Transcript Myocardial Infarction

Myocardial Infarction
• Myocardial Infarction
Myocardial Infarction
 blood vessels that supply blood to the heart are
blocked, preventing enough oxygen from getting
to the heart.
 Insufficient blood supply to the myocardium can
result in
myocardial ischemia,
myocardial injury or
myocardial infarction, or
all three.
Myocardial Infarction
Myocardial ischemia
generally appears first in the subendocardial region and is more
extensive
farthest from the blood supply
greater intramural tension and
More need for oxygen.
Myocardial Infarction
Subendocardial ischemia:
repolarization normally from
Epicardium-to-Endocardium.
delayed recovery in the Subendocardial
region due to ischemia merely
lengthens repolarization.
results in prolonged QT interval or
increased amplitude of T wave or both
Myocardial Infarction
Subepicardial or transmural ischemia
 ischemia extends subepicardially.
more visible effect on recovery of subepicardial
cells.
Recovery is more delayed
the subendocardial muscle fibers seem to recover
first.
Repolarization is endocardial-to-epicardial,
resulting in inversion of the T waves in leads
overlying the ischemic regions.
Myocardial Infarction
Injury
to the myocardial cells results when the ischemic
process is more severe.
Subendocardial injury - ST segment depression,
subepicardial or transmural injury - ST segment
elevation.
ischemia, injury and myocardial infarction
frequently coexist
producing mixed and complex ECG patterns.
Myocardial Infarction
Myocardial infarction
 necrosis or death of myocardial cells.
 The left ventricle - predominant site
 right ventricular infarction occasionally coexists.
 pathological Q waves in transmural myocardial infarction
 initial downward deflection of 40 msec or more in any
lead except III and aVR.
 infracted muscle is electrically inert
 vector directed away from the site of infarction
 seen as a negative Q wave
Myocardial Infarction
Transmural Infarction - Rupture
Myocardial Infarction
During acute myocardial infarction various stages of
myocardial damage can coexist
the central area of necrosis
surrounded by an area of injury
surrounded by an area of ischemia.
Transient myocardial ischemia produces T wave,
and sometimes ST segment abnormalities
can be reversible without producing permanent
damage
not accompanied by serum enzyme elevation.
Causes
 blood clot that blocks one of the coronary
arteries.
atherosclerosis
• The slow buildup of plaque, almost block one of
your coronary arteries, more likely during exercise
• The plaque itself develops cracks, platelets form a
blood clot, that can completely blocks the passage
of oxygen-rich blood to the heart.
• sudden, significant emotional or physical stress,
including an illness, can trigger a heart attack.
Atherosclerosis
Atherosclerosis –Hardening of Artery
Atherosclerosis
Infarction
Atherosclerosis
Infarction
Infarction
Risk factors
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for heart attack and coronary artery disease include:
Increasing age (over age 65)
Male gender
Diabetes
Family history of coronary artery disease - genetic
High blood pressure
Smoking
Too much fat in your diet
high LDL ("bad") cholesterol and low HDL ("good")
Chronic kidney disease
Risk factors
Risk factors
Symptoms
• Chest pain major symptom, may move from your chest
to your arms, shoulder, neck, teeth, jaw, belly area, or
back.
• severe or mild. It can feel like:
• A tight band around the chest
• Bad indigestion
• Something heavy sitting on your chest
• Squeezing or heavy pressure
• usually lasts longer than 20 minutes.
• Rest and a medicine called nitroglycerin may not
completely relieve the pain.
• Symptoms may also go away and come back.
sudden cardiac arrest
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Symptoms
Other symptoms of a heart attack include:
Anxiety
Cough
Fainting
Light-headedness, dizziness
Nausea or vomiting
Palpitations
Shortness of breath
Sweating - extreme
"silent heart attack" is a heart attack with no symptoms elderly, people with diabetes, and women, no chest pain
but unusual symptoms
unusual symptoms
Exams and Tests
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A heart attack is a medical emergency.
seek immediate medical help.
DO NOT try to drive yourself to the hospital.
DO NOT DELAY - greatest risk of sudden cardiac
death in the early hours of a heart attack.
• You may have a rapid pulse.
• Your blood pressure may be normal, high, or low.
Exams and Tests
Tests to look at your heart include:
• Coronary angiography
• CT scan
• Echocardiography
• Electrocardiogram (ECG) -- once or repeated
• MRI
• Nuclear ventriculography
• Blood tests - show if heart tissue damage
• Troponin I and troponin T
• CPK and CPK-MB
• Serum myoglobin
Tests EKG
TESTs
Echocardiography
CT Scan
Angiography
Treatment
• need to stay in ICU.
• arrhythmias - leading cause of death in the first
few hours -medications or electrical cardioverson
/defibrillation.
• oxygen
• An intravenous line, urinary catheter
Treatment
ANGIOPLASTY AND STENT PLACEMENT
called percutaneous coronary intervention
(PCI)
preferred emergency procedure, within 90
minutes but not later than 12 hours after MI
open narrowed or blocked blood vessels.
A stent is often placed after angioplasty.
prevent the artery from closing up again.
Treatment
THROMBOLYTIC THERAPY (CLOT-BUSTING DRUGS)
• drugs to break up the clot.
