Effect of intracoronary nifedipine on coronary bloodflow and myocardial metabolism during pacing-induced ischemia.

Abstract

The effects of intracoronary nifedipine on coronary bloodflow, its regional distribution, myocardial oxygen consumption and lactate metabolism during pacing-induced angina were evaluated in 15 subjects. These responses were directly compared to 10 subjects who received an alcohol-based control solvent. Myocardial bloodflow was measured by thermodilution, with changes in regional coronary flow assessed using a dual radiolabelled (technetium-99m and indium-111) intracoronary microsphere technique and single photon emission tomography. Neither intracoronary nifedipine (100 micrograms) or the control solvent produced changes in systemic arterial pressure (nifedipine -2 mmHg and control +2 mmHg, both not significant). Intracoronary nifedipine markedly increased left ventricular end diastolic pressure (pre-nifedipine 13.0 mmHg versus post nifedipine 20.1, P less than 0.05), while increasing total coronary sinus bloodflow (pre-nifedipine 134 mL/min versus post nifedipine 189, P less than 0.05): Regional coronary bloodflow increased in all myocardial segments, regardless of the severity of coronary stenosis (64 to 132% baseline, all P less than 0.05). In addition, intracoronary nifedipine increased myocardial oxygen consumption (pre-nifedipine 12.3 mL/min versus post nifedipine 15.7, P less than 0.05), with a trend towards improved lactate extraction (pre-nifedipine 0.24 mg/mL versus post nifedipine 0.12, not significant). Although decreased ventricular afterload (left ventricular systolic wall stress) may contribute to nifedipine's antianginal properties, a primary increase in regional coronary bloodflow also appears to be an important factor in the alleviation of myocardial ischemia.

• Authors: B P Kimball, R R Mildenberger, C A Lefkowitz, B L Ross, S Houle, P R McLaughlin
• Journal: The Canadian journal of cardiology (Can J Cardiol) Vol. 6 Issue 8 Pg. 333-9 (Oct 1990) ISSN: 0828-282X [Print] England
• PMID: 2268796 (Publication Type: Clinical Trial, Controlled Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Nifedipine

Topics

• Adult
• Angina Pectoris (drug therapy)
• Cardiac Pacing, Artificial
• Coronary Circulation (drug effects)
• Female
• Heart (diagnostic imaging, drug effects)
• Hemodynamics (drug effects)
• Humans
• Male
• Middle Aged
• Myocardium (metabolism)
• Nifedipine (administration & dosage, pharmacology, therapeutic use)
• Oxygen Consumption (drug effects)
• Radiography
• Thermodilution
• Tomography, Emission-Computed, Single-Photon