1. Complications of Acute M.I.
Douglas Burtt, M.D.

2. Left Anterior Descending Occlusion
Occlusion of the
left anterior descending
coronary artery

3. Experimental Data
Canine studies – transient artery clamping or ligation
Balloon angioplasty studies
Time dependent series of events
Chest Pain as a late event

4. ACUTE M.I. THE “ISCHEMIC CASCADE”
Diastolic dysfunction
Chest pressure, etc.
Acute MI
Release of CPK
Ischemic EKG changes
Localized systolic dysfunction

5. ACUTE M.I. THE “ISCHEMIC CASCADE”
Diastolic dysfunction
Localized systolic dysfunction
Ischemic EKG changes
Chest pressure, etc.
Release of CPK

6. Time course of cell death
minutes to irreversible cell injury
~ 24 hours to coagulation necrosis
5 - 7 days to “yellow softening”
1 - 4 weeks: ventricular “remodeling”
6 - 8 weeks: fibrosis completed

7. Think Anatomically!!
Left main coronary artery supplies two-thirds of the myocardium
LAD supplies ~ 40% of the L.V., including apex, septum and anterior wall
RCA supplies less L.V. myocardium, but all of the R.V. myocardium

8. Blood supply of the septum

9. Think Anatomically!!!
LAD supplies most of the conduction system below the A-V node (i.e. the His-Purkinje system)
RCA supplies most of the conduction system at or above the A-V node (i.e. the A-V node and, usually, the S-A node)

10. Conduction System of the Heart

11. Conduction System: detail

12. ACUTE M.I. Anatomical correlates
LAD occlusion causes extensive infarction associated with:
LV failure
High grade heart block
Apical aneurysm formation
Thrombo-embolic complications

13. ACUTE M.I. Anatomical correlates
RCA occlusion causes moderate infarction associated with:
RV failure
Bradyarrhythmias
Occasional mechanical complications

14. PVCs / ventricular tachycardia /ventricular fibrillation
ACUTE M.I. Arrhythmias
Sinus bradycardia
Sinus tachycardia
Atrial fibrillation
PVCs / ventricular tachycardia /ventricular fibrillation
Heart block

15. Arrhythmias: Inferior M.I.
Sinus bradycardia -- S.A. nodal artery and increased vagal tone
Heart block -- A-V nodal artery 1st degree A-V block Wenckebach 2nd degree A-V block A-V dissociation
Atrial fibrillation -- L.A. stretch
Ventricular tachycardia / fibrillation via “re-entry” or increased automaticity

16. Arrhythmias: Anterior M.I.
Sinus tachycardia -- low stroke volume
Heart block -- His-Purkinje system Left or Right Bundle branch block Complete Heart Block
Ventricular tachycardia / fibrillation due to “re-entry” or increased automaticity

17. ACUTE M.I. Hypotension Identify hemodynamic subset
Distinguish decreased preload from decreased cardiac output
Think about hemodynamic monitoring

18. Hemodynamic subsets
Starling curves to plot “preload” versus cardiac output
Identification of high risk subgroups
Definition of cardiogenic shock
Cardiac
Output
L.V.E.D.P.

19. 1 3
Cardiac
Index
(L/min/m2) 2 4
L.V.E.D.P.
Hemodynamic Subsets

20. Acute M.I. Mechanical Complications
Rupture of free wall Tamponade Pseudoaneurysm
Rupture of papillary muscle Acute Mitral regurgitation
Rupture of intraventricular septum Acute V.S.D.

21. ACUTE M.I. Papillary Muscle Rupture Leading to Acute M.R.

22. ACUTE M.I. Papillary Muscle Rupture Leading to Acute M.R.
Systolic murmur
Giant V - waves on PC Wedge tracing
Echo/Doppler confirmation
RX with Afterload reduction
Intra-aortic balloon pump

23. “Flail” Mitral Leaflet

24. Echo/Color Doppler of Acute M.R.LV RA LA

25. Development of giant “V waves”
P.C. Wedge pressure
P. A. pressure
V-wave

26. Acute Mitral Regurgitation: Treatment
Rapid diagnosis
Afterload reduction
Inotropic support
Intra-aortic balloon pump
Surgical valve replacement

27. ACUTE M.I. Acute Ventricular Septal Defect
Can occur with either anterior or inferior MI
Peak incidence on days 3-7
Causes an abrupt left-to-right “shunt”

28. ACUTE M.I. Acute Ventricular Septal Defect
Abrupt onset of a harsh systolic murmur, often with a “thrill”
Detected by an oxygen saturation “step-up”

29. Oxygen saturation “step-up”

30. Acute V.S.D.: Treatment Rapid diagnosis Afterload reduction
Inotropic support
Intra-aortic balloon pump
Surgical repair of ruptured septum

31. Intra-Aortic Balloon Pump
Augments coronary blood flow during diastole
Decreases afterload during systole by deflating at the onset of systole
Reduces myocardial ischemia by both mechanisms

32. Intra aortic balloon pump

33. Intra-aortic balloon pump

34. Free Wall Rupture Pseudoaneurysm
Enlarged cardiac silhouette
Echocardiographic diagnosis
Cardiac Tamponade Equalization of diastolic pressures Hypotension J.V.D. Clear lung fields Pulsus paradoxus

35. ACUTE M.I. Apical Aneurysm
Associated with large, transmural antero-apical MI
Can lead to LV apical thrombus
Is associated with ventricular arrhythmias

36. ACUTE M.I. Apical Aneurysm
Causes “dyskinesis” of the apex
Can be detected by cardiac echo
Can lead to systemic emboli
Anticoagulants may prevent embolization

37. Right Heart Failure Very commonly a sequela of Left Heart Failure
LVEDP
PCW
PA pressure
Right heart pressure overload
Cardiac causes
Pulmonic valve stenosis
RV infarction
Parenchymal pulmonary causes
COPD
ILD
Pulmonary vascular disease
Pulmonary embolism
Primary Pulmonary hypertension

38. ACUTE M.I. Right Ventricular Infarction
Jugular venous distention with clear lungs
Equalization of right atrial and PCW pressures
ST elevation in right precordial leads
Therapy with fluids

39. 1 3
Cardiac
Index
(L/min/m2) 2 4
L.V.E.D.P.
Hemodynamic Subsets

40. Radiation to the trapezius ridge Pericardial friction rub
ACUTE M.I. Pericarditis
Pleuritic chest pain
Radiation to the trapezius ridge
Fever
Pericardial friction rub

41. ACUTE M.I. CARDIOGENIC SHOCK
Large area of myocardial necrosis
Consider mechanical complications
Exclude correctable causes -- i.e. hypovolemia or R.V. infarct
I.A.B.P. C.A.B.G. OR P.T.C.A.

44. Summary Think anatomically!!! Think hemodynamic subsets!!! LAD vs. RCA
Watch for mechanical complications

45. THE END