Sublingual nitroglycerin did not alter forearm vascular resistance in normal subjects or patients with congestive heart failure due to offsetting reflex vasoconstriction and reduced vasodilator capacity.
Does sublingual nitroglycerin alter forearm vascular resistance differently in patients with congestive heart failure compared to normal subjects?
Sublingual nitroglycerin does not alter net forearm vascular resistance in either normal subjects or heart failure patients, though the underlying physiological mechanisms (balance of direct vasodilation and reflex vasoconstriction) differ between the groups.
This study examined the effects of sublingually administered nitroglycerin on forearm resistance vessels in normal subjects (n = 9) and in patients with congestive heart failure (n = 8). Forearm blood flow was measured with a strain-gauge plethysmograph and forearm vascular resistance was calculated. To assess the magnitude of reflex forearm vasoconstriction triggered by decreased central venous pressure after sublingual nitroglycerin, lower body negative pressure (LBNP) was applied to produce a comparable decrease in central venous pressure to that after nitroglycerin. The change in forearm vascular resistance during LBNP was compared with that after nitroglycerin. In normal subjects, LBNP increased but nitroglycerin did not change forearm vascular resistance. In patients with congestive heart failure neither nitroglycerin nor LBNP changed forearm vascular resistance. The direct vasodilator effect of nitroglycerin on forearm resistance vessels assessed by the difference between the change in forearm vascular resistance produced by nitroglycerin and that during LBNP tended to be less in patients with congestive heart failure than in normal subjects, which might have resulted from decreased vasodilator capacity of resistance vessels in patients with congestive heart failure. Changes in forearm vascular resistance with a cold pressor test were not different between normal subjects and patients with congestive heart failure. These data suggest that in normal subjects, nitroglycerin does not alter forearm vascular resistance because its dilator effect is offset by reflex vasoconstriction. In patients with congestive heart failure, reflex vasoconstriction is impaired but the direct vasodilator effect of nitroglycerin also tends to be reduced, so that as a net effect forearm vascular resistance is not altered.
Imaizumi et al. (1985) studied Congestive heart failure (n=17). Sublingually administered nitroglycerin vs. Lower body negative pressure (LBNP) was evaluated on Change in forearm vascular resistance. Sublingual nitroglycerin did not alter forearm vascular resistance in normal subjects or patients with congestive heart failure due to offsetting reflex vasoconstriction and reduced vasodilator capacity.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: