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ECG Interpretation Algorithm and A Mini Test
In some medical faculties, medical students are asked to comment on a given ECG during an oral examination. This may be stressful for some medical students since they are not accustomed to reading ECGs.
However, medical students are expected to know at least basic ECG knowledge.
Usually, medical students are expected to recognize at least the following diagnoses:
- Sinus bradycardia, sinus tachycardia
- APC, VPC, atrial flutter, atrial fibrillation, supraventricular tachycardia, ventricular tachycardia
- Right or left bundle branch block
- Myocardial infarction with ST elevation
- ST segment elevation or depression, PR depression (not to overlook myocardial ischemia or pericarditis)
- AV block in a patient with syncope.
Several more diagnoses may be added to the group of basic ECG diagnoses. I think, above is enough for a 4th-year medical student during an 8-week Cardiology rotation.
Even the above diagnoses may be difficult for a 4th-year medical student when learning ECG for the first time. Therefore, a basic ECG interpretation algorithm will be very useful for medical students.
When interpreting ECGs, I suggest you to use the following algorithm:
What is the heart rate (ventricular rate)?
Is the heart rhythm (ventricular rhythm) regular (are RR intervals regular)?
Are there P waves? Is PR interval prolonged? Does a QRS complex follow each P wave?
Is the QRS width normal or increased (is there bundle branch block) ?
Are there pathological q / Q waves?
Is there ST segment depression or elevation?
Are there tall or negative T waves?
Of course, more questions can be added to the above algorithm to cover more diagnoses. However, I believe that the above algorithm is sufficient for a 4th-year medical student.
Below you will find ECGs which are similar to the ones we ask to our medical students during oral examinations. Try to interpret them by using the above algorithm.
ECG 1. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 84/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal (<200ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? ST segment is normal (no sign of ischemia).
Are there tall or negative T waves? T waves are normal. T wave negativity limited to lead III may be accepted as a normal variant.
CONCLUSION: Above is a normal ECG.
Click here for a more detailed ECG
ECG 2. Above is an ECG from a 70 years-old woman. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 112/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal (<200ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal.
CONCLUSION: Above ECG shows sinus tachycardia.
Click here for a more detailed ECG
ECG 3. Above is an ECG from a man taking Bisoprolol (a beta blocker) and Diltiazem. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 32/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal (<200ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal. T wave negativity limited to lead III may be accepted as a normal variant.
CONCLUSION: Above ECG shows sinus bradycardia.
Click here for a more detailed ECG
ECG 4. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is ABOUT 45-55/minute. There is bradycardia.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is irregular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are no P waves. The PR interval is absent. QRS complexes do not follow P waves.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal < 120 ms. The ECG pattern is compatible with left anterior fascicular block.
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal.
CONCLUSION: Above ECG shows atrial fibrillation with low ventricular rate (bradycardia) and left anterior fascicular block.
Click here for a more detailed ECG
ECG 5. Above is an ECG from a 75 years-old man who had undergone coronary artery bypass surgery. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 81/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is prolonged (248 ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal.
CONCLUSION: Above ECG shows 1st degree AV block.
Click here for a more detailed ECG
ECG 6a. How do you interpret the above ECG by using the suggested algorithm?
Check the ECG 6b for the answer.
Click here for a more detailed ECG
ECG 6b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? Heart rate (ventricular rate) is 57/minute. Atrial rate (P wave rate) is 96/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular. The atrial rate is also regular (but unrelated to the ventricular rate)
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves but every P wave is not followed by a QRS complex. P waves are not related to QRS complexes (3rd degree AV block - complete AV block). Therefore, we cannot measure PR interval.
Is the QRS width normal or wide (is there bundle branch block)? The QRS comlexes are wide (compatible with right bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal (Negative T waves in leads V1 to V3 is normal in RBBB.
CONCLUSION: Above ECG shows 3rd degree AV block and right bundle branch block (RBBB).
Click here for a more detailed ECG
ECG 7. When using the suggested algorithm:
What is the heart rate (ventricular rate)? Heart rate (ventricular rate) is 82/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves . PR interval is normal (< 200 ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS comlexes are wide (compatible with left bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal (In left bundle branch block, ST and T wave are generally opposite in direction to QRS).
CONCLUSION: Above ECG shows left bundle branch block.
Click here for a more detailed ECG
ECG 8a. The ECG above belongs to a 59 years-old man with recent-onset retrosternal chest pain. He had undergone coronary arter bypass surgery 1.5 years ago.
How do you interpret the above ECG by using the suggested algorithm?
Check the ECG 8b for the answer.
Click here for a more detailed ECG
ECG 8b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 83/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is at the upper limit of normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are wide and compatible with right bundle branch block.
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is elevated in inferior leads (compatible with ACUTE inferior wall myocardial infarction).
