Sinus Bradycardia & AIVR

Report:

Sinus bradycardia 37 - 44/min

Second degree AV block(unspecified)

First degree AV block

Accelerated idioventricular rhythm (AIVR) 57/min

AV dissociation with interference

ST segment elevation consistent with ischæmia/infarction

Comment:

This is an example of narrow capture beats confirming the ventricular origin of the broad-complex rhythm, should anyone be in doubt.

The diagnosis of second degree AV block(unspecified) rests with the last P wave in the upper strip: it is remote enough from the preceding QRS and the next one to expect conduction. Even so, one can not be sure that 100% conduction would not have taken place without the usurping AIVR. Below (Fig 152a) is a similar situation, except that the sinus rhythm is faster and the escape rhythm (due to more obvious AV block) is junctional. The latter has slightly different QRS from sinus beats – an example of non-phasic aberrant conduction.

The intrinsic idioventricular rate is 20 - 40/min; this escape rhythm can therefore be called accelerated. A universally adopted lower rate limit for AIVR does not exist.

This patient died. Pacing is of practically no value in true cardiogenic shock unless some other reversible component can be addressed. Early intervention, if available (it was not then, in 1988), with counterpulsation support, would have improved her odds.

152a. Junctional escape beats and rhythm, with sinus captures. The AV block is obviously Wenckebach. 153. 81 year old man with ischæmic cardiomyopathy.