This document summarizes the stepwise interpretation of an ECG for a 78 year old woman with a heart murmur. It finds sinus rhythm at 77 beats per minute with sinus arrhythmia and first degree AV block. The QRS axis and duration are normal with no signs of bundle branch blocks. There are findings of left ventricular hypertrophy with ST-T abnormalities indicating strain pattern. No signs of myocardial infarction are seen.

1. Stepwise interpretation of ECG
ID 168

2. ID 168 78 year old woman with a heart murmur

3. ID 168 78 year old woman with a heart murmur
Can you see P waves?

4. ID 168 – Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block
Yes, there is sinus rhythm, 77/min. The P-P interval varies in keeping with sinus arrhythmia
(a common normal finding) – Each P is followed by a QRS – The P-R is prolonged to 230 msec.
(1st
degree AV block)

5. ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block
There are no signs of right or left atrial enlargement

6. ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block
Let’s now look at the QRS complexes: There is normal QRS axis (between 0 and 90 degrees

7. The QRS duration is normal : There is no right bundle branch block, left bundle branch block or
non‐specific block
ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block

8. ID 168 - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block –
Left ventricular hypertrophy with repolarization abnormality
There are findings of left ventricular hypertrophy with ST-T abnormality (“strain pattern”)

9. ID 168 Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block
Left ventricular hypertrophy with repolarization abnormality
There are no QRS changes of myocardial infarction

10. ID 168 Final diagnosis - Sinus rhythm, 77/min with sinus arrhythmia – First degree AV block
Left ventricular hypertrophy with repolarization abnormality