ischaemic heart disease

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Ischaemic (or ischemic) heart disease, or myocardial ischemia, is a disease characterized by reduced blood supply to the heart. It is the most common cause of death in most western countries.

Ischaemia means a "reduced blood supply". The coronary arteries supply blood to the heart muscle and no alternative blood supply exists, so a blockage in the coronary arteries reduces the supply of blood to heart muscle.

Most ischaemic heart disease is caused by atherosclerosis, usually present even when the artery lumens appear normal by angiography, see IVUS.

What is it?

• Initially there is sudden severe narrowing or a closure of either the large coronary arteries and/or of coronary artery end branches by debris showering downstream in the flowing blood. It is usually felt as angina, especially if a large area is affected.
• The narrowing or closure is predominantly caused by the covering of atheromatous plaques within the wall of the artery rupturing, in turn leading to a heart attack (Heart attacks caused by just artery narrowing are rare).
• A heart attack causes damage to heart muscle by cutting off its blood supply.

This can cause:

• Temporary damage and pain (ischemia)
• Loss of muscle activity (acute heart failure)
• Permanent heart muscle damage, heart muscle does not grow back (acute myocardial infarction /infarct)
• Long term loss of heart muscle activity (chronic heart failure)
• Cardiac arrhythmias: irregular heartbeat which can be fatal. Most death is due to arrhythmias, usually tachyarrhythmias.
• Other structural damage to the heart including damaged heart valves, actual perforation of the heart and a thin walled fibrous floppy heart.

Prevention

Prevent or delay atherosclerosis.

• Do not smoke
• Maintain low blood pressure - prevent/treat hypertension (high blood pressure)
• Exercise frequently - exercising the heart muscle strengthens it, like any other muscle
• Avoid obesity - increasing body fat stores, especially intra-abdominal fat, increases serum cholesterol, triglycerides, insulin requirements and promotes Diabetes Mellitus plus chronically increases heart muscle workload.
• Avoid trans-fats - these are found in any chemically modified fat product, such as margarine, in hydrogenated fats, and especially in superheated fats (such as those used for commercial deep frying). These fats are unreactive (not fitting in the enzymes designed for cis-fats) and should not be consumed in any amount; however, in many western countries, limitation may be the only practical option. Some mono-unsaturated fats are beneficial in reducing the risk of heart disease when consumed in moderation. When consumed in excess, however, other health concerns arise. An increase in polyunsaturated fats is also warranted in most American diets. Dietary cholesterol intake is known to have only limited effect on serum cholesterol.
• Monitor and reduce cholesterol - take LDLipoprotein cholesterol reducing and HDLipoprotein raising drugs and verfiy both LDLipoprotein particle counts and quantitative large HDLipoprotein response to treatment
• Aspirin may benefit some individuals

For more details on this topic, see Coronary_heart_disease#Aspirin.

• Take vitamin C - this micronutrient maintains healthy blood vessels (see scurvy), and prevents tears and fissures in the lumen wall that act as condensation nuclei on which the cholesterol molecules aglommerate, but overdoses may cause GERD which leads back to heart disease

Treatment of a heart attack

'The options required depends on the situation'.

• Specialised coronary care (the sooner the better); most deaths are due to sudden onset arrhythmias - time is crucial to survival.
• Cardiopulmonary resuscitation (breathing support, pulse and BP monitoring & possible chest compressions).
• A defibrillator can stop cardiac arrhythmias.
• An artificial pacemaker can speed up cardiac bradyarrhythmias.
• Drugs such as adrenaline can increase heart rate and strength of contractions, although also promote tachyarrhythmias.
• Thrombolytic agents can clear away compounding blood clots.
• Anticoagulation can impede additional blood clots.
• Inotropic drugs will raise blood pressure.
• Unblock arteries with angioplasty ("balloon angioplasty with or without stents") or surgery.

After a heart attack

• Possible angioplasty or cardiac surgery.
• Possibly the regular administration of anti-coagulants to prevent further blood clot complications.
• Possibly the administration of drugs to reduce heart arrhythmias although they many also induce arrhythmias.
• Lifestyle modifications are important in prevention of a second MI; increased exercise, reduction of stress, and improved dietary considerations are perhaps most important

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