Harvard Heart Letter

Ask the doctor: Racing heart and pneumonia

Q. When someone has pneumonia, is it common for the heart rate to fluctuate wildly?

A. Any significant lung disease can increase the heart rate. The stress of being sick causes surges in adrenaline levels, which make the heart accelerate. Lower oxygen levels in the blood also make the heart beat faster. In addition, pneumonia can push the heart into abnormal fast rhythms, such as atrial fibrillation (an irregular rhythm in which different parts of the atrium chaotically fire off electronic signals) or atrial tachycardia or flutter (regular rhythms at heart rates as high as 150 beats per minute or more). These abnormalities may appear because higher pressures in the blood vessels of the lung cause the right side of the heart to dilate, which can throw off the heart's electrical system.

Medications can usually be used to slow or stop these abnormal rhythms, but sometimes electrical shocks are needed to restore a regular rhythm. Of course, treating the lung disease is an important step in helping patients get better.

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