DEAR DR. DONOHUE: After wearing a heart monitor for three days, I have finally been told what I have: paroxysmal supraventricular tachycardia. It must be rare, since neither I nor anyone I know has ever heard of it. I can be sitting and reading a book when my heart jumps in my chest and beats fast. What causes it? The doctor doesn’t think I need treatment. Why not? – R.K.

ANSWER: Supraventricular tachycardia is a heart beating more than 100 times a minute for no good reason. The “paroxysmal” part means the beating starts suddenly and usually turns off suddenly. “Supraventricular” pinpoints the site of origin to the atria, the two upper heart chambers, the ones above (supra) the ventricles, the pumping heart chambers.

Causes are many. Some people are born with an extra pathway that the electric signal, generated in the heart’s pacemaker, takes to reach the ventricles. When the electric impulse takes that odd path, it can start the heart beating rapidly. Or the episode begins without finding the cause; it just happens.

If the occasions of supraventricular tachycardia are brief and infrequent, no treatment can be the best treatment. Or the doctor can show you how to end a spell by exhaling against a closed throat. Medicines can often put an end to more frequent attacks. And for the few who are unresponsive to medicines, the heart tissues responsible for initiating the fast heartbeat can be destroyed. This can often be accomplished by inching a soft catheter into the heart through a distant blood vessel. The catheter comes equipped with a device that emits radio waves. Those waves heat and destroy the tissues responsible for the heart’s speedup.

DEAR DR. DONOHUE: I have plants all over my house, including in my bedroom. My mother says that I shouldn’t sleep in a room with plants because I can get an infection from them. She says that’s the reason that hospitals don’t allow plants and flowers in patient rooms. Is this correct? – V.T.

ANSWER: You can keep plants in your bedroom. They won’t make you sick. In fact, they produce oxygen, so they freshen the air.

Hospitalized patients whose immune systems are not functioning or who are in a critical care unit aren’t allowed to have plants or flowers because they may carry bacteria. For all other hospitalized patients, however, flowers and plants are permitted.

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