Diagnosing a wide complex tachycardia using basic electrophysiologic properties of the cardiac conduction system.

65-year-old man with a history of coronary artery disease s/p percutaneous coronary intervention to the left anterior descending artery and atrial fibrillation s/p recent (<3 months) pulmonary vein isolation presented to the emergency department with symptoms of palpitations for 1 day after admittedly forgetting to take his medications found to be in a wide complex tachycardia. We discuss a stepwise approach using properties of the conduction system to diagnose the patient's tachycardia.