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ecent clinical studies have demonstrated that longterm right ventricular apical (RVA) pacing imposes a risk of heart failure, ventricular arrhythmias, and cardiac death. 1-5 RVA pacing causes left ventricular (LV) mechanical dyssynchrony because of altered ventricular excitation that bypasses the His-Purkinje system. 6-9 Longterm RVA pacing results in LV dilatation associated with asymmetric LV hypertrophy, 10,11 regional myocardial perfusion defects 12-14 and a decrease in the LV ejection fraction (LVEF). 12,15,16 Pacing on the right ventricular (RV) septum, RV outflow tract and His or para-His bundle has been introduced as a potentially favorable alternative to RVA pacing to preserve a more physiologic ventricular activation. 8 However, previous investigations of alternative pacing sites have yielded inconsistent results, 17-23 which may be attributable, in part, to the fact that the pacing site was determined on a topological rather than functional basis. 24 Indeed, acute hemodynamic studies have demonstrated that individual optimization of the RV pacing sites could preserve LV performance in patients without LV dysfunction, and that there are substantial individual variations in the optimal pacing sites. 25,26 The paced QRS duration seems to be a practical indicator for determining the optimal RV pacing site. 14,19,22,23 However, information on the most appropriate pacing site to preserve long-term LV function is still limited.To address this issue, we investigated the effect of RV septal (RVS) pacing guided by QRS morphology on longterm LV mechanical synchronicity and function in patients with normal QRS duration and preserved LV function at baseline. Methods PatientsWe retrospectively studied 55 patients (22 men, 32 women; 70±10 years) undergoing dual-chamber pacemaker implantation for advanced atrioventricular block (AVB; n=33) or sinus node dysfunction (SND, n=22). In 40 patients (n=24 for AVB, n=16 for SND), pace mapping was carried out at the junction between the upper and middle segments of the RV septum using a hand-shaped stylet under fluoroscopy

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BACKGROUND Ablation of the pulmonary vein (PV) carina is occasionally required for PV isolation (PVI). Marshall bundle and epicardial connections between the right-sided PV (RtPV) carina and right atrium (RA) may be one of the mechanisms that necessitates carina ablation.OBJECTIVE We sought to clarify anatomical characteristics predictive of the necessity of carina ablation.METHODS Forty-five consecutive patients undergoing radiofrequency catheter ablation of atrial fibrillation were prospectively included in this study. Left atrial (LA) and PV size and morphology, and interatrial distance in the posterior aspect, were measured on cardiac computed tomography (CT) images.RESULTS For right-sided PVI, the patients were divided into 2 groups based on the necessity of RtPV carina ablation, Carina-ABL group (n 5 21) and Non-Carina-ABL group (n 5 24). The distance between the anterior portion of the RtPV carina and RA was shorter in the Carina-ABL group vs in the Non-Carina-ABL group (7.7 6 1.7 mm/m 2 vs 9.5 6 2.3 mm/m 2 ; P 5 .005), whereas other anatomical parameters (LA and RA volumes, right inferior PV angle, and ostial diameters of the RtPVs) did not differ between the groups. For leftsided PVI, the ostial diameter and circumference of the left superior PV were smaller in the Carina-ABL group (n 5 13) vs the Non-Carina-ABL group (n 5 32) (8.6 6 2.1 mm/m 2 vs 7.3 6 1.5 mm/m 2 ; P 5 .044, and 34.9 6 6.0 mm/m 2 vs 30.1 6 5.1 mm/m 2 ; P 5 .017, respectively).CONCLUSIONS A shorter interatrial distance for right-sided PVI and a smaller PV ostium for left-sided PVI were associated with the necessity of additional carina ablation. The presence and location of the epicardial fibers may be affected by the atrial and PV geometry.