Slow Junctional Escape in Complete AV Block

Report:

Sinus rhythm 90/min

Third degree AV block

Junctional escape rhythm 19/min

Anterior infarction ? incomplete LBBB

QT/T wave changes consistent with ischæmia or preceding syncope.

Comment:

As in the previous case, the escape pacemaker, although a friend in need30, is somewhat unreliable. The QRS looks the same as in conducted sinus beats (Fig 47a below, with 2:1 and advanced block) and the escape focus is therefore junctional.

There is no real sinus tachycardia, probably reflecting a degree of chronotropic incompetence.

The diagnosis of incomplete LBBB remains doubtful because of the uncharacteristically small voltage of the QRS complexes. The absence of septal q wave in V6 is perhaps better explained by septal infarction even though there are no anteroseptal Q waves. The non-existent R wave progression from V1 to V5 is, after all, almost equivalent to Q waves.

The T wave in V6 is suspiciously prominent, dwarfing its QRS complex. This is consistent with infarction or ischæmia.