Some notes on mechanical complications of MI

Ng R, Yeghiazarians Y. Post Myocardial Infarction Cardiogenic Shock: A Review of Current Therapies. J Intensive Care Med. 2011 Jul. 11. Ahead of Print

[youtube http://www.youtube.com/watch?v=zY4WZdxwFf0&w=640&h=390]

Found this via R&R in the fast lane. Here’s a few notes and thoughts:

  • the bit on severe LV dysfunction isn’t as interesting because nothing really works here apart from reperfusion
  • the bits on complications of MI resulting in cardiogenic shock is much more interesting
  • Uses the big SHOCK registry for a lot of the data
Some factoids:
  • 75% of cardiogenic shock is LV dysfunction
  • echo really useful (well duh…)
  • Cardiogenic shock has mortality of 60% or so
  • Revascualrisation the most important thing
  • Recommendations for pressors but little evidence

ACUTE MITRAL VALVE RUPTURE

  • Acute MR and rupture in 8% of cardiogenic shock so really well worth looking for it seems; median time to rupture of 13 hrs
  • RCA infarcts with right dominant circulation the biggest risk as the PDA supplies valve. In a left dominant it’s supplied by two vessels
  • suggest SNP as a vasodilator to reduce afterload and keep forwards flow but of course not great when BP is low

VENTRIUCLAR SEPTAL RUPTURE

  • VSR occurs about 15 hrs post MI, not as late as we used to think
  • 5% of cardioggenic shock
  • usually LAD lesions
  • left to right shunt is the physiology
  • vasodilators might reduce shunt
  • IABP often needed
  • 80% mortality at 4 weeks – WOW

VENTRICULAR FREE WALL RUPTURE

  • 50% within first 5 days; 90% within 2 weeks
  • 2% of cardiogenic shock
  • 4 week mortality of 55% (given the mechanism I suspect it might be much higher than that!)
  • suggest that first MI and single vessel MI more at risk because of lack of collateral supply
  • lateral and post wall probably more at risk but due to their infrequency anterior (from LAD) is much more commonly seen in reality
  • most die immediately; those who survive have smaller ruptures which have plugged off
  • surgical repair the only option

Here’s a great talk from Stuart Swadron on valvular emergencies at All LA conference

About Andy Neill

EM Reg/Resident based near Dublin. Former anatomy lecturer, theology student and occasional musician @andyneill | + Andy Neill | Contact

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