Ablation for periaortic VTs
Two patients with periaortic VTs underwent catheter ablation. One
patient (Case1) could not undergo ablation because of double mechanical
valve replacement, which prevented access to the left ventricle.
In case2, clinical VT1 with LBBB and non-clinical VT2 with RBBB
configuration were provoked. The mechanisms of the VTs were diagnosed
with re-entry due to reproducible induction by programmed stimuli, and
branch block re-entry was unlikely based on intracardiac
electrocardiography. However, the precise circuits of the VT1/2 could
not be analyzed because of their hemodynamic instability. On substrate
mapping, local fragmented potentials with low voltage zones were
observed in the RVOT septal position in accordance with the distribution
of LGE on cardiac MRI. We obtained a good pace map for clinical VT1 in
the septal RVOT below AV in the low voltage zone (Figure 3A/B/C) with
pacing delay (Stimulus-QRS: 47.0ms) and for non-clinical VT2 in AMC near
the site of aortic valve. Diastolic potentials during the VTs were not
observed, respectively. We used radiofrequency in the areas of the
septal RVOT and the AMC, which resulted in successful immediate
suppression of each periaortic VT.
In case3, 3 types of VTs were provoked in the session. The mechanisms of
VT1-3 were diagnosed with re-entry but precise circuits could not be
analyzed in a manner similar to case2. We perfomed pace mapping and
found that clinical VT1 originated from the left coronary cusp (LCC),
VT2 was suspected from the epicardium side of the LV. VT3 was originated
from RVOT and we confirmed the local fragmented potential and low
voltage zone in RVOT septal side as same as case2. We used
radiofrequency in the area of LCC and RVOT and succeeded to suppress the
multiple VTs.