title: Visualizing Localized Reentry With Ultra-High Density Mapping in Iatrogenic Atrial Tachycardia: Beware Pseudo-Reentry.
abstract: BACKGROUND
  The activation pattern of localized reentry (LR) in atrial tachycardia remains incompletely understood. We used the ultra-high density Rhythmia mapping system to study activation patterns in LR.
  
  
  RESULTS
  LR was suggested by small rotatory activations (carousels) containing the full spectrum of the color-coded map. Twenty-three left-sided atrial tachycardias were mapped in 15 patients (age: 64±11 years). 16 253±9192 points were displayed per map, collected over 26±14 minutes. A total of 50 carousels were identified (median 2; quartiles 1-3 per map), although this represented LR in only n=7 out of 50 (14%): here, rotation occurred around a small area of scar (<0.03 mV; 12±6 mm diameter). In LR, electrograms along the carousel encompassed the full tachycardia cycle length, and surrounding activation moved away from the carousel in all directions. Ablating fractionated electrograms (117±18 ms; 44±13% of tachycardia cycle length) within the carousel interrupted the tachycardia in every LR case. All remaining carousels were pseudo-reentrant (n=43/50 [86%]) occurring in areas of wavefront collision (n=21; median 0.5; quartiles 0-2 per map) or as artifact because of annotation of noise or interpolation in areas of incomplete mapping (n=22; median 1, quartiles 0-2 per map). Pseudo-reentrant carousels were incorrectly ablated in 5 cases having been misinterpreted as LR.
  
  
  CONCLUSIONS
  The activation pattern of LR is of small stable rotational activations (carousels), and this drove 30% (7/23) of our postablation atrial tachycardias. However, this appearance is most often pseudo-reentrant and must be differentiated by interpretation of electrograms in the candidate circuit and activation in the wider surrounding region.
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Vishal
authors.initials: V
authors.lastname: Luther
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Markus
authors.initials: M
authors.lastname: Sikkel
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Nathan
authors.initials: N
authors.lastname: Bennett
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Fernando
authors.initials: F
authors.lastname: Guerrero
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Kevin
authors.initials: K
authors.lastname: Leong
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Norman
authors.initials: N
authors.lastname: Qureshi
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Fu Siong
authors.initials: FS
authors.lastname: Ng
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Sajad A
authors.initials: SA
authors.lastname: Hayat
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: S M Afzal
authors.initials: SM
authors.lastname: Sohaib
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Louisa
authors.initials: L
authors.lastname: Malcolme-Lawes
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Elaine
authors.initials: E
authors.lastname: Lim
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Ian
authors.initials: I
authors.lastname: Wright
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Michael
authors.initials: M
authors.lastname: Koa-Wing
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: David C
authors.initials: DC
authors.lastname: Lefroy
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Nick W F
authors.initials: NW
authors.lastname: Linton
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Zachary
authors.initials: Z
authors.lastname: Whinnett
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Prapa
authors.initials: P
authors.lastname: Kanagaratnam
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: D Wyn
authors.initials: DW
authors.lastname: Davies
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.).
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Peters
authors.affiliation: From the Department of Cardiology, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, United Kingdom (V.L., M.S., K.L., N.Q., F.S.N., S.A.H., S.M.A.S., L.M.-L., E.L., I.W., M.K.-W., D.C.L., N.W.F.L., Z.W., P.K., D.W.D., N.S.P., P.B.L.); and Boston Scientific Ltd, Marlborough, MA (N.B., F.G.). pblim@imperial.ac.uk.
authors.forename: Phang Boon
authors.initials: PB
authors.lastname: Lim
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000601:surgery; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007049:Iatrogenic Disease; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis* / Q000601:surgery; D013617:Tachycardia, Supraventricular / Q000175:diagnosis* / Q000601:surgery; D016896:Treatment Outcome
keywords: atrial fibrillation; cardiac electrophysiology; fibrosis; tachycardia, supraventricular