In a subacute experiment the au thors studied the effects of a four teen-day treatment with nebivolol, 5 mg once a day, in 10 healthy male vol unteers with a mean age of thirty- one, twenty-five to thirty-nine years, by comparing the results of the rest ing ratio of the preejection period (PEPc) to the left ventricular ejection time (LVETc), as measured by sys tolic time intervals (STI), with the results obtained by equilibrium ra dionuclide angiocardiography (ERNA), using technetium 99m-la beled autologous red blood cells as a marker. A submaximal treadmill ex ercise test performed before and dur ing treatment demonstrated that nebivolol significantly (p s 0.01) re duced peak exercise heart rate and systolic blood pressure from a mean value of 158 ± 5.4 bpm to 131 ± 4.3 bpm and from 171 ± 4.9 mmHg to 144 ± 4.5 mmHg respectively. The data from the STI and ERNA were calculated and analyzed indepen dently by two observers. A highly sig nificant (r=0.8182, p=0.0038) correlation was found between the changes of stroke volume (SV) and PEPc/LVETc during treatment with nebivolol. Furthermore end-diastolic volume significantly (p=0.03) in creased from a mean value of 177 ± 10.1 ml to 198 ± 6 ml and stroke vol ume significantly (p=0.01) increased from 120 ± 6.8 ml to 136 ± 6.3 ml. Systemic vascular resistance tended to decrease from a mean value of 11.4 ± 1.28 units to 10.6 ± 1.10 units. No changes could be observed either in ejection fraction or in cardiac output. The ratio of the PEPc/LVETc, as mea sured with STI, significantly (p=0.03) improved from a mean value of 0.34 ± 0.011 to 0.30 ± 0.010, and these changes were due to both a decrease of PEPc and an in crease of LVETc. The postexercise LVETc, which is a marker of the posi tive inotropy of the exercise, signifi cantly (p=0.002) shortened with 49 ± 4.6 msec in control conditions and also during treatment with nebivolol with 30 ± 4.6 msec (p=0.002). From all these data it appears that nebivolol, unlike classical beta-block ers, beneficially influences cardiac function at rest, owing to a combined effect on both preload and afterload. These ancillary hemodynamic activi ties of nebivolol may be useful in the treatment of elderly hypertensive pa tients with left ventricular damage.
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