This document describes the electrocardiographic features of atrial flutter. It discusses: - Typical atrial flutter involves a macroreentrant circuit around the tricuspid valve that rotates either clockwise or counterclockwise. - Atypical flutter has a less well defined circuit and rate over 350 bpm. - ECG shows sawtooth flutter waves at 250-350 bpm without isoelectric segments. The ventricular response is typically 2:1 but can be variable. - Counterclockwise flutter has negative flutter waves in inferior leads and positive in V1. Clockwise is reversed. - Right versus left atrial flutter can be distinguished by the polarity of flutter waves in V1

1. ECG FEATURES OF ATRIAL
FLUTTER

2. • Atrial flutter is characterized by a rapid, regular atrial rhythm at a rate
of 250 to 350 beats/min.
• There are usually no isoelectric segments between the regular,
uniformly shaped, biphasic, sawtooth-like oscillations.
• Most commonly the ventricular response in the absence of
treatment is 2:1 but may be 4:1, 3:1, 3:2, or any other manifestation
of atrioventricular (AV) block .

3. Type I, or typical, atrial flutter
• macroreentrant atrial tachycardia.
• type I flutter requires the isthmus of tissue between the inferior vena
cava (IVC) and tricuspid annulus as a necessary component, it is often
referred to as "isthmus-dependent" flutter.
• common form (=90%) of isthmus-dependent flutter, the reentrant
circuit rotates around the tricuspid annulus in a counterclockwise
direction.
• Less often(10%), the reentrant circuit rotates in the opposite
direction, type I, typical, isthmus-dependent flutter, "reverse", or
"clockwise" flutter.

4. Type II, or atypical, atrial flutter
• was considered unclassified because the mechanisms are not fully
understood.
• any tachycardia fulfilling the classic ECG definition of a continuously
undulating pattern but not fitting the typical flutter patterns
(counterclockwise or clockwise) .
• The main distinguishing characteristics were an atrial rate greater
than 340 or 350 beats/min
• the inability to be entrained.

5. Scheinman et al classification
• CAVO-TRICUSPID ISTHMUS-DEPENDENT ATRIAL FLUTTER
• NONCAVOTRICUSPID-DEPENDENT ATRIAL FLUTTER

6. CCW Atrial Flutter
• Typical
• Most common type - 90%
• From a left anterior oblique (LAO) fluoroscopic view, the circuit
rotates in a CCW direction

7. cranial caudal activation
sequence along the right
atrial lateral wall,
across the cavotricuspid
isthmus in a lateral-to-
medial direction
superiorly in the right atrial
septum

8. Clockwise (CW) Atrial Flutter
• Reversed version of CCW AFL
• 10%
• same boundaries as its counterclockwise counterpart

9. ELECTROCARDIOGRAM IN TYPE I ATRIAL FLUTTER
• P waves are absent.
• Biphasic "sawtooth" flutter waves (F waves) are present at a rate of
about 300 beats/min, with the range for type I being 250 to 350
beats/min; in comparison, the flutter rate is 340 to 440 beats/min in
type II flutter .
• The F waves usually do not have an isoelectric interval between them,
unless the rate of the atrial flutter is slow.
• F waves have the appearance of a down sloping segment followed
by a sharp negative deflection, a sharp positive deflection that may
have a positive overshoot leading into the next downward deflection .

10. Counter-clockwise flutter
• Lead V1 -initial isoelectric component followed by an upright
component.
• With progression across the precordium, the initial component
rapidly becomes inverted and the second component isoelectric
usually by V2 to V3
• this produces the overall impression of an upright flutter wave in V1
which becomes inverted by V6.
• Lead I is low amplitude/isoelectric
• aVL usually upright.

11. clockwise flutter
• inferior leads- flutter waves are usually broadly positive, with characteristic
notching.
• However, there is an inverted component preceding the upright notched
component.
• Depending on the amplitude of this component, the appearance can be of
continuous undulation without an obviously predominant upright or inverted
component
• On other occasions, it may appear that the inverted component is dominant,
thus superficially mimicking counterclockwise flutter.
• V1 -broad negative and usually notched deflection
• transition across the precordium to an upright deflection in V6.
• Lead I -upright
• aVL - low amplitude negative and notched

14. Atrial flutter with 2:1 block:

16. • The ventricular response (R-R intervals) is usually one-half the rate of the atrial
input (ie, 2:1 AV nodal conduction with a ventricular response of about 150
beats/min).
• AV block greater than 2:1 in the absence of drugs that slow the ventricular
response suggests AV nodal disease which, in turn, may be part of the sick sinus
or tachy-brady syndrome.
• 1:1 AV response suggests accessory bypass tracts, sympathetic excess, and
parasympathetic withdrawal
• Even ratios of input to output (eg, 2:1, 4:1) are much more common than odd
numbers (eg, 3:1, 5:1).
• Odd ratios and shifting ratios (eg, alteration of 2:1 with 4:1) probably reflect
bilevel block in the AV node.
• The QRS complex is narrow unless there is functional aberration, preexisting
bundle branch or fascicular block, or preexcitation.

17. • The general rule is the shallow stroke (one with a lesser slope) is to
be termed as antegrade / initial deflection that will determine the
direction of flutter waves.
• In lead the polarity of F waves in V1 it will be opposite of that of
inferior leads.

18. • aVF/lead I flutter wave amplitude ratio was > 2.5 in all
counterclockwise but < 2.5 in all clockwise atrial flutters.
• The flutter wave nadirs in the inferior leads corresponded to the
upstrokes in V1 in all counterclockwise atrial flutters, but
corresponded to the downstrokes in V1 in all clockwise atrial flutters.

