Left atrial tachycardia can be treated using catheter ablation guided by electrophysiological and anatomical mapping. Electrophysiological mapping involves identifying the earliest site of activation to target focal tachycardias, or locating protected isthmuses to target macroreentrant tachycardias. Anatomical mapping with 3D systems helps visualize barriers and isthmuses, improving localization of ablation targets. Success rates are limited by challenges locating all active circuits, but outcomes are better than drugs and ablation may improve left ventricular function.

1. ““SANTA MARIA” GENERAL HOSPITAL - TERNISANTA MARIA” GENERAL HOSPITAL - TERNI
THORACIC SURGERY ANDTHORACIC SURGERY AND
CARDIOVASCULAR DEPARTEMENT ARRHYTHMIA EP CENTER and CARDIACCARDIOVASCULAR DEPARTEMENT ARRHYTHMIA EP CENTER and CARDIAC
PACING UNITPACING UNIT
Stefano Nardi MD, PhD
How to manage ablation
of Left Atrial
tachycardia

2. • AADs treatment difficult, with long-term efficacy <50%
Clinical Features
Left Atrial Tachycardia
• AT my be incessant and can ultimately lead to TCM
• Previously Surgery and his-bundle CA were used

3. • Constant tachycardia CL during tachycardia
• Positive P wave in V1
• LA enlargement with diastolic dysfuction of LV
• EKG surface P wave different from typical AFL
Left Atrial Tachycardia

4. • Automaticity
• Triggered Activity
• Reentry
– macro (anatomical, functional)
– micro (anatomical, functional)
mechanisms
Left Atrial Tachycardia
DRUGS PES
++ -
+ +
- ++

5. • Prosthesis MV due to rheumatic or non-rheumatic disease
• Hypertrophic/dilated cardiomyopathy (HCM, DCM)
• LV hypertrophy due to hypertension
• Coronary artery disease (CAD)
• Unknown disease with LA enlargement
etiology
Left Atrial tachycardia

6. Post Surgical AT mechanismsPost Surgical AT mechanisms

7. • inflammation
• peric. effusion
• auton. imbalance
• catecholamines
• Δ vol. & prex.
• inflammation
• peric. effusion
• auton. imbalance
• catecholamines
• Δ vol. & prex.
• inflammation
• peric. effusion
• auton. imbalance
• catecholamines
• Δ vol. & prex.
Post Surgical AT MechanismsPost Surgical AT Mechanisms
Etiology and incidence (early < 7 days)
After CABG After valvular
SURGERY
After
CHD
10 – 40 % until >50% 10 – 40%

8. • Scar
• Atriotomy (RA)
• Scar
• Atriotomy (RA-LA)
• Post-inflammatory (LA)
• Scar
• Atriotomy (RA)
• Post-inflammatory (LA)
Post Surgical AT MechanismsPost Surgical AT Mechanisms
Etiology and incidence (late)
After CHD
surgery
After
CABG
After valvular
SURGERY
< 2 % *up to 30–40% **2 - 10%
* Mostly irregular forms
** Mostly regular forms

9. Ablation of Post-Operative AT
pathophysiology
- In regular atrial tachyarrhythmias, macro-reentry
is the most frequent mechanism
- Direct correlation eith the area of tissue incised by the
surgeon

10. Anatomical
Structures
(BARRIERS)
• Tricuspid Anulus
• Os Coronary Sinus
• Cava Veins
• Mitral Anulus
• Os PVs
Right Atrium Left Atrium
ZONE
of incisional
lesions
• Patches
• Prosthetic materials
• Scars post-
inflammatory response
• Scars post-
inflammatory
response
Left Atrial TachycardiaLeft Atrial Tachycardia
How does it work?
Barriers surrounding protected isthmuses

11. It’s really important to use the
appropriate technique for Atrial
Tachycardia management

12. - Pharmacological ( palliative )
Management of Left ATManagement of Left AT
• limited efficacy
• possible deterioration of LV function in pts with
associated LV impairment at base line (DCM)
- Interventional ( curative )
how to approach ?how to approach ?

