Mapping & RF-ablation of Atrial Flutter By Dr. Rania Samir Assistant Professor of Cardiology Ain Shams University Defin. Atrial flutter is a macro-reentrant AT characterized by a regular rate 200-350 bpm, a uniform flutter wave morphology. Often the re-entry wave is traveling around a natural or pathological iatrogenic obstacle. 1
Classification CTI- dependent atrial flutter The re-entry circuit is confined to RA & involves the CTI as a critical zone of slow conduction CCW atrial flutter CW atrial flutter Lower loop re-entry Double wave re-entry Partially isthmus dep.( SI) Short circuit Typical atrial flutter?? Atypical re-entry forms T Non CTI-dependent atrial flutter (=Atypical A. flutter) A heterogeneous group of macro-reentrant ATs, defined only by the absence of involvement of the CTI as part of the re-entry circuit and diff. ECG pattern Atypical RA flutters (e.g. lesion macro-reentrant AT) Atypical LA flutters (Della Bella et al 2002) (ACC/AHA/ESC Guidelines 2003) Basic mapping techniques Activation mapping Circular activation pattern Recorded atrial activation throughout TCL (>80%) (No diastolic pause) Caveats Comprehensive mapping is required Low amplitude EGMs not ignored LAO RAO Atrial scars delayed activation, low amplitude & fract. EGMs TCL=220 ms Ain Shams University EP lab 2
3D activation mapping Atypical A. macro-reentry multiple re-entry loops &/or SHD SVC DP SVC TCL= 240 ms Several studies, best results with 3D electroanatomical mapping + entrainment mapping Activation & substrate mapping Isochronal representation provides a more real indication of conduction pattern IVC TA TA IVC Isochronal map of activation You only get what you explore 3D mapping DOES NOT represent true anatomy (De Ponti et al 2007) Entrainment mapping Value: Establish the diagnosis of a reentrant mechanism Localize protected isthmuses Same activation seq. of intracardiac EGM PPI FCL 10-30 ms Stim time activ time 10-30 ms Concealed entrainment (Kalman et al, Cirulation 1996) 3
Typical Counterclockwise Atrial Flutter (concept,ecg and electrophysiological criteria) TA VCV CS Circular pattern of RA activation 3D maps of typical atrial flutter (CW &CCW) TCL= 240 ms SVC TA TA IVC IVC Isochronal map of activation Ain Shams University EP lab 4
Other CTI-dependent atrial flutters Lower loop re-entry (LLR) VCV CTI dependent One or more breakthroughs in CT a amplitude of late +ve def. in inf. leads Identical ECG pattern Typical Atrial Flutter (CTI dependent) (ablation) Ablation catheter 8 mm tipped better than 4 mm tipped (target temp 60⁰ C,50-60 W). Irrigated tip is the best. Cryo-ablation achieve deep painless ablation but dragging is not possible. SVC approach can be applied. Sheathes and different curves can help achieve contact. Ablation line (1) Position : 6 o'clock LAO Start : RV A : V ratio 1:3 Style: drag or point by point End: when A disappears. Disadvantages: Thick irregular muscle (poor contact). Ablation line(2) Position : more septal, two lines. If we cannot achieve ablation from the first line. Better contact. Disadvantages: painful. Risk of AV block Long 5
Typical Atrial Flutter (ablation end points) VCV VCV Atypical right atrial flutters 6
Atypical right atrial flutters Upper loop re-entry (ULR) upper portion of RA CW flutter circuit Breakthrough over lateral /anterolat. Annulus Isthmus: SVC-FO or IVC-FO Lesion incisional macro-reentrant AT Central obstacle is a scar Atriotomy, septal prosthetic patch, suture line, RF-abl. line of block Intraatrial baffle (senning, mustard), fontan Scar related atrial re-entry non-iatrogenic lesion macro-reentrant AT Large low voltage areas/ electrically silent (scars) Lesion macro-reentrant AT Atriotomy scar (yang et al,2001) (Ricard et al,2002) Arrhythmia circuits in post op. ASD patients The aim of mapping is to localize the entire circuit & its relation to surrounding barriers Entrainment is an essential mapping tool 3D & non-contact mapping is of great help to localize ongoing circuits around scars Short or transverse atriotomy posterior atriotomy, low locaton of atriotomy Long vertical line, incomplete at IVC, anterior location (Shah et al, 2002) 7
Scar related RA re-entry 37 yrs old male, recurrent freq. tachycardia, incessant tachycardia Inducible A flutter Ain Shams University EP lab Isochronal maps of RA activation Mapping of 98% of TCL Ablation sites 8
Atypical left atrial flutters LAF should be considered in all pts with AT whose ECG morphology not characteristic of typical A. flutter. Esp. in presence of sign. Lt heart disease (e.g. MVD, MVR), prev. ablation of AF targeting LA, with large silent areas over post. LA ECG features completely or dominantly +Ve deflection in V1 lower voltage deflections in standard leads less commonly, -Ve def. in inf. leads.. Pseudo-typical flutter 9
During activation mapping LAF is suspected : Sequential conventional mapping: RA activation time < 50% of TCL PPI in the RA > TCL by 40 ms in 3 different points in the RA, including the CTI & RA free wall Spontaneous variations of > 100 ms in the RA & < 20 ms LA variations. 3D mapping system is a very useful tool for mapping &locating the circuits & areas of protected isthmuses Different LAF circuits Single loop re-entry circuits LA septal circuits Perimitral flutter circuits RF abl.: line connecting RIPV& SP (post. App.) or SP & MA (ant. App.) Could be CCW or CW rotation PV/ SA circuit Multiple loop re-entry circuits Mostly, the arrhythmia rotates around MA, a zone of block (including the Rt or Lt PVs) or electrically silent areas Lines of block & silent areas act as lateral barriers allowing stabiliz. of the circuits & preventing short circuiting 10
Role of conventional mapping in atypical flutter To exclude typical, CTI dependent atrial flutter To determine the chamber of interest Entrainment mapping for localizing the critical loop & distinguishing the bystander ones. For the ablation of commonest form of incisional RA flutters Take home message Always think of scar related atrial flutter in patients with SHD or history of previous cardiac surgeries Don t let unusual patterns of flutter on ECG frustrate you it may be still the good old CTI AFL -in the other hand- Atypical AFL can masquerade as typical AFL. Electroanatomical mapping is always a good mapping tool in atypical RA & LA flutters esp. in presence of multiple loop circuits. Entrainment mapping is. Our Golden Goose 11
Thank You 12