CRAT Bundle Branch Blocks and Fascicular Blocks 2

Question 1

In left bundle branch block, the septal Q waves normally seen in leads I, V5, and V6 are typically:

Accepted Answer

Absent or eliminated

Answer

LBBB eliminates normal septal Q waves in leads I, V5, and V6 because septal depolarization now travels right to left rather than the normal left to right direction.

Question 2

An ECG shows a QRS of 0.14 sec with broad notched R waves in I, aVL, V5–V6 and a broad QS in V1. What is the most likely diagnosis?

Accepted Answer

Left bundle branch block

Answer

Broad notched R waves in lateral leads (I, aVL, V5–V6) combined with a QS pattern in V1 and a QRS ≥0.12 seconds are the hallmark features of left bundle branch block.

Question 3

The Sgarbossa criteria are used to identify acute MI in the presence of which ECG pattern?

Accepted Answer

Left bundle branch block

Answer

Sgarbossa criteria help identify acute MI in the setting of LBBB because LBBB causes secondary ST-T changes that can mask ischemic ST changes.

Question 4

In LBBB, T-wave deflections that are discordant (opposite direction) to the QRS complex are considered:

Accepted Answer

Normal secondary repolarization changes

Answer

Discordant ST-T changes are expected secondary repolarization abnormalities in LBBB resulting from the abnormal depolarization sequence and are not independently pathological.

Question 5

New-onset LBBB in a patient presenting with chest pain should be managed as which of the following until proven otherwise?

Accepted Answer

A STEMI equivalent requiring emergent reperfusion evaluation

Answer

New or presumably new LBBB with chest pain is treated as a STEMI equivalent per ACC/AHA guidelines because it may conceal ST elevation and indicate an acute coronary occlusion.

CRAT - Certified Rhythm Analysis Technician Practice Test

CRAT - Certified Rhythm Analysis Technician Practice Test

CRAT Bundle Branch Blocks and Fascicular Blocks 2