Sildenafil effects on Exercise, neurohormonal activation, and erectile dysfunction in congestve heart failure: a double-blind, placebo-controlled, randomized study followed by a prospective treatment dysfunction - Bocchi, Edimar Alcides; Guimarães, Guilherme; Mocelin, Amilcar; Bacal, Fernando; Belloti, Giovanni; Ramires, José Franchini (Journal of The American Heart Association, 2002)