The effects of 1-hydrazinophthalazine upon coronary hemodynamics and myocardial oxygen metabolism in essential hypertension

The effects of a new anti-hypertensive agent (endralazin) upon the general and coronary haemodynamics of the anaesthetized dog

The effects of a new anti-hypertensive drug (endralazin) was studied in the intact anesthetized dog; in a dose of 150 millimicron/kg intravenously, the drug increased heart rate, respiratory rate, cardiac output and coronary sinus flow. Systemic blood pressure fell 60 min after the injection. The drug decreased calculated peripheral, pulmonary, and coronary vascular resistance,, amd maintained calculated cardiac efficiency. It also increased blood glucose, non-esterified fatty acid, lactate and pyruvate values, but did not influence cardiac usage of these substrates. There was evidence also of catecholamine release during the period of the study.

Methods for the assessment of the effects of drugs on coronary blood flow in man

The methods currently available for measurement of coronary blood flow in man are reviewed and their advantages and limitations discussed. Most of the techniques are invasive and involve cardiac catheterization. The least invasive isotope techniques are either not quantitative or involve expensive equipment not available in many centres. Two of the most suitable methods for assessing the effects of drugs on coronary flow are coronary sinus thermodilution and isotope washout curves using 133xenon or [125I]-iodo-antipyrine. The ideal technique for measuring coronary blood flow has yet to be developed.

Hemodynamic responsiveness to short- and long-acting vasodilators in left ventricular failure

Vasodilators acutely reduce afterload and improve hemodynamics in congestive heart failure. Intravenous nitroprusside reduces left ventricular filling pressure and increases cardiac output while modestly reducing blood pressure and not changing heart rate in patients with heart failure in whom this response is characteristic. Comparably reduced blood pressure during nitroprusside infusion in normal subjects or hypertensive patients without failure results in a decrease in cardiac output and tachycardia. Long-acting vasodilators are also effective in patients with congestive heart failure. Nitrates, predominant venodilators, decrease left ventricular filling pressure as much as nitroprusside does, but increase cardiac output less. Hydralazine, an arterial dilator, increases cardiac output similarly to nitroprusside but decreases filling pressure less. Combining hydralazine with nitrates results in hemodynamic effects almost identical to those of nitroprusside. The quinazoline derivatives, trimazosin and prazosin, are also effective vasodilators, which act on both arteries and veins in patients with congestive heart failure. The hemodynamic response to vasodilators is influenced by the underlying hemodynamic status, as the change in cardiac output is directly related to base line ventricular filling pressure as well as systemic vascular resistance, and inversely related to the base line cardiac output. Response to vasodilators does not appear to be altered by age, diabetes, acute myocardial infarction or the cause of congestive myocardiopathy.

Systemic and coronary haemodynamic effects of the new hypotensive drug L 6150

The acute systemic and coronary haemodynamic effects of a new hypotensive drug L 6150 (3-hydrazino-6-[N,N-bis(2-hydroxyethyl)amino]pyridazine) have been studied in six patients with renal or essential hypertension. The drug, administered intravenously at a dose of 2-9 mg, caused a marked hypotension and increase of cardiac output in five cases. Though left ventricular work was reduced or unchanged after the drug, myocardial blood flow increased markedly, coronary resistance decreased and coronary A-V oxygen difference decreased by about 50% indicating coronary vasodilation. When compared with the available data on the effects of hydrazinophthalazine, L 6150 appeared to have qualitatively similar effects, but a somewhat greater direct coronary vasodilator effect.

The effects of 3-hydrazine-6[N,N-bis(2-hydroxyethyl)-amino]-pyridazine dihydrochloride (L6150) on the general and cardiac haemodynamics of the intact dog

1. The effects of 3-hydrazine-6[N,N-bis(2-hydroxyethyl)amino]-pyridazine dihydrochloride (L6150) were studied in intact anaesthetized dogs. 2. In a dose of 1 mg/kg/(i.v.) the drug increased respiration rate, cardiac output, and left and right ventricular work. 3. It decreased femoral pressure and systemic and total pulmonary resistance. 4. It increased coronary flow and coronary sinus O2 content. 5 The drug also increased whole body glucose, lactate, pyruvate and NEFA values.

Cardiovascular pharmacology of propranolol in man

The success of propranolol in treating the symptoms of angina pectoris has raised questions about the effects of beta-adrenergic blockade on the hemodynamic functions, myocardial mechanics, energetics, and metabolic functions. Five milligrams of propranolol was given intravenously to 27 human subjects, 18 with and nine without angiographically proven coronary atherosclerosis. The drug produced a decrease in externally measured indices of myocardial mechanical effort and consequently a fall in myocardial oxygen demands. The hemodynamic changes and resultant increases in myocardial oxygen consumption and coronary flow during supine leg exercise were also attenuated. Propranolol produced different changes in myocardial arteriovenous oxygen extraction depending upon whether the coronary circulation was normal or diseased. Although the data suggest that coronary vasoconstriction occurred in patients with atherosclerotic lesions, no significant change in myocardial lactate exchange was noted after administration of propranolol. Beta-adrenergic blockade caused a decline in cardiac filling pressures and volumes at the dose level used in this study, presumably by decreasing venous return.

Action of nitroglycerin on the coronary circulation in normal and in mild cardiac subjects

Nitroglycerin has been used extensively as a coronary vasodilator. Its remarkable clinical effect has been presumed to be related to a direct action on the smooth muscle of the coronary arteriole. No observations have been made of nitroglycerin action on the coronary circulation in man. This report presents studies of changes induced by the drug in 10 normal or nearly normal subjects. The authors present evidence that although coronary vasodilatation does indeed occur, it appears to be secondary to changes in myocardial oxygen requirements. Hemodynamic observations revealed a general decrease in pressures in both peripheral and pulmonary circuits; caution is urged concerning the occasional severe hypotensive effects of nitroglycerin.