Cardiac index during intravenous levarterenol infusion in man

Hemodynamics of angiotensin in man

These data demonstrate that in normal subjects, angiotensin II is 10 times as potent as norepinephrine which it resembles hemodynamically. An increase in the systolic pressure is associated with a significant increase in diastolic pressure, an increase in venous pressure, a decrease in heart rate, a slight decrease in cardiac output and a striking increase in total peripheral resistance, a decrease in renal blood flow, decreased glomerular filtration rate, increase in filtration fraction, and slight decrease in urinary volume.

Preliminary studies in patients in shock suggest that angiotensin II is 2 or 3 times as potent as norepinephrine. Continuous administration is not associated with the development of tachyphylaxis, and sloughing of tissues does not occur if there is leakage outside the vein.

Carotid sinus hypersensitivity: evaluation of the vasodepressor component

The basis of the vasodepressor response in patients with carotid sinus hypersensitivity (CSH) is unknown, and prevention of recurrent vasodepressor-induced hypotension in these patients has not been possible. In this study we assessed the effectiveness of atrioventricular sequential pacing and pharmacologic interventions in the prevention of carotid sinus massage (CSM)-induced vasodepressor responses in eight patients with CSH. Maintenance of constant heart rate (80 beats/min) and atrioventricular synchrony (atrioventricular interval 150 msec) with sequential pacing did not significantly alter mean CSM-induced fall in systolic pressure (CSM control, -60 +/- 12 mm Hg vs CSM with atrioventricular sequential pacing, -48 +/- 19 mm Hg). Similarly, neither pharmacologic muscarinic blockade nor combined muscarinic and beta-adrenergic blockade significantly attenuated CSM-induced fall in systolic pressure (CSM with atropine, -43 +/- 16 mm Hg; CSM with atropine plus propranolol, -47 +/- 18 mm Hg; both p = NS vs atrioventricular sequential pacing alone). On the other hand, intravenous norepinephrine and oral ephedrine blunted the CSM-induced drop in systolic pressure (CSM with norepinephrine, -19 +/- 12 mm Hg; CSM with ephedrine, -21 +/- 11 mm Hg; both p less than .01 vs atrioventricular sequential pacing alone). Thus, vasodepressor responses were not prevented by control of heart rate, maintenance of atrioventricular synchrony, pharmacologic muscarinic blockade, or combined muscarinic and beta-adrenergic blockade, but were attenuated by drugs believed to be predominantly alpha-adrenergic agonists. Consequently, atrioventricular sequential pacing alone may be inadequate to prevent hypotension in patients with pronounced vasodepressor responses, whereas administration of vasoconstrictors such as ephedrine may diminish symptoms.

Old and new inotropic drugs

An ideal cardiotonic agent should improve cardiac contractility and increase the oxygen supply to various tissues without inducing tachycardia, arrhythmias, decrease in coronary blood flow or increment in oxygen requirements of the myocardium. It should also be safe and orally active and have a persistent action. The aim of this paper is to describe various positive inotropic drugs at our disposal. The hemodynamic effects and the indications of adrenaline, noradrenaline, isoprenaline, dopamine, dobutamine and cardiac glycosides are presented first. Then several new promising orally active compounds are discussed.

The Direct Effects of Norepinephrine, Epinephrine, and Methoxamine on Myocardial Contractile Force in Man

The effects of 5 sympathomimetic amines on myocardial contractile force were determined with the Walton-Brodie strain-gage arch in 16 patients undergoing operations for congenital heart disease. Equal doses of norepinephrine and epinephrine produced almost identical increments in myocardial contractile force; equipressor doses of methoxamine resulted in little or no change in the force of contraction. Mephentermine and metaraminol produced increments in myocardial contractile force similar to those following norepinephrine administration but the duration of action was longer. The results of these studies indicate that there are no qualitative differences in the actions of these amines on cardiac contractile force of dog and man and provide a basis for the rational clinical use of these agents.