LOCALIZATION OF OPTIMAL ABLATION SITE OF IDIOPATHIC VENTRICULAR-TACHYCARDIA FROM RIGHT AND LEFT-VENTRICULAR OUTFLOW TRACT BY BODY-SURFACE ECG

Background - Idiopathic ventricular tachycardia (VT) is known to arise from the right ventricular (RV) and left ventricular outflow tracts ( LVOT). However, reliable noninvasive methods to localize the optimum a blation site for VT have not been reported. Methods and Results - Body surface maps (BSM) and 12-lead ECGs were investigated in 35 VTs from the RVOT and 5 VTs from the LVOT in which the origin was confirmed dur ing the ablation procedure. The RVOT was classified into 8 subdivision s with the use of a 3-dimensional anatomic relation: anterior (A)-post erior (P), right (R)-left (L), and superior (S)-inferior (I). On the B SM, the following 3 indexes differentiated each location of the origin , with a diagnostic accuracy of 88% (A-P), 92% (R-L), and 77% (S-I): ( 1) the location of the minimum at the early-to-mid QRS (right, A; left , P), (2) the isopotential distribution in the left shoulder area afte r 30 ms of QRS (positive, R; negative, L), and (3) the downward moving time of the minimum at the early-to-mid QRS (greater than or equal to 50 ms, S; <50 ms, I). On the 12-lead EGG, (1) the QRS duration (>140 ms, A; less than or equal to 140 ms, P) and the R-wave pattern in lead s II and III (RR' or Rr', A, R, P), (2) the QS wave amplitude in aVR a nd aVL (aVR greater than or equal to aVL, R; aVR < aVL, L), and (3) th e r-wave amplitude in V-1 and V-2 (high, S; low, I) localized the orig in with 80%, 86% (A-P), 80% (R-L), and 66% (S-I) accuracy. R/S greater than or equal to 1 in lead V-3 was an index suggesting the LVOT origi n. Conclusions - The origin or the optimum ablation site of idiopathic VT from RVOT and LVOT can be localized with the use of indexes obtain ed with a BSM or 12-lead EGG.