Cardiovascular Effects of Carotid Sinus Nerve Stimulation in Resting Man

¹ Chairman, Department of Medicine, McLaren Hospital, Flint, Michigan

The carotid sinus nerves were selectively stimulated in three patients and observations were made in basal state before and 15 minutes after the onset of continuous stimulation. The myocardial oxygen consumption decreased from 5.5 ± 0.6 to 4.8 ± 0.5 ml/min/100 gm, and the coronary blood flow from 48 ± 6 to 43 ± 6 ml/min/100 gm (mean ± SE). The coronary arteriovenous oxygen difference remained the same in two and narrowed in one patient who also showed a decrease in the coronary venous lactate:pyruvate ratio during stimulation. The lactate and pyruvate removal continued in all patients. The stimulation lowered the cardiac output from 3.0 ± 0.2 to 2.6 ± 0.2 L/min/M₂, and raised the systemic arteriovenous oxygen difference from 5.0 ± 0.3 to 5.7 ± 0.4 ml/100 ml. The total body oxygen consumption remained the same. The brachial artery mean pressure diminished from 103 ± 7 to 88 ± 6 mm Hg. The heart rate was not significantly different.