Cardiac Pathology Flashcards
What is the early myocardial response to ischaemia?
Cessation of aerobic metabolism (secs); inadequate production of high energy phosphates and accumulation of metabolites (e.g. lactic acid).
Loss of contractility within 60s.
Is myocardial cell death always responsible for death in MI?
No - cessation of function due to depletion of high energy phosphates induces loss of contractility within 60s.
What are the features of myocardial infarction
No changes visible via gross inspection or light microscopy. Electron microscopy: -relaxation of myofibrils -glycogen loss -mitochondrial swelling
Area of myocardium affected in LAD occlusion?
- Anterior wall of LV near apex
- Anterior portion of ventricular septum
- Apex circumferentially
Area of myocardium affected in RCA occlusion?
- inferior/posterior wall of LV
- posterior portion of ventricular septum
- inferior/posterior RV wall
Area of myocardium affected in LCA occlusion?
-lateral wall of LV except at apex
What is the typical mechanism of cell death in MI?
Ischaemic coagulative necrosis
Changes in gross MI appearance:
4-24h: Dark mottling
1-3d: mottling w/ yellow tan centre
3-7d: Hyperemic border, central yellow tan softening
7-10d: maximally yellow tan and soft, depressed red tan margins
10-14d: red gray depressed infarct borders
2-8w: gray white scar (progressive)
>2m: scarring complete
Changes in MI light microscopy appearance?
4-24h: Coag nec: pyknosis of nuclei, myocyte hypereosinophilia, early N0 inifltrate.
1-3d: Coag necrosis with loss of nuclei and striations, N0.
3-7d: disintegration myofibrils, dying neutrophils.
7-10d: phagocytosis of dead cells, early formation of granulation tissue at border
10-14d: established G. tissue w/ new blood vessels and collagen deposition
2-8w: increased collagen deposition with decreased cellularity
>2m: dense collagenous scar
What is the appearance of markedly ischaemic myocardium that has been reperfused?
Myocardial necrosis with haemorrhage and contraction bands (dark bands spanning some myofibrils).
What is sudden cardiac death?
Unexpected death from cardiac causes in individuals without symptomatic heart disease or early after symptoms onset.
What is SCD usually the consequence of?
Lethal arrhythmia (e.g. asystole, VFib). Most usually the result of IHD. ?myocardial ischaemic induced irritability that initiates malignant ventricular arrhythmias.
What are the primary electrical abnormalities of the heart that predispose to SCD?
- Long QT syndrome
- Brugada syndrome
- Short QT sydrome
- Catecholaminergic polymorphic ventricular tachycardia
- Wolff-Parkinson-White
- Congenital sick sinus syndrome
- Isolated cardiac conduction disease
What are channelopathies?
Mutations in channels required for normal ion function; responsible for conducting electrical current mediating myocardial contraction.
What causes long QT syndrome?
Mutations in 7 different genes: most frequently in genes encoding KCNQ1. Results in decreased potassium currents.
