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Study Confirms Viagra Risky To Those With Heart Disease
Physicians warned to be cautious in prescribing Viagra for erectile dysfunction.
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"I'm only 59, but seldom get an erection. I've tried Viagra, and all it did was give me a headache! I'm trying to resign myself to living the rest of my life without sex."
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The drug sildenafil citrate, better known as Viagra, has been one of the most successful drugs introduced within the last few years. The FDA approved Viagra, the first oral drug available to treat impotence or erectile dysfunction, in March 1998. It is estimated that erectile dysfunction affects as many as 100 million men around the world. Viagra has been a consistent high performer for drug company Pfizer since it was introduced. But the drug is not without risk. Since its launch, recommendations have cautioned prescribing this drug to men with severe cardiovascular disease, especially to those men using nitrates (such as nitroglycerin) to treat heart failure.

Viagra helps men with erectile dysfunction achieve and sustain an erection by targeting nerves acting on the smooth muscles that regulate blood flow to the penis. By relaxing the smooth muscle, blood flow is increased to these blood vessels and an erection is achieved. The drug is taken in pill form about an hour before sexual activity. Studies have shown that the drug has little or no effect in causing an erection in the absence of sexual stimulation.

Unfortunately, the action that Viagra has on nerve activity that causes relaxation of the smooth muscles in the penis, also seems to increase sympathetic nerve activity (the nerve activity that causes blood vessels to constrict). There have been several reports of heart attack, heart arrhythmia and even deaths that have been related to victims who were using Viagra.

A study published in the Dec. 19 issue of the professional journal Circulation looked at this nerve activity, focusing on its effect on heart function especially during physical and mental stress - exactly the kind of stress a man could encounter during sexual activity.

This study comes from the University of Iowa Cardiovascular Research Center. The researchers looked at the effect of Viagra both at rest and during stressful situations. The study participants were 14 healthy men, with no documented heart disease, between the ages of 25 and 39. Baseline measurements of blood pressure, heart rate, noradrenaline levels and sympathetic nerve activity were measured. During the study, the research subjects were given 100 mg tablets of Viagra or a placebo and then have a 60-minute rest period. The measurements were repeated at 30 and 60 min. After the rest period, each participant's cardiovascular response was measured during stressful situations which included exercise, mental stress and cold exposure.

The researchers found that study participants who took Viagra had more than double the sympathetic nerve activity and a 30 percent increase in blood levels of noraderenaline. Sympathetic nerve activity increased even more dramatically during stressful conditions.

Patients who have cardiovascular diseases like heart failure already have increased sympathetic nerve activity. The high and sustained sympathetic activity caused by Viagra during rest and stress is damaging to the heart and heart function over a long period.


  • Men with unstable cardiovascular disease should not use Viagra. These include history of heart attack or diagnosis of heart failure.
  • Men taking Viagra should notify their physicians if they have any problems while taking Viagra, such as dizziness, loss of consciousness or palpitations.
  • Men seeking a treatment for erectile dysfunction with Viagra need to obtain a prescription from a physician who has a complete knowledge of their health history and any medications that they may be taking.
  • Viagra is a very powerful medication that has improved life for a great many men, but it is also dangerous for many. If your medical condition prevents you from taking Viagra for Erectile dysfunction, talk to your doctor about alternative treatments.
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