THE EFFECT OF TEMPORARY OCCLUSION OF ARTERIOVENOUS FISTULAS ON HEART RATE, STROKE VOLUME, AND CARDIAC OUTPUT 1

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Abstract
The changes in heart rate and in cardiac output, as measured by the ballistocardiograph, occurring upon temporary compression of an arteriovenous fistula have been studied in a group of 25 patients. In 68% of the patients there was a significant decrease in heart rate (Branham''s Sign), which occurred almost immediately upon compression of the fistula and which was blocked by the use of atropine. In 88% of the patients there was a decrease in stroke volume and cardiac output which occurred rapidly and simultaneously with the compression of the fistula, but which was not altered by the use of atropine. The evidence indicates that the change in heart rate results from a nervous reflex mediated by the vagus nerve, and most likely arises from alterations in arterial pressure. It appears that the change in stoke volume is due to variations in diastolic relaxation of the ventricle or to variation in the completeness of systolic emptying. Although exactly comparable observations are difficult to obtain, the cardiac output found immediately upon closure of an arteriovenous fistula is approx. the same as that found several weeks after operative removal of the fistula.
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