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[Effect of the calcium antagonist nisoldipine on electrophysiologic parameters in the human]
Insights
Nisoldipine, a calcium antagonist, minimally impacts heart electrophysiology in humans. It slightly shortens sinus node recovery time and decreases right ventricular refractoriness, with heart rate increases attributed to blood pressure changes.
Area of Science:
- Cardiovascular Electrophysiology
- Pharmacology
Context:
- Calcium antagonists are crucial in managing cardiovascular diseases.
- Understanding the electrophysiological effects of new drugs like nisoldipine is essential for clinical application.
Purpose:
- To evaluate the impact of intravenous nisoldipine on cardiac electrophysiological parameters.
- Specifically assessing effects on sinus node function, intracardiac conduction, and cardiac refractoriness.
Summary:
- Nisoldipine (1.5 microgram/kg IV) shortened sinus node cycle length and recovery time by 10% without affecting sinoatrial or intracardiac conduction.
- A slight but significant decrease in right ventricular effective refractory period was observed; other refractory periods remained unchanged.
- Systolic blood pressure decreased by 6%, while diastolic pressure was constant, leading to a heart rate increase likely due to sympathetic reflex.
Impact:
- Nisoldipine demonstrates minimal adverse electrophysiological effects in humans.
- The observed hemodynamic changes suggest a potential role in vasodilation without significant cardiac electrical disruption.
Abstract:
We investigated the influence of nisoldipine, a new calcium antagonist, on sinus node function, intracardiac conduction times, and the refractoriness of different compartments of the heart. Three catheters were placed in the right heart: a quadripolar one in the high right atrium, a bipolar one in the His position, and one in the apex of the right ventricle. Nisoldipine given i.v. in a dose of 1.5 microgram/kg body weight shortened the sinus node cycle length and the sinus node recovery time by 10%. The rate corrected sinus node recovery time, the sinoatrial conduction time, and the intracardiac conduction times remained unaffected. The effective refractory period of the right ventricle decreased slightly but significantly. The refractoriness of the other compartments did not change significantly. Systolic blood pressure decreased by 6%, whereas diastolic blood pressure remained constant. Nisoldipine thus exhibits no major effects on electrophysiological parameters in man. The increase in heart rate is regarded as a sympathetic reflex mechanism due to the decrease of systemic resistance.