Case:
Our patient is a 61 year old man with a history of hypertension and
symptomatic paroxysmal atrial fibrillation who underwent pulmonary vein.
He remained symptom free with no evidence of recurrence of atrial
fibrillation for 7 years following his initial ablation procedure. He
then presented with persistent atrial fibrillation complicated by
congestive heart failure and severely reduced left ventricular ejection
fraction. He underwent electrical cardioversion and his left ventricular
systolic function subsequently improved back to normal. A stress test
revealed no evidence of ischemia. Given the hypothesis of a tachycardia
mediated cardiomyopathy, and limitations of AV nodal blockers in the
setting of profound sinus bradycardia, the decision was made to proceed
with electrophysiologic testing and repeat ablation despite this single
recurrence. Three dimensional electroanatomic mapping (CARTO 3, Biosense
Webster, Diamond Bar, CA) of the left atrium suggested persistent
isolation with voltage < .1 mV (entrance block) of the left
and right sided pulmonary veins. Pacing revealed exit block within the
right sided PVs. The left sided PVs showed exit block at paced cycle
length of 600 ms with capture of the sleeve. At a paced cycle length of
1000 ms, there was conduction to the left atrium, albeit with
significant delay (Figures 1 and 2).
We identified the site of electrical breakthrough in the LSPV using
escape mapping.5 We then proceeded to re-isolate the
PV and were subsequently unable to provoke non-pulmonary vein triggers,
with and without Isuprel. We then proceeded to isolate posterior wall
which demonstrated automaticity with exit block post-ablation.