• Best if given within 3 hours of first felt chest pain.
Contraindications :
• intracranial hemorrhage
• Brain tumors or blood vessel malformations
• Stroke within past 3 months
• Head injury within past 3 months
• Pregnant women
• Severe high blood pressure
Angioplasty
Treatment
• OTHER MEDICINES FOR HEART ATTACKS
• Nitroglycerin helps reduce chest pain.
• Antiplatelet medicines help prevent clots. Aspirin,
clopidogrel (Plavix), daily for at least one year
• Beta-blockers - atenolol help reduce the strain on
the heart and lower blood pressure.
• ACE inhibitors - enalapril, or captopril, to prevent
heart failure and lower blood pressure.
• Lipid-lowering medications, statins, lovastatin,
Treatment
• CORONARY ARTERY BYPASS SURGERY
• narrowing of the left main coronary artery emergency CABG).
CABG
Management
Healthy Diet
Regular Exercise
Possible Complications
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Cardiogenic shock
Congestive heart failure
infarct extension - rupture of the heart
Damage to heart valves or the wall
pericarditis)
ventricular tachycardia and ventricular fibrillation
pulmonary embolism
Stroke - Blood clot to the brain
Side effects of drug treatment
Stroke - CVA
Prevention
• BP, blood sugar, and cholesterol under control.
• Don't smoke.
• 1 glass of alcohol each day. larger amounts does more
harm than good.
• low-fat diet rich in fruits, vegetables and low in animal
fat. fish twice a week.
• Exercise daily or several times a week.
• Lose weight if you are overweight.
• one or more risk factors Aspirin therapy
• regular follow-up cardiac rehabilitation program
• Always follow the exercise, diet, and medication plan
Myocardial Infarction
Two types of myocardial infarction on EKG:
1. Q wave infarction - presence of pathological Q
waves, also called transmural infarction.
2. Non-Q wave infarction - presence of ST
depression and T wave abnormalities.
• Elevation of serum enzymes is expected in both
types of infarction.
• In the absence of enzyme elevation, ST and T
wave abnormalities - due to injury or ischemia
rather than infarction.
Site of infarction
Fairly accurately from analysis of the 12-lead ECG.
• Inferior (or diaphragmatic) wall: II, II and aVF
• Septal: V1 and V2
• Anteroseptal: V1, V2, Vf3 and sometimes V4
• Anterior: V3, V4 and sometimes V2
• Apical: V3, V4 or both
• Lateral: I, aVL, V5 and V-6
• Extensive anterior: I, aVL and V1 through V6
Posterior wall infarction - tall R waves in V1 and
V2.
Site of infarction
The classic changes seen during acute infarction.
 necrosis (Q waves)
 injury (ST elevation), and
 ischemia (T wave inversion)
In recovery
 the ST segment that normalizes earliest,
 then the T wave;
 the Q wave usually persists.
 the age of the infarction, roughly estimated from
appearance of ST segment and T wave.
 Q wave in the absence of ST and T wave generally
indicates prior or healed infarction.
ST segment elevation and T wave
abnormalities
Other causes of ST segment elevation
• Acute pericarditis: ST elevation is generally diffuse
and not accompanied by reciprocal depression of
the ST segment in other leads.
• Early repolarization: particularly young patients
without known disease.
• Ventricular aneurysm: persistent aneurysm in the
region of infarction, ST segment elevation may
persist indefinitely.
Abnormal T waves
conditions other than myocardial ischemia:
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Hyperventilation
Cerebrovascular disease
Mitral valve prolapse
Right or left ventricular hypertrophy
right or left bundle branch block
Ventricular preexcitation
Myocarditis
Electrolyte imbalance
drugs - digitalis and antiarrhythmic agents
No obvious cause, particularly in women
Myocardial infarction
• the death of a portion of heart muscle in an area
where there is sudden loss of blood supply.
• Death of the heart muscle often causes chest pain
• electrical instability of the heart muscle tissue
• rapid and disorganized heartbeat - ventricular
fibrillation.
• cannot pump/deliver oxygenated blood to brain.
• Permanent brain damage and death can occur
unless oxygenated blood flow is quickly resumed
Myocardial infarction
• usually by complete blockage of coronary artery
by blood clot.
• advanced coronary artery disease, having fatty
deposits, is damaged.
• blood clot on the damaged surface
• Chest pain or pressure is a common symptom.
• Cardiac chest pain is often vague, dull, pressure or
constricting band-like sensation, squeezing,
heaviness, or discomfort.
Consequences
A heart attack is potentially very serious, can lead to
full recovery
chronic disabling condition
permanent brain damage, rapidly fatal and
Death, unless blood flow is quickly resumed.
Invasive Procedures
• Coronary (balloon) angioplasty: A thin catheter is
inserted into the blocked artery with a tiny balloon on
the end. it is expanded to keep the artery open and the
catheter is removed.
• Stents: The insertion of a stent is similar to coronary
angioplasty except that over the balloon is a small
metallic tube (a stent) that stays in place to keep the
artery open while the catheter and the balloon are
removed.
• Atherectomy: laser cuts away the plaque
• Brachytherapy: Radiation to the blockages to remove
them from recurring after angioplasty.
Coronary Blood Flow