Objectives. The purpose of this study was to determine whether pulmonary artery responses to acetylcholine are abnormal in patients with chronic heart failure. Background. Defective pulmonary artery endothelium-dependent responses have been observed in chronic heart failure models in animals. However, pulmonary artery endothelial response in humans with chronic heart failure are unknown. Methods. Twenty-two patients with chronic treated heart failure (12 with secondary pulmonary hypertension, Group I; 10 with normal pulmonary artery pressure, Group II) and 8 control patients constituted the study groups. Intravascular ultrasound measurements of pulmonary artery area just beyond the tip of an 8F infusion sheath were obtained in response to acetylcholine (10-6, 10-5 and 10-4 mol/liter). The 10-6 mol/liter infusion was repeated after methylene blue infusion. Indomethacin (5 μg/ml) was sequentially added to this combination in 17 patients. Results. There were no significant differences among the three groups in vascular area responses to the lowest concentration (10-6 and 10-5 mol/liter) of acetylcholine, but the 10-4 mol/liter infusion resulted in significant constriction in Group II patients (p < 0.05, analysis of variance [ANOVA]). Pretreatment with methylene blue in Group II also resulted in significant pulmonary artery vasoconstriction to even the 10-6 mol/liter acetylcholine infusion (10.4 ± 7.8% in Group II vs. 1.7 ± 3.9% in the control group and 0.1 ± 4.3% in Group I, p < 0.05, ANOVA). The addition of indomethacin resulted in reversal of the constriction in Group II patients. Conclusions. These responses indicate that the pulmonary artery endothelium may play a significant role in inhibiting vasoconstriction in patients with chronic heart failure who maintain normal pulmonary artery pressure.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine