Background-Data on the comparative value of the circumferential pulmonary vein and the segmental pulmonary vein ablation for interventional treatment of atrial fibrillation are limited. We hypothesized that the circumferential pulmonary vein ablation approach was superior to the segmental pulmonary vein ablation approach. Methods and Results-One hundred patients with highly symptomatic atrial fibrillation were randomly assigned to undergo either circumferential (nϭ50) or segmental pulmonary vein ablation (nϭ50). Freedom from atrial tachyarrhythmias in a 7-day Holter monitoring at 6 months was the primary end point. Secondary end points were freedom of arrhythmia-related symptoms and a composite of pericardial tamponade, thromboembolic complications, and pulmonary vein stenosis (safety end point). On the basis of the results of the 7-day Holter monitoring at 6 months, 21 patients (42%) after circumferential pulmonary vein ablation and 33 patients (66%) after segmental pulmonary vein ablation (Pϭ0.02) were free of atrial tachyarrhythmia episodes. During the 6-month follow-up period, 27 patients (54%) after circumferential pulmonary vein ablation and 41 patients (82%) after segmental pulmonary vein ablation remained free of arrhythmia-related symptoms (PϽ0.01). No significant difference was found in the safety end point (6 versus 7 events; Pϭ0.77) in the circumferential versus segmental pulmonary vein ablation group, respectively. Conclusions-This study demonstrates no superiority of the circumferential pulmonary vein ablation over segmental pulmonary vein ablation for treatment of atrial fibrillation in terms of efficacy and safety.

Three-dimensional MR/CT images can be successfully extracted and registered to anatomically guided clinical AF ablations. The display of detailed and accurate anatomic information during the procedure enables tailored RF ablation to individual PV and LA anatomy.

Complication rates from AF ablation remain significant, despite improved techniques and increased awareness of procedural risks. Both advanced age and female gender predict major adverse events, suggesting careful consideration of the risk/benefit profile in these patients prior to ablation.

Background-New ablation strategies for atrial fibrillation or nonidiopathic ventricular tachycardia are increasingly based on anatomic consideration and require the placement of ablation lesions at the correct anatomic locations. This study sought to evaluate the accuracy of the first clinically available image integration system for catheter ablation on 3-dimensional (3D) computed tomography (CT) images in real time. Methods and Results-After midline sternotomy, 2.3-mm CT fiducial markers were attached to the epicardial surface of each cardiac chamber in 9 mongrel dogs. Detailed 3D cardiac anatomy was reconstructed from contrast-enhanced, high-resolution CT images and registered to the electroanatomic maps of each cardiac chamber. To assess accuracy, targeted ablations were performed at each of the fiducial markers guided only by the reconstructed 3D images. At autopsy, the position error was 1.9Ϯ0.9 mm for the right atrium, 2.7Ϯ1.2 mm for the right ventricle, 1.8Ϯ1.0 mm for the left atrium, and 2.3Ϯ1.1 mm for the left ventricle. To evaluate the system's guidance of more complex clinical ablation strategies, ablations of the cavotricuspid isthmus (nϭ4), fossa ovalis (nϭ4), and pulmonary veins (nϭ6) were performed, which resulted in position errors of 1.8Ϯ1.5, 2.2Ϯ1.3, and 2.1Ϯ1.2 mm, respectively. Retrospective analysis revealed that a combination of landmark registration and the target chamber surface registration resulted in Ͻ3 mm accuracy in all 4 cardiac chambers. Conclusions-Image

