Figure 4 Pseudo Reentrant Circuit in a Patient with Previous MV
Replacement
The block line and scar create the false diagnosis of small reentrant
circuit. Atrial tachycardia was mapped in the RA in Patient with a prior
MV replacement (AT TCL=204ms). A: LAT map of the RA during AT
demonstrating “chaotic activation”. B: Reannotating the points by
moving the window of interest resulted in the appearance of the
early-meets-late pattern in the posterior RA. C: There was a
non-conducting area on the bipolar map in the posterior RA. Based on the
early-meets-late pattern around the posterior RA corresponding to the
area of low voltage, small loop reentry was considered to be the
mechanism of AT. D, E, F: There was no evidence of wavefront rotation on
the ripple map, rather splitting of wavefronts on either side of the low
voltage area (See Movie VII in the Data Supplement). The ripple map
demonstrated that a line of conduction block prevented small loop
reentry around this pitch of scar, evident by a line of double
potentials long it (black dotted line). The pattern of activation is
represented by yellow arrow line. Finally, perimitral circuit was
confirmed, and ablation of anterior line in the LA terminated AT in this
case. MV: mitral valve; AT: atrial tachycardia; LA: left atrium; TCL:
tachycardia cycle length; abbreviations as in Figure 1.