DIFFERENT EFFECTS OF ACUTE INTRAVENOUS ADMINISTRATION OF K-STROPHANTIDIN AND PRENALTEROL ON THE DIASTOLIC PHASE OF LEFT-VENTRICULAR FUNCTION IN PATIENTS WITH CORONARY ARTERIAL-DISEASE

In 21 patients with coronary arterial disease, and with maintained (or mildly depressed) systolic function, we studied the effects of two well-known inotropic agents, namely prenalterol and k-strophantidin, on the diastolic phase. Selected variables of both systolic and diastolic function were assessed at controlled heart rate by cardiac catheterization and left ventriculography before and after acute intravenous administration of the beta-1 agonist prenalterol (35-mu-g/kg for 3 min) and of k-strophantidin (0.008 mg/kg for 5-10 min). Ten patients received prenalterol, and 11 patients were injected with k-strophantidin. Administration of prenalterol induced a remarkable diminution of end-systolic volume index (mean values from 41.8 +/- 11.9 to 32.2 +/- 10.4), while k-strophantidin showed only a tendency towards a decrease (mean values from 43.4 +/- 13.2 to 40.7 +/- 15.1). After k-strophantidin, we did not observe any significant changes in the peaks of maximal rate in volumetric increase during filling phase whereas, after prenalterol, a noteworthy increase of the first peak was accompanied by a significant decrease of the second peak. The lowest and end filling left ventricular pressures were decreased by prenalterol (mean values from -0.8 +/- 0.1 to -2 +/- 0.5 and from 10.6 +/- 4.6 to 4.1 +/- 1.1, respectively), whereas k-strophantidin increased left ventricular end diastolic pressure (mean values from 11.6 +/- 4.3 to 17.1 +/- 9.1). Prenalterol induced a relevant increase of ejection fraction (mean values from 0.52 +/- 0.1 to 0.61 +/- 0.008), whereas k-strophantidin produced only a nearly significant (P < 0.06) mild increase (mean values from 0.51 +/- 0.06 to 0.54 +/- 0.09). These data indicate that k-strophantidin and prenalterol have opposite effects on diastolic function. Prenalterol improves, whereas k-strophantidin slightly impairs, indexes of diastolic performance.