Calcium channel blockade with felodipine does not affect metabolic coronary vasodilation in patients with coronary artery disease.
The effect of calcium channel blockers may affect the feedback mechanism between myocardial metabolic activity and coronary blood flow. To test this hypothesis the effect of calcium channel blockade on metabolic coronary flow regulation was studied. In 10 patients with stable coronary artery disease, coronary sinus blood flow and myocardial oxygen supply and consumption (MVO2) were measured both at sinus rhythm and during atrial pacing (30 beats/min above sinus rate), at control and during infusion of felodipine, a vasoselective dihydropyridine. The myocardial oxygen supply-consumption ratio at control (i.e., the slope of the regression line characterizing normal metabolic flow regulation) was 1.58 (95% CI, 1.38-1.80). Following infusion of felodipine, systemic and coronary vascular resistance during sinus rhythm decreased by 20 +/- 11% and 23 +/- 15%, respectively, and coronary venous oxygen saturation increased from 36 +/- 6% at control to 42 +/- 7% (p = 0.047) during infusion of felodipine. The myocardial oxygen supply-consumption ratio, characterizing metabolic flow regulation during felodipine, was 1.52 (95% CI, 1.26-1.78) and thus not different from control. Metabolic coronary flow regulation was not affected by administration of felodipine, although the setpoint of this regulation mechanism might have been offset by the initial drug-induced coronary vasodilation, which persisted during pacing.
Kal
Jasper E
JE
Department of Anesthesiology, Cardiovascular Research Institute Amsterdam, Academic Medical Center, Amsterdam, The Netherlands.
Spaan
Jos A E
JA
van Wezel
Harry B
HB
D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000097:blood / Q000494:pharmacology*; D002302:Cardiac Output / Q000187:drug effects; D002304:Cardiac Pacing, Artificial; D003324:Coronary Artery Disease / Q000378:metabolism / Q000503:physiopathology*; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects*; D015736:Felodipine / Q000097:blood / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*
D002121:Calcium Channel Blockers; D015736:Felodipine