Prediction of PR interval prolongation after catheter ablation of incisional atrial tachycardia.

A three-dimensional (3D) mapping system is safe and effective for catheter ablation of incisional atrial tachycardia (IAT). Prolongation of the PR interval is occasionally observed after this procedure. Although a first-degree atrioventricular block is typically benign, an excessively prolonged PR interval can indicate a worse prognosis. Currently, a method to predict the PR interval after ablation therapy for IAT is lacking. We report the case of a 70-year-old woman with paroxysmal atrial tachycardia, in which our maneuver using a 3D mapping system and the electrophysiological findings enabled us to preoperatively predict the post-ablation PR interval. We believe that this method is useful for determining treatment strategies for IAT. Learning objective: Three-dimensional (3D) mapping systems can clearly visualize macro-reentrant circuits and enable the creation of precise ablation lines. When creating ablation lines for incisional atrial tachycardia, attention should be paid to the prolongation of the PR interval, because an excessively prolonged PR interval may indicate a worse prognosis. Herein, we have presented a method for predicting the post-ablation PR interval using a 3D mapping system and electrophysiological findings.

Influence of the right ventricular septum/free-wall boundary (hinge) on differentiation of the ventricular lead implantation site.

BACKGROUND: The prognosis associated with right ventricular (RV) free-wall pacing is worse than that of septal pacing. Identification of the pacing site using a 12­lead electrocardiogram (ECG) is controversial and may be influenced by ECG changes within the same septal or free-wall area. The relationship between the diagnostic capabilities of ECG and pacing sites has previously been qualitatively evaluated. However, in this study, this relationship was analyzed quantitatively, and accurate evaluation of the pacing site was determined using computed tomography (CT). METHODS: Of 779 consecutive outpatients, 65 who underwent pacemaker implantation and thoracic CT were prospectively included and classified into the following groups according to the lead tip position: free-wall, septal, or septum/free-wall boundary (hinge) group. The hinge was used as an anatomical marker, and the distance from the hinge to the lead tip was measured. Under RV pacing, a 12­lead ECG was obtained. ECG findings were evaluated using three criteria (including lead I, II, and aVL and precordial leads V5 and V6) previously reported to be useful in differentiating pacing sites. RESULTS: The lead tips were anchored at the free-wall in 10 patients, the septal wall in 19 patients, and the hinge in 32 patients. Paced QRS duration correlated with the distance from the hinge to the lead tip for the free-wall and septum (r = 0.47 and - 0.68, respectively). Estimation of the lead tip implantation site using the ECG algorithm was useful; however, the algorithm's accuracy decreased around the hinge. CONCLUSIONS: ECG is useful in differentiating pacing sites but is less accurate around the hinge, which may be the reason that the identification of the RV pacing site using ECG remains controversial.