Cutting away causes of heart disease

Thanks to ongoing medical research in many different areas, heart disease could soon be no more than a distant memory writes Vicki Swain.
In recent years a great deal of research has been going into the causes, prevention and treatment of coronary heart disease.

With the mapping of the human genome, more is being discovered about the genetic roots of coronary
heart disease. Scientists are trying to pinpoint which genes are involved and which environmental factors cause these genes to be activated. Itís already widely accepted that some genes affect the way cholesterol and fat behave in the blood and so predispose to heart attacks.

Identifying these genes will help some people with these characteristics limit any risk by taking specially tailored drugs. If these are prescribed to a patient already adopting a lifestyle designed to lower cholesterol, the likelihood of a healthy life is greatly increased. In future, gene therapy may even be used to replace faulty genes and so prevent coronary heart disease in those at risk.

Researchers are currently looking at specific risk factors such as homocysteine and high blood pressure, and trying to identify how they may increase the risk of coronary heart disease in different populations.

In the area of transplantation, work is being undertaken to improve immunosuppressant drugs that should make heart transplants safer and more effective. Other researchis directed towards engineering an artificial heart, a quest which has been going on since the 1950s, so far with only limited success. But the latest research means it is only a matter of time before the search to construct an effective artificial heart is successful, opening a new era for people who need a new heart.

Current treatment for coronary heart disease varies depending on age, the state of arteries, the severity of symptoms, and a variety of other factors, but in many cases coronary heart disease can be treated with drugs. In others, surgery or a procedure to open up blocked blood vessels may be necessary.

Coronary angioplasty or percutaneous transluminal coronary angioplasty (PTCA) is a procedure performed under local anaesthetic and is commonly used to treat angina when condition canít be controlled with drugs. It involves squashing the fatty build up in a blocked artery and stretching the artery walls so more blood and oxygen can flow to the heart muscle.

Balloon angioplasty, or balloon treatment, was the first type of angioplasty used. In it, the surgeon passes a fine hollow tube or catheter, on the end of which is a small balloon, into an artery in the groin or arm - and directs it under x-ray guidance to the blocked artery. The balloon is inflated, compressing the fatty build up against the artery walls. The surgeon then lets down the balloon and removes it.

Another common type of angioplasty involves inserting a short stainless steel mesh tube, a stent, at the same
time as the balloon. As the balloon deflates, the stent expands and is left in place to help keep the artery open.
This method helps to prevent the problem of reblockage (restenosis) which affects around a third of people following conventional balloon treatment.

Doctors are also trying out a number of newer ways to perform angioplasty using a variety of devices to cut or drill out fatty deposits, vapourise them with a laser, or blast them with ultrasound. However, as yet, these are not routinely available in most areas.

Coronary bypass surgery or coronary artery bypass graft (CABG), allows a blood vessel from another part of the body
to be grafted between the aorta and coronary artery or arteries to bypass blockages and restore blood flow to the heart. A bypass can be done on each of the four coronary arteries and the operation can be done using conventional surgical techniques or by microsurgery.

In recent years, an experimental technique known as transmyocardial laser revascularistion (TMR) has also been developed, which uses a laser beam to create channels in the wall of the left ventricle allowing oxygenrich blood to flow to the heart muscle.

In the past, heart transplants sometimes failed because the immune system rejected the transplanted heart. However, with the use of drugs to prevent rejection, heart transplants are now extremely successful. Unfortunately a shortage of donors means itís usually only recommended for those with advanced heart disease where the heart muscle has become wakend (cardiomyopathy) or the heartís blood vessels are blocked and the heart muscle damaged.

Apart from heart problems, the patient should be in good health, under 60 and prepared to adapt to lifestyle changes after the transplant. But most importantly, owing to the limited number, all other treatments should have been tried or excluded.

Recovery time after any procedure depends on the type of surgery and anaesthetic and what kind, age, and overall state of health. Itís extremely important that patients are able to attend a Cardiac Rehabilitation programme to ensure they reach the optimum level of health and understand how to modify lifestyles tominimise chances of future

A large range of drugs exist to treat and control the symptoms of coronary heart disease or risk factors, such as angina or high blood pressure. Most drugs fall into a handful of types which act in similar ways.

ACE angiotensin converting enzyme-inhibitors are used to treat heart failure and lower blood pressure, blocking the activity of the hormone, angiotensin II, which narrows the blood vessels, improving blood flow and decreasing the amount of work for the heart. Anti-arrhythmic drugs control the rhythm of the heart, but their effectiveness depends on keeping exactly the right amount in the bloodstream.

Anticoagulants inhibit blood clotting, preventing fibrin from forming. They are also used to treat deep vein thromboses and to prevent these from travelling to the lungs where they may cause a pulmonary embolism.

Aspirin and anti-platelets prevent blood clotting by reducing the stickiness of platelets. They can reduce the risk heart attacks or strokes, as well as for angina and to prevent blood clotting following bypass surgery and other procedures.

Beta blockers prevent angina and lower high blood pressure. They work by blocking the effects of stress hormones which make the heart beat faster and more forcefully. They can also be used to lower the risk of subsequent heart attacks and help control arrhythmias.

Calcium channel blockers or calcium antagonists can be used to treat angina, reduce high blood pressure and work by reducing the amount of calcium entering the arteriesí muscle cells. This relaxes and widens the arteries, increasing the blood flow to the heart and lowering blood pressure.

Lipid-lowering drugs reduce the levels of blood fats or lipids. They may work by raising levels of HDL cholesterol and/or lower circulating amounts of LDL cholesterol.

The main type are Ďstatins,í a group of cholesterollowering drugs that can inhibit the action of an enzyme involved in cholesterol synthesis to lower LDL cholesterol levels. They are intended to be used in alongside lifestyle measures to lower cholesterol, such as increasing physical activity, giving up smoking and eating a low-fat diet

However, while lowering cholesterol does help to combat cardio-vascular disease, some research suggests that statins could also be carcinogenic. Diuretics work on the kidneys to increase excretion of water in the urine. They are useful for treating heart failure, which causes an excess of water to accumulate in tissues, and to reduce blood pressure.

Nitrates relax the muscles in the walls of blood vessels, reducing the workload of the heartís left ventricle. They are used to treat angina and may be prescribed as sublingual tablets, as an aerosol spray, as tablets, or as skin patches.

Potassium channel activators act to relax the walls of the coronary arteries and improve blood flow, and are used to alleviate angina.

Thrombolytic drugs can dramatically reduce any risk of a fatal heart attack, and can help minimise the damage of a heart attack. They work by breaking up clots, restoring blood flow through the narrowed artery, and reducing damage to the heart muscle.

While this array of medication and medical procedures are already widely available and are effective in minimising the risks associated with heart disease, the medical profession continues to try groundbreaking procedures and researchers are continually looking for the one breakthrough that could eventually mean cure for all.
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