title: Improved myocardial oxygen utilization by diltiazem in patients.
abstract: Calcium entry blocking drugs produce different effects on systemic and coronary hemodynamics and myocardial oxygen extraction. To examine the effects on myocardial oxygen extraction, intravenous diltiazem (100 micrograms/kg bolus with a continuous 10 micrograms/kg/min infusion) was administered to 11 patients at rest and during controlled heart rates (100 +/- 5 and 120 +/- 5 bpm). At rest, diltiazem decreased mean arterial pressure from 109 +/- 13 to 99 +/- 14 mm Hg (p less than 0.01), increased heart rate from 64 + 12 to 74 +/- 14 bpm (p less than 0.01), and decreased coronary sinus resistance (1.02 +/- .41 to 0.87 +/- .40 U, p less than 0.05). Myocardial oxygen extraction was significantly reduced since coronary sinus oxygen content increased (6.0 +/- 0.9 to 7.8 +/- 1.2 ml/dl, p less than 0.01) and the arterial-coronary sinus oxygen difference decreased (12.0 +/- 1.7 to 10.6 +/- 1.6 ml/dl, p less than 0.01). Similar changes occurred with heart rate held constant. There were no significant changes in absolute coronary sinus blood flow, calculated myocardial oxygen consumption, or left ventricular dP/dt. Diltiazem decreases mean arterial pressure while reducing both myocardial oxygen extraction and coronary arterial resistance, suggesting that a principal mechanism of a beneficial effect upon the coronary circulation appears to be an improvement in myocardial oxygen extraction relative to myocardial oxygen demand.
mesh_terms: D000328:Adult; D000368:Aged; D001552:Benzazepines / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects; D004110:Diltiazem / Q000627:therapeutic use*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*
chemical_list: D001552:Benzazepines; D004110:Diltiazem