Timothy Deal first noticed the problem about a year ago.Deal, then 36, decided to go jogging - something he did about three times a week - after painting the outside of his house in American University Park.

After a few blocks, he said he felt very tired and "indigested." The symptoms became worse over the next few weeks. The problem returned whenever he jogged or ran for the bus.

Deal's physician ran some tests - first simple and then advanced. The tests revealed that three of the vessels carrying blood to his heart were blocked - one almost completely, another severely and a third about half. Deal was suffering from coronary artery disease, the leading cause of death in the United States.

Within two months, after a brief attempt to treat the problem with drugs, Deal underwent surgery. Using a vein from his leg, a surgeon bypassed the blocked portion of the arteries so that Deal's heart would receive an adequate blood supply.

A month later he was back at work. A year later, Deal is running two to three miles, four or five times a week. He has eliminated foods with a high animal fat content from his diet. He eats more chicken, less beef, more Italian, less French food. The only medication he takes regularly is three aspirin tablets daily to prevent his blood from clotting. In all other respects his life normal.

For all of the apparent good results, however, Deal and thousands of other persons who have received a coronary bypass operation last year are at the center of a controversy within the American medical community.

The issue could hardly be more dramatic. Coronary artery disease accounts for about 650,000 deaths in this country every year - more than half the number of people who die.That is more than twice as many persons who die from cancer, the second leading cause of death and more than three times the number of persons who die from cerebrovascular disease, such as strokes, the third leading cause of death. About 5 million men between 40 and 60 years old suffer from coronary artery disease.

Coronary artery diseases involves the partial or total blockage of one or more of the arteries carrying blood to the heart itself. A coronary artery bypass is performed by taking a vein from the patient's leg and using it to bypass the obstructed portion of the artery to carry blood to the heart. The vein is grafted onto the obstructed artery to carry blood around the obstruction and in to the heart.

The coronary bypass graft is the most effective operation yet developed to treat the disease - in some instances relieving the crippling symptoms of severe angina- heart pain - in some instances prolonging life and in some instances accomplishing both results.

With 70,000 operations performed last year at an average cost of $12,500 and a total cost of almost $1 billion - and with the number of procedures and the cost rapidly increasing - the medical results of the procedure still are not yet fully known. After several studies, heart specialists in these country still do not agree whether surgeons are performing too many of the procedure - or not enough.

The issue is not whether the operation "works".Even skeptical heart specialists describe the procedure in glowing terms. The debate is over when the procedure should be used, on what kinds of patients with what problems. Skeptics and critics see the coronary bypass operation as a prime - and costly - example of a technology that has become widely employed before its full efficacy has been clearly determined.

The procedure is almost universally acknowledged to be an effective treatment for chronic, severe angina or heart pain after attempts to treat the symptoms with drugs prove unsuccesful. Studies showing that the procedure increases longevity for patients with severe obstructions in certain blood vessels also have been widely accepted.

Still at issue is whether the procedure is the most effective treatment, compared to carefully designed drug therapy, for several categories of patients with angina or with obstructions in one or more blood vessels.

The argument is made more difficult by the relative lack of firm figures on how many bypass operations are performed in this country every year, what problems the patients have and what the outcomes are. Studies to determine the effectiveness of the procedure were not begun until four or five years after the first bypass was performed in 1967. Ten years later, in the opinion of some heart specialists, what is not known about the procedure's effectiveness is at least as important as what is known.

Eugene Braunwald, director of medicine at Boston's Peter Bent Brigham Hospital, professor of medicine at the Harvard Medical School and one of the foremost heart specialists in the United States, said in an interview that half "of the coronary bypass grafts are done for what I would consider to be indications that have been well established. And the other 50 per cent for indications that I consider to be questionable."

Braunwald said his estimates were based on observation, conversations with specialists and visiting hospitals around the country.

Braunwald prefaced his remarks by asserting that he believes the procudure "is a legitimate operation . . . fantastic operation . . . But I think it should be reserved for people who really need it. I think it's one of the great things that has happened. I think it's overuled.

"Very common is this kind of situation now," Braunwald said. "A patient wakes up one day and gets angina. The first day, he calls the doctor. The doctor makes his diagnosis - angina. The patient . . . gets an exercise test. The exercise test is positive. He gets a coronary arteriogram, a test allowing observation of blood flowing in the heart's arteries. It shows a couple of vessels are diseased and he gets a bypass graft without going through serious medical management (drug therapy). That patient might have been a candidate (for surgery) had you really worked with him, but might not. And in many instances, he might have been quite successfully treated by drugs.

"And some people are called medical failures, I think prematurely. In other words," Braunwald said. "I'm not sure medical treatment is given a fair chance all the time."

