3.9 l/min per m2 in the resting state; the exercise CI improved from 3 to 4.5 l/min per m2 (P < 0.005); there was a marked decrease in left ventricular end-diastolic pressure at rest from 27-13 mm Hg (P < 0.001) and during exercise from 39-20 mm Hg (P < 0.001). There was no significant change in heart rate and blood pressure. In study B, there was a significant reduction in left ventricular end-diastolic volume index from 210-183 ml/m2 (P < 0.05) and left ventricular end-systolic volume index from 159-102 ml/m2 (P < 0.001) with a significant increase in ejection fraction from 28% to 46% (P < 0.01). Indices of myocardial performance showed significant improvement in LVdp/dt max [maximum rate of fall of left ventricular pressure] (P < 0.02), Vpm (P < 0.001), Vmax [maximum velocity] (P < 0.01), Vce (P < 0.001), V5 [ECG lead] (P < 0.02) and V40 [ECG lead] (P < 0.05). Salbutamol infusion significantly decreased end-diastolic circumferential wall stress (P < 0.001), total passive diastolic stiffness (P < 0.02), elastic stiffness (P < 0.001) and increased total left ventricular diastolic compliance (P < 0.01). Salbutamol produces significant improvement in overall cardiac function and in both systolic and diastolic function of the left ventricle.