VASODILATOR THERAPY DURING CORONARY-ARTERY SURGERY - COMPARISON OF NITROGLYCERIN AND NITROPRUSSIDE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 77  (2) , 301-309
Abstract
Intraoperative hypertension is a common problem in patients undergoing myocardial revascularization. Patients [20] who developed acute hypertension after sternotomy were studied. Ten patients received 3 doses of i.v. nitroglycerin (32, 64, and 96 .mu.g/min), and 10 patients received nitroprusside (20, 40 and 60 .mu.g/min). All patients were anesthetized with morphine, diazepam, nitrous oxide, O2 and pancuronium bromide. Patients (5) in each group also received enflurane. The study compared the effects of nitroglycerin and nitroprusside on systemic hemodynamics, myocardial O2 supply/demand relationships, and ischemic changes on the ECG. Both drugs decreased preload and afterload in a dose-related manner. Heart rate increased significantly only with the largest dose of each drug. Myocardial O2 demand was decreased significantly by both drugs, while the coronary perfusion pressure was decreased more by nitroprusside. Both nitroglycerin and nitroprusside improved left ventricular performance. Nitroglycerin improved ST-segment depression in eight of 10 patients; while nitroprusside improved the ST segments in 6 patients, and worsened the ST segments in 3 patients. None of the nitroglycerin group had worsening of the ECG ST segments. These findings demonstrate that both drugs can control intraoperative hypertension and can decrease myocardial O2 demand. Nitroglycerin was shown to improve ischemic changes on the ECG more often than nitroprusside.

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