Published online before print February 21, 2005, doi: 10.1161/01.HYP.0000158405.04387.bf
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(Hypertension. 2005;45:487.)
© 2005 American Heart Association, Inc.
Editorial Commentaries |
Treating Hypertension
When to Say Win
From the Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, Minn.
Correspondence to Michael J. Joyner, MD, Department of Anesthesiology, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905. E-mail joyner.michael@mayo.edu
An extract of the first 250 words of the full text is provided, because this article has no abstract. |
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Introduction |
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What do we really know about sympathetic outflow and blood pressure in humans? For example, in healthy normotensive young subjects, baseline sympathetic outflow can vary 2-fold to 3-fold.1,2 We also know that in healthy aging subjects, baseline sympathetic outflow can be increased dramatically with only a modest impact on vascular resistance and little or no impact on blood pressure.1 Additionally, there is no clear evidence for dramatic increases in baseline sympathetic outflow in "garden variety" essential hypertension.1 If we stop here, a position of "nihilism" about sympathetic outflow and blood pressure seems reasonable.
However, when the sympathetic nervous system is destroyed by disease or surgery, blood pressure is highly labile.3 We also know that many "stressors" that evoke a pressor response also evoke marked sympathetic activation, and that the magnitude of these pressor responses can be a harbinger of future hypertension.4,5 Finally, in disease states like congestive heart failure, excessive sympathetic activation is a "bad thing."6,7 If we emphasize these points, sympathetic vasoconstriction seems more important to blood pressure and perhaps survival.
In the middle of this confusion about sympathetic activity and blood pressure lie the baroreflexes that sense changes in arterial pressure and evoke increases in heart rate and sympathetic outflow when blood pressure is "low" and reciprocal responses when blood pressure is "high." Together with their allies in the brain stem and kidney, they make the needed physiological adjustments so that in "normotension" there is an appropriate blood pressure for any given behavioral state.
One mechanism that is
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Hypertension 2005 45: 513-521.