The heart and circulation. Modern medicines.




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6. Modern medicines

Picture 6.1 Number of deaths per year per 100,000 people due to coronary heart disease and other circulatory diseases.

The graph shows that deaths from heart and circulatory diseases have dropped dramatically over the last 30 years. Modern medicines and new ways of treating people with circulatory problems have made a big contribution to this improvement.

Prevention

Prevention is always better than cure. As well as being an effective painkiller, Aspirin also reduces the chances of blood platelets clumping together to form a blood clot. This lowers the chance of a blood clot forming in a coronary artery and triggering a heart attack.

Aspirin may have harmful effects in children and should not be taken by children under the age of 12. A recent proposal recommends that this is raised to 16 in the UK. In the USA, it is recommended that aspirin should not be taken by anyone under 19.

Picture 6.2 The structure of aspirin, thrombolysins and beta-blockers.

Treatments and cures
	During a heart attack, thrombolysins can be injected to remove the clot and restore the blood supply to the damaged area of heart muscle.

Beta-blockers directly affect the heart to reduce the force and rate of contractions. They are very effective in preventing attacks of angina and in treatment of high blood pressure. By returning the blood pressure to normal beta-blockers help to reduce the risk of a heart attack or stroke.

Smoking makes a big contribution to heart problems. A person under the age of 50 who smokes is ten times more likely to have a heart attack than one who does not. Many smokers want to give up but find that they are addicted to the nicotine. Nicotine replacement therapy and a new medicine called bupropion help people to give up smoking.

Picture 6.3 The Philips Heartstart FR2+ Defibrillator.

Not all circulatory disorders can be prevented and if a person suffers a heart attack it is vital to get their heart beating normally as quickly as possible. Paramedics or doctors use a defibrillator to do this by giving the heart an electric shock but normally they take vital minutes to reach the patient. Many lives could be saved by use of Automated External Defibrillators by people who are not medically trained. These are small, portable devices that attach quickly to a person showing the first symptoms of a heart attack. They automatically monitor the heart and can deliver the correct electric shock to restore the heartbeat.

Disorders of heart rhythm, arrhythmias, can be treated by anti-arhythmic medicines.

Aspirin				Close
Aspirin is a very versatile medicine It is used to relieve pain, reduce fevers and as an anti-inflammatory. In the treatment of heart disorders it reduces the "stickiness" of blood platelets so that they do not break open and stimulate the formation of a blood clot. If a clot forms in a coronary artery it can trigger a heart attack. Aspirin reduces the risk of dying after a heart attack and of having a further heart attack or stroke in people who have already suffered one.

Thrombolysins				Close
Blood clots can block coronary arteries and cause a heart attack. Permanent damage to the heart muscle happens quickly as it is starved of blood. Thrombolysins, like streptokinase and tissue plasminogen activator, are medicines that activate an enzyme normally found in the blood called fibrinase. This enzyme dismantles the fibrous blood clot. Thrombolysins are given to a person suffering a heart attack by an intravenous injection (into a vein) and quickly cause a clot in the coronary artery to be dissolved so that blood flow to the heart muscle is restored.

Beta-blockers				Close
During times of stress or activity, the heart beat is increased by nerves which use adrenaline in their synapses with the heart muscle. Beta-blockers have a similar shape to adrenaline and fit into the adrenaline-receptors on the heart muscle. This blocks the adrenaline which, in turn, reduces the speed and force of the heart's contractions. Using beta-blockers can lower the blood pressure and help to prevent angina attacks and reduce the risk of a further heart attack in people who have already had one. Some beta blockers can help control abnormal heart rhythms and heart failure.

Automated External Defibrillators (AED)

During most heart attacks, the ventricles go into "fibrillation". This means they twitch rapidly and do not pump any blood. If untreated the person can die within minutes. Defibrillators deliver an electric shock to the heart and help to "kick" it back into its correct rhythm but they must be used as soon as possible after the heart goes into ventricular fibrillation.

Most defibrillators need a medically trained person to operate them but new Automated External Defibrillators (AED) have two pads which can be easily attached to the chest of a person suspected of having a heart attack. The AED monitors the heart beat and then gives clear instructions, either on a screen or by a computer-synthesised voice, to allow anyone to give the correct electric shock.

AED's in all public buildings such as stadiums, airports, office buildings shopping centres could save thousands of lives a year in the UK.

Anti-arrhythmics				Close
Following a heart attack, or in some other heart disorders, the natural rhythm of the heart beat can be disrupted. This is because the heart's natural "pacemaker" is damaged and not working properly. The normal electrical control of the heart muscle is unbalanced. One new type of medicine that helps to regulate heart rhythm are potassium channel blockers, like amiodarone. These slow down the movement of potassium ions out of the cells in the pacemaker. This "smoothes out" the electrical waves that stimulate the heart muscle and allows the heart to beat in a more co-ordinated and efficient way.