Xylocaine and the δ Wave

Report:

Sinus tachycardia

Wolff-Parkinson-White conduction

Transient normal conduction following injection of 50 mg xylocaine

Comment:

This patient with postural hypotension ( 90 mmHg drop!) and on multiple medications, was seen in consultation with view to simplifying his treatment. When frusemide, procainamide, chlorpromazine and a tricyclic antidepressant were stopped, his pulse rate slowed down and WPW pattern emerged. Xylocaine was used to assess his bundle of Kent’s responsiveness to it and obtain a repeat 12-lead ECG without pre-excitation.

Patients with intermittent pre-excitation are less at risk from atrial fibrillation or flutter with very rapid ventricular rates. A strip with only occasional δ waves is shown below (Fig 16a). A suggestion of the concertina effect is seen between the 3rd and the 6th beat in the top strip.

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