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ISCHAEMIC HEART DISEASE

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					                             ISCHAEMIC HEART DISEASE


Heart disease is the predominant cause of death in all industrialised nations, accounting for
40% of all mortality.

Ischaemic heart disease is the single biggest contributor to cardiac mortality.

Reduction in coronary blood flow is the cause of myocardial ischaemia in over 90% of cases.

The arterial supply of the heart is unique because blood flow is confined to diastole - the
coronary arteries being compressed during systole. There is considerable overlap in the
distribution of the individual coronary arteries and, in disease, collateral flow may develop.

Coronary artery disease which may or may not lead to ischaemia also includes coronary artery
aneurysm.

CAUSES:

The vast majority of ischaemic heart disease is caused by coronary artery atherosclerosis.

Rarer causes of ischaemic heart disease include:

       arteritides:
            o systemic lupus erythematosus
            o polyarteritis nodosa
            o syphilis
            o Takayasu's arteritis
            o rheumatoid arthritis
            o ankylosing spondylitis

       embolism:
           o infective endocarditis
           o left heart thrombus or tumour
           o prosthetic valve thrombus
           o cardiac catheterisation
           o paradoxical embolism

       coronary artery wall thickening:
            o amyloidosis
            o radiation therapy
            o Hurler's disease
            o pseudoxanthoma elasticum

       aortic dissection causing coronary dissection

       coronary spasm

       congenital arterial disease:
           o anomalous derivation of coronary arteries from the pulmonary artery
           o arteriovenous fistula

PRESENTATION:
The four priniciple presentations of ischaemic heart disease include:

       angina
       heart failure
       sudden death
       acute myocardial infarction

RISK FACTORS:

Factors most strongly implicated in atherosclerosis are:

       male sex
       age
       smoking - two to three fold increase in risk
       hypertension - two to three fold increase in risk
       diabetes - two to three fold increase in risk
       syndrome X
       hypercholesterolaemia:
            o there is probably no "safe" level, although 5 mmol/L is used as the cut-off
       family history of premature coronary heart disease
            o male first degree relative's first CHD event occurred before the age of 55, or a
                female first degree relative's first CHD event occurred before 65

PREVENTION:

Prevention of coronary heart disease is considered in terms of:

       primary prevention of coronary heart disease
       secondary prevention of coronary heart disease (for patients with established coronary
        heart disease or with other major atherosclerotic disease)

Lifestyle targets in primary and secondary prevention of CHD include (2):

       stop smoking
       make healthier food choices
       increase aerobic exercise
       only drink alcohol moderately within sensible limits

Other targets:

       body mass index < 25 kg/m^2 is desirable with no central obesity
       blood pressure –
            o blood pressure < 140 mm Hg systolic and < 85 mm Hg diastolic (except
                patients with diabetes - see menu)
       cholesterol – less than 4 and LDL less than 2 in secondary prevention
       diabetes – good blood glucose control.

Drug therapy for secondary prevention:

All patients who have had an acute MI should be offered treatment with a combination of the
following drugs:

       ACE (angiotensin-converting enzyme) inhibitor
   aspirin
   beta-blocker
   statin

				
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posted:1/6/2012
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