Asymptomatic 40-year old patient. Describe the ECG.
Describe and interpret this ECG
ECG ANSWER and INTERPRETATION
- Irregular narrow-complex rhythm (overall rate = 72 bpm).
- Normal sinus P waves are seen (upright in lead II), indicating a sinus origin of the rhythm.
- QRS complexes cluster in groups, separated by non-conducted P waves.
- The PR interval progressively prolongs within each group.
- The PR prolongation can be appreciated by comparing the first and last PR interval of each group.
This is the typical appearance of 2nd degree AV block with Mobitz I conduction (Wenckebach phenomenon).
In comparison to patients with Mobitz II, who typically require a pacemaker for prophylaxis of complete heart block and ventricular standstill, patients with Mobitz I do not necessarily need any intervention.
The risk of progression to haemodynamically unstable AV block in these patients is very low.