Chronic carotid compression in dogs: a study of hemodynamic changes with and without sinus denervation.

Abstract

In two groups of dogs the carotid sinuses were chronically compressed bilaterally by the application of plastic Wakerlin clamps. In the first series of three dogs, the carotid sinus nerves were sectioned and the adjacent vessel walls thoroughly cleaned. Chronic carotid sinus compression resulted in an increase in arterial systolic pressure, diastolic pressure, average arterial pressure, pulse pressure, and heart rate over a period of 422 to 485 days. In the second series of five dogs, in which the carotid sinus innervation was preserved, chronic carotid sinus compression resulted in a variable but slight change in arterial systolic pressure, a consistent increase in diastolic pressure, a variable but slight change in average arterial pressure--with only one dog showing a consistent significant increase, a consistent decrease in pulse pressure, and a variable effect on heart rate over a period of 593 to 695 days. The daily administration of 6 Gm. of sodium chloride per day to the second series of dogs resulted in no appreciable changes in pressure. However, there was a tendency for the heart rate to decrease, with three dogs showing a significant decrease. When the salt administration was stopped, the heart rates returned to values near those observed prior to salt administration. The results suggest that in the first series of dogs, with the carotid sinuses denervated chronically, there is an increase in cardiac output and a decrease in peripheral resistance. In the second series of dogs, with innervation of the sinuses intact and with chronic compression, the results suggest a decrease in cardiac output and an increase in peripheral resistance.