AIVR: False Asystole

Report:

Sinus rhythm

SVEBs

Runs of accelerated idioventricular rhythm (AIVR)

AV dissociation

Ventricular fusion

Comment:

The AIVR takes over during slowing of the sinus mechanism following SVEBs in the middle and bottom strips and (perhaps) irregular sinus arrhythmia or sinus exit block in the top strip. Its complexes are small and narrow, causing repeated inquiries from the staff about their nature. The proof that they are of ventricular origin comes from the presence of fusion beats at the onset of the AIVR (one in top, the other in the bottom strip) and one at its termination (top strip). In some other lead, they would look more properly “ventricular”.

The runs are associated, regularly, with a fall in blood pressure. The presence of a preceding P wave, even dissociated, maintains the baseline pressure, bespeaking atrial transport.

Below (Fig 183a) is the patient’s 12-lead ECG, with rather marked diffuse ST/T changes originally ascribed to blunt chest trauma. Echocardiogram, however, showed completely normal left ventricle, hyperdynamic on inotropes. The hyperdynamic state is, perhaps, reflected on the ECG itself, with “electromechanical association” addition to the QRS complexes in V1. There is also small voltage (note the double standardisation markers) and a right-axis P wave, close to +90o. These changes reflect the severe ARDS and hypokalæmia134 manifest after the initial resuscitation. It was all reversible (Fig 183b).

183a. Lead V1 transmits cardiac mechanical impulse as well. This would make an interesting echocardiographic study. Right atrial contraction? 183b. ECG after recovery, a month later. 184. 50 year old lady with dilated (6.3 cms) LV and fractional shortening 14% despite mitral incompetence. She had apical and septal hypokinesia.