Cardiovascular Diseases 1: Coronary Artery Disease

Angina

Angina occurs when the heart muscle does not receive enough blood, i.e. oxygen. It usually means there is a narrowing or partially blocked coronary artery during times of stress or exercise.

Characteristics: intense pain, pale, perfuse perspiration, dyspnoea, normal cardiac enzymes, ECG may show some ischemic changes but is not definitive for angina

  1.   Stable Angina
  • Most common
  • Chest pain during activity or stress
  • Pain begins slowly and worsens over a few minutes before disappearing
  • Means there is an increased risk of heart attack, but does not guarantee occurrence
  • Requires medical treatment for occlusion within coronary arteries
  2.   Unstable Angina
  • Acute chest pain with cardiac hypoxia
  • Warning sign of heart attack
  • Not slow like stable angina, occurs as a severe episode
  • Occurs at any time

Myocardial Infarction

Myocardial infarction is a result of longterm schema to the myocardium (heart muscle), causing irreversible cell damage and even cell death. Normally, it presents as a blood clot termed an 'occlusion'. 50% of occlusions occur in the left anterior descending cardiac artery, 30% in the right coronary artery and 20% in the left circumflex artery.

Some myocardial infarctions are termed the 'widow maker' and occurs in the left circumflex artery or left anterior descending artery, as these supply a large area of the heart and will cause severe disruption to heart function. Because occlusions in these arteries are specifically common in men and can be fatal, this is why it is called widow maker. 

Manifestations: intense chest, retrosternal pain for 30-60 minutes which radiates up neck to jaw, shoulder and ulnar aspect of left arm, feeling of indigestion, nausea and vomiting, cool skin, decreased blood pressure, dyspnoea

Blood serum test: CK, CK-MB, LDH and cTn in the blood indicate necrotic tissue

Consequences: dysrhythmias, cardiogenic shock, oliguria (indicating acute kidney failure), pericarditis, stroke, infarcted ventricle wall ruptures, systemic thromboembolism and sudden death

Prognosis: 1 in 3 mortality rate, half of deaths occur prior to hospital and some patients die within first year after the myocardial infarction with prior rehospitalisation.

  1.   Non ST elevation MI (30%)

Complete occlusion of minor coronary artery or partial occlusion of major coronary artery → partial thickness of heart muscle is damaged

  2.   ST elevation MI (70%)

Complete occlusion of a major coronary artery previously affected by atherosclerosis → complete thickness of heart muscle is damaged

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