Revatio for Heart Disease in Duchenne Muscular Dystrophy and Becker Muscular Dystrophy

This study, supported by Charley's Fund, Inc., is being done to determine if the drug Revatio®(also known as Sildenafil), as compared to placebo (an inactive substance that looks like the study drug, but contains no medication), improves heart function in people with Duchenne Muscular Dystrophy and Becker Muscular Dystrophy (DBMD). In people with DBMD, dystrophin is not present or lacking in heart and muscle. This is associated with abnormalities in an enzyme called "neuronal nitric oxide synthase" or nNOS, and leads to decreases in "cyclic GMP," which is necessary for proper function of those muscles. Revatio blocks an enzyme called phosphodiesterase 5 (PDE5), and helps to restore the normal amounts of cyclic GMP. The purpose of this research is to determine if Revatio is safe for people with DBMD and if it can improve heart function. Hypothesis : PDE5 inhibition, with the use of Revatio, will improve cardiac function in patients with DBMD.