Abstract
Summary
The question of the precise role of the heart in shock has been largely unresolved. Previous separate reports have shown that both excitatory and depressant actions on the myocardium after endotoxin are observed. The purpose of the present study was to assay the possibility of a direct myocardial toxic action of endotoxin or a circulating myocardial depressant factor released in the blood of endotoxin shocked animals. This was accomplished by utilization of beta adrenergic blockade (propranolol) under the experimental conditions of constant cardiac output and aortic pressure in an isolated canine heart preparation exchanging blood with an intact support animal shocked by endotoxin.
Results from the study fail to reveal a myocardial depressant effect following a lethal injection of endotoxin. Cardiac performance is relatively unimpaired after endotoxin in the presence of beta adrenergic blockade as evidenced by normal cardiac work and power, dP/dT, LVEDP, and oxygen uptake. Myocardial performance is postulated to be maintained in the presence of endotoxin and shocked blood by increased coronary blood flow and effective oxyhemoglobin dissociation in an acid medium under conditions of maintained cardiac output and coronary perfusion pressure.
Get full access to this article
View all access options for this article.