Differentiation of atypical atrioventricular node re-entrant tachycardia from orthodromic reciprocating tachycardia using a septal accessory pathway by the response to ventricular pacing.
OBJECTIVE
The purpose of this study was to determine whether the response to ventricular pacing during tachycardia is useful for differentiating atypical atrioventricular node re-entrant tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT) using a septal accessory pathway.


BACKGROUND
Although it is usually possible to differentiate atypical AVNRT from ORT using a septal accessory pathway, a definitive diagnosis is occasionally elusive.


METHODS
In 30 patients with atypical AVNRT and 44 patients with ORT using a septal accessory pathway, the right ventricle was paced at a cycle length 10 to 40 ms shorter than the tachycardia cycle length (TCL). The ventriculo-atrial (VA) interval and TCL were measured just before pacing. The interval between the last pacing stimulus and the last entrained atrial depolarization (stimulus-atrial [S-A] interval) and the post-pacing interval (PPI) at the right ventricular apex were measured on cessation of ventricular pacing.


RESULTS
All 30 patients with atypical AVNRT and none of the 44 patients with ORT using a septal accessory pathway had an S-A-VA interval >85 ms and PPI-TCL >115 ms.


CONCLUSIONS
The S-A-VA interval and PPI-TCL are useful in distinguishing atypical AVNRT from ORT using a septal accessory pathway.
Michaud
G F
GF
Division of Cardiology, Department of Internal Medicine, Rhode Island Hospital, Brown University, Providence, Rhode Island 02905, USA. gmichaud@lifespan.org
Tada
H
H
Chough
S
S
Baker
R
R
Wasmer
K
K
Sticherling
C
C
Oral
H
H
Pelosi
F
F
Knight
B P
BP
Strickberger
S A
SA
Morady
F
F
D000328:Adult; D002304:Cardiac Pacing, Artificial; D003937:Diagnosis, Differential; D005260:Female; D006329:Heart Conduction System; D006346:Heart Septum / Q000294:innervation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis* / Q000628:therapy; D013614:Tachycardia, Paroxysmal / Q000175:diagnosis* / Q000628:therapy