Nine site mapping schema for RVOT tachycardia

The septal aspect of the right ventricular outflow tract (RVOT) is depicted as seen in the 30° RAO view, divided into posterior (1, 4, and 7), intermediate (2, 5, and 8), and anterior (3, 6, and 9) sites. Pacing from posterior sites (1 and 7) results in a dominant R wave in lead I, and frequently in a small R wave before a dominant S wave in lead aVL. Pacing from anterior sites (3 and 9) always produces an initial Q wave (QS, Qr, or qR) in lead I, and a QS complex in a VL. Early precordial R wave transition (R/S >1 in V1, V2, or V3) is observed during pacing from posterior and superior sites. Moving diagonally from superior-posterior to inferior-anterior results in progressive delay in the precordial R wave transition.