EFFECT OF DOBUTAMINE ON LEFT-VENTRICULAR RELAXATION AND FILLING PHASE IN PATIENTS WITH ISCHEMIC-HEART-DISEASE AND PRESERVED SYSTOLIC FUNCTION

The beneficial effects of dobutamine on left ventricular systolic and diastolic phases have been described in patients with congestive heart failure. Its influence on left ventricular diastolic phase in patients with preserved systolic function, absence of dys- or akinetic areas, and left ventricular dilatation has not yet been adequately investigated. Thus a simultaneous echo-Doppler and hemodynamic study was performed in 15 patients with ischemic heart disease and preserved systolic function in order to assess the effect of dobutamine on left ventricular relaxation and filling phase. The infusion of dobutamine at a rate of 10 mug/kg/min induced a marked inotropic action, as shown by the significant increase in positive dP/dt (from 1392 +/- 224 to 2192 +/- 295 mmHg/sec, p < 0.001), dP/dt/P (from 32 +/- 8.1 to 50 +/- 17 sec-1; p < 0.0001), and in peak of systolic pressure (from 143 +/- 25 to 168 +/- 36 mmHg; p < 0.005). In addition, dobutamine reduced the end-systolic volume index (from 30 +/- 16 to 26 +/- 19 ml/m2; p < 0.05), the end-systolic stress (from 222.2 +/- 65.3 to 198.4 +/- 84 g/cm 2; p < 0.006), and had favorable effects on relaxation and the early filling phase. The constant T (tau) significantly decreased (from 46 +/- 9 to 36 +/- 11 msec; p < 0.0001), while the left atrial left ventricular lowest pressure difference from 7.2 +/- 3.3 to 13.3 +/- 4.7 mmHg; p < 0.05), peak E velocity (from 0.52 +/- 0.08 to 0.65 +/- 0.18 m/sec; p < 0.05), and E velocity integral (from 12 +/- 3.2 to 15.39 +/- 6.10 cm; p < 0.05) significantly increased. In contrast, the late diastolic filling did not change. The positive effect of dobutamine on the diastolic phase might be explained by its mechanism at the subcellular level and by the reduction of both left ventricular end-systolic volume and end-systolic stress. We might conclude that in coronary artery disease patients with preserved systolic function dobutamine improves both relaxation and the early filling phase; these results add further information to the pharmacological effects of this drug.