Heart Blocks ECG Quiz 11 Answer

1. Atrial fibrillation with a slow ventricular response
2. Right bundle branch block
3. Prolonged QT interval (with normal QTc interval)

The QRS complex is irregular and coarse "fibrillatory waves" are present (see atrial fibrillation review by clicking below) indicating the presence of atrial fibrillation. There is quite a slow ventricular response which likely indicates AV nodal disease, perhaps even underlying complete heart block (unknown since the rhythm is not a normal sinus rhythm). As the ventricular rate slows, the QT interval prolongs. The absolute QT interval on this ECG is approximately 640 ms which is quite long, but the QTc when accounting for the slow heart rate is about 380 ms which is normal. This is why the "corrected QT interval" or "QTc" is frequently used. This is calculated using Bezett's formula below:  

Bezetts

Related Topic Reviews: Atrial Fibrillation ECG, Right Bundle Branch Block, Prolonged QT