This
is a rapid, regular atrial tachyarrhythmia, less common than
PSVT’s or atrial fibrillation. It can occur with underlying
atrial fibrillation. It can occur with underlying atrial disease,
cardiomyopathies, and less frequently coronary artery disease,
mitral valve disease (see fig
44a), congenital heart disease, especially post operative
transposition of great vessels (see fig
23e), tetralogy of Fallot (see fig
23c), or atrial septal defect (see fig
112a,
112b). See other causes below.
Type
1:
has a rate of 250-320/m (close to 300/m) or low as 240-250/m
to high of 340-350/m (figure
5a).
Type
2:
atrial rate 350-450/m, with the ventricular rate a fraction
of the atrial rate, 2:1 conduction or 4:1 conduction at 150
and 75/m most commonly. The ekg pattern is the same as type
1 above ( only the rate is faster). Figure
5c shows type 2 with with a complete AV block and an atrial
rate of 366 per minute and a ventricular rate of 40 a minute.
Atrial flutter generates a defined pattern of atrial activity
in the EKG with a "sawtooth" pattern in leads II, III, AVF without
a defined isoelectric line between F waves (see
figure 5a).
But lead V1 records definite isoelectric lines.
Massage
of the carotid sinus may unmask the flutter waves, and also
it increases the F wave rate (see figure 5b).
| Sites
of Occurence of Atrial Flutter |
1.
The most common form of atrial flutter is attributable to a
large reentrant loop confined to the right atrium that travels
in a counterclockwise direction, caudiocrandially in the interatrial
sptum and craniocaudally in the right free atrial wall.
A.
This common form of atrial flutter is characterized electrocardiographically
by sawtoothed flutter waves that are negative in leads 11, 111,
and aVF and show continual electrical activity ( lack of an
isoelectric interval between flutter waves, see figure
5a).
B.
In this type of atrial flutter, an area of slow conduction is
present in the posterolateral to posteromedial inferior right
atrium between the tricuspid valve annulus and the inferior
vena cava orifice ( figure
11f ).
Reference:Schwartzman,D.
and OTHERS,Conduction Block in the Inferior Vena Caval-Tricuspid
Valve Isthmus:Association With Outcome of Radiofrequency Ablation
of Type 1 Atrial Flutter,J AM Coll Cardiol 1996;28:1519-31
This
critical isthmus of slowed conduction is crucial to the maintenance
of the reentrant conduction and represents the site of successful
radiofrequency ablation that eliminates atrial flutter.
Reference:Schwartzman,D.
and OTHERS,Conduction Block in the Inferior Vena Caval-Tricuspid
Valve Isthmus:Association With Outcome of Radiofrequency Ablation
of Type 1 Atrial Flutter,J AM Coll Cardiol 1996;28:1519-31
2.
Due to reentry around an area of fibrosis in either atrium
Reference:Zipes,D.P.,Clinical
Application of the Electrocardiogram,JACC,vol.36,no/6,2000,pp.1746-8
