Journal of the American College of Cardiology
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J. Am. Coll. Cardiol. · Mar 1993
Randomized Controlled Trial Comparative Study Clinical TrialNoninvasive assessment of the direct action of oral nifedipine and nicardipine on left ventricular contractile state in patients with systemic hypertension: importance of reflex sympathetic responses.
This study was designed to noninvasively assess the direct action of calcium channel blockers on left ventricular contractility in humans and to establish a framework for determining the importance of reflex sympathetic responses to any pharmacologic intervention. ⋯ Totally noninvasive techniques showed a differential effect on left ventricular contractility between nifedipine and nicardipine when alterations in afterload and reflex sympathetic responses were eliminated as confounding variables. This diagnostic approach, based on the use of pharmacologic probes, should have wide applicability for assessing the direct inotropic effect of any agent, even in the presence of complex primary and secondary physiologic modes of action.