20. • typical atrial flutter (AFL)
• negative flutter waves in leads II, III, and aVF
• positive flutter waves in lead V1
• reverse typical AFL
• positive flutter waves in inferior leads
• negative flutter waves in lead V1

23. ECG features of type II AFL
• P waves are absent.
• Biphasic flutter waves (F waves) are present at a rate of 340 to 440
beats/min.
• The F waves usually do not have an isoelectric interval between them.
• There often is more apparent positivity in the F waves recorded in
the inferior leads.
• The F waves are regular and have a rather constant amplitude,
duration, morphology, and reproducibility throughout the cardiac
cycles. This uniformity distinguishes type II atrial flutter from coarse
atrial fibrillation.

25. Right atrial flutter
• Circuits due to anatomic obstacles that exist remote from the CTI.
• Right atrial scars due to surgical repair of congenital heart defects
serve as anatomic obstacles for macro-reentry.
• Scars in the posterolateral and inferolateral right atrium have been
found to be involved in flutter circuits.
• The ECG appearance of free wall AFL is highly variable
• Hallmark for a right atrial free wall flutter– inverted flutter wave in V1.
• Depending on the predominant direction of septal activation, right
atrial free wall flutter can mimic either clockwise or counterclockwise
flutter

27. Left atrial flutter
• less common
• Association with SHD including hypertension, mitral valve disease, left
atrial dilation, and cardiac failure.
• Circuits occur around regions of spontaneous scarring frequently
located in the posterior LA.
• Circuits may propagate around the mitral valve annulus, around
regions of scarring, and the ostia of the pulmonary veins or
infrequently may involve the septum rotating around the fossa ovalis.
• Surface ECG findings are variable, though the flutter wave amplitude
tends to be low.

28. Left atrial flutter
• The flutter wave usually shows a prominent positive deflection in lead
V1 and uncommonly is flat or isoelectric.
• The flutter waves in leads II, III, and aVF may be upright but are
frequently of low amplitude
• Owing to a high prevalence of generalized atrial disease and slower
conduction, longer cycle lengths with a greater isoelectric interval
between flutter waves have been observed.
• Mimic a focal atrial tachycardia

30. right-sided vs. left-sided
• A broad-based upright V1 is highly predictive of a left-sided AFL.
• V1 is deeply inverted, this is highly suggestive of a right-sided flutter.
• V1 has an initial isoelectric (or inverted) component (followed by an
upright component), this is consistent with a right AFL.
• V1 is biphasic or isoelectric, it is not helpful in predicting the chamber
of origin.

32. Atrial flutter
• should be considered in all regular narrow complex tachycardia with a
ventricular rate of ~150 bpm.
• Vagal manoeuvres may help differentiate sinus tachycardia from atrial
flutter.
• In atrial flutter vagal manoeuvres may be ineffective or result in a
rapid decrease in rate allowing flutter waves to be more easily seen.
• In atrial flutter with variable block the R-R distances will be multiples
of each other unlike atrial fibrillation in which no relationship exists
e.g. assuming atrial rate of 300bpm the R-R distance in 2:1 block is
400ms, in 3:1 block 600ms, in 4:1 block 800ms.

33. NARROW QRS TACHYCARDIA
• RESPONSE
• slowing of SA nodal activity can cause a temporary decrease in
the atrial rate (in patients with sinus tachycardia).
• slowing of AV nodal conduction can lead to AV nodal block,
which may "unmask" atrial electrical activity (ie, reveal P waves
or flutter waves) by decreasing the number of QRS complexes
that obscure the electrical baseline.
• Carotid sinus massage

34. NARROW QRS TACHYCARDIA
• some narrow QRS complex tachycardias that require AV nodal
conduction (especially AVNRT and AVRT)= the transient
slowing of AV nodal conduction can terminate the arrhythmia
by interrupting the reentry circuit.
• Less commonly, CSM can cause some atrial tachycardias to
slow and terminate.
• In some cases, no response is obtained.
Carotid sinus massage

35. Carotid sinus massage
NARROW QRS TACHYCARDIA

36. NARROW QRS TACHYCARDIA

37. NARROW QRS TACHYCARDIA
• Termination of the arrhythmia
• Termination with a P wave after the last QRS complex is
• most common in AVRT or AVNRT and is rarely seen with AT.
• Termination with a QRS complex can be seen with
• AVRT, AVNRT, or AT.
• If the tachycardia continues despite successful induction of at
least some degree of AV nodal blockade, the rhythm is almost
certainly AT or atrial flutter; AVRT is excluded and AVNRT is
very unlikely
Carotid sinus massage

38. A FLUTTER vs
• Focal atrial tachycardias classically exhibit alterations in cycle length with
speeding (‘warm up’) and slowing (‘cool down’) at the onset and
termination of tachycardia.
• The tachycardia cycle length is less helpful in differentiating between focal
and macro-re-entrant mechanisms. Although the cycle length is usually
≥250 ms in focal atrial tachycardia, shorter cycle lengths are now well
described. In this situation, particularly in the presence of intra-atrial
conduction delay, there may be no observable isoelectric interval between
P-waves, and an undulating baseline resembling AFL may be seen.
• conversely, macro-re-entrant circuits may have long cycle length in the
presence of SHD and anti-arrhythmic agents. 2 Furthermore, in the
presence of significant atrial scarring, there may be a long isoelectric
interval between flutter waves, incorrectly suggesting a focal mechanism

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