Acute influence of different beta-blocking agents upon left heart hemodynamics at rest and during exercise in patients with coronary artery disease

The study investigated the acute hemodynamic changes induced in patients with angiographically confirmed coronary artery disease by 3 beta-blockers: metoprolol, cardioselective without intrinsic sympathomimetic activity (ISA), group I, 11 patients; bunitrolol, noncardioselective with ISA, group II, 11 patients; oxprenolol, noncardioselective with ISA, group III, 11 patients. Hemodynamic variables were obtained at rest and during exercise, before and 45 min after 10 mg i.v. of the drug. Changes in LVEDP and cardiac indexes were such as LV function was improved in 1 patient of group I, 7 patients of group II and 5 patients of group III; impaired in 4 patients of group I and in 1 patient of group III; unchanged in the others. Contractility indexes were less influenced by bunitrolol and oxprenolol. During exercise there was a significant difference between groups for LVEDP which was lower in group II (P less than 0.01). The data seem to indicate that the choice of the beta-blocker may be of importance when it is desirable that an already compromised cardiac function be not further impaired by pharmacological intervention.

Evidence for improved cardiac performance after beta-blockade in patients with coronary artery disease

The study was undertaken to investigate the acute haemodynamic effects of bunitrolol (0-2-hydroxy-3-(tert.butylamino)-propoxy)-bity. Right and left heart catheterization was performed in eleven patients with documented coronary artery disease. After bunitrolol (10 mg i.v.), there was a statistically significant decrease in left ventricular and aortic systolic pressures left ventricular end-diastolic pressure, aortic diastolic and mean pressures, pressure-rate product and compliance index (delta P/delta V). Left ventricular dp/dt, left ventricular dp/dt over isovolumic pressure, systemic resistance and heart rate tended to decrease, stroke volume and left ventricular stroke work index tended to increase, without statistical significance. Cardiac index showed individual variations, the mean values for the group being unchanged. Correlation of left ventricular end-diastolic pressure and left ventricular stroke work index showed a shift toward improved ventricular function curve in most cases, deterioration in no instance. Supine exercise was performed in ten patients. Angina occurred in nine patients; in five only before and in four before and after beta-blockade. Post-drug exercise heart rate, pressure-rate product and left ventricular end-diastolic pressure were significantly lower, the latter also in the four patients who still presented exercise angina. It is concluded that certain beta-blockers can improve cardiac performance at rest and during exercise in patients with coronary artery disease. This is explainable on the basis of a more favourable balance between oxygen supply and demand, together with a less marked negative inotropic effect due to the partial agonist activity of the agent used in the study.

Evaluation of the contractile state of the human heart from the first derivative of the apexcardiogram

The first derivatives of the left ventricular pressure pulse (dp/dt LV) and of the apexcardiogram (Δ ACG) were recorded 73 times in 45 subjects, and the time intervals from the peak of the R wave of the electrocardiogram to the peak of the derivatives (t-dp/dt LV and t-Δ ACG) were determined under different circulatory conditions. These parameters express the duration of the development of maximum tension during isometric contraction of the ventricle. The values obtained from the left ventricular pressure pulse and from the ACG showed close correlation both at rest and after pharmacological interventions which enhanced or depressed the myocardial contractile state. During orciprenaline infusion, t-dp/dt LV and t-Δ ACG were consistently shortened, while they increased in most cases after beta-adrenergic receptor blockade.

Determination of the time to peak derivative of the ACG, a parameter so far unexplored, is proposed as a simple method of detecting changes in the myocardial contractile state in the intact human being.