Viagra May Prevent And Improve Heart Failure

Researchers at Johns Hopkins find that the erectile dysfunction drug Viagra may prevent and improve heart failure, following studies performed on animal models. The study is the first to show that Viagra (sildenafil) may protect the heart from the ravages of high blood pressure, and improve changes that take place in the heart muscle leading to heart failure.

Viagra, known as a PDE5A Inhibitor, blocks the crucial enzyme phosphodiesterase 5, which causes enlargement of the heart muscle (hypertrophy). In the presence of high blood pressure, the heart muscle pumps harder, producing enlargement and weakness of the muscle fibers of the heart. PDE5A is also the enzyme that prevents blood vessels in the penis from relaxing, blocking blood flow necessary to maintain erection.

According to David Kass, M.D., a professor at The Johns Hopkins University School of Medicine and its Heart Institute, "A larger-than-normal heart is a serious medical condition, known as hypertrophy, and is a common feature of heart failure that can be fatal." Enlargement of the heart also occurs because of high blood pressure.

PDE5A in Viagra breaks down the GMP molecule, responsible for relaxation of the blood vessels. Until now, no one knew that the GMP enzyme pathway was active when the heart muscle experiences stress, that leads to enlargement and heart failure.

When scientists fed Viagra to mice with surgically induced enlarged hearts, they found they could disrupt the adaptive response seen when the heart becomes stressed from hypertrophy. Rather than harming the heart's function, the researchers saw improvements. The mice treated with Viagra had improved heart function, and smaller hearts when they were given Viagra in their food.

Dr. Kass and colleagues conducted several experiments. During their first trial, they stimulated hypertrophy in male mice for up to nine weeks. The mice who consumed daily doses of Viagra experienced only half as much enlargement of the heart muscle, or hypertrophy. In a second experiment, they used Viagra to see if heart damage could be reversed. The mice who received Viagra showed improvements in ten measure of heart function. Dr. Kass says, "This study shows that sildenafil [Viagra] can make hypertrophy go away. Its effects can be both stopped in their tracks and reversed."

More studies are needed to determine the role of Viagra for treating heart failure. The active ingredient in Viagra, sildenafil, marketed as Revatio, is used as a treatment for pulmonary hypertension, a rare condition that causes high pressure in the blood vessels of the heart and lungs. The manufacturers of Viagra played no role in the current study.

Source:
SILDENAFIL EFFECTIVELY TREATS ENLARGED HEARTS, MOUSE STUDY SHOWS