Sympathoadrenal imbalance before neurocardiogenic syncope

David S. Goldstein, Courtney Holmes, Steven M. Frank, Mohammad Naqibuddin, Raghuveer Dendi, Sally Snader, Hugh Calkins

Research output: Contribution to journalArticle

Abstract

Neurocardiogenic syncope is the most common cause of acute loss of consciousness in adults. The present study attempted to identify neuroendocrine and hemodynamic changes before syncope that could therefore play a pathophysiologic role. Twenty-five patients referred for chronic orthostatic intolerance had plasma catecholamines measured serially; 21 patients during tilt-table testing (evoking syncope in 13) and 4 others with spontaneous syncope while supine. Forearm blood flow was measured by impedance plethysmography. All 12 patients with blood sampled before tilt-induced syncope had progressive, marked increases in plasma epinephrine levels (mean 11 times baseline, p <0.0001) before syncope. Simultaneously obtained norepinephrine levels increased to a much smaller extent than did epinephrine levels ("sympathoadrenal imbalance"). In the same patients, forearm vascular resistance decreased by 21% before syncope. Proportionate changes in forearm vascular resistance before syncope correlated negatively with those in the epinephrine:norepinephrine ratio (r = -0.75, p = 0.005). Patients without syncope had forearm vasoconstriction and no sympathoadrenal imbalance during tilt. Patients with syncope while supine also had sympathoadrenal imbalance before loss of consciousness. Sympathoadrenal imbalance precedes tilt-evoked and spontaneous neurocardiogenic syncope and correlates with concurrent skeletal muscle vasodilation. Sympathoadrenal imbalance may contribute to hemodynamic derangements precipitating neurocardiogenic syncope.

Original languageEnglish (US)
Pages (from-to)53-58
Number of pages6
JournalAmerican Journal of Cardiology
Volume91
Issue number1
DOIs
StatePublished - Jan 1 2003

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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