[Primary dysautonomia in the elderly: the diagnostic value of the inversion of the circadian rhythm of arterial blood pressure]

Ambulatory blood pressure monitoring allows characterization of the circadian variations in blood pressure.In order to investigate the diagnostic value of circadian variations in blood pressure in the elderly, 11 patients with autonomic failure and 11 control subjects paired on age, blood pressure level and daily life activity range were studied.Periodic postural disorders, positive response to passive tilt-test and alpha denervation supersensitivity to noradrenaline were found in all patients with autonomic failure. In control subjects, blood pressure levels assessed by ambulatory monitoring were lower at night. Conversely, circadian variations in blood pressure were higher at night and lower in the morning in patients with autonomic failure. The nadir of blood pressure measurement was related with the reported time of peak incidence of orthostatic symptoms.Ambulatory 24-hour blood pressure monitoring may therefore be of value in the diagnosis and management of patients with autonomic failure.