Figure 6.

Ventricular extrastimulus testing revealed multiple retrograde atrial activations, including an earliest atrial activation in the distal CS (red arrows). This finding was reproducible, suggesting the presence of a left lateral pathway. The atrial activations of the extrastimulus beats (blue arrows) possibly represent fusion with the pathway. The VA times are stable for the first two beats (left lateral pathway) and decremental, following the vetricular extrastimuli. The a VH is stable and HA is decremental, suggestive of retrograde conduction through the AV node.