BY

Dr. Rania samir

Associate Professor of Cardiology

Ain Shams University

Atrial flutter occurs when the atria are stimulated to contract at 200-350 bpm usually because electrical impulses are traveling in a circular fashion around and around the atria.

Often the impulses are traveling around an obstacle like the mitral valve, tricuspid valve or the openings of the superior or inferior vena cavae.

The re-entry circuits often occupy large areas of the atrium & are referred to as “macro-reentrant”

characterized by a regular rate, a uniform flutter wave morphology with characteristic saw-toothed electrocardiographic appearance.

Atrial flutter represents the most important & most

common atrial tachyarrhythmia after AF The overall incidence of atrial flutter in a recent

population study was 0.88%,

0.05% in patients < 50 years old

5.87% among individuals > 80 years of age.

2.5 times more common in males Risk increases 3.5 times in presence of CHF Risk increases 1.9 times in presence of COPD

(Granada et al, 2000)

In 1905, William Ritchie first recorded atrial flutter with an ink-polygraph recorder

In 1913, Sir Thomas Lewis made the first clear-cut ECG description of atrial flutter

In 1921, Lewis considered that atrial flutter was the result of a circus movement

In 1970, Puech et al identified 2 types of atrial flutter: common type and rare type

Many different forms of atrial flutter exist & since it

was first described in 1911, many terms have been

used to characterize atrial flutter, particularly

recently, to the point that atrial flutter terminology

has become quite confusing

This has led to multiple classification schemes.

Based mainly on ECG criteria, the first simple

classification in 1970:

2 subclasses

Typical atrial flutter (common)

Atypical atrial flutter (rare or uncommon)

Typical atrial flutter:

Dominant -ve sawtooth

flutter waves with terminal low amplitude +Ve component in ECG leads II, III and aVF

+ve flutter waves in V1,

transition to –Ve in V6

Lead I is low amplitude

–Ve/isoelectric, aVL is

upright

Ain Shams University EP lab

Atypical atrial flutter:

+Ve , broad based, notched

flutter waves in II, III, aVF

- Ve, broad flutter waves in V1 ususally notched transitioning to +Ve across the pericordium to +Ve flutter waves in V6

lead I is upright, aVL is low amplitude –Ve & notched

Ain Shams University EP lab

Based on advanced EP mapping techniques which identified different EP- mechanisms of atrial flutter

Isthmus dependent atrial flutter

Non-Isthmus dependent atrial flutter

Atypical atrial flutter

The re-entry circuit is confined to RA & involves the CTI as a critical zone of

slow conduction

• CCW A. flutter

(commonest 90%)

• CW A. flutter (less

commom 10%)

• Lower loop re-entrry

any fixed macroreentrant atrial

circuit that doesn’t involve the CTI

• Lesion macroreentrant atrial tachycardia (most common)

• upper loop reentry

• LA flutter (rare)

Type II atrial flutter

heterogenous flutter wave morphology

May be due to rapid reentry with

variable fib. Conduction

ACC/AHA/ESC Guidelines 2003

Usually paroxysmal, occasionally persistent

Occurs commonly after open heart surgery

Associated with COPD, MVD or TVD, PE, thyrotoxicosis, and atrial enlargement.

Frequent association with AF.

In the presence of WPW syndrome, it may lead to 1:1 AV conduction and dire consequences.

A. Flutter is one of atrial tachyarrythmias occurring with SSS.

Most common ECG presentation HR 150 bpm, 2:1 AV conduction

HR 60 bpm

Reentry prerequisites:

Anatomical, natural

barriers or obstacles

Ant. Barrier………. TA

Post. Barrier…….. CT, ER

Acting as fixed or functional lines

of block establishing a circuit large

enough that the circulating

wavefront does not impinge on its

own tail of refractoriness

“Short circuiting”

Olgin, J. E. et al. Circulation 1995;92:1839-1848

isthmus dependent atrial

flutter was determined to be

due to a macroreentrant

circuit rotating in either a

counterclockwise

(common) or clockwise

(uncommon) direction in

the right atrium, with an

area of relatively slow

conduction in the low

posterior right atrium

IAS

CT

IVC ER

CS

TA

Esp with the use of class IC AADs

25-50 J

Elective restoration of SR

38-79%

20-40%

Atrial flutter is most often a nuisance arrhythmia & its clinical significance lies largely in its frequent association with AF or rapid ventricular response which is principally responsible for many of the associated symptoms So, maintenance of SR after CV is mandatory in cases of recurrent A. flutter

Based on the available long term data, drug treatment offered a limited ability to maintain SR without occasional to frequent recurrences of A.flutter, even when multiple agents are used.

