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Back to Cardiovascular Diseases
AV Junctional tachycardia
Updated: September 22, 2006
Introduction
Any tachyarrhythmia arising from the atria or the
atrioventricular junction is a supraventricular tachycardia. The
term supraventricular tachycardia is usually reserved for atrial
tachycardias and arrhythmias arising from the region of the
atrioventricular junction as a result of a re-entry mechanism (junctional
tachycardias). Junctional tachycardias cause a narrow complex
tachycardia.
Impulses originate in the AV junctional pacemaker at a rate
140-220/min and are conducted retrograde to the atria and antegrade
to the ventricles. P waves are negative in L2 and positive in AVR
and may closely precede, follow or coincide with normal QRS
complexes. When P waves precede QRS complexes, the PR interval is
less than 0.12 sec; when P waves follow QRS complexes, they appear
as splinters deforming the ST segment; when P waves coincide with
QRS complexes, they are not discernible. The paroxysmal form of
tachycardia is characterized by a ventricular rate 140-220, sudden
onset and offset and sudden termination or no change upon vagal
stimulation; the nonparoxysmal form is characterized by a
ventricular rate 100-140, gradual onset and gradual slowing or no
change upon vagal stimulation.
Epidemiology
Incidence
In the US, Junctional rhythms are common in patients with sick
sinus syndrome or in patients who have significant bradycardia that
allows the AV nodal region to determine the heart rate. Incidence of
paroxysmal supraventricular tachycardia is approximately 1-3 per
1000.
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Gender
Junctional escape rhythms, which are common in younger and/or
athletic individuals during periods of increased vagal tone (eg,
sleep), occur equally in males and females.
Age
Episodes of atrioventricular nodal re-entrant tachycardia may
occur at any age. It commonly presents for the first time in
childhood or adolescence, although it may appear at any age.
Junctional rhythms during sleep are common in children and in
athletic adults.
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