Page 37 - Medicine and Surgery

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Chapter 2: Ischaemic heart disease 33

in ischaemia of the myocardial tissue. The predomi- Chronic stable angina
nant cause of cardiac ischaemia is reduction or inter-
Definition
ruption of coronary blood flow, which in turn is due to
Chest pain occurring during periods of increased my-
atherosclerosis+/−thrombosiscausingcoronaryartery
ocardial work because of reduced coronary perfusion.
narrowing.
Incidence Incidence
Ischaemic heart disease results in 30% of all male deaths Angina is common reflecting the incidence of ischaemic
and 23% of all female deaths in the Western world. heart disease.

Age Age
Increases with age. Incidence increases with age.

Sex
Sex
M > F
M > F. Premenopausal women are relatively protected.
Geography
Geography
More common in the Western world where it is the com-
Predominantly a disease of the Western world, but this
monest cause of death.
pattern is changing with the increasing affluence of the
developing world.
Aetiology/pathophysiology
Risk factors can be divided into those that are fixed and
those that are modifiable: Aetiology
Fixed: Age, sex, positive family history.
Angina is most commonly associated with atheroma, al-
Modifiable: Smoking (direct relationship to the num-
though exertional chest pain can occur with other condi-
ber of cigarettes smoked), hypertension, diabetes mel- tions,suchasaorticstenosisandhypertrophiccardiomy-
litus,LDLandtotalcholesterollevels(HDLcholesterol opathy. In ‘stable angina’, pain is precipitated by physical
is protective). exertion, meals, cold weather and high emotion (anger,
Ischaemic heart disease is essentially synonymous with excitement), and it is relieved by rest.
coronaryarterydisease.Rarelycardiacischaemiamayre-
sult from hypotension (reduced perfusion pressure), se- Pathophysiology
vere anaemia, carboxyhaemoglobinaemia or myocardial The pathology of stable angina is the presence of high-
hypertrophy. grade stenosis of at least one coronary artery resulting
Four main syndromes are associated with coronary in a reduction of at least 50% of the lumen diameter
artery disease: or 75% of the lumen area. The underlying mechanism
Chronic stable angina results from the presence of is atheroma, which affects large and medium-sized ar-

atherosclerotic plaques within the coronary arteries teries. The true pathogenesis of atheroma is not fully
reducing the vessel lumen and limiting the blood flow. understood but the following factors are thought to play
Symptoms are only present on exertion (see below). arole:
Acute coronary syndrome encompasses unstable Stage I: Damage to the endothelium of the arteries al-

angina, non-ST elevation myocardial infarction and lowstheentryofcholesterolrichLDLsintotheintima.
acute myocardial infarction with ST elevation. It re- At this stage the cholesterol is extracellular.
sults from rupture of an atherosclerotic plaque and Stage II: Normally macrophages are unable to phago-
subsequent thrombosis (see page 36). cytose cholesterol as they lack the required recep-
Variant/Prinzmetal’s angina (see page 40). tor; however, once the LDLs are oxidised they are

Ischaemic heart failure/cardiomyopathy, which may taken up by macrophages by a receptor-independent

occur without overt acute symptoms. pathway. The resultant lipid-laden macrophages are