How about this for a routine day? You get up at five am., work all day, and get to bed at 11 p.m. During the day you perform the odd bit of heart surgery - like unblocking a clotted coronary or replacing a defective valve, or even doing the really tricky bits of a transplant.

Not every day is as easy as that. Next week, for example, you start on a foreign trip that involves chairing a few meetings and giving several lectures in maybe five countries and a dozen cities, always fitting the visits in with planning new techniques with fellow heart surgeons and researchers.

So what is so amazing about that? After all, internationally-renowned heart surgeons have to expect a fairly strict schedule and a big workload. But to do it at 90 years old?

That's D. Michael DeBakey for you. In the Second World War, he developed the U.S. Army mobile hospitals - immortalised in M.A.S.H. Since 1948 he has been a professor at the Baylor College of Medicine in Houston, Texas, training more than 1,000 surgeons in his time there.

He invented the first artificial artery, was the first to remove stroke-inducing clots from the arteries in the neck, and the first to place grafts around the main artery from the heart - the aorta. He has done hundreds of heart transplants.

And at 90 his hands and brain are said to be just as good as they were 40 years ago. Mind you, he is said to have his faults - like having a big opinion of himself, and being impatient with people who can't measure up to his high standards.

But maybe that's what has helped him live this long into a healthy old age. He is slim, he doesn't eat much, often missing his midday meal altogether. He lives on fruit and vegetables, seafood and chicken, leaving red meat for rare occasions.

Of course he has never smoked, but he is also teetotal. He accepts that a glass of wine with a meal is probably harmless, and may be good for you, but he sees too much alcohol (what we would probably see as moderate drinking) as being bad for the heart. He advises everyone, whether or not there is heart disease in the family, to lower high blood pressure, to keep their blood cholesterol low, never to smoke (even one a day), to keep their weight normal for their height, and to take moderate exercise.

The last piece of advice is a good one! For Michael DeBakey the most efficient moderate exercise means walking briskly for two miles every day. He walks everywhere at work, which includes the six flights of stairs up to his office. And he stresses that this is just as important for people over 65 as for younger people. Slumping around the TV is bad news.

Michael DeBakey's birthday (on September 7) coincided with the British Heart Foundation's new guidelines for returning to work after a heart illness - and with increasing worries that too many people are taking too much sick leave, when they could be easily back at work.

If heart patients can get back to work quickly, then there's little excuse for many of the people who stay off, for example, with "bad backs".

For example, if your work doesn't involve heavy exercise, you can go straight back to work after a balloon angioplasty. That's when a balloon on a catheter is used to widen a narrowed coronary artery. If you have a strenuous job you will be given only one month off, and then an exercise test will tell whether or not you can start again.

After a coronary by-pass graft, you will be off for four to eight weeks. You should be able to organise your work to avoid attacks of angina. After a heart attack, most people return to work after four to six weeks - delays in getting back to work are more often for psychological than physical reasons. Gone are the days when people could take months off and employers could keep their jobs for them.

The most important aspect of being a "heart" patient is that you CAN exercise, up to the point of provoking pain in the chest and becoming breathless. But it's equally important to stop if you reach that point, and not to go beyond it.

For most common heart problems, regular exercise helps, rather than hinders, and keeps you fitter and feeling better than if you rest all the time.

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.