title: 4:2:1 conduction of an AF initiating trigger.
abstract: A 44 year old male with idiopathic dilated cardiomyopathy was undergoing persistent atrial fibrillation (AF) ablation. Following antral ablation, AF terminated into a regular narrow complex rhythm. Earliest activation was mapped to a focus in the superior vena cava (SVC) which was conducted in a 2:1 ratio to the atria which in turn was conducted with 2:1 ratio to the ventricles, resulting in an unusual 4:2:1 conduction of the SVC tachycardia. 1:1 conduction of the SVC tachycardia to the atrium preceded initiation of AF. During AF, SVC tachycardia continued unperturbed. Sinus rhythm was restored following catheter ablation of the focus.
authors.affiliation: National University Heart Centre, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block, Level 9, 119228, Singapore.
authors.forename: Pipin
authors.initials: P
authors.lastname: Kojodjojo
authors.affiliation: National University Heart Centre, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block, Level 9, 119228, Singapore.
authors.forename: Eric
authors.initials: E
authors.lastname: Chong
authors.affiliation: National University Heart Centre, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block, Level 9, 119228, Singapore.
authors.forename: Toon Wei
authors.initials: TW
authors.lastname: Lim
authors.affiliation: National University Heart Centre, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block, Level 9, 119228, Singapore.
authors.forename: Swee Chong
authors.initials: SC
authors.lastname: Seow
keywords: Ablation; Atrial fibrillation; Superior vena cava tachycardia