Leonardo drew the heart's four valves

The intricate diagrams of the heart were made by Leonardo 500 years ago.

Mr Francis Wells from Papworth Hospital, Cambridge, says Leonardo's observations of the way the heart valves open and close was revelatory.

Mr Wells has used this understanding to modify current repair operations, and has successfully treated 80 patients.

What Leonardo was saying about the shape of the valve is important. It means that we can repair this valve in a better way

Heart surgeon Mr Wells

The drawings allowed him to work out how to restore normal opening and closing function of the mitral valve, one of the four valves in the heart.

Until now, surgeons have repaired a floppy valve by narrowing its diameter. However, this can restrict the blood flow further when the individual is exercising and working their heart to the maximum.

Mr Wells said: "It's a complete rethink of the way we do the mitral valve operation.

"What Leonardo was saying about the shape of the valve is important. It means that we can repair this valve in a better way."

Valve repair

The job of the mitral valve, which is made up of two flaps, is to stop blood flowing in the wrong direction in the heart.

It works a bit like a pair of doors, slamming shut to stop blood returning from where it came.

In some people it stops working properly, and becomes like a swing door, letting blood flow backwards through it, which means the heart has to work harder to do its job of getting blood out into the arteries and around the body.

LEONARDO FACTS Italian artist, scientist and engineer 1452-1519 His anatomical knowledge came from his post-mortem dissection work, which the Church forbade He disproved the belief that the heart was not a muscle and showed it consists of four chambers and not two, as was commonly held He suggested that arteries fur up over a lifetime, creating a health risk

Narrowing the diameter of the valve opening with surgery helps, but Mr Wells, with help from Leonardo, believes he has found a better way.

Leonardo worked out in the 1500s that the opening phase of the mitral valve was extremely important - this can be compromised with conventional surgery because the opening is made narrower than normal.

Mr Wells says he can now repair the floppy mitral valve in such a way that it does not alter the normal diameter of the valve when it is open which means that the individual can return to more vigorous exercise without any problems.

He said Leonardo had a depth of appreciation of the anatomy and physiology of the body - its structure and function - that perhaps has been overlooked by some.

The Italian artist had no formal medical training and brought together a number of disciplines, including mechanics and engineering, when he looked at a problem.

Mr Wells is now looking back at many of Leonardo's other drawings of the body to see if these might help medicine now.

Mr Wells and Leonardo feature in The Secret of Drawing which begins on BBC Two on October 8.

London's Victoria and Albert museum will be hosting an exhibition of Leonardo's work in art, science and technology starting 14 September 2006 to 7 January 2007, in collaboration with Universal Leonardo, Central Saint Martins College of Art and Design, University of the Arts, London.