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.

Fig 47a. Sinus rhythm with advanced (“high-grade”) 2o AVB.

Fig 47b. Sinus rhythm with 2:1 AVB and LBBB. The QT/T appearance probably reflects a “cerebral” event, probably a Sokes-Adams attack rather than the reported “grayout”.

Fig 47c. Days later, trigeminy due to blocked SVEBs during paced rhythm.

Fig 48. 52 year old man with history of hypertension, admitted with dysphasia and hemiparesis. A CAT scan showed infarcts in the territory of the left anterior cerebral artery. What evidence is there of a bilateral bundle branch block (BBBB)?