Flávio Maciel de Freitas

General Circulatory Alterations Induced by Intravenous Infusion of Synthetic Bradykinin in Man

The general hemodynamic effects induced by a continuous intravenous infusion of synthetic bradykinin were studied in ten patients submitted to simultaneous right- and left-heart catheterization. A significant drop in systemic arterial pressure and in total peripheral resistance was observed, coincident with an increase of the cardiac output, heart rate, and stroke volume. There was no consistent change of the pulmonary arterial and left atrial pressures, but the pulmonary vascular resistance decreased significantly.

Determination of Pulmonary Blood Volume by Single Intravenous Injection of One Indicator in Patients with Normal and High Pulmonary Vascular Pressures

Determinations of the pulmonary blood volume were carried out in 12 patients with pulmonary hypertension and in 12 patients with normal pressures in the pulmonary circulation, by the use of a single intravenous injection of one indicator, blood sampling being made through catheters in the pulmonary artery and left atrium and connected with two densitometers of similar characteristics. Pulmonary blood volume measured by this technic includes the major portion of, or the entire left atrial volume. Values obtained from duplicate or triplicate determinations performed in each patient have shown that this technic provides very good reproducibility of the results expressed by an average percentile variation around the mean equal to 3.2±2.7. The mean pulmonary blood volume as referred to body surface area was 375±97 ml./M.2 for patients with pulmonary hypertension, and 310±21 ml./M.2 for patients with normal pulmonary intravascular pressures. This difference was found to be significant (p<0.05) but was attributed, at least in part, to a difference in the mean left atrial volume between the two groups studied.Some possible advantages and limitations of the method, as well as the poor correlation between pulmonary blood volume and other variables, like pulmonary intravascular pressures, stroke volume, and cardiac output, were discussed.

Action of Bradykinin on Human Pulmonary Circulation Observations in Patients with Mitral Valvular Disease

Twenty-one patients with pulmonary hypertension secondary to rheumatic mitral valve disease were submitted to right and left heart catheterization and received a continuous intravenous infusion of synthetic bradykinin (average dose, 0.98 &mgr;g/kg/min).The drug elicited an appreciable fall of the systemic vascular resistance simultaneously with a decrease of the mean systemic arterial pressure and an increase of the cardiac output in all cases. The rise in cardiac output derived mainly from an increase in heart rate, since the modifications of the stroke volume were generally of low magnitude.In the pulmonary circulation, the increase in blood flow was coincident with a rise of the mean arterial and venous (left atrial) pressures in 19 and all patients, respectively. The pulmonary vascular resistance fell in 19 patients, but no appreciable modifications were noted in pulmonary blood volume.The changes in the lesser circulation were interpreted as expressing secondary effects, either mechanical or reflex, consequent to theaction of bradykinin on the systemic vessels and heart rather than a direct effect of the drug on the pulmonary vessels.