Myocardial Infarction Complications Pump Failure
Dr. Khaled Buresly
BMBCh, ABIM, FRCPC Cardiologist- Chest Hosp.
Done By AMNA
Acute Myocardial Infarction
• Regional myocardial ischemia and injury
• Loss of regional myocardial functions
•
Any pump that fails, two things will happen:
1. Fluid over load in one side 2. dryness on the other side
•
•
So, we have backward and forward failure
What happen in MI is that patient have acute occlusion of the coronary arteries, which supply certain area of myocardium that will has a regional loss of function The defect depending on how big that affected area is, the infarction could be in a small area that the heart is not affected too much, or it could be in half of the ventricle
•
• To pump blood the heart has to: • Receive / be filled Diastolic function • Send / eject blood Systolic function • Depending on infarct size, some degree of LV diastolic and systolic functions will be affected.
Pathophysiology of Pump Failure in AMI
• Contractile (systolic) dysfunction • Diastolic dysfunction
- Not only just as a pump (systolic and diastolic function), but also the valves have to be contributed bcoz closing the valve is very imp. and patients with MR
will have inefficient or failed pump
• Other complications of AMI
Pathophysiology: Systolic Dysfunction
• Infarcted myocardial region can be: -Hypokinetic (reduced contraction) -Akinetic (lack of contraction) -Dyskinetic (paradoxical systolic expansion) -Aneurysmal (persistent ballooning/dilatation) The Larger and more severe the infarcted area Lower ejection fraction (EF)
and higher systolic dysfunction
Normal EF 60%
Systolic dysfunction EF 20%
• If patient have MI in anterior septum of the anterior wall, then half of the heart will not functioning well and EF will be 20% and this significantly will lead to CS
Pathophysiology: Diastolic Dysfunction
• Ischemic and necrotic myocardial tissue • Fibrotic healed scar post acute phase
Loss of regional myocardial elasticity
Impaired LV compliance “stiff LV” Impaired LV filling “Diastolic dysfunction”
Systolic dysfunction
Diastolic dysfunction
High LV end diastolic pressure
High LV filling pressure (Pulmonary Capillary Wedge Pressure)
Pulmonary congestion & edema
High Pulmonary venous & Capillary pressures
High LVEDP
• High LVEDP will lead to high pulmonary venous and capillaries hydrostatic pressure leading to pulmonary congestion and edema
Systolic dysfunction
High LV end systolic volume & Low EF Low stroke volume Low C.O.
Hypotension & hypoperfusion
•
What are the signs of hypoperfusion on the bedside? 1. Oligouria 2. Cold extremities 3. Poor cerebral function • So when reaching hypotension and hypoperfusion state, that means patient reaches the CS stage
Pump Failure: other MI Complications
• • • • • Acute MR Acute VSD Free wall rupture Tachy or brady arrhythmias RV failure
If present… All can contribute to pump failure in AMI,
bcoz in order to have an effective pump, all things have to be intact
• Not all AMI patients have clinically evident pump failure • Clinical evidence of LV failure when > 25% of LV is affected • Cardiogenic shock when > 40% of LV is affected
• If patient lose > 25% of LV, they will start having pulmonary edema • But if < 40% it depends in that: If patient have preexisting low EF or previous MI, then they already lost 50% previously and know they lose other 50%, so they start to have failure this time (accumulative effects of previous MI)
Clinical Manifestation of Pump Failure
• • • • • Dyspnea Crepitation (Rales) S3 gallop Hypotension High JVP (if RV infarct) • Hypoperfusion (oliguria, impaired mental status) • Pulmonary edema on CXR
MI-Pump Failure: Management
• • • • • • • • • • Admit to CCU Supplemental oxygen IV Diuretics (furosemide) IV nitrates Morphine ACE-I Positive inotropic agents (e.g dopamine) Echo to rule out other mechanical complications Intra aortic balloon pump (esp. in Shock) Revascularization (coronary angio)
Killip Classification: Bed-side Prognosis
Class
I II III
IV
Definition
No rales or S3 Rales < 50% of lung Rales > 50% of lung
Cardiogenic shock
In-hosp. Death 1-3% 7% 19%
~ 50%
6 months death 4% 10% 28%
~ 60%
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