DEAR DR. DONOHUE: I have not seen you address SVT, supraventricular tachycardia. I have had it since 2003. In September of 2007, I had the procedure, in which a tube was inserted into my heart to ablate tissue there. However, I continue to have attacks, and they are increasing in duration and frequency. I have seen three electrophysiologists, and the one who did the procedure told me I might need to go for another. Another solution is taking medicines such as flecainide, dofetilide or amiodarone. What do they do to the heart rate? — A.T.

ANSWER: Tachycardia is a fast heartbeat. “Supraventricular” indicates that the origin of this rapid beat is in the upper heart chambers, the ones above the ventricles — the lower, pumping chambers.

Many supraventricular tachycardias occur in sudden attacks, paroxysms that are short-lived and stop as quickly as they start. During an attack, people feel heart palpitations, the wild, and forceful beating of a fast heart. They might also experience lightheadedness and feel like they are on the verge of passing out. Your attacks are lasting for longer time periods and are occurring more often. They should be ended, and they can be with either another ablation or with medicines.

Ablation, as you say, is done with a specially equipped catheter — a thin, pliable tube that is inched into the heart through a surface blood vessel. Electrophysiologists are cardiologists with special training in heart rhythm disorders and in putting an end to them. When the doctor reaches the part of the heart generating the rapid signals, he or she applies radio waves through the catheter to eradicate that tissue. Ablation’s success is quite high.

Medicines also can end supraventricular tachycardias, and you mentioned three popular ones. They can have side effects, and some have to be started in the hospital, where the heart can be monitored immediately and for a short time after taking them. They work by dampening the activity in the tissue generating SVT.

Either treatment has its pros and cons. For myself, I’d try the ablation again. I don’t like to take daily medicines.

The booklet on abnormal heart rhythms describes the more common kinds, like atrial fibrillation. People can order a copy by writing: Dr. Donohue — No. 107, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I would like to know if polycythemia is the same thing as polymyalgia. — D.S.

ANSWER: Polycythemia (poly — many; cyt — cells; hemia — blood), pronounced “POL-ee-sigh-THEME-ee-uh,” is an overproduction of blood cells by the bone marrow. Symptoms include dizziness, headache, sweating, fatigue and itching after taking a hot shower. Treatment is removal of blood from time to time.

Polymyalgia (poly-many; my-muscles; algia-pain) is muscle and joint pain and stiffness. It occurs at older ages and is due to an errant immune attack. Treatment is with cortisone drugs, usually prednisone.

DEAR DR. DONOHUE: I am a heart patient and have undergone two surgeries four years apart. I am concerned about more testing that might be done on me in the future, like catheterization or a Doppler echo. Could such testing adversely affect my heart? — D.B.

ANSWER: You must have undergone catheterization prior to your past heart surgeries. A catheter is a soft tube that is snaked into heart arteries from a blood vessel beneath the skin. When it’s in place, dye is release to see if there is any buildup in the heart arteries. Complications from this procedure are few. Injury to a heart vessel can happen, but such injuries are correctable by surgery.

A Doppler echo is a sound-wave picture of the heart or of a large artery. Complications from a Doppler echo are as close to zero as anything in life comes.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.

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