Second Degree Block & Right Bundle Branch Block
A 70-year-old man is seen in the clinic because of breathlessness, which began over a few days 3 months ago. This is his ECG: what does it show and what treatment is needed?
- Sinus rhythm
- Second degree (2:1) heart block (most obvious in lead V3)
- Ventricular rate 30/min
- Normal PR interval in the conducted beats
- Normal axis
- QRS duration prolonged (160 ms)
- RSR pattern in leads V1-V3and a wide S wave in lead V6
- Prominent U wave in leads V3-V6
This patient has second degree block and right bundle branch block, so he clearly has extensive conduction tissue disease.
The slow heart rate is probably the cause of his heart failure, and he needs a permanent pacemaker. The story suggests that the onset of heart failure was not associated with chest pain, so the underlying disease is probably fibrosis of the conducting system rather than ischaemia. He needs an echocardiogram and treatment with an angiotensin-converting enzyme inhibitor if there is evidence of left ventricular dysfunction.