In 13 dogs, creating a linear lesion on the right atrial free wall resulted in lesion reentry in 4 dogs and single-loop reentry in 9 dogs, with no figure-of-8 reentry induced.
In a canine model, the location of a fixed line of block and its functional extension determine the type of atrial flutter reentry, providing mechanistic insight into chronic atrial flutter following surgical repair of congenital heart lesions.
BACKGROUND: A line of block in the right atrium (RA) between the venae cavae is necessary to obtain classic atrial flutter (AFL). We tested the hypothesis that the location of that line of block would determine whether the AFL reentrant circuit would be due to single-loop reentry or figure-of-8 reentry. METHODS AND RESULTS: Simultaneous mapping from 392 sites (both atria and the atrial septum) was performed in 13 normal dogs before and after creating a linear lesion on the RA free wall. The lesion was 1 to 1.5 cm anterior and parallel to the crista terminalis (7 dogs) or posterior and close to the crista terminalis region (6 dogs). Sustained AFL (>2 minutes) was then induced. In 4 dogs with an anterior lesion, the AFL reentrant circuit traveled around the lesion (lesion reentry). In 9 dogs (3 with anterior lesions and 6 with posterior lesions), the AFL reentrant circuit included the anterior RA free wall, the atrial septum, and Bachmann's bundle (single-loop reentry). In these 9 dogs, the fixed line of block was extended to the superior and/or inferior vena cava by a functional line of block, thereby preventing lesion reentry. No figure-of-8 reentry was induced. CONCLUSIONS: In this model, the location of a fixed line of block and its functional extension determine the type of AFL reentry. These data provide an explanation for the chronic AFL that occurs in some patients after surgical repair of congenital heart lesions.
Tomita et al. (2001) studied Atrial flutter (n=13). Linear lesion on the right atrial free wall was evaluated on Type of atrial flutter reentrant circuit. In 13 dogs, creating a linear lesion on the right atrial free wall resulted in lesion reentry in 4 dogs and single-loop reentry in 9 dogs, with no figure-of-8 reentry induced.