13. Electrophysiologic approachElectrophysiologic approach
to LATto LAT

14. • Despite the discrete geometry of focal AT, localization
of such substrates requires a 3D mapping system
Forward
criteria of localization
Focal Atrial Tachycardia
• Earliest local activation
• Mechanical block by means of catheter manipulation

15. Methodology
• Identification of protected isthmuses of
conducting tissue
• electrically (entrainment with concealed fusion)
• anatomically (computer-assisted,3D-mapping)
• RF lesion bridges between constraining barriers
Reentrant LA TachycardiaReentrant LA Tachycardia
Interventional Therapy

16. Use of Entrainment
• Entrainment, (PPI) is commonly used in the study of AMRT
• AADs can alter the electrical conduction proprierties,
then the response to entrainment (>35%) could be
non-optimal for defining a sussesful ablation site
• This approach has several limitation (may not be able to
define the critical isthmus) because can cause arrhythmia
temination or degeneration into AF, or cannot be
performed because the lack of electrical capture in a
specific site
LA macroreentrant TachycardiaLA macroreentrant Tachycardia

17. Left Atrial TachycardiaLeft Atrial Tachycardia
Drawbacks of
Electrophysiologic Approach
• Complexity of surgical model
• Multiplicity of simultaneously
ongoing wave-fronts
• Short CL (<225ms)
• Variation of AT
• Haemodynamic instability
with 1:1 AV conduction.

18. Which is the impact
of the new
technologies ?

19. different Technologiesdifferent Technologies
MappingMapping
• Point by pointPoint by point
• LassoLasso
• SpiralSpiral
• BasketBasket
TrackingTracking
• XrayXray
• CARTOCARTO
• LocaLisaLocaLisa
• NavXNavX
• RPMRPM
• ICEICE
AblationAblation
• ConventionalConventional
• 8 mm tip8 mm tip
• Irrigated tipIrrigated tip
• InvestigationalInvestigational
(balloon, cryo...)(balloon, cryo...)- Framework for ablationFramework for ablation
- Mapping guidanceMapping guidance
- Anatomic localizationAnatomic localization
- Tagging of ablation sites- Tagging of ablation sites
- DetermineDetermine
catheter contactcatheter contact
- ImprovedImproved
efficiency ofefficiency of
power deliverypower delivery
Interventional Approach to LAT

20. 3D mapping system in AFib3D mapping system in AFib
Cutaneous patches and
conventional catheter
for tracking (NavX)
Superimposed EM field
With a dedicated mapping
catheter (CARTO)

21. Atrial Fibrillation ablationAtrial Fibrillation ablation
virtual geometry reconstructionvirtual geometry reconstruction

22. • ACT for at least 4 weeks
• TEE: no LA thrombus
• Replacement of Warfarin by i.v heparin to maintain aPTT at
2-3 times.
• Stop i.v heparin for 6-8 hours before transseptal puncture
• Antibiotics for pts with valve prosthesis
pre-ablation requisites
Left Atrial TachycardiaLeft Atrial Tachycardia

23. • The part of AT cycle analysed
by system
• Identifying the signal
annotated for the “activation
map“ and evaluated for the
creation of the “voltage map“
• Include the backward and the
forward interval that precede
and follow the reference‘s
EA mapping of LA tachycardiaEA mapping of LA tachycardia
1st
step: set the Windows of Interest
• Identification of the P wave is the key
point when using this method (adenosine)

24. 1st
step: set the Windows of Interest
• CS bipolar signal is generally choose as reference‘s signal
Left Atrial TachycardiaLeft Atrial Tachycardia
• The mechanism of LAT (focal vs macroreentrant) will determine
how the WoI should be set

25. • The onset is set 70-80 ms before
the P wave onset and terminates
20-30 ms after the termination
of the P wave.
• If AT with a very short lenght
increase the value in order to
avoid to have a VD in the limits of
the WoI (erroneously computed
for calculate the voltage
amplitude)
Left Atrial TachycardiaLeft Atrial Tachycardia
Focal arrhythmias
• Unipolar deflection analisys is
crucial since the origin of AT is
associated with a rapid downstroke
in unipolar signal

26. ablation strategy
• In extrapulmonary
forms, the CA
strategy was aimed
at the earliest
activated area.
• In forms located
inside PVs, the latter
is electrically PVI
Focal LA tachycardiasFocal LA tachycardias

27. • The onset is fixed in mid-diastole (P wave on the EKG)
• The lenght should span no more than 90-95% of ATCL, in
order to avoid (minimal variation of CL) two deflection
whithin the window
Left Atrial TachycardiaLeft Atrial Tachycardia
macro-reentrant arrhythmias
De Ponti R: From signals to colours (Atlas) ‘08

28. Left Atrial TachycardiaLeft Atrial Tachycardia
macro-reentrant arrhythmias

29. • Raimbow of colours identify
the activation sequence
• Each colour is indicative of a
given chronology
• Red/yellow identify the
mid/late diastolic activation
and dark blue/purple identify
early/mid-diastolic
activation
• Critical isthmus is identified
by the red/purple interface
Left Atrial TachycardiaLeft Atrial Tachycardia
macro-reentrant arrhythmias

30. • No LA atriotomy in pts with septal
approach for MVR
CS
IVC
SVC
• For identifying a by-stander
activation patterns
1st
step: Right Atrium mapping
• Coexistence with RAMRT or AFL