The horizontal and vertical circulation of the Weddell Gyre is diagnosed using a box inverse model constructed with recent hydrographic sections and including mobile sea ice and eddy transports. The gyre is found to convey 42 6 8 Sv (1 Sv 5 106 m3 s-1) across the central Weddell Sea and to intensify to 54 6 15 Sv further offshore. This circulation injects 36 6 13 TW of heat from the Antarctic Circumpolar Current to the gyre, and exports 51 6 23 mSv of freshwater, including 13 6 1 mSv as sea ice to the midlatitude Southern Ocean. The gyre's overturning circulation has an asymmetric double-cell structure, in which 13 6 4 Sv of Circumpolar Deep Water (CDW) and relatively light Antarctic Bottom Water (AABW) are transformed into upper-ocean water masses by midgyre upwelling (at a rate of 2 6 2 Sv) and into denser AABW by downwelling focussed at the western boundary (8 6 2 Sv). The gyre circulation exhibits a substantial throughflow component, by which CDW and AABW enter the gyre from the Indian sector, undergo ventilation and densification within the gyre, and are exported to the South Atlantic across the gyre's northern rim. The relatively modest net production of AABW in the Weddell Gyre (6 6 2 Sv) suggests that the gyre's prominence in the closure of the lower limb of global oceanic overturning stems largely from the recycling and equatorward export of Indian-sourced AABW.

Abstract-In catheter ablation of scar-related monomorphic ventricular tachycardia (VT), substrate voltage mapping is used to electrically define the scar during sinus rhythm. However, the electrically defined scar may not accurately reflect the anatomical scar. Magnetic resonance-based visualization of the scar may elucidate the 3D anatomical correlation between the fine structural details of the scar and scar-related VT circuits. We registered VT activation sequence with the 3D scar anatomy derived from high-resolution contrast-enhanced MRI in a swine model of chronic myocardial infarction using epicardial sock electrodes (nϭ6, epicardial group), which have direct contact with the myocardium where the electrical signal is recorded. In a separate group of animals (nϭ5, endocardial group), we also assessed the incidence of endocardial reentry in this model using endocardial basket catheters. Ten to 12 weeks after myocardial infarction, sustained monomorphic VT was reproducibly induced in all animals (nϭ11). In the epicardial group, 21 VT morphologies were induced, of which 4 (19.0%) showed epicardial reentry. The reentry isthmus was characterized by a relatively small volume of viable myocardium bound by the scar tissue at the infarct border zone or over the infarct.In the endocardial group (nϭ5), 6 VT morphologies were induced, of which 4 (66.7%) showed endocardial reentry. In conclusion, MRI revealed a scar with spatially complex structures, particularly at the isthmus, with substrate for multiple VT morphologies after a single ischemic episode. Key Words: ventricular tachycardia Ⅲ catheter ablation Ⅲ MRI C atheter ablation of scar-related monomorphic ventricular tachycardia (VT) is a promising therapy that may reduce morbidity and mortality associated with this condition. 1 Substrate voltage mapping allows ablation of scar-related VT during sinus rhythm in patients with hemodynamically unstable VTs where conventional activation mapping is difficult. 2 This electroanatomical mapping technique defines scar in the endocardium or the epicardium during sinus rhythm, and the infarct border zones are ablated.However, scar detection using the voltage-based substrate mapping has several limitations. First, it is essentially 2D because it defines the extent of scar on the surface, either endocardial or epicardial, and does not provide complex 3D anatomy of the scar. Second, spatial resolution of the voltagebased scar definition is limited by the number of points studied by the catheter operator. Lastly, electrically defined scar may not necessarily be identical with anatomical scar. For example, anatomically scarred myocardium with hypertrophy may be electrically defined normal. 3 To elucidate the 3D anatomical correlation between the fine structural details of the scar and scar-related VT circuits, we registered VT activation sequence with the 3D scar anatomy derived from high-resolution contrast-enhanced MRI in a swine model of chronic myocardial infarction (MI). To achieve precise registration between the electrode l...

Despite oral anticoagulation treatment, there is a small but significant incidence of LA thrombus by TEE prior to AF ablation. A CHADS(2) score >or= 2 and larger LA diameter are independent predictors of LA thrombus in this patient population, while type of AF or rhythm at the time of TEE is not. The risk of LA thrombus is low in patients with a CHADS(2) score of 0 and in patients with an LA diameter < 4.5 cm.

Our study shows a high rate of recurrence in ARVD/C patients undergoing RFA of VT. This likely reflects the fact that ARVD/C is a diffuse cardiomyopathy with progressively evolving electrical substrate. Further studies are needed to define the precise role of RFA of VT in ARVD/C.