Reported long term success rates ranging from 50% for

class I to 73% for class III (oral dofetilide) Also, long-term rate control alone usually requires large

doses of AV nodal blocking agents

Singh et al, Circulation 2000

Approaches to endocardial mapping of A flutter

include standard multielectrode catheters, Expanding

electrode arrays or 3D mapping techniques but still

Standard multielectrode catheter-based mapping still

remains the main tool for the study of A flutter

The recent advances in this therapeutic approach were associated with high success rates, low recurrence rates and minimal complications.

IAS

Isthm

IAS

Isthm IVC

LAO LAO

Large randomized trials, RF- ablation creating linear lesions across the critical zone of slow conduction (CTI) till achievement of CBIB as an endpoint of ablation

High success rates 90-100%

Low recurrence rate 6-9%

over a period of 9-17 mo

(Tai et al., 1998) (Wu et al.,2002)

RAO LAO

Ain Shams University EP lab

ACC/AHA/ESC guidelines,2003

Comparing the published success rates of AADs in maintaining SR to significantly high long term success rates of RF-ablation Favors RF ablation as an acceptable therapeutic approach of A . flutter

Although the success rates of RF-ablation using conventional & 3D mapping techniques are similar

Shorter fluoroscopy time (3.9±15 vs 22 ±6.3 min)

(Kottkamp et al, 2000)

Precise identification of discrete gaps within non-contiguous lesion lines the ability to renavigate to previously mapped & ablated sites

Extremely important for mapping & ablation of non-isthmus dependent A flutter.

Isthmus ablation in patients with atrial flutter has proved positive impact on QOL.

Catheter ablation is curative in many patients obviating the need for life-long AADs, and may be more cost effective on the long term than AAD therapy.

Substantial fluoroscopy exposure, which is necessary for conventional isthmus ablation, is significantly reduced with 3D mapping for isthmus ablation which have an impact on the long-term safety of this invasive treatment strategy.

First simple classification based on ECG patterns, in 1970

-Typical atrial flutter (Counter-clockwise)

- Atypical atrial flutter (Clockwise)

CT

IAS

IVC ER

During PCS pacing

Before ablation After ablation

Complete CW block

Ain Shams University EP lab

LRA pacing

Before ablation After ablation

Complete CCW block

Ain Shams University EP lab

Variation in the isthmus width

Wide isthmus (49 mm) making sharp angle with IVC 79°

Craniocaudally elongated RA with short isthmus (17 mm)

Isthmus width 17-54 mm

Isthmus width > 39 mm or Cath-IVC angle <81° assoc with difficuilty of reaching TA

Heidbüchel et al Circulation 2000

Variations in morphological features:

In ≈50% of pts the isthmus has global concave morphology (A)

In ≈ 45% of pts the isthmus is divided into flat smooth vestibule near TA side & pouch like recess near IVC side (4.3±2.1 mm)

Prominent thick EV (20%) of pts causing difficulty in reaching behind EV needing abl cath with shorter curve

Heidbüchel et al Circulation 2000

pouch like recess (varying from 1.5 to 9.4 mm deep), > 5mm deep pouch

Need for prompt restoration of sinus rhythm

DC cardioversion (25-50 J)

Elective restoration of sinus rhythm

Antiarrhythmic drug (ibutilide or class IC agent)

Rapid atrial pacing

Ventricular rate control: often required (β-blocker or calcium channel blocker), especially with use of class IC antiarrhythmic agent

TCL 240 ms

Ain Shams University EP lab

CS pacing before ablation CS pacing after ablation showing CW isthmus block

Ain Shams University EP lab

Before ablation After ablation

Ain Shams University EP lab