Ischaemic heart disease

Ischaemic heart disease

Ischaemic heart disease

Definition

In the normal heart there is a balance between the oxygen supply and demand of the myocardium. A supply of oxygen insufficient for the myocardial demand results in ischaemia of the myocardial tissue. The predominant cause of cardiac ischaemia is reduction or inter-ruption of coronary blood flow, which in turn is due to atherosclerosis+/− thrombosis causing coronary artery narrowing.

Incidence

Ischaemic heart disease results in 30% of all male deaths and 23% of all female deaths in the Western world.

Age

Increases with age.

Sex

M > F

Geography

More common in the Western world where it is the commonest cause of death.

Aetiology/pathophysiology

Risk factors can be divided into those that are fixed and those that are modifiable:

·        Fixed: Age, sex, positive family history.

·        Modifiable: Smoking (direct relationship to the number of cigarettes smoked), hypertension, diabetes mellitus, LDL and total cholesterol levels (HDL cholesterol is protective).

Ischaemic heart disease is essentially synonymous with coronary artery disease. Rarely cardiac ischaemia may result from hypotension (reduced perfusion pressure), severe anaemia, carboxyhaemoglobinaemia or myocardial hypertrophy.

Four main syndromes are associated with coronary artery disease:

·        Chronic stable angina results from the presence of atherosclerotic plaques within the coronary arteries reducing the vessel lumen and limiting the blood flow. Symptoms are only present on exertion (see below).

·        Acute coronary syndrome encompasses unstable angina, non-ST elevation myocardial infarction and acute myocardial infarction with ST elevation. It results from rupture of an atherosclerotic plaque and subsequent thrombosis.

·        Variant/Prinzmetal’s angina.

·        Ischaemic heart failure/cardiomyopathy, which may occur without overt acute symptoms.