Are there tall or negative T waves? Tall T waves in inferior leads further suggest ACUTE inferior wall myocardial infarction.
CONCLUSION: Above ECG shows ACUTE inferior wall myocardial infarction and right bundle branch block.
Click here for a more detailed ECG
ECG 9. The ECG above belongs to a man with recent-onset chest pain.
How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 86/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide and not compatible with bundle branch block. The ST segment elevation in chest leads may give the impression of wide QRS complexes, at first glance. However, the limb leads on the left side of this ECG shows normal QRS width.
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of OLD myocardial infarction).
Is there ST segment depression or elevation? The ST segment is elevated in anterior leads (compatible with ACUTE anterior wall myocardial infarction).
Are there tall or negative T waves? Tall T waves in inferior leads further suggest ACUTE anterior wall myocardial infarction.
CONCLUSION: Above ECG shows ACUTE anterior wall myocardial infarction.
Click here for a more detailed ECG
ECG 10a. The ECG above belongs to a an asymptomatic man.
How do you interpret the above ECG by using the suggested algorithm?
Check the ECG 10b for the answer.
Click here for a more detailed ECG
ECG 10b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 82/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide. No bundle branch block.
Are there pathological q / Q waves? Pathological Q waves in inferior leads are compatible with OLD inferior myocardial infarction.
Is there ST segment depression or elevation? The ST segment is not elevated, and does not suggest acute ischemia (compatible with OLD inferior myocardial infarction).
Are there tall or negative T waves? Negative T waves in inferior leads further support the diagnosis of OLD inferior myocardial infarction.
CONCLUSION: Above ECG shows OLD inferior myocardial infarction. (This patient had experienced acute inferior myocardial infarction one month before recording of this ECG. Now, he is asymptomatic)
Click here for a more detailed ECG
ECG 11. How do you interpret the above ECG by using the suggested algorithm? The patient is asymptomatic.
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 63/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide. No bundle branch block.
Are there pathological q / Q waves? Pathological Q waves in anterior leads are compatible with OLD anterior myocardial infarction.
Is there ST segment depression or elevation? The ST segment is elevated in chest leads V2 and V3. This may be due to acute ischemia or due to left ventricular aneurysm from old anterior myocardial infarction (still it is compatible with OLD anterior myocardial infarction.
Are there tall or negative T waves? Negative T waves in anterior leads (V1 to V3) further support the diagnosis of OLD anterior myocardial infarction.
CONCLUSION: Above ECG shows OLD anterior myocardial infarction. (This ECG belongs to a 49 years-old man with OLD anterior myocardial infarction. His ECHOcardiography showed a large apical left ventricular aneurysm and left ventricular systolic dysfunction.
Click here for a more detailed ECG
ECG 12. Above is an ECG from a 62 years-old asymptomatic man.How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 102/minute (sinus tachycardia).
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rhythm (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide. No bundle branch block.
Are there pathological q / Q waves? No pathological Q waves (no clue for old myocardial infarction).
Is there ST segment depression or elevation? The ST segment is depressed in inferior leads and leads V4 to V6 (compatible with myocardial ischemia.
Are there tall or negative T waves? Tall or negative T waves are not seen.
CONCLUSION: Above ECG shows sinus tachycardia and ST depression suggesting myocardial ischemia.
When this ECG was recorded, the patient was asymptomatic. After seeing the above ECG, he underwent coronary angiography. His dominant Cx coronary artery showed significant stenosis and was stented.
Horizontal ST segment depression is more important for the diagnosis of coronary artery disease.
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ECG 13a. Above is an ECG from a middle-aged man with chest pain. How do you interpret the above ECG by using the suggested algorithm? Check ECG 13b for the answer.
Click here for a more detailed ECG
ECG 13b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? Heart rate (ventricular rate) is 89/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. PR interval is normal (at the lower limit). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? 0.5-1 mm ST segment depression is seen in leads C4 to C6.
Are there tall or negative T waves? There are biphasic and negative T waves in precordial leads, suggesting myocardial ischemia (coronary artery disease).
CONCLUSION: Above ECG shows precordial T wave negativity with ST segment depression. Taking into account his chest pain, this is compatible with unstable angina pectoris. He underwent coronary angiography after recording the above ECG. Coronary bypass artery surgery was performed for LAD and Cx coronary artery stenoses.
Click here for a more detailed ECG
In some medical faculties, medical students are asked to comment on a given ECG during an oral examination. This may be stressful for some medical students since they are not accustomed to reading ECGs.
However, medical students are expected to know at least basic ECG knowledge.
Usually, medical students are expected to recognize at least the following diagnoses:
- Sinus bradycardia, sinus tachycardia
- APC, VPC, atrial flutter, atrial fibrillation, supraventricular tachycardia, ventricular tachycardia
- Right or left bundle branch block
- Myocardial infarction with ST elevation
- ST segment elevation or depression, PR depression (not to overlook myocardial ischemia or pericarditis)
- AV block in a patient with syncope.
