What are the complications of a MI? (Robbins pp 562)

There are many complications, which will be discussed below in chronological order:

• 1-3 days

  • Arrhythmias: sinus bradycardia, sinus tachycardia, ventricular premature contractions, ventricular tachycardia, atrial/ventricular fibrillation, asystole, atrial flutter.

  • Pericarditis: usually develops after a transmural infarct (not subendocardial). It occurs due to migration of underlying myocardial inflammation to pericardial surfaces.

• 3-5 days

  • Myocardial rupture: myocardial inflammation causes weakening therefore 1) rupture of ventricular wall resulting in haemopericardium + cardiac tamponade (usually fatal), 2) ventricular septum rupture leading to left-right shunt, 3) papillary muscle rupture cause mitral insufficiency (Fig 13-10 pp 562). Other causes of mitral insuffiency is papillary muscle dysfunction due to ischaemia, LV dilatation (physically pulling mitral valve apart), ventricular wall necrosis nearby papillary muscle emergence.

• 5-10 days

  • Mural thrombus: local contractility problems (stasis) + endocardial damage = thrombus formation = potential thromboembolism.

• 10 days +

  • Contractile dysfunction: LV contraction impaired, causing hypotension, pulmonary vascular congestion 》interstitial transudation 》pulmonary oedema. If infarct causes 20-25% of ventricle size = abnormal ventricule function, uif 40%+ = cardiogenic shock.

  • Ventricular aneurysm: Anterseptal infarct heals by forming fibrotic tissue, which is thin. This paradoxically bulges during systole – causing an aneurysm .

Category: Pathology Notes