The American journal of cardiology
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The hemodynamic effects of tazolol, a new long-acting beta-stimulating drug, were studied in dogs with acute pump failure caused by experimental myocardial infarction and the results were compared with the actions of isoproterenol given in small and large doses. Tazolol produced a significant and sustained increase in cardiac output and stroke volume, while causing a decrease in peripheral resistance and mean aortic pressure. Heart rate was only modestly increased. ⋯ The increase in double product (systolic pressure X heart rate) produced by tazolol was also considerably less than that of isoproterenol. Tazolol may prove to be a useful addition to the drugs available for the treatment of myocardial failure of various causes. It is now being studied in patients with heart failure due to coronary artery disease.
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Dopamine and isoproterenol were each administered in two different doses to 12 patients with coronary artery disease in the period immediately after open heart surgery. The two doses of dopamine resulted in respective increases in cardiac output of 23 and 43 percent and reductions in systemic vascular resistance of 23 and 32 percent; neither dose significantly altered heart rate. The two doses of isoproterenol caused respective increases of 23 and 37 percent in cardiac output and 18 and 28 percent in heart rate and reductions in systemic vascular resistance of 22 and 29 percent. We conclude that lack of chronotropic effect of dopamine as compared with isoproterenol may make the former the agent of choice in patients requiring inotropic agents for their care in the early period after cardiac surgery.