Previously reported experimental studies have indicated that outflow obstruction can be produced within the normal left ventricle of the dog under conditions of reduced cardiac output or augmented myocardial contractile force, or both. This hypothesis was re-examined in the experiments described. In 36 normal dogs, isoproterenol and other inotropic drugs were administered before and during hemorrhagic shock or a period of controlled decreased venous return. In 21 dogs, systolic pressure gradients between the left ventricle and central aorta were recorded when left ventricular pressure was measured from a catheter introduced from the aorta or left atrium. The elevated left ventricular pressures responsible for the gradients were shown to be artifacts, however, when the pressure was simultaneously measured from a catheter in the apex of the ventricle. It is concluded that there is presently no valid hemodynamic evidence that outflow obstruction can be induced within the normal ventricle of the dog, and consideration is given to possible mechanisms responsible for the factitious pressure pulses recorded in these and other investigations.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine