Hemodynamic recognition of pure autonomic failure: A case report

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.

Keywords: Atropine sulfate; Isoproterenol; Non-invasive cardiac output monitor; Orthostatic hypotension; Pure autonomic failure; Supine bicycle exercise stress test.

Fig. 1

The supine exercise stress test using the ergometer. The red, orange, and green lines represent systolic blood pressure, diastolic blood pressure, and heart rate, respectively. BP, blood pressure; HR, heart rate; sBP, systolic blood pressure; dBP, diastolic blood pressure.

Fig. 2

The active standing test. The upper graph shows the systolic blood pressure as a red line, diastolic blood pressure as an orange line, and heart rate as a green line before and after the active standing load. The lower graph shows the stroke volume as a light blue line, cardiac output as a navy blue line, and stroke volume variability as a blue line. BP, blood pressure; HR, heart rate; sBP, systolic blood pressure; dBP, diastolic blood pressure; CO, cardiac output; SV, stroke volume; SVV, stroke volume variability.

Fig. 3

Isoproterenol loading. The upper graph shows the systolic blood pressure as a red line, diastolic blood pressure as an orange line, and heart rate as a green line before and after isoproterenol loading. The lower graph shows the stroke volume as a light blue line, cardiac output as a navy blue line, and stroke volume variability as a blue line. BP, blood pressure; HR, heart rate; sBP, systolic blood pressure; dBP, diastolic blood pressure; CO, cardiac output; SV, stroke volume; SVV, stroke volume variability.