New concepts of digitalis

The data presented in this review have substantiated the following ideas:* There is a direct relationship between digitalis dosage and myocardial contractile force. A small dose of digitalis produces a small increase of the contractile force of the heart and a large dose increases the force of the heart's contraction by a much greater amount, whether the heart is normal, has a poor reserve, or is in frank failure.* Digitalis is of benefit to the patient with cardiovascular disease whether his heart is in failure or not.

Hemodynamic effects of glucagon in patients with heart disease

The intravenous administration of 3 or 5 mg of glucagon to 13 patients with heart disease resulted in a statistically significant increase in heart rate, cardiac index, stroke power index, mean rate of left ventricular ejection, and maximum rate of rise of left ventricular pressure, whereas systemic vascular resistance declined. A moderate increase in mean stroke volume index and stroke work index and a slight fall in left ventricular end-diastolic pressure also occurred, although these changes were not statistically significant. The increase in cardiac index averaged 19%, with nine of the patients demonstrating an increase exceeding 10% of their respective control value. These effects of glucagon generally reached a maximum within 15 min after drug administration and also were of short duration.

Positive inotropic and chronotropic effects of glucagon were observed in most but not all of these patients. In addition, the magnitude of these effects varied considerably among patients; the variation, however, did not appear to be related to the severity or duration of the heart disease.

In eight patients, the infusion of isoproterenol produced greater increases in cardiac index and decreases in left ventricular end-diastolic pressure than glucagon did.

Although the effect of glucagon was short, the frequent improvement in hemodynamics which occurred in the absence of significant side effects, notably arrhythmias, indicates that the inotropic actions of this agent may be useful under certain clinical conditions.

Ethiopian cardiovascular studies. II. Treatment of pulmonary oedema in outpatients

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Hemodynamic effects of diuresis at rest and during intense upright exercise in patients with impaired cardiac function

Although diuretic therapy appears to improve the exercise capacity of patients with moderately impaired cardiac function, the hemodynamic basis for this improvement is not clear. It is also unknown to what extent the moderate diuresis that often occurs during the first few days of hospitalization contributes to the normal or nearly normal hemodynamic measurements obtained in certain patients with cardiac impairment who are thought clinically to have signs and symptoms of pulmonary congestion. Accordingly, the circulatory response to moderate diuresis resulting in a loss of weight averaging 3.4 kg was investigated in 15 patients with heart disease. At rest in the supine position mean pulmonary arterial wedge pressure fell after diuresis from an average of 24 to 13 mm Hg. Reductions also occurred in mean pulmonary arterial pressure (42 to 26 mm Hg), mean right atrial pressure (9 to 4 mm Hg), and right ventricular end-diastolic pressure (11 to 6 mm Hg). Cardiac output decreased by an average of 20%, mean systemic arterial pressure by 12%, right ventricular stroke work by 44%, and left ventricular stroke work by 25%. Diuresis also caused similar reductions in these values in the sitting position at rest and during mild and intense levels of treadmill exercise. Despite the reductions in cardiac output, all but one of the patients studied achieved substantial clinical improvement from the diuresis. Such improvement probably resulted from the fact that the beneficial effects of lower pulmonary vascular pressures outweighed the deleterious effect of a reduction in cardiac output. Thus, moderate changes in body weight brought about by either fluid retention or fluid loss may result in substantial alterations in circulatory dynamics. These changes, if unrecognized, can lead to considerable confusion when attempts are made to correlate the hemodynamic findings with the degree of cardiac decompensation as judged clinically.