The operation is relatively quick and often has dramatic results. For patients seeking a "quick solution," according to Dr. Michael Mock, assistant chief of the cardiac disease branch of the Heart, Lung and Blood Institute, the operation has appeal. "We're an impatient people," Mock said. "This just reflects the American personality."

Last month the prestigious New England Journal of Medicine reported a study conducted at 13 Veterans Administration hospitals across the country. The study, which is continuing, found that after excluding one group of patients - those with left main coronary artery disease - there was no statistically significant difference in the mortality rate of patients who received surgery and those who were treated with drugs.

The study itself has provoked controversy. W. Gerald Austen, a heart surgeon and president-elect of the American Heart Association, criticized the study on the grounds that the mortality rate for patients receiving the operation at VA hosptials was three times higher than the results reported in previous studies at other hospitals.

"I really believe that this procedure is not the kind of procedure that should be done except by people who do a great deal of it and who do it extremely well," Austen said in an interview. "I would say it ought to be done in centers that have the capacity."

Despite Austen's belief - shared by other cardiac surgeons and heart specialists interviewed - that coronary artery bypass surgery operations should be conducted only at major medical centers, Braunwald asserts that the procedure is spreading to community hospitals that are not adequately equipped and that surgeons who are not the finest are doing the procedure. "I think that the farther away you go from established centers, the more questionable the indications become."

Some critics go further, Richard Ross, a cardiologist and dean of the Johns Hopkins Medical School, testified before a Congressional subcommittee last July that "Hospitals have come to see cardiac surgery programs as status symbols. They complete with each other to have the latest equipment and the biggest case loads.Cardiac surgical programs are developing in suburban hospitals which 10 years ago would never have considered such a program to be economic feasibility, and in most of these hospitals the bypass procedure is the only heart operation being done."

Part of the problem with the rapid application of bypass surgery is that the United States does not have a central authority - comparable to the Food and Drug Administration's control over the introduction of new drugs - to check the widespread use of medical machinery, operations and other technology before they have been fully tested.

Sweden, for example, has tightly controlled the number of bypass procedures performed until more clinical data is gathered on the operation's effectiveness.

Austen, and others interviewed, find that situation undesirable. "I suppose ideally 10 years ago, before people had all sorts of prejudices . . . the government in a different kind of country perhaps should hav said, 'we will now do a randomized study, and the next 500 patients with such and so will be randomized." The problem with that is that this is kind of unrealistic in a democratic society in an enormously large country like America."

If the government is not to control the spread of new, and often costly, technology before it is proven effective, who should, and how? Terry Strom, a kidney specialist at Peter Bent Brigham Hospital, criticized what he described as a "hit or miss system" of experimentation with new procedures in American medicine, allowing wide application of new procedures before they have been proven.

Austen said he thought that bypass operations were not widely performed until the initial procedures showed good results. It was only after the procedure had been done on patients who had no alternative and it went well, Austen said, "that people became very enthusiastic about the procedure and I don't think that that is wrong. I think that that is a reasonable reaction to a good operation, which it is."

Braunwald, however, sees a tendency in American medicine to adopt new procedures with a low level of proof. "I think I don't agree with Dr. Austen," Braunwald said. "I think we have to retract an awful lot of things in medicine, which means that they were adopted prematurely."

In human terms, however, the questions are not so abstract. "You have to be in the position of facing patients day after day in their 30s, young men - it hits young men much earlier than women - who at the peak of what they assume to be their healthy years suddenly develop coronary insufficiency and suddenly find they have something wrong with them," said Dr. Warren Hawthorne, a cardiologist at Massachusetts General Hospital and a member of the Harvard Medical School faculty.

"And they find this syndrome progressing to the point of being incapable of supporting their families and incapable of working . . . and trying to find some solution for that particular problem.

"It's not that coronary bypass grafting suddenly came upon the scene and droves of patients were operated upon without prior scientific investigation. The operation was investigated in the animal laboratories for years and years before it was carried out in humans. And the early operations done in humans were done in fairly urgent situations of people. If you've got somebody with unstable angina, recurring hospitalizations, six, eight, 10 times a year, unable to support their families and you've got nothing else to offer them, both you and the patient are willing to try something that might by today's standards sound desperate - but by the standards of yesterday seemed more than appropriate."

Few, however, disagree that carefully designed studies of coronary artery bypass operations to determine exactly when they are beneficial - when heart pain is relieving, when heart attacks are prevented, and when life is prolonged - should have begun earlier.

"I think we have a proven effective tool," Dr. Adolph Hutter, also a cardiologist at Massachusetts General Hospital and a Harvard Medical School faculty member, said. "It's the proper application of that tool, in other words, the diffuseness with which it should be used, including the diffuseness of the centers that should be using it, that has to come under extreme scrutiny."