IMPROVEMENT OF CARDIAC-PERFORMANCE BY INTRAVENOUS-INFUSION OF L-ARGININE IN PATIENTS WITH MODERATE CONGESTIVE-HEART-FAILURE

Objectives. The aim of this study was to evaluate the hemodynamic effe ct of L-arginine infusion in patients with congestive heart failure. B ackground. Endothelium-dependent vasodilation is impaired in patients with congestive heart failure. Nitric oxide, which was identified as e ndothelium-derived relaxing factor, is generated by nitric oxide synth ase from L-arginine. Our hypothesis was that administration of L-argin ine in patients with congestive heart failure may increase nitric oxid e production and have a beneficial hemodynamic effect. Methods. Twelve patients with congestive heart failure (New York Heart Association cl ass II or III) due to coronary artery disease (left ventricular ejecti on fraction <35%) mere given 20 g of L-arginine by intravenous infusio n over Ih at a constant rate. Stroke volume, cardiac output and left v entricular ejection fraction were determined with Doppler echocardiogr aphy at baseline and at 30 and 60 min and 1 h after the end of infusio n. Blood and urinary levels of nitrite/nitrate (NO2NO3), stable metabo lites of nitric oxide, were measured and clearance was calculated. Res ults. One hour of infusion of L-arginine resulted in a significant inc rease in stroke volume (from 68 +/- 18 ml to 76 +/- 23 ml [mean +/- SD ], p = 0.014) and cardiac output (from 4.07 +/- 1.22 liters/min to 4.7 +/- 1.42 liters/min, p = 0.006) without a change in heart rate. Mean arterial blood pressure decreased (from 102 +/- 11 mm Hg to 89 +/- 9.5 mm Hg, p < 0.002), and systemic vascular resistance decreased signifi cantly. Within 1 h after cessation of L-arginine infusion, blood press ure, stroke volume, cardiac output and systemic vascular resistance we re statistically not different from baseline values. Clearance of NO2/ NO3, increased significantly during L-arginine administration (from 13 .28 +/- 0.42 ml/min to 29.97 +/- 1.09 ml/min, p < 0.001). Conclusions. Infusion of L-arginine in patients with congestive heart failure resu lts in increased production of nitric oxide, peripheral vasodilation a nd increased cardiac output, suggesting a beneficial hemodynamic and p ossibly therapeutic profile.