Effects of diltiazem on cardiac function and regional blood flow at rest and during exercise in a conscious rat preparation of chronic heart failure (myocardial infarction).

The effects of intravenous infusion of diltiazem on regional blood flow (radioactive microspheres), hemodynamics, and maximum rate of oxygen consumption were evaluated in conscious rats with congestive heart failure caused by large myocardial infarction (n = 10, infarct size 41.8% of left ventricle) and compared with data obtained from rats subjected to sham surgical procedures (n = 9). In both groups data were obtained at rest and during submaximal treadmill exercise during alternate infusion of diltiazem and saline. In the group with heart failure, diltiazem increased stroke volume at rest and during exercise (p less than .05), reduced heart rate (p less than .05), and improved cardiac output during exercise (p less than .05) without increasing left ventricular end-diastolic pressure in any of the animals. Blood flow to renal and splanchnic circulations was reduced in the group with heart failure but was increased by diltiazem to values similar to those observed in sham-operated animals. Although skelet...