Atheroma

Atheroma¹ is the main killer in the western world. Most deaths in Ireland are due to cardio-vascular events and the majority of these are due to myocardial infarction.

**Table 1:** Causes of death in Ireland 1995, data from the Central Statistics Office
Cause of Death	%
Circulatory Diseases	43
Malignant Neoplasms	24
Respiratory Diseases	15
Injury and Poisioning	6
Other	12

**Figure 1:** Cardiovascular causes of death in Ireland, 1995. Data from the Central Statistics Office
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Plaque like material accumulates on the inside of the arteries and this results in a narrowing of the vessels with poor blood flow to the tissues down stream. The plaque may rupture with ejection of athermatous material into the circulation, this material will cause downstream blockages and ischaemia. The resultant ulcerated area in the plaque acts as a nidus for the formation of small clots which consist primarily of platelets, these clots in turn may break off and embolise into the distal circulation. If the clotting is exuberent the clot may actually block the artery. Another complication is haemmorhage into the plaque, which will result in acute narrowing of the vessel with superimposed thrombosis and occlusion.

If we take the example of coronary artery disease we can see parallels with arterial disease in other locations;

**Table 2:** Arterial disease in different vascular beds
Pathophysiology	Stenosis (pressure drop on distal vasodilatation)	More severe stenosis (pressure drop at rest)	Distal embolisation	Occlusion or embolisation
Coronary circulation	Angina on exertion	Angina at rest (Unstable angina)	?	Myocardial infarction
Carotid circulation	?	?	Transient ischaemic attack	Stroke
Lower limb circulation	Claudication	Rest pain	Blue toe syndrome	Ulceration and necrosis

Mitchell et al [MW⁺97] noted that retinal artery emboli were detectable in a large number of asymptomatic elderly australians.

**Table 3:** Prevelance of retinal artery emboli in asymptomatic Australians[MW⁺97]
Age	Rate (%)
Younger than 60	0.8
60-69	1.4
70-79	2.1
Older than 80	1.5