There must be ten thousand books on the human heart, so I recently asked Dr. Michael DeBakey, the famed heart and blood vessel surgeon, why he wanted to write another.

DeBakey said, "There is no book like this one, nothing else that brings together all the thins the average person wants to understand. I couldn't find anything in print that said all the things I wanted to say to my own patients."

The underlying problem in most so-called heart disease, as he and his colleague, Dr. Gotto, explain, is not really disease of the heart but disease of the arteries that feed it. There are scores of varying heart and blood vessel abnormalities, however, and these surgeons explain them.

They do so not in the simplest or most graceful Language, but certainly in rich detail. In short, this is a book for information, not for entertainment.

Among its most valuable features, therefore, are its hugely informative drawings by Herbert Smith. Like DeBakey and Gotto here, Smith is an elucidator rather than an artist. There are many more stunning anatomical drawings, but few more useful to the ordinary person. (McKay, $14.95)

In You and Your Heart, Dr. Paul Kezdi brings us up to date on how to keep strong-hearted, and what to do if the heart falters. Kendi is as pale of language as DeBakey-Gotto.This is a brief doctor's lecture, or series of them, on sensible living.

His lectures are of value, however, for their very plain-ness and brevity. The things he suggests sound modest and possible.

In fact, I want to reread his chapter on "How to Relax" --elsewhere, in setting down some simple prescriptions without mantras or mumbo-jumbo. (Atheneum, $9.95).