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Abnormal vascular responses in human chronic cardiac failure are both endothelium dependent and endothelium
S M Maguire1, A G Nugent, C McGurk
1Department of Medicine, Institute of Clinical Science, Royal Victoria Hospital, Belfast, UK.
Objective:
To study underlying vascular responses in chronic heart failure in patients without ACE inhibitor treatment, and to compare them with age matched controls.
Design:
Forearm blood flow was studied using venous occlusion plethysmography in patients with chronic heart failure (n = 12) and matched controls (n = 13), after infusion of L-NMMA (a nitric oxide synthase inhibitor), glyceryl trinitrate (an endothelium independent vasodilator), and serotonin (an endothelium dependent vasodilator).
Results:
L-NMMA produced significant vasoconstriction in normal subjects (forearm blood flow reduced by 24%), but not in patients (6%; difference between groups p < 0.03). The vasodilator responses to glyceryl trinitrate were impaired in patients (p < 0.02). In normal controls, serotonin produced initial dilatation, followed by vasoconstriction at high doses. In patients, no vasodilator responses were observed, only late vasoconstriction (p < 0.03).
Conclusions:
The vascular responses of patients are confirmed as being abnormal. The lack of response to L-NMMA suggests that nitric oxide does not contribute to basal vascular tone in patients with chronic heart failure. The responses to glyceryl trinitrate and to serotonin suggest that there is both smooth muscle and endothelial dysfunction in patients with chronic heart failure.