Xylocaine Reflex

Report:

Top & middle:

Atrial fibrillation

Rate-dependent left bundle branch block

VEB

Bottom:

Sinus rhythm

SVEBs with LBBB aberration

Comment:

This is a fine example of xylocaine reflex, compounded by two 200 Joule shocks! There was no need for it: the broad-complex tachycardia continued the irregular irregularity of its slightly slower narrow-complex predecessor. It was AF throughout! Things always look scarier on the monitor. This is not to say that irregular monomorphic VT does not exist, confusing some ICDs93. But the ICDs do not have the benefit of 12-lead ECGs on demand!

The sinus rhythm was restored, with SVEBs showing the same rate-dependent LBBB aberrancy. There was no immediate improvement in the blood pressure: the countershocks always cause some degree of myocardial depression. The DCCSs are undesirable in patients returning from the OR with freshly stitched abdominal wounds; dehiscence can of course be prevented by re-paralysing the patient.

The treatment of choice would have been (i) taking 12-lead ECG, checking ABGs and potassium, (ii) giving amiodarone bolus + infusion to both control the rate and cardiovert the patient. Digoxin would (eventually) control the ventricular rate, but it is not of value in terminating AF or maintaining sinus rhythm later.

Below (Fig 100a) is the patient’s 12-lead ECG taken before the onset of AF: sinus tachycardia, SVEBs (two couplets, single one in aVR), LAHB, LVH and a soupçon of anterior infarction.

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