ECG changes during myocardial infarction include more than ST segment or T wave changes.


Other ECG changes that may be observed during myocardial infarction

  Atrioventricular (AV) block

  Arrhythmias

  Prolongation of the QT interval

  Negative U waves

  Bundle branch block

  QRS alternance





ECG 1. The ECG above belongs to a patient with unstable angina pectoris.
Negative T waves are observed in leads C2-C5
while
negative U waves are seen in leads C2-C4. Additionally, the PR interval is above 200 msec (1st degree AV block).
Coronary angiography showed significant stenosis of the LAD and Circumflex (Cx) arteries.

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ECG 2a. Atrial fibrillation developing during acute anterior wall myocardial infarction.

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ECG 2b. Ten minutes later, the ECG of the same patient shows junctional (nodal) rhythm (QRS complexes without preceding P
waves
). Coronary angiography showed total occlusion of the LAD and significant (80%) stenosis of the intermedier artery; the
RCA and Cx arteries were normal.

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ECG 3. The ECG above was recorded during acute anterolateral myocardial infarction. The anterior and lateral leads show

ST segment elevation
and tall T waves . Another finding in this ECG is prolonged QT interval .

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ECG 4. The ECG above was recorded during acute inferior wall myocardial infarction. Atrial couplet is seen.
The
P waves of the atrial extrasystoles have a different configuration than sinus P waves.

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ECG 5. The ECG above belongs to a 58 years-old man who admitted lately to the hospital and was diagnosed as
inferior myocardial infarction.
Q waves , ST segment elevation and negative T waves are seen in inferior leads.
Also,
the P waves are not related to the QRS complexes : complete AV block .

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ECG 6. Sinus bradycardia during acute inferior myocardial infarction. The heart rate is approximately 25/minute.
Inferior leads show ST segment elevation.
Immediately after recording of the above ECG, the patient underwent coronary angiography which revealed 99% stenosis of
the proximal Right Coronary Artery (RCA).

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ECG 7a. The ECG above is from a 63 years-old man experiencing acute anterior myocardial infarction.
Right bundle branch block is seen. The rhythm is atrial fibrillation: P waves are absent and the RR intervals are irregular.
Coronary angiography, soon after recording of the above ECG, showed total ostial occlusion of the LAD artery.

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ECG 7b. The above ECG belongs to the same patient. It was recorded immediately after stenting of the LAD coronary artery.
The rhythm is still atrial fibrillation. ST elevation in anterior leads persist.
In late admitting patients, opening of the major epicardial arteries does not necessarily mean that the microvascular vessels
will be opened immediately. Despite the successful percutaneous intervention, the ST segment elevation in this patient
did not resolve immediately.
On the left side, some limb leads also show 50/60 Hz AC interference artifact.

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ECG 7c. The above ECG was recorded 12 hours after stenting of his LAD coronary artery.
Atrial fibrillation is not seen any more. The rhythm is sinus.
ST segment elevation has not resolved completely.
Some limb leads and V2 show 50/60 Hz AC interference artifact.

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ECG 7d. The above ECG was recorded 24 hours after stenting of his LAD coronary artery.
Right bundle branch block persists. The rhythm is sinus. Chest leads do not show ST segment elevation.
Now, 1st degree AV block and left posterior fascicular block have developed.

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ECG 7e. The above ECG was recorded a few hours after recording of the ECG 7d. It shows
atrial tachycardia with complete AV
block
. Configuration of the P waves in the above ECG are not similar to that of the P waves in ECG 7d: ectopic
atrial tachycardia with block. Now, the wide QRS complexes have different shapes: idioventricular rhythm.
Because of the myocardial infarction, some part of the left ventricle is not contracting.
Loss of synchronised atrioventricular contraction further decreases the cardiac output.
The heart (ventricular) rate is low due to idioventricular rhythm.
The patient had developed signs of low cardiac output at the time of the recording of the above ECG.
Transvenous temporary pacemaker was implanted immediately.

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ECG 7f. The above ECG was recorded after temporary pacemaker implantation.
Unipolar electrode results in recording of large
pacemaker spikes.
The pacemaker mode is VVI. It senses only the ventricle and paces only the ventricle.
P waves are not related to the
paced QRS complexes.
Some P waves are not easily discernible since they coincide with the T waves.

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ECG 8. The above ECG is from an old man with old inferior and old anterior myocardial infarctions.
Coronary angiography showed 3-vessel (extensive) coronary artery disease.
QT interval prolongation is seen.
The P wave is positive in lead I and negative in lead C6: left atrial rhythm.

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