One of the things they didn't tell me before they put a new valve in my heart was that my blood would have to be monitored forever after.

After the operation, the patient is put on a potent blood thinner for which precise dosage must be maintained to guard against either clotting or hemorrhage.A blood sample is drawn and analyzed every two weeks, and the amount of medicine prescribed is regulated accordingly.

Regular bloodlettings can become a drage in short order, especially for a man who really hates to be stuck with needles. However, one aspect of this Dracula routine helps make these bi-weekly journeys to the doctor tolerable: I'm getting to know Rex Morgan's other patients now.

They used to be just faceless strangers - people with troubles of their own, but troubles I didn't have to worry about because I'd never see them again. Now that I'm spending so much time in their company, each is becoming an individual with an identity and a story of his own. It's like becoming involved in a soap opera with 47 subplots.

I'm getting to know which ones are gabby and which are quiet, which are cheerful and which are glum, which smoke in spite of the "Thank You For Not Smoking" signs and which do not. (Thus far, all the smokers have been females. I have not seen a man smoke since the signs went up.)

In some cases, the regular visitor to a doctor's office also begins to compile a catalogue of the ailments that go with each patient. The prime topic of conversation in a doctor's waiting room is, after all, poor health. So, after a while, everybody can help Mrs. Smith worry about her liver, and we can all help Mr. Brown keep track of his blood pressure.

On my most recent visit to the doctor, one patient kidded another about his forgetfulness. "Oh, that's normal for an old goat my age," said the target of the jest. "I don't mind. Besides, being forgetful has its compensations."

"Like what?" asked the other.

"Like when you're watching all these reruns they have on TV," was the reply. "Very often I have a vague feeling I've seen the dang thing before, but I can't remember how it comes out so I enjoy it as much the second time as the first."

My problem is that I remember exactly how the needle comes out - and goes in - so I enjoy it less the second time than the first but, as they say on the tax forms, not less than zero.