Enhanced vagal activity and normal arginine vasopressin response in carotid sinus syndrome: implications for a central abnormality in carotid sinus hypersensitivity

• Published in: Cardiovascular research Vol. 21; no. 7; pp. 545 - 550
• Main Authors: KENNY, ROSE ANNE, LYON, CALUM C, INGRAM, ANN M, BAYLISS, J, LIGHTMAN, STAFFORD L, SUTTON, RICHARD
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.07.1987
• Subjects: Aged; arginine vasopressin; Arginine Vasopressin - blood; Biological and medical sciences; Blood Pressure; Carotid Sinus - physiopathology; carotid sinus syndrome; Cranial nerves. Spinal roots. Peripheral nerves. Autonomic nervous system. Gustation. Olfaction; Female; head-up tilt; Heart Rate; Humans; Male; Medical sciences; Middle Aged; Nervous system (semeiology, syndromes); Neurology; Posture; Reflex, Abnormal - blood; Reflex, Abnormal - etiology; Reflex, Abnormal - physiopathology; Space life sciences; Syncope - blood; Syncope - etiology; Syncope - physiopathology; Syndrome; Vagus Nerve - physiopathology; vasovagal syncope; Human; Nervous system diseases; Hyperactivity; Etiopathogenesis; Central nervous system; Normal; Vasopressin; Response; Arginine; Syncope; Diseases of the autonomic nervous system; Vagus nerve; Hypersensitive carotid sinus syndrome
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1093/cvr/21.7.545

The relation between arginine vasopressin and vagal activity in carotid sinus syndrome was studied in 10 patients and 17 age matched controls using head up tilt as a stimulus. Of the controls, seven had unexplained syncope and 10 were healthy elderly subjects with no previous history of syncope. Subjects were studied supine for 45 min and thereafter during 120 min head up tilt to 40°. Phasic arterial pressure and heart rate were monitored throughout. Serum was sampled at frequent intervals to measure arginine vasopressin, noradrenaline, and adrenaline concentrations. Seventy per cent of carotid sinus patients had vasovagal syncope at (mean(SD)) 25(4) min after tilt compared with 43% of subjects with unexplained syncope and one healthy elderly control. The maximum (mean(SD)) fall in systolic blood pressure and heart rate was 70(20) mmHg and 20(7) beats·min−1 (p<0.001 and p<0.01 respectively). Arginine vasopressin, noradrenaline, and adrenaline concentrations rose significantly in syncopal subjects (p<0.001, p<0.01, and p<0.05 respectively). Changes in systolic blood pressure, heart rate, and hormone concentrations were similar for patients with carotid sinus syndrome and control subjects. For those who completed the tilt period without the development of symptoms, systolic blood pressure and arginine vasopressin and adrenaline concentrations were unchanged, whereas noradrenaline concentrations and heart rate rose significantly. Vasovagal activity is thus appreciably increased in carotid sinus syndrome. Furthermore, the afferent limb of the carotid sinus reflex appears to be intact in patients with carotid sinus syndrome since the pattern of arginine vasopressin release was not different from controls. Additionally, if the abnormality in carotid sinus syndrome is increased gain centrally it must exist beyond the afferent connections of the reflex arc.