What is the simplest and accurate way to predict the origin of Right atrial tachycardia(RAT) from left atrial tachycardia(LAT) ?
Look at the P waves in V 1 ( Don’t look further ! )
- A negative or a biphasic (+/- ) P wave in V 1 is 100% specific for a right atrial tachycardia
- A positive P in V1 or a biphasic ( –/+ ) P-wave in lead V1 has 100% sensitivity for a left atrial tachycardia
What are the incidence of left and right atrial tachycardia ?
RA- 75%
LA -25%
What are the common focus of right atrial tachycardia ?
- Crista terminalis (60% of all RAT)
- Tricuspid annulus
- Coronary sinus ostium
- Perinodal tissue
- Right side of IAS
- Right atrial appedage
What are the left atrial focus in Left atrial tachycardia ?
- Right & left pulmonary vein (50% of all LAT)
- Superior mitral annulus
- LAA
- CS body
- Left septum
(Please note this rule is not applicable for re-entrant tachycardias, atrial flutter, AV nodal tachycardias)
Source :
P-Wave Morphology in Focal Atrial Tachycardia
Development of an Algorithm to Predict the Anatomic Site of Origin
peter M. Kistler et all.
This paper from Melburne, Australia is a rare gem of an article for understanding atrial tachycardia .This paper won the the Eric and Bonny Prystowsky Heart Rhythm society Fellows Clinical Research Award, New Orleans, Louisiana, 2005.
Click on the Link to reach the article
http://content.onlinejacc.org/cgi/content/full/48/5/1010
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Dr.S.Venkatesan MD 
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