Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Myocardial Infarction Lecture PPT
MYOCARDIAL
INFARCTION.
Myocardial infarction ( MI ),
or acute myocardial infarction ( AMI ).
commonly known as a heart
attack, occurs when blood flow decreases or stops to a part
of the heart, causing damage to the heart muscle.
Most common symptom is chest pain or discomfort which
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.
other symptom may include shortness of breath, nausea,
feeling faint, feeling tired.
CHEST PAIN(MI).
WHAT is heart attack ?
Occurs when the coronary arteries that supply the
heart muscle become blocked.
Partially blocked is called angina.
When fully blocked it causes a myocardial infarction or a
heart attack.
CAD.
Ischemic heart disease( IHD) or coronary artery
disease(CAD) :
Heart attack:
A heart attack occurs when
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
that artery begins to die.
MI.
Myocardial infarction(MI) is a disease condition
which is caused by reduced blood flow in a coronary
artery due to atherosclerosis and occlusion of an
artery by an embolus or thrombus.
Most myocardial infarction occur due to coronary
artery disease.
The complete blockage of a coronary artery caused by
a rupture of an atherosclerotic plaque.
Blockage of coronary artery.
COMPLICATION OF MI.
About 30% of people have atypical symptoms.
Women more often have atypical symptoms than men.
An MI may cause : -
Heart failure, an irregular heart beat, cardiogenic
shock, or cardiac arrest.
Symptom angina/mi.
RISK FACTORS.
Unchangeable risk factor :--
Age- the older you get, the greater the
chance.
Sex----males have a greater rate aven after women pass
menopause.
Family history---if family members have had CHD, there is
a greater chance.
Changeable risk factors.
Hypertension
Serum cholesterol
Obesity
Diabetes mellitus
Physical inactivity
Cigarette smoking
Alcohol intake
CHOLESTEROL.
Waxy fat substance in the blood.
Liver makes all the cholesterol it need to survive,
other source of cholesterol come from food.
GOOD CHOLESTEROL---
HDL---it does not tendency to clog
arteries.
Level should be > 35.
Cholesterol.
LDL--
bad cholesterol.
Tendency to increase risk of CHD.
Major component of the atherosclerotic plaque that
clogs arteries.
Levels should be < 130.
DIABETES.
2-4 fold risk for CHD.
Asymptomatic CHD~ 30-40 %.
Painless AMI,arrythmias, CCF.
CHD- A major ( 60% ) cause of mortality.
PHYSICAL INACTIVITY--
Increasing physical activity has been shown to decrease
blood pressure.
Moderate to increase physical activity for 30-45 minutes on
most days of the week is recomended.
SMOKING.
SMOKING-
Contribute to development of atherosclerosis.
Lowers levels of HDL.
Female smokers have a higher risk than male smokers.
ALCOHOL not too good either!
Alcohol kills brain cells
Damage liver
Increases BP
Increases risk of heart attack.
PATHOPHYSIOLOGY.
Coronary artery cannot supply enough blood to the heart in
response to the demand due to CAD.
|
Within 10 seconds myocardial cells experience ischemia.
|
Ischemic cells cannot get enough oxygen or glucose.
|
Cells convert to anaerobic metabolism, and produces Lactic as
waste---Pain develops from lactic acid accumulation.
|
Patient feels anginal symptoms until receiving demand
increeases O2 requirements of myocardial cells.
RISK OF HIGH CHOLESTEROL.
Criteria of MI.
Troponin or CK-MB increased with one of these:
Chest pain
Positive ischemic change in ECG( ST segment elevation and
T wave changes )
Pathological Q wave presence in ECG Newly.
MI DIAGNOSIS.
WHO CRITERIA.
History of ischemic type of chest discomfort.
Evolutionary ECG changes.
Rise and fall in serum cardiac marker.
LAB.DIAG :
Best marker: Troponins.
Next test : CK-MB.
Predictive
CRP > 3mg/L( highest risk).
CLINICAL DIAGNOSIS OF MI.
Silent MI-
in diabetes mellitus, elderly, cardiac transplantation
recipients.
Typical features-
profuse sweating, dyspnea, chest pain,
rapid, weak pulse etc.
TESTES USEFUL FOR DIAGNOSIS OF MI.
1.Electrocardiograms(ECG).
2.Blood tests.
3.Coronary angiography.(CAG).
An ECG which is a recording of the heart's electrical
activity, may confirm an elevation MI(STEMI), if ST
elevation is present.
Commonly used blood test include troponin and less
often creatne kinase MB.
STEMI.
CARDIACBIOMARKERS.
Cardiac biomarkers are used to detect cardiac
diseases.
Acute coronary syndrome resulting from myocardial
ischemia.
Congestive heart failure.
CARDIAC MARKERS TESTED IN
ACUTE CHEST PAIN
UNSTABLE ANGINA
SUSPICIOUS ECG CHANGES
HISTORY SUGGESTIVE OF MYOCARDIAL
INFARCTION.
CARDIAC MARKERS.
A. CARDIAC MARKERS FOR ACUTE CORONARY SYNDROME
1.CREATINE KINASE (CK-MB )
2.CARDIAC TROPONINS ( cTnT )
3.HIGH SENSITYVITY TROPONIN
4.BNP and NTproBNP
B. RISK MARKER FOR CARDIAC DISEASE (PREDICTION)
1.PLASMA hsCRP
2.TOTAL CHOLESTEROL LEVEL IN SERUM
3.LDL- CHOLESTEROL and Apo-B100 level
4.HDL level and ApoA1 level
5.Lp(a) level
6.Serum homocysteine level
ELECTROCARDIOGRAM.
ACUTE ANTERIOR MI.
MI-Management.
MEDICAL management MI.
This post was last modified on 30 November 2021