A 33-Year Old with Wide Complex Tachycardia.

A 33-year-old woman presented to the emergency department (ED) with dizziness and palpitations and was found to be in wide complex tachycardia. EP study the following day showed consistent pre-excitation with atrial extra-stimuli. While unable to sustain tachycardia, a brief induced run displayed A-V dissociation with matching 12-lead morphology. VA conduction with RV pacing was concentric and decremental. Parahisian pacing ruled out a retrograde para-septal pathway. Working diagnosis of a nodo-ventricular pathway was made with further support from cessation of pre-excitation with adenosine administration. Electroanatomic mapping was performed with the earliest V mapped with pre-excited beats. Ablation at this site in the slow pathway region eliminated all pre-excitation, and the patient has remained symptom-free.