METHODS AND RESULTS: Thirty-one patients with
congestive heart failure (New York Heart Association functional class II-III) and five age-matched normal subjects were studied. Regional vascular responses in the forearm to infusions of
acetylcholine, an endothelium-dependent
vasodilator (10(-7) to 10(-5) mol/L) and
nitroglycerin, an endothelium-independent
vasodilator (10(-6) mol/L) in the brachial artery were determined with venous occlusion plethysmography before and after regional alpha-
adrenergic blockade with intra-arterial
phentolamine (25 micrograms/min) and systemic
cyclooxygenase with oral
indomethacin (50 mg). Administration of
phentolamine significantly increased resting baseline forearm blood flow in 11 patients with
congestive heart failure (2.9 +/- 0.4 to 5.4 +/- 0.8 mL.min-1.100 mL-1) and normal subjects (4.6 +/- 0.3 to 11.3 +/- 2.1 mL.min-1.100 mL-1). Before administration of
phentolamine,
intra-arterial infusions of
acetylcholine 10(-7), 10(-6), and 10(-5) mol/L increased forearm blood flow to 4.0 +/- 1.0, 6.0 +/- 1.7, and 16.1 +/- 4.0 mL.min-1.100 mL-1, respectively, in patients with
congestive heart failure and to 14.7 +/- 6.2, 20.2 +/- 4.7, and 38.7 +/- 7.9 mL.min-1.100 mL-1, respectively, in normal subjects. After administration of
phentolamine, the vasodilatory responses to
intra-arterial infusions of
acetylcholine and
nitroglycerin did not change in either patients or normal subjects. Administration of
indomethacin did not alter resting forearm blood flow in 15 patients with
congestive heart failure (2.7 +/- 0.4 to 2.7 +/- 0.4 mL.min-1.100 mL-1) or normal subjects (4.6 +/- 0.3 to 5.4 +/- 0.8 mL.min-1.100 mL-1). Administration of
indomethacin significantly increased the vasodilatory response to infusion of
acetylcholine by an average of 39% in patients with
congestive heart failure but did not change the vasodilatory response to
acetylcholine in normal subjects. In patients with
congestive heart failure, baseline forearm blood flow and the vasodilatory responses to
intra-arterial infusions of
acetylcholine and
nitroglycerin were significantly less than those of normal subjects both before and after administration of
phentolamine and
indomethacin.
CONCLUSIONS: