Forearm vasoconstriction during dynamic leg exerci

Authors: John J Atherton Laurence G Dryburgh Helen L Thomson Thomas D Moore Karen N Wright Gerry W F Muehle Loretta E Fitzpatrick Michael P Frenneaux

Publish Date: 2012/09/14

Volume: 13, Issue: 6, Pages: 278-289

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Abstract

Previous studies assessing vascular responses in nonexercising beds during exercise in patients with chronic heart failure CHF have yielded varying results We proposed that the clinical and hemodynamic severity of heart failure may explain some of the variation We reasoned that diastolic ventricular interaction DVI by limiting the ability of such patients to increase left ventricular LV volume and stroke volume during exercise would attenuate baroreflex activation resulting in increased sympathetic activation and hence exaggerated vasoconstriction We hypothesized therefore that vasoconstriction in nonexercising beds would be exaggerated in patients with symptomatic and hemodynamically severe heart failure particularly if associated with DVIWe measured forearm vascular resistance FVR during semierect cycle exercise in 22 CHF patients and 23 control subjects DVI was assessed by measuring changes in ventricular volumes radionuclide ventriculography during volume unloading −30 mmHg lowerbody negative pressure in the heart failure patients and was inferred when LV enddiastolic volume paradoxically increasedPatients with symptoms of heart failure developed larger increases in FVR during exercise than did asymptomatic patients There were significant correlations between the change in FVR during peak exercise and the resting mean pulmonary arterial pressure and pulmonary vascular resistance CHF patients with DVI developed exaggerated increases in FVR median 25th to 75th percentile compared with the remaining patients during lowworkload exercise 138 66 to 171 vs 64 −43 to 28 units P = 0002 and during peak exercise 160 90 to 384 vs 61 −74 to 75 units P 002Vasoconstriction in nonexercising beds is exaggerated in CHF patients with clinically and hemodynamically severe heart failure particularly if associated with DVI This may explain some of the reported variation in the degree of sympathetic activation that occurs during exercise in CHF patients

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