complications of acute m.i
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Bio-Med 350
Complications of Acute Complications of Acute M.I.M.I.
Douglas Burtt, M.D.
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Coronary atherosclerosisCoronary atherosclerosis
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Schematic of an Unstable PlaqueSchematic of an Unstable Plaque
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Cross section of aCross section of acomplicated plaquecomplicated plaque
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Journey down a coronary…Journey down a coronary…
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Frank Netter: View of the Frank Netter: View of the HeartHeart
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Left Anterior Descending OcclusionLeft Anterior Descending Occlusion
Occlusion of theleft anterior descendingcoronary artery
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Experimental DataExperimental Data
Canine studies – transient artery clamping or ligation
Balloon angioplasty studiesTime dependent series of eventsChest Pain as a late event
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ACUTE M.I.ACUTE M.I.THE “ISCHEMIC CASCADE”THE “ISCHEMIC CASCADE”
Chest pressure, etc.
Localized systolic dysfunction
Diastolic dysfunction
Release of CPK
Ischemic EKG changes
Acute MI
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ACUTE M.I.ACUTE M.I.THE “ISCHEMIC CASCADE”THE “ISCHEMIC CASCADE”
1. Diastolic dysfunction2. Localized systolic dysfunction3. Ischemic EKG changes4. Chest pressure, etc.5. Release of CPK
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Time course of cell deathTime course of cell death
20 - 40 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
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Think Anatomically!!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
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Blood supply of the Blood supply of the septumseptum
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Think Anatomically!!!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)
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Conduction System of the Conduction System of the HeartHeart
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Conduction System: detailConduction System: detail
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ACUTE M.I.ACUTE M.I.Anatomical correlatesAnatomical correlates
LAD occlusion causes extensive infarction
associated with: LV failure
High grade heart block Apical aneurysm formation
Thrombo-embolic complications
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ACUTE M.I.ACUTE M.I.Anatomical correlatesAnatomical correlates
RCA occlusion causes moderate infarction
associated with: RV failure
Bradyarrhythmias Occasional mechanical
complications
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ACUTE M.I.ACUTE M.I.ArrhythmiasArrhythmias
Sinus bradycardia Sinus tachycardia Atrial fibrillation
PVCs / ventricular tachycardia /ventricular
fibrillation Heart block
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Arrhythmias:Arrhythmias:Inferior M.I.Inferior M.I.
Sinus bradycardia -- S.A. nodal artery and increased vagal tone
Heart block -- A-V nodal artery1st degree A-V blockWenckebach 2nd degree A-V blockA-V dissociation
Atrial fibrillation -- L.A. stretch Ventricular tachycardia / fibrillation --
via “re-entry” or increased automaticity
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Arrhythmias:Arrhythmias:Anterior M.I.Anterior M.I.
Sinus tachycardia -- low stroke volume
Heart block -- His-Purkinje systemLeft or Right Bundle branch blockComplete Heart Block
Ventricular tachycardia / fibrillation due to “re-entry” or increased automaticity
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ACUTE M.I.ACUTE M.I.HypotensionHypotension
Identify hemodynamic subset Distinguish decreased preload
from decreased cardiac output Think about hemodynamic
monitoring
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Hemodynamic subsetsHemodynamic subsets
0123456
Starling curves to plot “preload” versus cardiac output
Identification of high risk subgroups
Definition of cardiogenic shock
L.V.E.D.P.
CardiacOutput
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00.5
11.5
22.5
3
L.V.E.D.P.
CardiacIndex
(L/min/m2)4
31
2
Hemodynamic Subsets
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Acute M.I.Acute M.I.Mechanical ComplicationsMechanical Complications
Rupture of free wall Tamponade
Pseudoaneurysm Rupture of papillary muscle
Acute Mitral regurgitation
Rupture of intraventricular septum
Acute V.S.D.
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ACUTE M.I.ACUTE M.I.Papillary Muscle RupturePapillary Muscle Rupture
Leading to Acute M.R.Leading to Acute M.R.
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ACUTE M.I.ACUTE M.I.Papillary Muscle RupturePapillary Muscle Rupture
Leading to Acute M.R.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
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““Flail” Mitral LeafletFlail” Mitral Leaflet
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Echo/Color Doppler of Acute M.R.Echo/Color Doppler of Acute M.R.
