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Dr. Roach: Slow heart rate can be a sign of sinus node trouble

Keith Roach
To Your Health

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

Dear PS.: 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.”

Sinus bradycardia needs to be treated when it is causing symptoms, and a cardiologist with special training in rhythm disorders, called an electrophysiologist, is the best referral when the slow heart is not due to other causes. Patients with extreme bradycardia (below 40) would also rate a referral, even if they don’t report symptoms, as many will note improvement with treatment. The most common treatment is a permanent pacemaker.

Dear Dr. Roach: I was recently diagnosed with low grade prostate cancer. For now, my urologist recommends simply monitoring the situation closely through PSA testing and another biopsy in a year; no surgery, radiation or chemo at this time. I’m not on any medication. I recently asked my doctor at my HMO if I could donate blood and he did not see a reason I could not. However, when I tried to set up an appointment at the blood bank, I was turned down due to my cancer diagnosis. When asked, the blood bank representative could offer no other reason nor could he explain the risk. I can understand the need for caution at the blood bank, but was wondering if there was any medical evidence of transmitting cancer or other diseases through blood transfusions where the blood originated from an individual with cancer, such as myself. I would guess that there have been cases where people with undiagnosed cancer have donated blood and am very curious about the risks.

M.R.

Dear M.R.: There has never been a confirmed case of cancer transmitted by blood transfusion. Cancer can be transmitted by organ transplant, and in theory, blood cancers such as leukemia might be transmitted to a person with a weakened immune system. Solid cancers -- such as prostate, breast, lung and colon -- would not be expected to transmit cancer, so the observation that they have not is unsurprising.

Blood banks are understandably very conservative when accepting blood. They want for the blood not only to be safe, but also to appear safe. That can lead them to make decisions that seem illogical. However, taking blood donations from a person with active cancer may also be unwise from the standpoint of the donor: You may need your blood to best deal with your own cancer, even though it sounds like in your case, your prostate cancer is very low risk.

Readers may email questions to ToYourGoodHealth@med.cornell.edu