Electrophysiologic characteristics and radiofrequency catheter ablation in atrioventricular node reentrant tachycardia with second-degree atrioventricular block.
BACKGROUND
Detailed electrophysiologic study of AV nodal reentrant tachycardia (AVNRT) with 2:1 AV block has been limited.


RESULTS
Six hundred nine consecutive patients with AVNRT underwent electrophysiologic study and radiofrequency catheter ablation of the slow pathway. Twenty-six patients with 2:1 AV block during AVNRT were designated as group I, and those without this particular finding were designated as group II. The major findings of the present study were: (1) group I patients had better anterograde and retrograde AV nodal function, shorter tachycardia cycle length (during tachycardia with 1:1 conduction) (307 +/- 30 vs 360 +/- 58 msec, P < 0.001), and higher incidence of transient bundle branch block during tachycardia (18/26 vs 43/609, P < 0.001) than group II patients; (2) 21 (80.8%) group I patients had alternans of AA intervals during AVNRT with 2:1 AV block. Longer AH intervals (264 +/- 26 vs 253 +/- 27 msec, P = 0.031) were associated with the blocked beats. However, similar HA intervals (51 +/- 12 vs 50 +/- 12 msec, P = 0.363) and similar HV intervals (53 +/- 11 vs 52 +/- 12, P = 0.834) were found in the blocked and conducted beats; (3) ventricular extrastimulation before or during the His-bundle refractory period bundle could convert 2:1 AV block to 1:1 AV conduction.


CONCLUSIONS
Fast reentrant circuit, rather than underlying impaired conduction of the distal AV node or infranodal area, might account for second-degree AV block during AVNRT. Slow pathway ablation is safe and effective in patients who have AVNRT with 2:1 AV block.
Lee
S H
SH
Department of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Chen
S A
SA
Tai
C T
CT
Chiang
C E
CE
Wen
Z C
ZC
Ueng
K C
KC
Chiou
C W
CW
Chen
Y J
YJ
Yu
W C
WC
Huang
J L
JL
Cheng
J J
JJ
Chang
M S
MS
D000368:Aged; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation / Q000009:adverse effects; D004594:Electrophysiology; D005260:Female; D006327:Heart Block / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*