A slow decrementally conducting accessory pathway ablated at an unusual
location: Aorto-Mitral continuity
34 years old man with frequent palpitations referred to our center.
Three standard diagnostic catheters were introduced through left and
right femoral veins and placed in right atrium, right ventricle and
coronary sinus positions. A narrow complex tachycardia with long
RP-short PR could be initiated after extarstimulation from HRA following
an AV nodal jump. The earliest retrograde atrial activation was recorded
from His bundle position. RV apical pacing showed decremental with
earliest atrial activation in His area, although no fused V-A potential
was recorded in either CS or His position. His synchronous pacing from
RV apex failed to advance or reset the arrhythmia. Morady maneuver by RV
overdrive pacing repeatedly terminated the tachycardia. Mapping was
initiated from His region and extended to all anticipated areas from
parahisian region to tricuspid annulus, posteroseptal TV ring and CS.
The construction of RA activation map failed to reveal earliest
activation site. Mapping catheter was introduced through femoral artery
and advanced to the left ventricle. At anteroseptal mitral annulus
corresponding to Aorto-Mitral continuity, we recorded the earliest
retrograde atrial activation (A-distal CS =50 ms). RF energy (30 W) was
delivered using an irrigate tip catheter during tachycardia and resulted
in termination of tachycardia immediately.