Myocardial Infarction: Pathology Flashcards
What is the primary cause of ischemic heart disease?
> 90% of cases of IHD are a consequence of reduced coronary blood flow secondary to obstructive atherosclerotic vascular disease.
What are other causes of ischemic heart disease?
- Increased demand (increased heart rate or hypertension)
- Diminished blood volume (hypotension or shock)
- Diminished oxygenation (pneumonia or congestive heart failure)
- Diminished oxygen carrying capacity (anaemia or carbon monoxide poisoning)
What is ischemic heart disease?
A broad term!
- several related syndromes caused by myocardial ischemia
- an imbalance between cardiac blood supply (perfusion) and myocardial oxygen and nutritional requirements
What are the 4 cardiac syndromes classified as ischemic heart diseases?
- Angina pectoris
- Acute myocardial infarction
- Chronic IHD with heart failure
- Sudden cardiac death
What is angina pectoris?
Literally, “chest pain”
= ischemia that induces pain but is not sufficient to cause myocyte death
What are the three types of angina pectoris?
- Stable angina (occurs predictably at certain levels of exertion)
- Prinzmetal angina (angina caused by vessel spasm)
- Unstable angina (occurring with progressively less exertion or even at rest)
Which cardiac syndromes can be considered acute coronary syndromes?
Applies to the three catastrophic manifestations of IHD:
- Unstable angina
- Acute MI
- Sudden cardiac death
What is acute myocardial infarction?
When the severity and duration of ischemia is sufficient to cause cardiomyocyte death.
What is chronic IHD with CHF?
Progressive cardiac decompensation after acute MI, or secondary to accumulated small ischemic insults.
What can cause sudden cardiac death (SCD)?
- Myocardial infarction
2. Most commonly results from a lethal arrhythmia without myocyte necrosis
What is the primary pathogenesis of IHD?
Inadequate coronary perfusion relative to myocardial demand.
- imbalance occurs as a consequence of the combination of pre-existing (“fixed”) atherosclerotic occlusion of coronary arteries and new, superimposed thrombosis and/or vasospasm.
What occurs in a fixed occlusion of <70%?
Asymptomatic even on exertion
What occurs in a fixed occlusion of >70%?
Fixed, critical stenosis symptoms = stable angina
What occurs in a fixed occlusion of <90%?
Symptoms at rest = unstable angina
What can be protective against MI, even if a coronary vessel becomes occluded?
Progressively occluded coronary artery at a slow rate (years), can allow for the development collateral perfusion which can protect against MI even if the vessel becomes completely occluded.
