Atrial tachycardias are an uncommon cause of supraventricular tachycardia, accounting for around 5-15% of cases depending on whether the patient has congenital heart defects. Atrial tachycardias can be focal, originating from a single site, or macroreentrant utilizing existing anatomical barriers; 3D mapping systems have improved localization of focal atrial tachycardia origins by providing better atrial anatomy visualization. Successful focal atrial tachycardia ablation is identified by termination of tachycardia within 10 seconds of beginning radiofrequency delivery and inability to reinduce tachycardia with drug provocation.

1. Atrial Tachycardia
Huang Bien‐Hsien
Kuang Tien General Hospital
Taichung
Taiwan

2. Atrial Tachycardia
Atrial tachycardias (ATs) are an uncommon cause of
supraventricular tachycardia (SVT):
Adults ‐ 5% of all SVTs subject to EP studies
Pediatric patients:
10‐15% of the SVTs in pediatric patients without
congenital heart defects (CHD)
More in those who have undergone a surgical
correction of their CHD
(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500)

3. Outline
• Mechanism of atrial tachycadia
• Locations of focal atrial tachycaria
• Surface EKG of different sites of atrial
tachycardia
• Mapping
• New mapping technology (Introduction)
• Ablation

4. Classification of Mechanisms
Focal
Macroreentrant tachycardias.
(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 500-501)

5. Focal Atrial Tachycardia
Focal AT exhibits activation spreading from a
single focus either radially, circularly or
centrifugally without an electrical activation
spanning the tachycardia cycle length.

6. Mechanisms (Chen et al. Circulation 1994)
• Abnormal or enhanced automaticity
• Triggered Activity (delayed afterdepolarization)
• Microreentry

7. Effects of Adenosine on Reentrant AT
Microreentrant AT (probably focal AT)
Macroreentrant AT
Reentrant circuit with zones of
conduction can
demonstrate adenosine sensitivity

8. Classification of Atrial Tachycardia:
Response to Adenosine
Termination Transient No Effect
Suppression
Macroreentrant Focal Automatic AT
Intra-Atrial Reentry
Cristal Repetitive (Non-Decremental Tissue)
AT Monomorph
ic AT
Intra-Atrial Reentry
(Decremental Tissue)
Markowitz, et al, JCE 1999; 10: 489

9. Origins of Focal Atrial Tachyarrhythmias
Atrial Origin Venous Origin
RA LA SVC CS VOM PV
Cristal terminalis Appendage
Koch＇s triangle Atrial septum
Appendage Bachmann＇s bundle
Atrial septum Mitral anulus
Bachmann＇s bundle
Tricuspid anulus

10. CT Pathology
The crista terminalis (CT)
originates from the
superior rim of the oval
fossa (OF), swings in front
of the orifice of the
PM
superior vena cava,
continues downwards in
the posterolateral wall, CT
OF
turns in beneath the
orifice of the inferior vena CS
cava (IVC) to ramify as a IVC ER
series of trabeculations in
the inferior isthmus.

11. CT Pathology
Sanchez-Quintana and Ho et al, Heart 2002

12. Mapping and Ablation of Focal AT (I)
ECG P wave polarity
Body surface potential mapping of atrial
activation
Single catheter mapping with bipolar
recording ‐‐‐ earliest activation
Single catheter mapping with unipolar
recording ‐‐‐ QS pattern

13. Mapping and Ablation of Focal AT (II)
Double ring catheters mapping
Mechanical pressure by catheter tip
3‐D mapping using Carto or Ensite system
to find the earliest activation site
Intracardiac echocardiography to identify
the anatomic site
Angiography, 3‐D MRI, 3D‐CT to identify
the atrial – venous structure

14. EKG characteristics of
atrial tachycardia

15. Electrocardiographic Localization of Focal AT
(Zipes DP, Jalife J.
Cardiac
Electrophysiology:
From cell to
bedside, 4th
edition. 2004; pg.
503)
Superolateral Inferolateral Annulus Septal
Focal atrial tachycardia is characterized by P waves separated by an isoelectric interval in all
ECG leads. There are various algorithms available that look at P-wave morphology. These
are useful, but the P-wave can often be obscured by the T wave or QRS complexes during the
tachycardia.

16. Intracardiac EKG
If the earliest signal is recorded by The origin of the AT is most likely
the… the…
HIS EGM Anteroseptal RA
Proximal CS EGM Posteroseptal RA
Low or high RA EGM Somewhere in the RA
Distal CS EGM Lateral LA
HRA EGM Right superior pulmonary vein

17. AF
SR AT

19. C. Before Ablation D. After Ablation

29. Surface ECG of repetitive nonsustained atrial tachycardia (AT)
originating from the right superior pulmonary vein (PV).

30. Differential Diagnosis of AT During
EP study

31. Differential Diagnosis of AT
• Ventricular burst pacing can be performed for longer periods of time
at a rate just slightly faster than the tachycardia cycle length, and
when the atrial activation is accelerated to the pacing rate,
indicating 1:1 ventriculoatrial conduction,
(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 505)

32. AT with a VAAV Pattern
(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 1061)

35. Prevalence and diagnostic value of
Baseline observation
J Am Col Cardiol 2000; 36:574-82 – Morady et al.

36. Prevalence and diagnostic value of
Tachycardia features
J Am Col Cardiol 2000; 36:574-82 – Morady et al.

37. Diagnostic value of
Pacing Maneuvers During PSVT
J Am Col Cardiol 2000; 36:574-82 – Morady et al.

38. Diagnostic value of
Pacing Maneuvers During PSVT
J Am Col Cardiol 2000; 36:574-82 – Morady et al.

42. New Mapping Technologies
• New mapping technologies such as basket catheters,
electroanatomic mapping and non-contact mapping have helped to
locate the site of the focus much quicker than the standard
mapping techniques. Now with the advent of Spiral type catheters
they also can be used to map the lower RA by the IVC, upper RA
and SVC and CSos.
(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 508)

43. What is the benefit of 3‐D mapping in focal AT?
3‐D mapping really improves the knowledge and
ablation results of focal AT?

44. Hypothesis: Wavefront Propagation during AT
QS pattern Multi-component
pattern
Wrap- Wrap-
around around
Effect (-) Effect (+)
Surrounding tissue Surrounding tissue with
without anisotropic anisotropic conduction
conduction

45. Single Focal AT

46. • Key Locations
– Identification of Focal Sites (if applicable) ‐
Focal
– Identification of Anatomical Barriers (if
applicable) ‐ Macroreentrant
– Identification of Scar (if applicable) –
Microreentrant (Focal)

47. Focal Ablation
•Once the site is identified 25 to 30Watts of RF energy are
delivered for 30‐60 seconds
•Acceleration of the tachycardia before termination is an
excellent sign.
•Also rapid termination of the tachycardia within 10 seconds of
starting the RF delivery is also a good sign.
•Successful focal ablation is verified by failure to reinduce the
AT before and during an isoproterenol infusion.
(Zipes DP, Jalife J. Cardiac Electrophysiology: From cell to bedside, 4th edition. 2004; pg. 1062-1063)