Pacing maneuvers from the aortic cusps: A useful technique during ablation of focal arrhythmias arising from the aortic root.

BACKGROUND: The ablation of arrhythmias arising near the His-bundle region in the non-coronary aortic cusp (NCAC) is challenging. Among the aortic sinuses of Valsalva, the NCAC is located between the right atrium and the left atrium. For this reason, pacing from the NCAC should result in atrial capture while pacing from the right and left coronary cusps (LCC) may result in ventricular capture. The objective of this study is to prove that atrial capture during pacing from the sinuses of Valsalva may be used to confirm a correct position in the non-coronary cusp. METHODS: A total of 30 patients with structurally normal heart undergoing left sided ablation procedures, underwent electrophysiological study of the aortic cusps. Each of the aortic valve cusps was paced with increasing outputs and analyzed offline to determine their unique electrocardiographic characteristics. RESULTS: In the NCAC, we obtained an atrial capture in 29 out of 30 patients (96.6%). The atrial capture was highly specific for a position in the NCAC (p < .001). The median output required to capture from the cusp was 10 mA (range 5-25 mA) at a pulse width of 2 ms. In the right coronary cusp (RCC) and LCC, we obtained ventricular capture in all patients (100%). The median output required to capture from the cusp was 10 mA (range 10-25 mA) in RCC and 25 mA (range 10-25 mA) in LCC at a pulse width of 2 ms. CONCLUSIONS: Atrial capture during a pacemapping from the aortic cusps can be considered proof of a correct position in NCAC.