Several more diagnoses may be added to the group of basic ECG diagnoses. I think, above is enough for a 4th-year medical student during an 8-week Cardiology rotation.
Even the above diagnoses may be difficult for a 4th-year medical student when learning ECG for the first time. Therefore, a basic ECG interpretation algorithm will be very useful for medical students.
When interpreting ECGs, I suggest you to use the following algorithm:
What is the heart rate (ventricular rate)?
Is the heart rhythm (ventricular rhythm) regular (are RR intervals regular)?
Are there P waves? Is PR interval prolonged? Does a QRS complex follow each P wave?
Is the QRS width normal or increased (is there bundle branch block) ?
Are there pathological q / Q waves?
Is there ST segment depression or elevation?
Are there tall or negative T waves?
Of course, more questions can be added to the above algorithm to cover more diagnoses. However, I believe that the above algorithm is sufficient for a 4th-year medical student.
Below you will find ECGs which are similar to the ones we ask to our medical students during oral examinations. Try to interpret them by using the above algorithm.
ECG 1. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 84/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal (<200ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? ST segment is normal (no sign of ischemia).
Are there tall or negative T waves? T waves are normal. T wave negativity limited to lead III may be accepted as a normal variant.
CONCLUSION: Above is a normal ECG.
Click here for a more detailed ECG
ECG 2. Above is an ECG from a 70 years-old woman. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 112/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal (<200ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal.
CONCLUSION: Above ECG shows sinus tachycardia.
Click here for a more detailed ECG
ECG 3. Above is an ECG from a man taking Bisoprolol (a beta blocker) and Diltiazem. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 32/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal (<200ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal. T wave negativity limited to lead III may be accepted as a normal variant.
CONCLUSION: Above ECG shows sinus bradycardia.
Click here for a more detailed ECG
ECG 4. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is ABOUT 45-55/minute. There is bradycardia.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is irregular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are no P waves. The PR interval is absent. QRS complexes do not follow P waves.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal < 120 ms. The ECG pattern is compatible with left anterior fascicular block.
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal.
CONCLUSION: Above ECG shows atrial fibrillation with low ventricular rate (bradycardia) and left anterior fascicular block.
Click here for a more detailed ECG
ECG 5. Above is an ECG from a 75 years-old man who had undergone coronary artery bypass surgery. How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 81/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is prolonged (248 ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal.
CONCLUSION: Above ECG shows 1st degree AV block.
Click here for a more detailed ECG
ECG 6a. How do you interpret the above ECG by using the suggested algorithm?
Check the ECG 6b for the answer.
Click here for a more detailed ECG
ECG 6b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? Heart rate (ventricular rate) is 57/minute. Atrial rate (P wave rate) is 96/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular. The atrial rate is also regular (but unrelated to the ventricular rate)
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves but every P wave is not followed by a QRS complex. P waves are not related to QRS complexes (3rd degree AV block - complete AV block). Therefore, we cannot measure PR interval.
Is the QRS width normal or wide (is there bundle branch block)? The QRS comlexes are wide (compatible with right bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal (Negative T waves in leads V1 to V3 is normal in RBBB.
CONCLUSION: Above ECG shows 3rd degree AV block and right bundle branch block (RBBB).
Click here for a more detailed ECG
ECG 7. When using the suggested algorithm:
What is the heart rate (ventricular rate)? Heart rate (ventricular rate) is 82/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves . PR interval is normal (< 200 ms). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS comlexes are wide (compatible with left bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is normal (no sign of myocardial ischemia).
Are there tall or negative T waves? T waves are normal (In left bundle branch block, ST and T wave are generally opposite in direction to QRS).
CONCLUSION: Above ECG shows left bundle branch block.
Click here for a more detailed ECG
ECG 8a. The ECG above belongs to a 59 years-old man with recent-onset retrosternal chest pain. He had undergone coronary arter bypass surgery 1.5 years ago.
How do you interpret the above ECG by using the suggested algorithm?
Check the ECG 8b for the answer.
Click here for a more detailed ECG
ECG 8b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 83/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is at the upper limit of normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are wide and compatible with right bundle branch block.
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? The ST segment is elevated in inferior leads (compatible with ACUTE inferior wall myocardial infarction).
Are there tall or negative T waves? Tall T waves in inferior leads further suggest ACUTE inferior wall myocardial infarction.
CONCLUSION: Above ECG shows ACUTE inferior wall myocardial infarction and right bundle branch block.
Click here for a more detailed ECG
ECG 9. The ECG above belongs to a man with recent-onset chest pain.
