Heart Blocks ECG 7
- Normal sinus rhythm
- Left bundle branch block
- First degree AV block
- Carbrera's sign - possible myocardial infarction
Cabrera’s sign is used to diagnose an acute myocardial infarction in the setting of a left bundle branch block and consists of notching at 40 milliseconds in the upslope of the S wave in lead V3 and V4. This has a poor sensitivity of 27% for myocardial infarction.
Historically it has been taught that detecting myocardial ischemia is not possible on an ECG in the setting of a left bundle branch block, however there are three different changes that can be seen in this setting suggesting an acute myocardial infarction. These include the Sgarbossa criteria, Chapman's sign and Cabrera's sign. Click the left bundle branch block review below for details.