Ischaemic heart disease

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ja:虚血性心疾患

Ischaemic heart disease 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, even when the artery lumens appear normal by angiography.

What is it?

• Initially there is sudden severe narrowing or 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 (ischaemia)
• Most death is due to arrhythmias, usually tachyarrhythmias
• 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.
• 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.
• prevent/treat hypertension (high blood pressure)
• Exercise regularly (Exercising the heart muscle strengthens it, like any other)
• Avoid obesity: increasing body fat stores, especially intra-abdominal fat, increases serum cholesterol, triglycerides, insulin requirements and promotes Diabetes Mellitus plus chronicly increases heart muscle workload.
• Avoid excess process modified saturated fats, often called transfats in the diet. Some mono-unsaturated fats are probably beneficial in reducing the risk of heart disease when consumed in moderation. Dietary cholesterol intake is known to have only limited effect on serum cholesterol.
• Take LDLipoprotein cholesterol reducing and HDLipoprotein raising drugs and verfiy both LDLipoprotein particle counts and quantitative large HDLipoprotein response to treatment.

Treatment of a heart attack.

The option required depends on the situation.

• Specialised coronary care (the sooner the better); most deaths are due to sudden onset arrhythmias, time is muscle and 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.
• Increase exercise within limits of safety (see prevention) to train the heart.