Nitric Oxide NO is a potent endogenous vasodilator synthesized from the amino acid L-arginine by NO synthase. Different results have been obtained after L-arginine oral administration in patients with primary pulmonary hypertension (PPH). Little data exist about the effect of this therapy on right ventricular function.
Our study examined the effect of oral L-arginine (dose;1 gr. per 10 Kg body weight daily during twelve weeks) on exercise capacity and right ventricular function evaluated through six minutes walk testing (6MWT) measurements at baseline, 3,6,9 and 12 weeks and contrast echocardiography (CE)at baseline and 12 weeks. L-arginine or placebo were given in a randomized double blind fashion.
We evaluated 12 patients (p) with precapillary pulmonary hypertension (mean PAP=62±13 mmHg); PPH (10p) and Pulmonary hypertension related to collagen vascular disease (2p); 9 females and 3 males (age;31±10). 6MWT (12p) did not show any statistically difference when compared baseline (B) vs 12 weeks (12w) of either placebo (B;385±54 and 12w;353±94m) or L-Arginine administration (B;334±34 and 12w;348±58). Although groups were different at baseline, the placebo group did show a trend to walk less. CE was performed in 6p; 3p receiving L-Arginine and 3p receiving placebo. CE showed in patients on L-Arginine a slight decrease at the PSAP B;90±24 and 12w; 75±28 mmHg and an increase in both the diastolic diameter of the right ventricle DDRV and in the shortening fraction of the right ventricle SFRV.
L-Arginine does not improve exercise capacity in a statistically significant manner in our study, changes on the right ventricular performance may need further evaluation.
L-Arginine has not shown a clear benefit on treatment in PPH patients.
E.G. Bautista, None.