Intraventricular Conduction Delay (IVCD)

Report:

Sinus rhythm 60/min

Intraventricular conduction delay (defect, IVCD)

Diffuse nonspecific ST/T changes

Prominent U wave

Comment:

Characteristically, the patient’s potassium fell from 3.5 to 1.8 mEq/L following absorption of hydroxychloroquine; some of the repolarisation changes may be due to this. The QRS distortion and widening (and probably most of the ST/T changes as well) are due to hydroxychloroquine itself. The same is true of the relative bradycardia in the presence of shock. The VTs shown below (Fig 34a) coincided with the nadir of serum potassium level but could, again, be equally due to chloroquine cardiotoxicity. Her blood hydroxychloroquine levels were very high15. Before the advent of diazepam/adrenaline therapy16 such levels were uniformly fatal.

The term IVCD is used as the QRS widening to 0.14” cannot be ascribed to ether left or right bundle branch block. In lead V1 it can be seen to affect both the R and the S wave.

A shallow but definite U wave is well seen in Lead 2 strip and the left precordial leads.

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