Acetylcholine but not sodium nitroprusside exerts vasodilation in pulmonary hypertension secondary to chronic congestive heart failure.
BACKGROUND
Reduced endothelium-dependent vasodilation contributes to the development of pulmonary hypertension in chronic congestive heart failure (CHF). We investigated pulmonary endothelium-dependent and independent vasodilation in patients with CHF.


METHODS
We studied 42 patients with CHF (age 55 +/- 10, NYHA Classes II-III, left ventricular ejection fraction 27 +/- 10%, mean PAP 29 +/- 12 mmHg). The endothelial vasodilator capacity of pulmonary resistance vessels was assessed by the infusion of acetylcholine into a pulmonary artery branch while measuring the blood flow velocity with a Doppler flow wire. For comparison endothelium-independent vasodilation was measured with the response to sodium nitroprusside. The conductance vessel diameter (4.4 +/- 0.2 mm) was determined by intravascular ultrasound. Acetylcholine was administered at concentrations of 10(-6) to 10(-4) mol/l, sodium nitroprusside was administered at concentrations of 0.125 and 0.25 microg/kg per min. The effects on conductance vessel diameter were investigated in 12 patients by the measurement of diameter and flow velocity following the administration of acetylcholine and sodium nitroprusside.


RESULTS
Acetylcholine markedly increased blood flow velocity (+39 +/- 7% at 10(-4) mol/l; p < .05). This correlated with the baseline PAP (r = 0.58; p < .05) and pulmonary vascular resistance (r = 0.58; p < .05). Sodium nitroprusside caused a small increase in the flow velocity (5 +/- 2% at 0.125, 12 +/- 4% at 0.25 microg/kg per minute; p < .05) that was accompanied by systemic vasodilation. The conductance vessel diameter was unchanged after acetylcholine was administered and was only marginally decreased after the administration of sodium nitroprusside.


CONCLUSIONS
In CHF acetylcholine reveals preserved receptor-mediated endothelial vasodilation, that is positively correlated to pulmonary hypertension, and cannot be reproduced by sodium nitroprusside.
Wensel
R
R
Humboldt University Berlin, Germany.
Opitz
C F
CF
Kleber
F X
FX
D000109:Acetylcholine / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001783:Blood Flow Velocity / Q000187:drug effects; D002908:Chronic Disease; D006333:Heart Failure / Q000150:complications*; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D008875:Middle Aged; D009599:Nitroprusside / Q000627:therapeutic use*; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D018084:Ultrasonography, Interventional; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000627:therapeutic use*
D000959:Antihypertensive Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D000109:Acetylcholine