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.