Interview: Gordon Lowe - Blood clots – the 150-year battle to save lives

Published on Monday 3 August 2009 20:25

MORE than 150 years ago, a Glasgow surgeon named Andrew Buchanan became one of the first people to suggest the existence of clotting agents in the blood.

He discovered fibrinogen – the viscous agent that helps dry and heal wounds but also helps create clots in the body that can lead to heart attacks, strokes and deep vein thrombosis.

Today, few people know more about blood clots and fibrinogen than Glasgow-based Professor Gordon Lowe, whose work was recently awarded the Investigator Award by the International Society on Thrombosis and Haemostasis.

Over the past 35 years, more than 60,000 blood samples have passed through Prof Lowe's laboratory at Glasgow University – and his team's discoveries have had a major influence on public health policy in Scotland, and around the world.

By studying the results from thousands and thousands of blood tests, the laboratory, based alongside Glasgow Royal Infirmary, has been able to study the impact of risk factors such as obesity, deprivation, smoking, cancer and hormone replacement theory on blood clotting.

Prof Lowe, who still works as a doctor in the hospital, says he was drawn to study blood clots in an attempt to make a contribution to understanding Scotland's biggest killers. "Heart attacks and strokes are the number one cause of death in Scotland and in most developed countries," he says. "Every day, people in Glasgow are clotting. Whenever I give a paper, the theme of my talk is, 'there are lots of clots and Scots'."

He adds: "Often people die of blood clots before they get into hospital. We should be trying to understand why clots occur and we should be doing something about it."

The primary focus of Prof Lowe's research was deep vein thrombosis (DVT) – a condition he describes as an "orphan" in relation to the research on heart attacks and strokes. While heart disease gets major funding and strokes have become more prominent because of an ageing population, the causes of DVT, also caused by blood clots, have attracted less attention.

The risk of DVT is at its highest among hospital patients – particularly those who have undergone major surgery. One in 2,000 people in the general population suffers from DVT – among hospital patients the figure is one in 200.

And yet the problem, which can become fatal if it leads to a pulmonary embolism – a clot on the lung – can be avoided with the right combination of anti-coagulant drugs.

Age, obesity, varicose veins, smoking, prolonged travel, previous deep vein thrombosis, hormone treatments such as the pill and HRT, cancer and genetic factors have all been identified as putting people at risk.

There may also be a "Scottish factor" – which could explain the particularly high incidence of heart attacks, strokes and deep vein thrombosis in Scotland.

One of the benefits of Prof Lowe's research has been improved guidelines drawn up by the Scottish Intercollegiate Guidelines Network (Sign) giving doctors a check list of risk factors to help them identify which patients should be prescribed heparin and other blood-thinning drugs while in hospital.

"During the 1990s, surgeons got the message and started prescribing to at-risk patients and the rate of deep vein thrombosis has greatly improved – but medical wards have taken longer to adopt the practice," Prof Lowe says.

Thanks to the improved research the use of blood-thinning agents in hospitals has doubled over the past 30 years – but recent research estimates only 80 per cent of medical patients who are at risk are being prescribed heparin or other anti-coagulants.

"I have been promoting awareness of blood clots in the legs and the lungs for 35 years and I am pleased the message is now getting through," Prof Lowe says.

His team's work has helped governments formulate lifestyle advice, to reduce the risk of heart attack, stroke and DVT. The smoking ban is a case in point.

Smokers have a level of fibrinogen – the blood clotting agent – 20 per cent higher than non-smokers. Studies show that smokers who quit can return to normal levels of fibrinogen within 15 years. The studies also prove unequivocally that passive smoking has an effect on the levels of fibrinogen in the blood. "It is not just theoretical. We have identified mechanisms by which passive smoking and HRT can increase risks – that has led to changes in public health policy," Prof Lowe says.

The work has changed the advice doctors offer about the effects of hormone replacement therapy and the contraceptive pill. These practical benefits are one of the main reasons Prof Lowe was awarded the Investigator Award. "This award is not just for my research – it is partly for education and for helping to put guidelines in place," he says.

On the verge of retiring from medicine, Prof Lowe is packing up his lab and preparing to move to a new site at the Western General. He will soon give up teaching but continue research as an emeritus professor.

In the future, he believes more will be understood about how to identify people at risk of heart attacks, strokes and DVT and more preventative treatment will be available.

"The question is, 'is there something else we could be doing to prevent heart attacks and strokes apart from giving lifestyle advice?'" he says. "Is giving anti-coagulant drugs something we should be doing for people who are at risk?

"In the future I would like to see studies set up looking at old people, aged 70-plus, who have high risk factors, and to see big clinical trials to see the effect of giving people a low dose of anti-coagulant drugs and see if it reduces their risk of heart attacks and strokes."

Looking at the way blood clotting factors relate to dementia, cancer and degenerative diseases is another area the professor believes will be important in future research.

As he watches the dismantling of the laboratory where he has spent so much of his working life, he is proud to have continued in the great tradition of Scottish medicine, following in the footsteps of pioneers such as Buchanan. He says: "For me it has been nice that the main blood clotting factor we have studied is fibrinogen, because it was discovered on this very spot. I think Andrew Buchanan might have been pleased to discover that what he discovered 150 years ago has related to some of the modern problems of Scots."

WHAT HAPPENS WHEN BLOOD CLOTS

BLOOD is designed to clot when outside of the artery or vein in order to protect us from a severe loss of blood in the event of injury. When it clots within the bloodstream, a thrombosis occurs.

Although a thrombosis can happen anywhere in the body, certain locations can cause particular medical problems.

When a clot forms in an artery around the heart (an arterial thrombosis), it can stop the blood flow to the heart muscle, thereby reducing the amount of oxygen and causing damage to the organ – this is a heart attack. Similarly, when a blood clot forms in an artery in the brain (a cerebral thrombosis), it is one of the major causes of stroke. Again, the flow of blood to the brain is disrupted, causing damage.

Deep vein thrombosis, or DVT, occurs when a blood clot blocks a vein – either partially or completely – causing pain and swelling. This usually occurs in the leg and can cause severe immobility in the limb.

If a thrombosis dislodges and travels elsewhere in the body, it is known as an embolism. If the clot travels to the lungs, it can cause a pulmonary embolism - which can be fatal.

Thrombosis is most common among older people, and family history, as well as a lack of exercise and obesity, may make you more likely to experience it.

Recent research has found that people who have experienced DVT are in greater danger of heart attacks and strokes. But DVT is relatively rare, and the NHS says about one in every 2,000 people in the UK is affected each year.

DVT is treated using anti-coagulant medicines such as heparin and warfarin, which stop new clots forming but do not break down existing clots.