Download MBBS Myocardial Infarction Lecture PPT

MYOCARDIAL

INFARCTION.

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Myocardial infarction ( MI ),
or acute myocardial infarction ( AMI ).
commonly known as a heart

attack, occurs when blood flow decreases or stops to a part

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of the heart, causing damage to the heart muscle.

Most common symptom is chest pain or discomfort which

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may travel to the shoulder, arm, back , neck or jaw. Often it

occurs in centre or left side of the chest and last for more

than a few minutes.

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other symptom may include shortness of breath, nausea,

feeling faint, feeling tired.
CHEST PAIN(MI).

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WHAT is heart attack ?

Occurs when the coronary arteries that supply the

heart muscle become blocked.

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Partially blocked is called angina.

When fully blocked it causes a myocardial infarction or a

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heart attack.
CAD.

Ischemic heart disease( IHD) or coronary artery

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disease(CAD) :

Heart attack:
A heart attack occurs when

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the blood flow to a part of the heart is blocked by a

blood clot. If this clot cuts off the blood flow

completely , the part of the heart muscle supplied by

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that artery begins to die.


MI.

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Myocardial infarction(MI) is a disease condition

which is caused by reduced blood flow in a coronary

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artery due to atherosclerosis and occlusion of an

artery by an embolus or thrombus.

Most myocardial infarction occur due to coronary

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artery disease.

The complete blockage of a coronary artery caused by

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a rupture of an atherosclerotic plaque.


Blockage of coronary artery.
COMPLICATION OF MI.

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About 30% of people have atypical symptoms.

Women more often have atypical symptoms than men.

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An MI may cause : -

Heart failure, an irregular heart beat, cardiogenic

shock, or cardiac arrest.

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Symptom angina/mi.
RISK FACTORS.

Unchangeable risk factor :--

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Age- the older you get, the greater the

chance.

Sex----males have a greater rate aven after women pass

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menopause.

Family history---if family members have had CHD, there is

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a greater chance.
Changeable risk factors.

Hypertension
Serum cholesterol

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Obesity
Diabetes mellitus
Physical inactivity
Cigarette smoking
Alcohol intake

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CHOLESTEROL.

Waxy fat substance in the blood.
Liver makes all the cholesterol it need to survive,

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other source of cholesterol come from food.

GOOD CHOLESTEROL---
HDL---it does not tendency to clog

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arteries.

Level should be > 35.
Cholesterol.

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LDL--
bad cholesterol.
Tendency to increase risk of CHD.
Major component of the atherosclerotic plaque that

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clogs arteries.

Levels should be < 130.
DIABETES.

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2-4 fold risk for CHD.
Asymptomatic CHD~ 30-40 %.
Painless AMI,arrythmias, CCF.
CHD- A major ( 60% ) cause of mortality.

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PHYSICAL INACTIVITY--

Increasing physical activity has been shown to decrease

blood pressure.

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Moderate to increase physical activity for 30-45 minutes on

most days of the week is recomended.
SMOKING.

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SMOKING-
Contribute to development of atherosclerosis.
Lowers levels of HDL.
Female smokers have a higher risk than male smokers.

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ALCOHOL not too good either!
Alcohol kills brain cells
Damage liver
Increases BP

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Increases risk of heart attack.


PATHOPHYSIOLOGY.

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Coronary artery cannot supply enough blood to the heart in

response to the demand due to CAD.

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Within 10 seconds myocardial cells experience ischemia.
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Ischemic cells cannot get enough oxygen or glucose.
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Cells convert to anaerobic metabolism, and produces Lactic as

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waste---Pain develops from lactic acid accumulation.

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Patient feels anginal symptoms until receiving demand

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increeases O2 requirements of myocardial cells.

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RISK OF HIGH CHOLESTEROL.
Criteria of MI.

Troponin or CK-MB increased with one of these:

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Chest pain
Positive ischemic change in ECG( ST segment elevation and

T wave changes )

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Pathological Q wave presence in ECG Newly.
MI DIAGNOSIS.

WHO CRITERIA.

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History of ischemic type of chest discomfort.
Evolutionary ECG changes.
Rise and fall in serum cardiac marker.

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LAB.DIAG :

Best marker: Troponins.
Next test : CK-MB.

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Predictive

CRP > 3mg/L( highest risk).
CLINICAL DIAGNOSIS OF MI.

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Silent MI-
in diabetes mellitus, elderly, cardiac transplantation

recipients.

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Typical features-
profuse sweating, dyspnea, chest pain,

rapid, weak pulse etc.
TESTES USEFUL FOR DIAGNOSIS OF MI.

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1.Electrocardiograms(ECG).
2.Blood tests.
3.Coronary angiography.(CAG).

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An ECG which is a recording of the heart's electrical

activity, may confirm an elevation MI(STEMI), if ST

elevation is present.

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Commonly used blood test include troponin and less

often creatne kinase MB.
STEMI.

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CARDIACBIOMARKERS.

Cardiac biomarkers are used to detect cardiac

diseases.

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Acute coronary syndrome resulting from myocardial

ischemia.

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Congestive heart failure.

CARDIAC MARKERS TESTED IN

ACUTE CHEST PAIN

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UNSTABLE ANGINA

SUSPICIOUS ECG CHANGES

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HISTORY SUGGESTIVE OF MYOCARDIAL

INFARCTION.

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CARDIAC MARKERS.

A. CARDIAC MARKERS FOR ACUTE CORONARY SYNDROME
1.CREATINE KINASE (CK-MB )
2.CARDIAC TROPONINS ( cTnT )

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3.HIGH SENSITYVITY TROPONIN
4.BNP and NTproBNP
B. RISK MARKER FOR CARDIAC DISEASE (PREDICTION)
1.PLASMA hsCRP
2.TOTAL CHOLESTEROL LEVEL IN SERUM

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3.LDL- CHOLESTEROL and Apo-B100 level
4.HDL level and ApoA1 level
5.Lp(a) level
6.Serum homocysteine level
ELECTROCARDIOGRAM.

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ACUTE ANTERIOR MI.
MI-Management.
MEDICAL management MI.

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