As generalists, on the post-call ward round, we are often faced with difficult ECG dilemmas. Important findings are easily missed or misinterpreted.

A 35 old man presents with palpitations of sudden onset. He reports a long history of similar self-limiting episodes. On this occasion, his symptoms are persistent and he has presented to the ER. He has no cardiac history. His ECG recorded on presentation is shown below. His tachycardia failed to respond to several interventions, including escalating doses of intravenous adenosine. Eventually he reverted to normal sinus rhythm after administration of intravenous verapamil. He remained hemodynamically stable throughout with a systolic blood pressure in the region of 120 mmHg.

What is going on?

Which of the following statements is true?

A. The ECG findings are consistent with the presence of an SVT B. There is evidence of AV dissociation on the ECG C. The response to verapamil rules out a ventricular tachycardia as the cause of his tachycardia D. There is right axis deviation on the ECG E. None of the above statements are true