1. Mechanical Complications of Myocardial Infarction
Armed Forces Academy of Medical Sciences

2. Epidemiology 1.5 Million MI’s yearly in U.S. 30% mortality
decline by 30% in last decade
In hospital mortality ~5%
50% of deaths occur in first hr. secondary to ventricular arrhythmias- later lecture
Mechanical complications responsible for 15% of deaths

3. Mechanical Complications
Free Wall Rupture
Pseudoaneurysm
Rupture of Intraventricular septum
Rupture of Papillary Muscle

4. LV Free Wall Rupture Mean Age 69 8-15% of all deaths from MI
10% of hospital deaths
Peaks 3-6 days post MI, 25% within 24 hrs.

5. Ventricular Free Wall Rupture

7. LV Free Wall Rupture Pathophysiology
Usually involves anterior or lateral walls in distribution of terminal LAD
Large, transmural MI’s involving > 20% of myocardium.
Tear in myocardium or dissecting hematoma at junction of infarct and normal muscle. Shearing effect produces laceration of myocardial microstructure

8. LV Free Wall Rupture Risk Factors
Sustained HTN
AGE, Female sex
First MI, Normal LV function
Increased shearing forces
Corticosteroids, NSAID’s
Impaired wound healing
Late use of Thrombolytics
decreased incidence with early therapy
Persistent occlusion, lack of collaterals

9. LV Free Wall Rupture Clinical Course
Ruptured free wall leads to hemopericardium and death through tamponade, cardiogenic shock
Nausea, hypotension, pericardial pain, agitation
? prodromal bleeding, seen in 80% of pts with rupture
25% have new murmur
Deviation from expected Evolutionary T-wave pattern- 94% of pts.
EMD, Bradydysrhythmias, AIVR common

10. Free Wall Rupture T-Waves

11. LV Free Wall Rupture Diagnosis
Death often occurs prior to imaging . SCD 70%
Echo shows pericardial effusion, tamponade
Organized thrombus in pericardial space
Incomplete rupture may be missed by TTE, TEE
PA catheter shows equalization of pressures-tamponade

12. LV Free Wall Rupture Management
90% medical mortality; sugical case reports of correction
Inotropic agents
Volume Loading
Pericardiocentesis

13. LV Free Wall Rupture Management
IABP, hemodynamic stabilization
Coronary Angiography controversial
Blind bypass of palpable lesions
Infarctectomy with closure of viable myocardium
avoid suture in infarcted tissue
Dacron, Teflon or Pericardial patch

14. Free Wall Rupture Repair

15. Ruptured Papillary Muscle

16. Rupture Papillary Muscle

17. Papillary Muscle Rupture
MR Transiently present in up to 80% of MI pts.
usually of no hemodynamic significance
Mitral Annular Dilitation, Wall motion asynergy, Papillary muscle dysfunction/rupture
0.9-5% of all deaths from MI
50% mortality within 24hrs., 80% within 2 weeks

18. Papillary Muscle Rupture
Inferior MI leads to rupture of Postero-medial pap muscle/AMI-antero-lateral pap muscle (rare)
PM pap muscle single supply from PDA
AL pap muscle dual supply from LAD/Cx
Complete transection incompatible with life
Occurs with small infarctions, moderate CAD
50% have subendocardial infarct, single vessel dz
Greater shearing forces
Length of coronary vessels, subendocardial location may predispose to ischemia

19. Papillary Muscle Rupture Presentation
Mean age 65
Peak incidence 3-5 days post-MI
75% Inferior MI
New Holosytolic Murmur in 50%
pressure equalization may blunt murmur
Acute hemodynamic decompensation, pulmonary edema

20. Papillary Muscle Rupture Diagnosis
Physical exam often non-diagnostic
Echo may visualize chordal rupture, head of pap muscle, flail leaflet
LV fxn well preserved in setting of hemodynamic decompensation
Coronary angiography prior to surgery if condition permits

21. Papillary Muscle Rupture Management
33% immediate death, 50% at 24 hrs., 80% within 2 weeks
Afterload reduction, vasodilators
IABP-afterload reduction
MV replacement or repair
may be delayed up to 6 weeks if pt. stable to allow myocardial healing s/p MI
50% of those initially stabilized will decompensate

22. Papillary Muscle Repair

23. Interventricular Septal Rupture

24. Interventricular Septal Rupture
0.5-2 Percent of MI’s
5 % of peri-infarction deaths
Mean Age 63
Hypertension
Poor collateral network

25. Interventricular Septal Rupture Risk Factors
Large Transmural Infarctions
Anterior-Apical, Inferior-Basal
Virtually all patients have severe, multi-vessel CAD
First MI

26. Interventricular Septal Rupture Clinical Features
Harsh, Loud Holosystolic Murmur at LLSB with thrill (50%)
Acute right sided heart failure
May have increased chest pain, SOB
Cardiogenic Shock

27. Interventricular Septal Rupture Diagnosis
Step up in oxygen saturation of RV
Angiography if hemodynamically stable for coronary anatomy, ventriculography
Echo
Highly sensitive (96%) with careful apical-basal, and anterior-posterior sweeps of septum
doppler to detect complex defects

28. Intraventricular Septal Rupture Management
Diuretics, Ionotropes, Vasodilators-enhance forward flow, decrease shunting.
IABP
Surgical repair
25% mortality at 24 hrs., 65% at 2 weeks without surgery
Cardiogenic shock 100% mortality without surgery
LV Fxn, magnitude of shunt do not correlate with outcome

29. VSD Repair

30. Percutaneous VSD Repair

31. LV Pseudoaneurysm Rare complication of MI
Results from incomplete rupture of wall sealed by thrombus and pericardium

32. Pseudoaneurysm

33. Pseudoaneurysm

34. LV Pseudoaneurysm Diagnosis
Difficulty to distinguish from true anuerysm
To and Fro murmur
Pericardial friction rub
Enlarging LV bulge on lateral or posterior wall
Narrow neck seen on Echo, or LV gram

35. LV pseudoaneurysm Management
High propensity rupture
Urgent surgical repair indicated
Technique similar to free wall rupture
Survival 90% in stable pts.