How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 86/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide and not compatible with bundle branch block. The ST segment elevation in chest leads may give the impression of wide QRS complexes, at first glance. However, the limb leads on the left side of this ECG shows normal QRS width.
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of OLD myocardial infarction).
Is there ST segment depression or elevation? The ST segment is elevated in anterior leads (compatible with ACUTE anterior wall myocardial infarction).
Are there tall or negative T waves? Tall T waves in inferior leads further suggest ACUTE anterior wall myocardial infarction.
CONCLUSION: Above ECG shows ACUTE anterior wall myocardial infarction.
Click here for a more detailed ECG
ECG 10a. The ECG above belongs to a an asymptomatic man.
How do you interpret the above ECG by using the suggested algorithm?
Check the ECG 10b for the answer.
Click here for a more detailed ECG
ECG 10b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 82/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide. No bundle branch block.
Are there pathological q / Q waves? Pathological Q waves in inferior leads are compatible with OLD inferior myocardial infarction.
Is there ST segment depression or elevation? The ST segment is not elevated, and does not suggest acute ischemia (compatible with OLD inferior myocardial infarction).
Are there tall or negative T waves? Negative T waves in inferior leads further support the diagnosis of OLD inferior myocardial infarction.
CONCLUSION: Above ECG shows OLD inferior myocardial infarction. (This patient had experienced acute inferior myocardial infarction one month before recording of this ECG. Now, he is asymptomatic)
Click here for a more detailed ECG
ECG 11. How do you interpret the above ECG by using the suggested algorithm? The patient is asymptomatic.
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 63/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide. No bundle branch block.
Are there pathological q / Q waves? Pathological Q waves in anterior leads are compatible with OLD anterior myocardial infarction.
Is there ST segment depression or elevation? The ST segment is elevated in chest leads V2 and V3. This may be due to acute ischemia or due to left ventricular aneurysm from old anterior myocardial infarction (still it is compatible with OLD anterior myocardial infarction.
Are there tall or negative T waves? Negative T waves in anterior leads (V1 to V3) further support the diagnosis of OLD anterior myocardial infarction.
CONCLUSION: Above ECG shows OLD anterior myocardial infarction. (This ECG belongs to a 49 years-old man with OLD anterior myocardial infarction. His ECHOcardiography showed a large apical left ventricular aneurysm and left ventricular systolic dysfunction.
Click here for a more detailed ECG
ECG 12. Above is an ECG from a 62 years-old asymptomatic man.How do you interpret the above ECG by using the suggested algorithm?
What is the heart rate (ventricular rate)? The heart rate (ventricular rate) is 102/minute (sinus tachycardia).
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rhythm (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. The PR interval is normal. Every P wave is followed by a QRS complex. No AV block.
Is the QRS width normal or wide (is there bundle branch block)? The QRS complexes are not wide. No bundle branch block.
Are there pathological q / Q waves? No pathological Q waves (no clue for old myocardial infarction).
Is there ST segment depression or elevation? The ST segment is depressed in inferior leads and leads V4 to V6 (compatible with myocardial ischemia.
Are there tall or negative T waves? Tall or negative T waves are not seen.
CONCLUSION: Above ECG shows sinus tachycardia and ST depression suggesting myocardial ischemia.
When this ECG was recorded, the patient was asymptomatic. After seeing the above ECG, he underwent coronary angiography. His dominant Cx coronary artery showed significant stenosis and was stented.
Horizontal ST segment depression is more important for the diagnosis of coronary artery disease.
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ECG 13a. Above is an ECG from a middle-aged man with chest pain. How do you interpret the above ECG by using the suggested algorithm? Check ECG 13b for the answer.
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ECG 13b. When using the suggested algorithm:
What is the heart rate (ventricular rate)? Heart rate (ventricular rate) is 89/minute.
Is the heart rhythm (ventricular rhythm) regular (are the RR intervals regular)? The heart rate (ventricular rhythm) is regular.
Are there P waves? Is the PR interval prolonged? Does a QRS complex follow each P wave? There are P waves. PR interval is normal (at the lower limit). Every P wave is followed by a QRS complex.
Is the QRS width normal or wide (is there bundle branch block)? The QRS width is normal (no bundle branch block).
Are there pathological q / Q waves? No pathological Q waves are seen (no clue of previous myocardial infarction).
Is there ST segment depression or elevation? 0.5-1 mm ST segment depression is seen in leads C4 to C6.
Are there tall or negative T waves? There are biphasic and negative T waves in precordial leads, suggesting myocardial ischemia (coronary artery disease).
CONCLUSION: Above ECG shows precordial T wave negativity with ST segment depression. Taking into account his chest pain, this is compatible with unstable angina pectoris. He underwent coronary angiography after recording the above ECG. Coronary bypass artery surgery was performed for LAD and Cx coronary artery stenoses.
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