Postoperative hypertension: a comparison of diltiazem, nifedipine, and nitroprusside

In previous studies, the treatment of postoperative hypertension with sodium nitroprusside induced ischemic metabolism without a decrease in coronary sinus blood flow. In contrast, the calcium antagonists diltiazem and nifedipine reduce blood pressure and may improve myocardial metabolism. A prospective randomized trial was performed in 62 patients, in whom hypertension developed (mean arterial pressure greater than 95 mm Hg) after coronary bypass procedures, to compare diltiazem (n = 22), nifedipine (n = 20), and nitroprusside (n = 20). All three agents reduced blood pressure equally (p less than 0.0001, by analysis of variance). Heart rate decreased with diltiazem (p = 0.006) but increased with nifedipine and nitroprusside (p less than 0.05). Left ventricular diastolic function (the relation between left atrial pressure and left ventricular end-diastolic volume) was not changed with the three drugs. Systolic function (the relation between systolic blood pressure and left ventricular end-systolic volume) was depressed with diltiazem (p = 0.05 by analysis of covariance) and nifedipine (p = 0.05) but not with nitroprusside. Myocardial performance (the relation between left ventricular stroke work index and end-diastolic volume) was depressed most by diltiazem (p = 0.001 by analysis of covariance), and to a lesser extent with nifedipine (p = 0.03), but not with nitroprusside. Myocardial lactate flux in response to the stress of atrial pacing decreased with nitroprusside but not with diltiazem or nifedipine (p = 0.03 by analysis of variance). Diltiazem and nifedipine are effective agents for treating postoperative hypertension after coronary artery bypass operations.