myocardial infarction (MI) risk factor symptoms signs ECG Cardiac enzymes

1. Myocardial infarction
ABDALLAH SABRY EL GAMEEL
HOUSE OFFICER
ALEXANDRIA MAIN UNIVERSITY HOSPITAL

2. When MI is suspected
1. Risk factors
2. Symptoms ( most important is chest pain)
3. Signs
Any chest pain must be respected

3. ■ Risk factor for MI
 Old age >35
 DM
 HTN
 SMOKING
 Previous MI or cardiac dis.
 Hyperlipidemia
 Sedentary lifestyle
 Psychological stress

4. Symptoms
 Chest pain ( typical or typical) ( mey be absent in DM)
The typical chest pain of acute MI usually is intense and unremitting for 30-60 minutes. It is retrosternal
and often radiates up to the neck, shoulder, and jaws, and down to the left arm. The chest pain is
usually described as a substernal pressure sensation that is also perceived as squeezing, aching,
burning, or even sharp. In some patients, the symptom is epigastric, with a feeling of indigestion or of
fullness and gas.
 Lightheadednesswith or without syncope
 Anxiety or sense of discomfort
 Cough
 Nausea / vomiting
 Shorteness of breath
 Fullness/indigestion/choking feeling
Patients with typical MI may have the previous symptoms in the days or even weeks
preceding the event (although typical STEMI may occur suddenly, without warning)

5. Signs
 Heart rate
Mey be ass. With tachycardia, bradycardia or arrhythmia (either tachy or
brady).
 Blood pressure
May ass. With high BP dt adrenergic Response to pain and anxiety
Low blood pressure may indicate large infarction area affect rt or lt
ventricle.
 Respiratory rate
high RR may be attributed to anxiety or pulmonary congestion
 Temperature
Usu. Present in 24- 48 hours; parallel to elevation of CK

6. Signs
 Neck vein
congestion of neck vein is attributed to rt ventricle dysfunction.
 Heart
lateral displacement of the apical impulse, dyskinesis, a palpable S gallop, and a soft S sound indicate
diminished contractility of the compromised left veventricle.
New mitral regurgitation indicates papillary muscle dysfunction or rupture, or mitral annular dilatation
A holosystolic murmur that radiates to the midsternal border and not to the back, possibly with a palpable
thrill, suggests a ventricular septal rupture
 Chest
wheezes / rales dt pulmonary congestion and hypertension secondary to rt ventricular dysfunction
 Abdomen
Hepatomegaly and hepato-jugular reflux may indicate Tricuspid regurgitation.
 Extremities
Peripheral cyanosis, edema, pallor, diminished pulse volume, delayed rise, and delayed capillary refill may
indicate vasoconstriction, diminished cardiac output, and right ventricular dysfunction or failure

7. Workup
 ECG( most important)
 Cardiac enzymes
Any pt present with chest / epigastric pain must exclude
MI at least by ECG

8. ECG
 Acute MI affects ST segment and T wave
 ST Segment begins at J point( end of QRS complex) and ends at
beginning of T wave ( green in colour )
 ST segment is normally iso-electric

9.  Elevation of the “ J point “ above the iso-electric line called ST elevation.
 ST elevation of more than 1mm ( 1small square) in limb leads and 2 mm ( 2 small
square) in chest leads in two or more consecutive leads ( facing the same area )is
pathological and indicate acute Myocardial infarction ST Elevation
Myocardial Infarction = STEMI
 STEMI is ass. with T wave change in the form of T wave inversion .
ECG
STEMI

10.  There is other type of MI not ass. with ST elevation Non ST Elevation
Myocardial Infarction = NSTEMI
 Also NSTEMI is ass. with T wave change in the form of inversion or flattening
of T wave
 ST wave depression +/- T wave inversion (NSTEMI) mey be just myocardial
ischemia NOT infarction so need to be confirmed by cardiac enzymes
ECG
NSTEMI

11. NSTEMISTEMI
depressionElevationSt
Flattening or depressiondepressionT wave
ElevatedElevatedcardiac
enzyme
Comparison between STEMI and NSTEMI

12. How to localize the site of infarction from
ECG ???
AnteriorSeptalPosteriorLateral
lateralSeptalLateralInferior
LateralAnteriorInferiorInferior
V4V1aVR1
V5V2aVL11
V6V3aVF111

13. Inferior MI

14. Anterolateral MI

15. Cardiac Enzymes
 Types of cardiac enzymes used in Dx of MI :
 Cardiac Troponin ( Troponin I and T )
 Creatine kinase – MB ( CK-MB)
 Serum level of Troponin increase within 3-12 hour from the onset of chest pain, peak at 24-48
hour , return to baseline over 5-14 days
 Cardiac troponin is the most sensitive one in Dx of MI
 CK-MB is the second-line diagnostic test after cardiac troponin.
 CK-MB is less sensitive and specific than cardiac troponin
 CK-MB normalize after 48 – 72 hour, so a raising level after normalization confirm that an other
MI has occur.
 One should not delay treatment waiting for cardiac marker because their
sensitivity is not high in the early hours after infarct.