Carotid Sinus Baroreceptor Reflex Effects upon Myocardial Contractility.

• At the present time, the reflex effects of stimulation of the carotid sinus baroreceptors on atrial and ventricular dynamics are the subject of controversy. Several investigators have suggested that stimulation of the carotid sinus baroreceptors has a reflex negative inotropic effect directly upon cardiac performance." The work of Sarnoff and co-workers ° has adduced substantial evidence for this concept. Salisbury et al., however, after comparing the effects of occluding the aorta, brachiocephalic artery, and common carotid artery, denied the existence of this reflex effect. They suggested that the changes in cardiac performance observed by previous investigators might have been the indirect result of reflex changes in venous return, arterial impedance, and heart rate; or that they might have been due to the existence of excessively high heart rates, or to concomitant cerebral ischemia.