Viagra doesn't only help in boosting a man's performance in the bedroom, but as researchers have also found, it can also help improve heart function.
This finding means that the popular drug prescribed for erectile dysfunction can potentially save the lives of people with specific heart problems.
The study was conducted by researchers at the University of Alberta who are now encouraging doctors to consider prescribing the drug when a patient has a failing right ventricle of the heart, a dire condition for which there are currently no treatments available.
Dr. Jayan Nagendran, a cardiac surgery resident at the U of A and the first author of the paper, said that the finding was important as Viagra can be clinically and immediately relevant to help these patients.
"There are a number of medical conditions in both children and adults for which there is a need to boost the performance of the right ventricle, and this drug can be clinically and immediately relevant to help these patients," he said.
"Sometimes the right ventricle can fail rapidly and even result in death, like in lung transplant surgery, for example. In such a case, Viagra may increase the right ventricle's performance and save the patient," Dr Nagendran added.
Dr. Evangelos Michelakis, a U of A cardiologist, the Canada Research Chair in Pulmonary Hypertension and the senior author of the paper, said that another reason boffins were thrilled with the results of the study was because whiel there are a number of drugs and therapies available to treat the left ventricle of the heart from failing or afterwards, there are no current treatments for the right ventricle.
"We have a number of drugs and therapies available to treat the left ventricle of the heart to prevent it from failing or to treat it after it has failed, but we don't have anything for the right ventricle. The phosphodiesterase type 5 inhibitors, which include Viagra, Cialis and Levitra, may offer some important benefits in this case," he said.
In a healthy person, phosphodiesterase type 5 constricts arteries in two places in the body-the lungs and the penis. In the lungs, it prevents excessively low blood pressure. In the penis, it prevents excessive engorgement.
However, undue phosphodiesterase type 5 can constrict these arteries too much and cause problems, as it does in the case of pulmonary hypertension, where lung arteries constrict and put a strain on the right ventricle of the heart.
Phosphodiesterase type 5 inhibitors allow the arteries to relax so that blood can flow more easily.
The researchers studied human hearts and showed that phosphodiesterase type 5 is expressed in large amounts in thickened (hypertrophied) right ventricles, but not in healthy hearts. They replicated their results in animal models and also showed that Viagra enhanced the output of hypertrophied right ventricles.
Michelakis noted that this might be the first example of a drug that can improve the function of the right ventricle (which is diseased in pulmonary hypertension), without affecting the left ventricle (which is normal in pulmonary hypertension).
"This selectivity is important and has direct clinical implications. Relaxing the lung arteries alone may not be sufficient to help the patient, if the right ventricle is too weak to push blood through them. A drug such as Viagra, with a combined beneficial effect both in the lung arteries and the right ventricle of the heart, offers a significant advantage," Michelakis said.
"Viagra is a drug that millions of people take every year, and we've just learned something new and essential about how it works," Nagendran said.
"This drug can have an immediate and direct clinical application, so we're pretty excited about these findings," Michelakis added.
The research will appear next week in Circulation, a journal of the American Heart Association.