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Figure 3 (A) An endocardial activation sequence map of the left ventricle (LV) from Patient 22. A large area of earliest endocardial activation at the mid-anterior LV (red) suggests the mechanism of the tachycardia being of focal origin; however, the ventricular tachycardia (VT) could be entrained. Radiofrequency (RF) applications at the earliest endocardial sites failed to abolish VT. (B) An epicardial activation sequence map of the same VT as in (A). The activation sequence is consistent with a large re-entry circuit. Sites with green tags are close to the phrenic nerve, as the pacing at these sites produced phrenic nerve stimulation. (C) The epicardial voltage map. Normal voltage (>1.5 mV) tissue is purple. A large area of low-voltage scar is shown. Radiofrequency ablation in the isthmus created by the dense, unexcitable scars (tagged as gray) was not performed owing to proximity to the phrenic nerve (green tags). A series of RF applications along the inner loop sites over the right ventricle did not terminate VT. Additional RF applications from the dense scar to the normal voltage area near the exit over the LV terminated VT. A series of RF applications near the exit was made from the gray area to the normal voltage area, which terminated and abolished inducible VT, but was limited by proximity to the left anterior descending coronary artery (LAD). Ventricular tachycardia recurred 27 days later, likely as a result of the healing of these lesions.
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