A 32-year-old woman with a long-standing history of palpitation varying from moderately rapid and regular to “a few thumps” in the precordium has the following ECG recorded during a typical episode of rapid palpitation:

• Ventricular tachycardia, 115/min.
• The QRS pattern is compatible with right ventricular out-flow tract VT 

There is evidence of AV dissociation, with the sinus rate very close to that of the VT.
The P waves at first follow the QRS complexes. Later, as the sinus rate increases, they precede the QRS complexes and there is fusion and eventually AV capture.

This ECG is recorded 65 minutes after ECG 1:

• Sinus rhythm, with frequent and consecutive premature ventricular complexes
• Ventricular rate 94/min

The arrhythmia is the only abnormality.