31. 1st
step: Right Atrium mapping

32. • RA activation time: short part (%) of ATCL
• PPI – TCL > 50 ms
2nd
step: RA activation pattern

33. • Both BIPOLARBIPOLAR and UNIPOLARUNIPOLAR signal EGM were
filtered at bandpass settings of 30 to 500 Hz and
0.05 to 200 Hz, and were digitally recorded.
• Systemic IV ANTICOAGULATIONANTICOAGULATION was starting with
heparin-Na+ after transeptal puncture
• ANGIOGRAMANGIOGRAM of the PVs, was performed in two
different axis (LAO/RAO), before mapping
• ACTACT was mantaining between 250 and 300s.
Peri-procedural settingPeri-procedural setting
Left Atrial TachycardiaLeft Atrial Tachycardia

34. • Bipolar signal amplitude <0,05 mV (not distinguishable from the
baseline noise) are defined as electrically silent areas (grey dot)
• Electrical signal in sites with minimal but still-present
a bipolar deflection.
• If multi-component/fragmented potential, annote the
1st
deflection
Left Atrial TachycardiaLeft Atrial Tachycardia

35. Left Atrial TachycardiaLeft Atrial Tachycardia
Mid-diastolic isthmus is the ablation target
(site with the weakest part of the circuit)

36. Left Atrial TachycardiaLeft Atrial Tachycardia

37. Left Atrial TachycardiaLeft Atrial Tachycardia
• Energy settings
Conventional RF:
Power limit of 55 W, maximal temp of
55°C and duration 120“
Irrigated RF:
Power and temp. limit of 40 W and 45° C,
maximal duration of 110“
(30ml/min)
• RF endopoint
- 80%
decrease of bipolar atrial
amplitude
- Double potentials

38. Left Atrial TachycardiaLeft Atrial Tachycardia
Interruption

39. Validation of conduction block
• Pacing close to the ablation line
and demonstration of marked
delay and reversal on the
direction of activation on the
opposite side of linear lesion
when RF closed the isthmus
between the posterior wall and
the lateral MA
• Counterclockwise activation
around the MA during SR when
RF at the anterior isthmus near
the MA

40. • ECHOCARDIOGRAPHYECHOCARDIOGRAPHY after ablation
Post-ablation managementPost-ablation management
• SYSTEMIC ANTICOAGULATIONSYSTEMIC ANTICOAGULATION was starting
with heparin-Na+ six hours after the end of the procedure
• ORAL ANTICOAGULATIONORAL ANTICOAGULATION 24 hs later
Left Atrial TachycardiaLeft Atrial Tachycardia
• After LAT has been interrupted, and ablation
completed, induction of Arrhythmia by PES with
multiple extrastimuli and burst is attempted

41. • Unusual geometry of target tisue
• Complexity of the surgical model
• Multiplicity of simultaneously ongoing wavefronts
Inability to identify protected isthmuses
Ablation of Reentrant LAT
causes of future recurrence
Inability to bridge protected isthmuses
• Thickness of atrial wall
• Inadequate temperature at intramyocardial/epicardial
depth (a poor cooling by reduced blood flow)
• Multiplicity of active isthmuses

42. • Conventional EP mapping is not always a really
appropriate strategies for left AT’s ablation because it
provides very limited understanding of these complex
arrhythmias which are highly variable from one pt to
the other.
• The main drawback of a pure EP approach is that the
identification of all putative “end-point” could be
extremely difficult to achieve.
Ablation of LA TachycardiaAblation of LA Tachycardia
conclusionsconclusions
• Success of CA is limited by a number of factors,
including the inability to identify or severe the active
protected isthmuses sustaining macro-reentry

43. • In pts with ventricular dysfunction, elimination of AT
leads to immediate relief of symptoms, followed by
progressive improvement of LV function
• Efficacy of CA differ between right-sided and left-
sided ATs
Ablation of LA TachycardiaAblation of LA Tachycardia
conclusionsconclusions
• Success of CA is limited by a number of factors,
including the inability to identify or severe the active
protected isthmuses sustaining macro-reentry

44. • The implemented use of virtual geometry and 3D mapping
system W or w/o a merge integration could fulfill some
important clinical demand for detailed anatomic guidance,
especially in case of abnormal anatomy, condition that can
increase the risk of damage if not adequately realized.
Ablation of LA TachycardiaAblation of LA Tachycardia
conclusionsconclusions
• Inherent EA limitations can lead to a potential source
of error, however we believe that represents a
significant improvement respect to previous only EP
criteria
• This approach may be USEFULUSEFUL in the treatment of pts
with cardiac arrhythmias where ablation therapy is
primarily ANATOMICALLY BASEDANATOMICALLY BASED