This 76-year-old woman with hypertension and arthritis has a long history of episodes of paroxysmal palpitation, associated with dyspnea, weakness and often neck pulsation. Her medication includes digoxin and sotalol. She is in the Emergency Department 2 hours after onset of her usual palpitation:

• Supraventricular tachycardia, 200/min
• Most likely AV nodal re-entrant tachycardia
• Nonspecific ST abnormality possible digitalis effect

There has been no response to vagal stimulation. The arrhythmia subsides spontaneously:

• Supraventricular tachycardia (SVT), rate 214/min, followed by one sinus-originated complex and a short run of aberrantly conducted SVT (left bundle branch block pattern)
• There is eventually restoration of sinus rhythm, 95/min.

Comment: The wide complex rhythm starts after a pause and resumption of tachycardia – this is another example of Ashman phenomenon whereby aberrant conduction can occur after a relative pause.

The patient is now symptom-free and ready to be discharged from the Emergency Department:

• Sinus rhythm 98/min  
• Normal ECG