Comparative therapeutic effect of the L-arginine and sildenafil on beta-thalassemia children with increased tricuspid regurgitant jet velocity oleh Hosny Mohammed Ahmed El-Masry, Mohammed Ramadan El-Shanshory, Alaa- Eldin Ali Hassan Mahmoud, Osama Abdrabelrasool Tolba, Hossam Ahmed Mohammed Abd-Elmoety Elsharkawy