3.3 PMF electrophysiological characteristics
During the procedures, 32 PMF (25 clockwise and 7 counterclockwise) were
detected in 28 patients (24 with AT and 4 with AF as the clinical
arrhythmia). In 20 of the 32 PMF circuits (16 clockwise and 4
counterclockwise) it was possible to construct a high-density map and
measure the CVs as described earlier (Figure 4 , Videos
5,6 ). The mean CL of PMFs with pseudo-block (all clockwise) did not
differ significantly from the mean CL of usual PMFs (254±10 ms vs 248±13
ms, respectively; P=0.340). However, the lower CV in PMFs with
pseudo-block was of significantly lower value in comparison with the
lower CV in other thoroughly mapped PMF circuits (0.07±0.02 m/s vs
0.25±0.07 m/s, respectively; P<0.001). The same was true for
patients with PMF who had undergone additional LA ablation beyond PVI
(Figure 5 ). Conduction channels with width ≤1cm were found in 3
patients with PMF without MI pseudo-block. In these channels the mean CV
was 0.34±0.08m/s (range: 0.25-0.4 m/s) (Figure 6, Video 7 ). In
patients with PMF and ΜΙ pseudo-block the comparison of the ΜΙ length as
well as the MI width of the ablation area showed no difference compared
to patients with successful MI ablation. However, the width of the MI
ablation area was significantly longer in patients with unsuccessful MI
ablation (Table 2 ).