Acute Effects of a Single Dose of Phosphodiesterase Type 5 Inhibitor (Sildenafil) on Systemic Arterial Blood Pressure During Exercise and 24-Hour Ambulatory Blood Pressure Monitoring in Heart Transplant Recipients - Guimarães, G. V.; d'Avila, V. M.; Bacal, F.; Stolf, N. A. G.; Bocchi, E. A. (Transplantation Proceedings, 2007)