Heart attack on right side? Just say NO

Inhaling nitric oxide, or NO for short, appears to improve blood flow to the lungs in patients who've suffered a right-sided heart attack, new research suggests. This, in turn, helps the heart pump better.

Heart attacks typically involve damage to the left side of the heart, which impairs the organ's ability to pump blood throughout the body. In contrast, when an attack occurs on the right side, the heart is less able to pump blood into the lungs. Either type of attack can cause serious problems if left untreated.

NO (not to be confused with nitrous oxide, laughing gas) is thought to work by opening up or dilating the blood vessels that leave the right side of the heart. As a result, the heart doesn't need to work as hard to pump the blood out.

As reported in the Journal of the American College of Cardiology, Dr. Ignacio Inglessis and colleagues, from Massachusetts General Hospital in Boston, recorded blood flow measurements before, during, and after 10 minutes of NO inhalation.

Breathing NO produced various changes that indicated that the lung blood vessels had, in fact, dilated. At the same time, the researchers noted that the right side of the heart was now pumping a greater amount of blood each minute.

The effects of NO seemed to be limited to the right side of the heart, based on the fact that blood pressure and heart rate, indicators of left heart function, did not change.

NO was found to be particularly useful in three patients with a congenital defect, a hole between the left and right sides of their heart, the researchers note.

In these patients, some of their blood would bypass the lungs by moving through this hole, a condition doctors call a right-to-left shunt. This is important because without visiting the lungs first, blood carries no oxygen to the rest of the body. Treatment with NO reduced blood flow through this hole and improved oxygen levels throughout the body.

Despite these apparent beneficial effects, further studies are needed to determine if NO therapy actually increases survival in patients with right-sided heart attacks.

SOURCE: Journal of the American College of Cardiology, August 18, 2004.