Steady, rapid heartbeat during the morning cause for concern

ASK THE DOCTORS By Robert Ashley, M.D.

Dear Doctor: Every morning upon waking, I feel an even/steady pulsing of about 200 beats per minute, although my pulse is normally about 60 beats per minute. I’m 84, with no symptoms of atrial fibrillation and a body mass index of 24. I take no medications and have no aches and pains. Again, this high pulse rate occurs only when I wake up, and I feel normal at the time. What could be causing this, and should I be concerned?

Dear Reader: Yes, you should be concerned. At the age of 84, even with extreme exertion, your pulse should not be so high.

Before we explore potential causes, let’s discuss what creates the pulse, or heart rate. The pulse rate that you feel in your wrist or neck occurs with contraction of the ventricles, the large muscular portions of the heart. Normally, the atria, which sit atop the ventricles, initiate the pulse, which then travels down the ventricles.

The pulse rate can be affected by, among other things, disorders of the atria, including — as you mentioned — atrial fibrillation. This haphazard rhythm of the atria can indeed produce pulse rates of 200, but not the even, steady pulse that you describe. Atrial flutter — a regular rapid beating of the heart that, like fibrillation, can originate from multiple parts of the atria — is possible but perhaps unlikely because the fast beating of the atria would only be able to cause contraction of the ventricles at certain intervals. Thus, pulse rates of 300, 150, 100, 75 or 60 are possible, but a 200 rate would occur only under certain conditions. Atrial tachycardia — a regular rapid beating originating from one section of the atrium — can cause rates of 200, so this is a possibility.

Disorders of the ventricles also can cause a very rapid heart rate. Here, instead of the atria initiating the pulse rate, a portion of the ventricles creates its own rate. This can occur when the muscular part of the heart is damaged, leading to an electrical impulse that causes the whole ventricle to contract. Ventricular fibrillation, like atrial fibrillation, is a disorganized rhythm of the heart and the leading cause of sudden cardiac death. Due to your lack of symptoms and the regularity to your pulse rate, this seems unlikely.

Perhaps most likely is ventricular tachycardia, which has a regular rhythm with rates greater than 100 and can have rates as high as 250. Besides having a fast heart rate, those with short bursts of ventricular tachycardia may not feel any other symptoms.

We also have to consider the fact that this happens only in the morning. That takes us to our bodies’ circadian rhythm, which means the core processes of the body fluctuate depending upon the time of day. For that reason, increased blood pressure, heart rate, blood vessel constriction and clotting are greatest in the morning. Similarly, heart attacks are more frequent in the morning, as are ventricular fibrillation and tachycardia.

Note that alcohol withdrawal and intoxication can increase this risk of abnormal heart rhythms.

Conditions like atrial fibrillation and atrial flutter increase your risk for strokes, while ventricular fibrillation and tachycardia may increase the risk of sudden death. Undoubtedly, I recommend seeing your doctor. He or she can order a heart monitor to measure your heart rate and, more important, determine what type of rhythm is causing this.

Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.