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<strong>KCE</strong> Reports 82 Multislice CT in Coronary Heart Disease 5<br />

2 BACKGROUND<br />

2.1 CORONARY HEART DISEASE<br />

2.1.1 Pathophysiology<br />

Coronary heart disease (CHD) or coronary artery disease (CAD) refers to any cardiac<br />

disease caused by an impaired blood flow and deficient oxygen supply to <strong>the</strong><br />

myocardium, due to a<strong>the</strong>romatous narrowing of <strong>the</strong> coronary arteries. It is one of <strong>the</strong><br />

main causes of mortality and morbidity in Western countries. It can be manifested by<br />

stable angina pectoris, acute coronary syndromes (ACS) - including myocardial<br />

infarction (MI) and unstable angina -, or sudden death. Loss of myocardial tissue due to<br />

MI can lead to heart failure and it can constitute <strong>the</strong> anatomical basis for arrhythmias,<br />

leading to “sudden death”. Cardiac disease may also be related to high blood pressure,<br />

valvular dysfunction, congenital abnormalities, primary cardiac muscle problems, or<br />

o<strong>the</strong>r rarer conditions. These are not part of <strong>the</strong> disease spectrum of CHD.<br />

Two separate arteries carry oxygenated blood to <strong>the</strong> heart muscle: <strong>the</strong> right and <strong>the</strong><br />

left coronary artery. The first part of <strong>the</strong> left coronary artery, known as <strong>the</strong> “left main<br />

stem”, shortly after its origin divides into two branches: <strong>the</strong> circumflex artery (Cx) and<br />

<strong>the</strong> left anterior descending artery (LAD). Because <strong>the</strong> two branches of <strong>the</strong> left<br />

coronary artery are generally considered separately in clinical practice, it is common to<br />

refer to three coronary arteries instead of <strong>the</strong> anatomically more correct “two”.<br />

Depending on whe<strong>the</strong>r one, two or three coronary arteries are significantly involved in<br />

<strong>the</strong> a<strong>the</strong>romatous proces, <strong>the</strong> labels single, double, or triple vessel disease are<br />

attributed. Due to its prognostic significance, if <strong>the</strong> left main stem is involved in <strong>the</strong><br />

a<strong>the</strong>romatous process in a given patient, it is stipulated as such.<br />

The underlying mechanism of CAD is a gradual build-up of fatty material into <strong>the</strong><br />

coronary vessel wall that leads to <strong>the</strong> formation of a<strong>the</strong>romatous plaques. The<br />

pathophysiological mechanisms leading to stable angina pectoris or an ACS are different.<br />

It is traditionally accepted that a plaque has to reduce <strong>the</strong> internal diameter if a vessel by<br />

at least 50% (or >75% reduction in cross sectional area), in order to reduce blood flow<br />

through <strong>the</strong> coronary artery during exertion and provoke ischemia and angina pectoris.<br />

ACSs on <strong>the</strong> o<strong>the</strong>r hand result from a sudden blockage of coronary blood flow, due to<br />

rupture of a vulnerable a<strong>the</strong>romatous plaque, not necessarily involving flow-limiting<br />

stenoses. 1-3<br />

The main risk factors for CAD development are tobacco use, high blood pressure,<br />

raised blood cholesterol, and diabetes mellitus. Several interventions aiming to prevent<br />

CAD have been well documented, ranging from lifestyle changes to a daily and lifelong<br />

intake of drugs. The best documented are smoking cessation, blood pressure lowering,<br />

anti-platelet aggregation <strong>the</strong>rapy (low-dose aspirin) and pharmaceutical lipid<br />

management (statins).<br />

2.1.2 Definitions<br />

Symptomatic CAD can be manifested ei<strong>the</strong>r by stable angina pectoris, as an ACS or as<br />

sudden death. Loss of a substantial part of myocardial tissue can lead to heart failure,<br />

cardiogenic shock and death. Heart failure is a distinct clinical syndrome characterised<br />

by symptoms such as breathlessness and fatigue and signs such as fluid retention. The<br />

clinical spectrum of CAD is displayed in Table 1.<br />

Table 1: Clinical spectrum of CAD.<br />

Pathology<br />

Symptomatic CAD<br />

Asymptomatic CAD<br />

stable angina<br />

ACS<br />

O<strong>the</strong>r<br />

Manifestations<br />

unstable angina<br />

AMI<br />

Sudden death, heart<br />

failure, …

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