Viagra Helps Enlarged Hearts?

A drug commonly used to rev up a man's love life may also eventually be used to help reverse abnormal growth of the heart, according to a new study in mice.

Researchers found Viagra reversed the abnormal growth of heart muscles and restored normal heart function to mice with enlarged hearts.

"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," says researcher David Kass, MD, professor at The Johns Hopkins University School of Medicine and its heart institute, in a news release.

The condition often develops as a result of chronically uncontrolled high blood pressure; this forces the heart to pump harder in order to meet the body's needs. To adapt to these high forces, the muscles of the heart enlarge.

People with hypertrophy or enlarged hearts have a higher risk of developing heart disease, heart failure, or sudden cardiac death.

Researchers say the findings are the first to show that Viagra may be an effective treatment for a chronic heart condition. The next step will be to conduct a study to see if the drug will have the same beneficial effect in humans that it had in mice.

Viagra May Heal Hearts

In the study, which appears in the Jan. 23 online edition of Nature Medicine, researchers conducted several experiments on mice using Viagra.

In the first experiment, researchers induced the enlarged hearts (hypertrophy) in mice by subjecting their hearts to high blood pressure. But they found mice fed Viagra in their food at a dose similar to those used by humans developed hypertrophy at half the rate as mice that ate regular food.

The mice fed Viagra also showed 67 percent less scarring of heart muscles, a common complication seen in enlarged hearts. Researchers say the mice that got Viagra had smaller hearts and better heart function than the untreated mice.

In a second test, researchers used the same dose to examine its effects at reversing pre-existing hypertrophy. The hearts of the mice were exposed to high blood pressure to induce hypertrophy for seven to 10 days, during which they experienced muscle growth and stiffness of nearly 65 percent.

After two weeks of treatment with Viagra, the muscle stiffness and enlargement almost completely disappeared.

Researchers also found that heart function, which deteriorates with hypertrophy, improved after the muscle growth had been stopped with Viagra treatment.

"This study shows that sildenafil (Viagra) can make hypertrophy go away," says Kass. "Overall, the results provide a better understanding of the biological pathways involved in hypertrophy and heart dilation, leading contributors to heart failure. They suggest possible therapies in the future, including sildenafil, which has the added benefit of already being studied as safe and effective for another medical condition."

Kass says "more study is required before we fully understand the benefits of sildenafil on the heart."

Sources: Takimoto, E. Nature Medicine, Jan. 23, 2005 online edition. News release, Johns Hopkins Medical Institutions.

By Jennifer Warner
Reviewed by Brunilda Nazario, MD
© 2005, WebMD Inc. All rights reserved