LA
LV
RA
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Development of giant “V Development of giant “V waves”waves”
P. A. pressureV-wave
P.C. Wedge pressure
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Acute Mitral Regurgitation:Acute Mitral Regurgitation:TreatmentTreatment
Rapid diagnosis Afterload reduction Inotropic support Intra-aortic balloon pump Surgical valve replacement
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ACUTE M.I.ACUTE M.I.Acute Ventricular Septal Acute Ventricular Septal
DefectDefect
•Can occur with Can occur with either anterior or either anterior or inferior MIinferior MI•Peak incidence on Peak incidence on days 3-7days 3-7•Causes an abrupt Causes an abrupt left-to-right “shunt”left-to-right “shunt”
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ACUTE M.I.ACUTE M.I.Acute Ventricular Septal Acute Ventricular Septal
DefectDefect
•Abrupt onset of a Abrupt onset of a harsh systolic harsh systolic murmur, often with a murmur, often with a “thrill”“thrill”•Detected by an Detected by an oxygen saturation oxygen saturation “step-up”“step-up”
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Oxygen saturation “step-Oxygen saturation “step-up”up”
IV C sat
7 0 %
SV C sat
6 5 %
RA sat
6 8 %
RV sat
8 8 %
PA sat
8 8 %
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Acute V.S.D.:Acute V.S.D.:TreatmentTreatment
Rapid diagnosis Afterload reduction Inotropic support Intra-aortic balloon pump Surgical repair of ruptured septum
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Intra-Aortic Balloon PumpIntra-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
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Intra aortic balloon pumpIntra aortic balloon pump
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Intra-aortic balloon pumpIntra-aortic balloon pump
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Free Wall RuptureFree Wall Rupture Cardiac
Tamponade
Equalization of diastolic pressures
Hypotension
J.V.D.
Clear lung fields
Pulsus paradoxus
Pseudoaneurysm
Enlarged cardiac silhouette
Echocardiographic diagnosis
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ACUTE M.I.ACUTE M.I.Apical AneurysmApical Aneurysm
Associated with large, transmural antero-apical MI
Can lead to LV apical thrombus
Is associated with ventricular arrhythmias
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ACUTE M.I.ACUTE M.I.Apical AneurysmApical Aneurysm
Causes “dyskinesis” of the apex
Can be detected by cardiac echo
Can lead to systemic emboli
Anticoagulants may prevent embolization
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Right Heart FailureRight Heart Failure
Very commonly a sequela of Left Heart Failure LVEDP PCW PA pressureRight heart pressure
overload
Cardiac causes Pulmonic valve stenosis RV infarction
Parenchymal pulmonary causes COPD ILD
Pulmonary vascular disease Pulmonary embolism Primary Pulmonary
hypertension
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ACUTE M.I.ACUTE M.I.Right Ventricular InfarctionRight Ventricular Infarction
Jugular venous distention with clear lungs
Equalization of right atrial and PCW pressures
ST elevation in right precordial leads Therapy with fluids
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00.5
11.5
22.5
3
L.V.E.D.P.
CardiacIndex
(L/min/m2)4
31
2
Hemodynamic Subsets
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ACUTE M.I.ACUTE M.I.PericarditisPericarditis
Pleuritic chest pain Radiation to the trapezius ridge
Fever Pericardial friction rub
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ACUTE M.I.ACUTE M.I.CARDIOGENIC SHOCKCARDIOGENIC 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.
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Summary for RCA (orSummary for RCA (orcircumflex) infarctcircumflex) infarct
H ypotension due todecreased L.V. filling
R ight ventricular infarct
Bradyarrhythm ias1st degree A-V block
M obitz I 2nd degree blockA-V dissociation
S-A nodal infarctA-V nodal infarct
Acute m itral regurgitation(w ith or w ithout
papillary m uscle rupture)
Postero-m edial papillarym uscle infarct
R ight coronary artery
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Summary for LAD infarct Summary for LAD infarct
Cardiogenic shock due to loss of large amount of
myocardium
Acute ventricular septal defect
Intraventricular septum (upper two-thirds)
Ventricular arrhythmias
Arterial embolism originating in the L.V.
Apical thrombus formation
Apical L.V. aneurysm
Antero-apical wall
40% of LV myocardium
Advanced Heart Block (LBBB, 3rd degree A-V block
and Mobitz II 2nd degree)
His-Purkinje system
Left anterior descending artery
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SummarySummary
Think anatomically!!!
LAD vs. RCA
Think hemodynamic subsets!!!
Watch for mechanical complications
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THE ENDTHE END
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