Valsalva's maneuver revisited: a quantitative method yielding
insights into human autonomic control.
Smith, Michael L., Larry A. Beightol, Janice M. Fritsch Yelle, Kenneth
A. Ellenbogen, Thomas R. Porter, and Dwain L. Eckberg.
Departments of Medicine and Physiology, Hunter Holmes McGuire
Department of Veterans Affairs Medical Center, and Medical College of
Virginia, Richmond, Virginia 23249
APStracts 3:0083H, 1996.
Seventeen healthy supine subjects performed graded Valsalva maneuvers.
In four subjects, transesophageal echographic aortic cross sectional
areas decreased during, and increased after straining. During the
first seconds of straining, when aortic cross sectional area was
declining and peripheral arterial pressure was rising, peroneal
sympathetic muscle neurons were nearly silent. Then, as aortic cross
sectional area and peripheral pressure both declined, sympathetic
muscle nerve activity increased, in proportion to the intensity of
straining. Post straining arterial pressure elevations were
proportional to preceding increases of sympathetic activity.
Sympathetic inhibition after straining persisted much longer than
arterial and right atrial pressure elevations. Similarly, R R
intervals changed in parallel with peripheral arterial pressure,
until about 45 s after the onset of straining, when R R intervals
were greater, and arterial pressures were smaller than pre straining
levels. Conclusions: Opposing changes of carotid and aortic
baroreceptor inputs reduce sympathetic muscle, and increase vagal
cardiac motoneuronal firing; parallel changes of barosensory inputs
provoke reciprocal changes of sympathetic, and direct changes of
vagal firing; and pressure transients lasting only seconds reset
arterial pressure-sympathetic and -vagal response relations.
Received 21 December 1995; accepted in final form 14 February
1996.
APS Manuscript Number H1192-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96