Influence of baseline hemodynamic status and sympathetic activity on the response to nicardipine, a new dihydropyridine, in patients with hypertension or chronic congestive heart failure

Abstract

We evaluated the immediate hemodynamic response to nicardipine, administered as an intravenous bolus and 30-minute sustaining infusion, in 10 patients with systemic hypertension (HTN) and 10 patients with chronic congestive heart failure (CHF). Baseline systemic vascular resistance and the response to nicardipine for HTN (1968 +/- 657 to 905 +/- 256 dynes X sec X cm-5) and CHF (2002 +/- 988 to 1089 +/- 216 +/- 99 dynes X sec X cm-5) were virtually identical (P less than 0.01). In both groups there was a significant increase of cardiac index in response to afterload reduction: HTN, 2.70 +/- 0.46 to 4.47 +/- 1.01; CHF, 1.90 +/- 0.33 to 2.88 +/- 0.80 L/min/m2 (P less than 0.01), so that a negative inotropic effect was not evident. In HTN the increase in cardiac index was primarily the result of reflex increase of heart rate (67 +/- 16 to 95 +/- 25 bpm [P less than 0.05]), associated with norepinephrine increase from 402 +/- 243 to 744 +/- 364 pg/ml (P less than 0.001). In CHF the cardiac index increase was caused by a stroke volume index increase (23 +/- 4 to 33 +/- 9 ml/min; P less than 0.01), with no significant change in heart rate or norepinephrine. Thus nicardipine, by means of calcium channel antagonism, induced reversal of vasoconstriction. Differences in the cardiac response identify the importance of characterizing the pathophysiologic status of cardiac impairment to more accurately interpret pharmacologic interventions.