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.