DEAR DR. DONOHUE: My problem concerns an irregular heartbeat. I have had the problem for two years. It’s called Wenckebach heart block. I have had a heart scan and stress tests, and they were normal. My doctors indicate that my heart functions normally. Is there a period of time that I should be concerned – if, let’s say, the heart skips a beat every ninth, fifth or third time? Would a pacemaker eliminate these episodes? – R.K.

ANSWER: “Block” is used for so many different and unrelated heart conditions that it confuses people. It’s used to indicate arteries clogged with cholesterol deposits. It’s used to denote a glitch in the way the heart’s electrical activity is generated by its natural pacemaker. Such blocks come in first, second and third degrees, with third being the worst. It’s also used to denote trouble in the heart’s electrical cables – bundle branch blocks.

A Wenckebach (WINK-uh-bahk) heart block is a second-degree heart block. Some, but not all, of the heartbeats generated by your heart’s natural pacemaker cause a contraction of the heart muscle and a heartbeat. Every now and then, there is a missed beat. You can feel that. It also shows up on an electrocardiogram.

Wenckebach heart block doesn’t usually progress. Don’t sit around and count your beats, or you’ll drive yourself crazy. It rarely needs a pacemaker. In the rare situation when it does, you’ll know by feeling faint. Your doctor will also know when he or she sees specific changes on your EKG.

Wenckebach heart block is almost never a serious heart condition. Worrying about it is a more serious threat to your health.

DEAR DR. DONOHUE: Please end this argument once and for all. I drink a lot of Diet Pepsi. My family doctor says “drink all you want.” A neighbor doctor who stops in once in a while says it will kill me. Who is right? – H.S.

ANSWER: Neither is completely right. You can’t drink all you want of anything and expect there to be no consequences, but Diet Pepsi will not kill you.

Caffeine in any caffeine-containing beverage can raise blood pressure if you insist on drinking enormous volumes. Diet drinks, in large quantities, can damage teeth, even though they contain no sugar. They might also weaken bones.

Can’t you strike a happy medium with your pop?

DEAR DR. DONOHUE: Is lordosis a disease? I have it. My girlfriend is a nurse, and she’s the one who told me. What can I do about it? – L.R.

ANSWER: Lordosis is an inward curve of the spine. Normally the spine has two inward curves. One is in the neck. The other is in the lower back, and it is a more pronounced curve than the neck curve.

Only if the curves are greatly exaggerated do they constitute a problem. If you stand with your back against a wall, a fist should not be able to fit between the lower back and the wall. If it can, the curve is too great. Postural exercises can straighten it. Stand against the wall again. Make a deliberate attempt to flatten the lower back so it can’t admit a fist between it and the wall. The back shouldn’t be perfectly flat. It needs a bit of a curve.

Learning how to reduce the curve and maintaining that posture when standing, walking or sitting can minimize a too-prominent lumbar lordosis, as the lower-back curve is called.

DEAR DR. DONOHUE: I had to have a doctor’s exam and chest X-ray for my job. The X-ray report says, “slight cardiomegaly.” The doctor says it’s not meaningful. What do you say? I am 33. – R.V.

ANSWER: Cardiomegaly is heart enlargement. Hearts enlarge for good reasons. Athletes usually have a bigger-than-normal heart. The heart is a muscle, and exercise increases its size. Hearts also enlarge for bad reasons. Unrelieved high blood pressure, heart failure and a condition called cardiomyopathy produce large hearts. Those illnesses also produce symptoms. If you have no symptoms and if the doctor says your heart is fine, then you can forget the remark on the chest X-ray report.

DEAR DR. DONOHUE: Can you give me some information about this new fiber supplement inulin? Is it better for me than the psyllium I get in Metamucil?

I see that the new tablet with inulin also contains sorbitol. Is it true that sorbitol also helps with regularity? — E.S.

ANSWER: Inulin is a long chain of fructose molecules, fruit sugar. It isn’t digested, so no fructose enters the blood. Inulin moves undigested food through the digestive tract and retains water in the food residue. It does keep people regular, as other indigestible fiber products do. In the colon – the large intestine – bacteria breakdown inulin, and the byproducts might prove valuable to colon health.

Sorbitol is a sugar alcohol. The words “sugar alcohol” are a source of great confusion. Those substances are neither sugars nor alcohols. In large enough quantities, they can have a laxative effect.

You’re going to have to be the judge of its usefulness for you. Different things work differently for different people.

The daily fiber requirement is 25 grams to 30 grams. It shouldn’t all come from inulin or psyllium, or any other pure-fiber product. Vegetables, fruits and whole grains count as valuable fiber sources.

The booklet on constipation deals with how to prevent this common complaint. Readers can order a copy by writing: Dr. Donohue – No. 504, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6.75 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

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