Characteristics of wavefront propagation in circuits causing human ventricular tachycardia

The conduction characteristics of human ventricular tachycardias (VT) have not been fully defined. The authors used a non-contact system to map 11 reentrant VT in 8 patients. Propagation velocities and 3-dimensional angles of turn were calculated from Cartesian co-ordinates. The complete diastolic pathway (DP) was mapped in 7 VT patients. DP wavefront velocity was 0.82±0.49 m/s. Significant changes (>5 degrees/mm) in trajectory of propagation (TOP) occurred within 8 DP segments, in which propagation slowed to 0.41±0.11 m/s compared with 0.91±0.16 m/s preceding (p<0.05) and 1.07±0.33 following (p<0.05) change in TOP. At entry turning points (TP) propagation velocity slowed from 1.3±0.4 ms to 0.6±0.26 ms (P<0.001), but did not change at exit TP on leaving the distal DP (0.72±0.28 vs 0.8±0.25 m/s, p=ns). In conclusion, slowing of propagation in human VT circuits occurs over regions of wavefront turning