Circulation, Vol 62, 901-908, Copyright © 1980 by American Heart Association
RS Williams and TM Bashore
We evaluated a patient who had transient episodes of hypotension with
clinical and laboratory features apparently distinct from previously
recognized disorders of vasomotor regulation. In between his abrupt attacks
of hypotension, the patient is asymptomatic and demonstrates normal
autonomic modulation of heart rate and blood pressure in response to
changes in body position, Valsalva maneuver, cold, and exercise. During
periods of hypotension, his plasma norepinephrine falls markedly and he has
blunted or absent responses to stimuli that normally have a pressor effect
due to sympathetic efferent discharge. Mechanical or known hormonal
disorders that produce episodic hypotension have been excluded by extensive
testing. We suggest two possible causes for our patient's paroxysmal
sympathetic withdrawal: first, a centrally mediated inhibition of
sympathetic discharge to peripheral resistance and capacitance vessels, but
with no afferent stimulus reflexly producing sympathetic withdrawal readily
evident; or second, an episodic release of an unknown endogenous compound
with inhibitory effects upon central or preganglionic sympathetic neurons
or upon postganglionic sympathetic neurons by a presynaptic inhibition of
norepinephrine release.
ARTICLES
Paroxysmal hypotension associated with sympathetic withdrawal. A new disorder of autonomic vasomotor regulation