Experimental, Pathologic, and Clinical Findings of Radiofrequency Catheter Ablation of Para-Hisian Region From the Right Ventricle in Dogs and Humans.

BACKGROUND: Ablation of para-Hisian accessory pathway (AP) poses high risks of atrioventricular block. We developed a pacing technique to differentiate the near-field (NF) from far-field His activations to avoid the complication. METHODS AND RESULTS: Three-dimensional mapping of the right ventricle was performed in 15 mongrel dogs and 23 patients with para-Hisian AP. Using different pacing outputs, the NF- and far-field His activation was identified on the ventricular aspect. Radiofrequency application was delivered at the NF His site in 8 (group 1) and the far-field His site in 7 dogs (group 2), followed by pathologic examination after 14 days. NF His activation was captured with 5 mA/1 ms in 10 and 10 mA/1 ms in 5 dogs. In group 1, radiofrequency delivery resulted in complete atrioventricular block in 3, right bundle branch block with HV (His-to-ventricular) interval prolongation in 1, and only right bundle branch block in 2 dogs, whereas no changes occurred in group 2. Pathologic examination in group-1 dogs showed complete or partial necrosis of the His bundle in 4 and complete necrosis of the right bundle branch in 5 dogs. In group 2, partial necrosis in the right bundle branch was found only in 1 dog. Using this pacing technique, the APs were 5.7±1.2 mm away from the His bundle located superiorly in 20 or inferiorly in 3 patients. All APs were successfully eliminated with 1 to 3 radiofrequency applications. No complications and recurrence occurred during a follow-up of 11.8±1.4 months. CONCLUSIONS: Differentiating the NF His from far-field His activations led to a high ablation success without atrioventricular block in para-Hisian AP patients.

[Arrhythmia in adults with congenital heart defects : Atrial tachycardia]. / Arrhythmien bei Erwachsenen mit angeborenen Herzfehlern : Atriale Tachykardien.

Atrial arrhythmias are frequently encountered in patients with congenital heart disease (CHD) with or without corrective surgery and respond to pharmacological therapies with only limited success. This review describes the technologies currently available for performing successful ablation procedures in this very complex patient cohort. In addition to an understanding of the underlying anatomy, which can be supplemented by 3D imaging with the aid of magnetic resonance imaging (MRI) or computed tomography (CT), the choice between the different 3D mapping systems (sequential versus simultaneous) is presented. Finally, conventional manual navigation is compared with magnetic navigation and then discussed with regard to the respective arrhythmias encountered with the different forms of CHD.