Abstract
Neurogenic orthostatic hypotension (OH) causes severe orthostatic intolerance. We evaluated hemodynamic parameters in a patient with pure autonomic failure (PAF) using various unique approaches. A 60-year-old woman had worsening light-headedness, fatigue, and severe OH without compensatory tachycardia. PAF was diagnosed based on negative neurological findings, testing, and imaging results. The active standing test did not increase the heart rate (HR), and it decreased cardiac output, indicating impaired sympathetic control of cardiovascular activity. HR did not change during the supine bicycle exercise stress test, whereas blood pressure decreased. The patient had an accentuated reaction to isoproterenol but did not respond to atropine sulfate. Isoproterenol 0.01 μg/kg/min caused a 153 % increase in HR that required more than 30 min to return to its original value, suggesting hypersensitivity to catecholamines and decreased parasympathetic activity. As for why atropine sulfate (0.04 mg/kg) did not increase HR, we assumed that parasympathetic activity was already suppressed or the sympathetic effects were not predominant. Intravenous atropine sulfate may be useful in diagnosing PAF, which generally lacks specific neurological physical findings. A proper understanding of the hemodynamics involved in the management of PAF-associated OH is crucial. LEARNING OBJECTIVE: The autonomic control of cardiovascular function is impaired in pure autonomic failure, and neurogenic orthostatic hypotension can be diagnosed by evaluating changes in heart rate. Treatment should be based on the hemodynamic characteristics using non-invasive cardiac output monitoring, pharmacological approaches, and supine bicycle exercise stress tests.