Myocardial Infarction Flashcards
What are the consequences and complications of an AMI?
Contractile dysfunction / pump failure
Arrhythmia
Myocardial rupture
Tamponade
Papillary muscle dysfunction
Valvular dysfunction
Mural thrombus –> embolism
Pericarditis
Ventricular aneurysm
Death
What are the main cardiac rupture syndromes?
Free wall rupture –> tamponade
Septal rupture –> VSD, shunt
Papillary muscle infarction –> mitral regurgitation
What changes occur in ventricular remodelling?
Hypertrophy and Dilatation, leading to increased myocardial oxygen demand
–> ischamia, depressed cardiac function.
Stiffened ventricles, scar formation.
What systemic factors affect infarct healing?
Nutritional: protein, Vit C
Metabolic: diabetes
Circulatory: arterial or venous
Hormonal: glucocorticoids
Describe the timecourse of myocardial injury after acute coronary artery occlusion.
Reversible changes:
Cessation of aerobic metabolism within seconds
Loss of contractility within 2 mins
ATP depletion
Irreversible injury begins after 20mins
Subendocardial portion infarcts first
Coagulative necrosis after 2 hours
What are the potential consequences of reperfusion after an AMI?
Oxygen free radicals / oxidative stress - damage to the cardiac myocytes that are injured but still at the reversible stage and vulnerable. Inflammatory cells recruited.
