Functional characteristics and inducibility of atrioventricular nodal re-entry in rabbits of different ages.
OBJECTIVE
Many issues regarding atrioventricular nodal re-entry (AVNR) remain unexplored; however, no stable animal model for the study of AVNR has yet been developed. Clinically, AVNR is found more commonly in adults than children. We attempt to characterize AV nodal functional properties and inducibility of AVNRT using rabbits of three different age groups since we hypothesize that the inducibility of AVNR may increase as the subject ages.


RESULTS
We evaluated the inducibility of AVNR and the functional characteristics of the AV node in 6-month-old (Group 1), 2-month-old (Group 2), and at 1-week-old (Group 3) rabbits using a well-established rabbit heart model. We found that the inducibility of AVNR was higher in the 2-month-old group, compared with the 1-week-old group (30%). There was no functional difference between the two older groups (6-month-old and 2-month-old groups), however the youngest group (Group 3) showed better AV nodal functional properties. Regarding the correlation between inducibility and nodal functional properties, subgroups with AVNR demonstrated a longer AH maximum (AHmax) compared with the non-re-entry group, although there is no difference in age-adjusted AHmax. Regarding the correlation between inducibility and nodal functional properties, for the 1-week-old rabbits, subgroups with AVNR demonstrated a shorter AH minimum compared with the non-re-entry group (39.0 vs. 61.0, P=0.017).


CONCLUSIONS
Our results demonstrate that both 2-month-old and 6-month-old rabbits represent stable models for AVNR. Longer AH conduction time may lead to greater re-entry inducibility.
Wang
Jieh-Neng
JN
The Institute of Clinical Medicine, National Cheng Kung University Medical College, and Department of Internal Medicine, Chi-Mei Foundation Hospital, 138 Sheng Li Road, Tainan 70428, Taiwan.
Wu
Jing-Ming
JM
Wu
Wen-Shiann
WS
Lin
Li-Jen
LJ
D000375:Aging; D000818:Animals; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D011817:Rabbits; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology*