PERSISTENCE OF SINGLE ECHO BEAT INDUCIBILITY AFTER SELECTIVE ABLATIONOF THE SLOW PATHWAY IN PATIENTS WITH ATRIOVENTRICULAR NODAL REENTRANTTACHYCARDIA - RELATIONSHIP TO THE FUNCTIONAL-PROPERTIES OF THE ATRIOVENTRICULAR NODE AND CLINICAL IMPLICATIONS
C. Tondo et al., PERSISTENCE OF SINGLE ECHO BEAT INDUCIBILITY AFTER SELECTIVE ABLATIONOF THE SLOW PATHWAY IN PATIENTS WITH ATRIOVENTRICULAR NODAL REENTRANTTACHYCARDIA - RELATIONSHIP TO THE FUNCTIONAL-PROPERTIES OF THE ATRIOVENTRICULAR NODE AND CLINICAL IMPLICATIONS, Journal of cardiovascular electrophysiology, 7(8), 1996, pp. 689-696
Residual Slow Pathway Conduction Effects on AVN Function. Introduction
: Residual slow pathway conduction with or without reentrant echo beat
s has been reported in 25% to 30% of patients undergoing ablation for
AV nodal reentrant tachycardia (AVNRT), Methods and Results: Fifty-eig
ht consecutive patients (aged 45 +/- 12 years) with slow-fast AVNRT un
derwent radiofrequency catheter ablation of the slow AV nodal pathway
(SP), Residual slow-fast echo beat was documented in 21 (36%) of 58 pa
tients (group A), The pre- and postablation AH intervals triggering th
e echo beats were similar (346 +/- 8 msec vs 352 +/- 6 msec, P = NS),
as were the pre- and postablation echo zones (55 +/- 6 msec vs 52 +/-
5 msec, P = NS) and functional refractory period of the SP, A consiste
nt prolongation of the AV nodal effective refractory period (AVN-ERP;
from 265 +/- 28 msec to 340 +/- 50 msec, P < 0.001) and the Wenckebach
cycle length (WBCL; from 298 +/- 41 msec to 438 +/- 43 msec, P < 0.00
1) was observed in all patients with abolition of SP conduction (group
B), In group A patients, the prolongation of WBCL was less (285 +/- 3
3 msec preablation, and 334 +/- 41 msec postablation, P < 0.001). Addi
tional pulses abolished the residual echo in 16 of 21 patients, and fu
rther prolongation of the AVN-ERP and WBCL comparable to those found i
n patients without a residual echo beat was observed, During 19 +/- 8
months follow-up, no patient had clinical recurrence of AVNRT. Conclus
ion: Residual single echo beat after SP ablation for AVNRT reflects th
e persistence of some portion of the SP with unchanged functional cond
uction properties whose prognostic significance is uncertain, A consis
tent increase of WBCL can be a reliable marker of complete abolition o
f slow pathway conduction and termination of AVNRT.