Sudden, fast heart rate not normal

Dear Dr. Roach: I recently had a sudden, fast heartbeat with a very irregular and erratic pulse (approximately 150-161) for about six hours, along with low blood pressure, ranging from 74 over 59 to 79 over 52. I felt a strange thumping in my neck area. I take amlodipine, losartan and HCTZ for high BP. I had never had an episode like this. I called my doctor a day later, and he ordered a Holter monitor. My other medications include thyroxine. I am 90 years old, in good health, mild arthritis, alert and oriented. What causes such an episode? — E.P.

A sudden, fast heart rate without exertion can be caused by anxiety or fright; however, that doesn’t sound like what happened to you. Your report sounds very much as though you had an episode of atrial fibrillation. The atria are the top chambers of the heart, which fill with blood passively from the veins of the body (on the right side) or the lungs (on the left), and contract to fill the ventricles. The right atrium also normally provides the electrical stimulation for the heart. In atrial fibrillation, instead of 60 beats a minute, the atria may put out a thousand impulses a minute. The heart cannot possibly respond to all those impulses (there is a safeguard built into the electrical system), so the heart rate becomes highly irregular and variable. The rate may be normal, but more frequently it is too fast. One of the goals in atrial fibrillation is to control heart rate, to protect the heart from going too fast. A rate of 160 in a 90-year-old is not safe, and the fact that your blood pressure went down is concerning. I would have admitted you to the hospital and recommended that you get an EKG.

The other major goal of treating atrial fibrillation is to reduce stroke risk. This requires anticoagulation.

There are other possible causes, but the erratic nature makes me think atrial fibrillation is the diagnosis.

Write to Dr. Roach at ToYourGoodHealth @med.cornell.edu.