Dear Dr. Roach: I am an 84-year-old female in relatively good health. My doctor is concerned that my heart rate is too slow, consistently in the 50s. I have worn a Holter monitor and had an echocardiogram test. Both came back negative for any problems. What could be causing my sinus bradycardia? — PS
Answer: The “sinus” in sinus bradycardia has nothing to do with your nose. It refers to a cavity that exists embryologically that becomes part of the wall of the right atrium. The natural pacemaker of the heart is contained there, and is called the “sinus node” or “sinoatrial node.” “Bradycardia” is from the Greek words meaning “slow heart” and is a common condition that only occasionally becomes a problem. Bradycardia is having less than 60 beats per minute, and sinus rhythm means the impulse is coming from the usual place.
Trained athletes often have slow heart rates; occasionally, some diseases — especially Lyme disease, hypothyroidism and sleep apnea — can cause sinus bradycardia. Many medications, especially beta blockers, can cause a slow heart rate. However, in the elderly, slow heart rates can be an early sign that the cells in the sinus node aren’t working as well as they used to. One cardiologist where I trained called them “gray hairs in the heart.”