Jana Zdarska

Electrophysiological findings after surgical thoracoscopic atrial fibrillation ablation

BACKGROUND Hybrid ablation (a combination of thoracoscopic epicardial ablation and catheter ablation) has become a new technique for atrial fibrillation treatment. OBJECTIVE The goal of this study was to evaluate the success and electrophysiological follow-up after using the COBRA Fusion device to deliver a circumferential lesion set anterior to the pulmonary veins in an attempt to isolate the posterior left atrium (box isolation). METHODS Surgical ablation was carried out via a thoracoscopic approach using the COBRA Fusion radiofrequency catheter. An electrophysiology study was done 2-3 months later to verify box isolation (and to complete it, if needed) and to perform right-sided isthmus ablation. Fat thickness along the presumed box lesion line was measured using preprocedural computed tomography. RESULTS Thirty patients (mean age 60.0 ± 11.6 years; 22 men; 8 with long-standing persistent AF and 22 with persistent atrial fibrillation) were enrolled. The duration of the EP study was 216.3 ± 64.2 minutes. Box isolation, based on the EP study, was complete in 12 patients (40%) and incomplete in 18 patients (60%). Successful box isolation was achieved with catheter ablation in 16 of 18 patients (89%). A total of 39 gaps in these 16 patients were identified. Typical gap locations were the anterior-superior part of the superior pulmonary veins and the roofline. Fat thickness along the roofline was substantially higher than that along the inferior line (4.58 ± 1.61 mm vs 2.37 ± 0.76 mm; P < .001). CONCLUSION There is a relatively low rate of complete isolation using the COBRA catheter ablation system. The superior line and anterior parts of superior pulmonary veins have most conduction gaps.

Residual echocardiographic and computed tomography findings after thoracoscopic occlusion of the left atrial appendage using the AtriClip PRO device

OBJECTIVES Thoracoscopic occlusion of the left atrial appendage (LAA) has become a routine part of thoracoscopic ablation for the treatment of atrial fibrillation (AF). Evaluation of residual findings of the occluded LAA by echocardiography has yet to be described. METHODS Patients with AF indicated for hybrid ablation (thoracoscopic procedure followed by catheter ablation) were enrolled in this study. LAA was occluded as a routine part of the thoracoscopic procedure. Follow-up transoesophageal echocardiography was performed at the end of the procedure, 2-5 days and 2-3 months after the procedure (before the endocardial stage). The residual pouches of the LAA were measured in the mitral valve view (30-110°) and in the perpendicular view. The depth of the residual pouch was measured from the ostial plane (connecting the Coumadin ridge and the circumflex artery) to the deepest part of the residuum. The volume of the residual pouch and the distance from the circumflex artery to the proximal and the distal ends of the AtriClip were measured using computed tomography. RESULTS Forty patients were enrolled in this study. The success rate for the occlusion of the LAA, assessed on transoesophageal echocardiography 2-5 days after surgery, was 97.5%. Regarding the residual findings, no reperfused LAAs were found, and only residual stumps remained. The depth of the stump was 12.9 ± 5.9 mm, the area was 2.2 ± 1.1 cm2, and the volume was 3.6 ± 1.9 ml (all data are shown as mean ± standard deviation). CONCLUSIONS The occlusion of the LAA using an AtriClip PRO device was a clinically safe procedure with high efficacy and was associated with the presence of a small residual pouch after occlusion. Clinical trial registration NCT02832206.

Double-gap-in-roof reentrant tachycardia following surgical thoracoscopic atrial fibrillation ablation

A case of macro-reentrant tachycardia associated with a box lesion after thoracoscopis left atrial surgical atrial fibrillation (AF) ablation yet to be described. The goal was to clarify the mechanisms and electrophysiological characteristics of this type of tachycardia. A patient was admitted for an EP study following surgical thoracoscopic AF ablation (box lexion formation by right-sided Cobra thoracoscopic ablation). Thoracoscopic ablation was done as the first step of the hybrid ablation approach to the persistent AF; the second step was the EP study. At the EP study, he presented with incessant regular tachycardia (cycle length of 226 ms). An EP study with conventional, 3D activation and entrainment mapping was done to assess the tachycardia mechanism. Two conduction gaps in the superior line (roofline) between the superior pulmonary veins were discovered. The tachycardia was successfully treated with a radiofrequency application near the gap close to the left superior pulmonary vein; however, following tachycardia termination, pulmonary vein isolation was absent. A second radiofrequency application, close to the roof of the right superior pulmonary, vein closed the gap in the box and led to the isolation of all 4 pulmonary veins. No atrial tachycardia recurred during the 6-month follow-up. Conduction gaps in box lesion created by thoracospcopic ablation can present as a novel type of man-made tachycardia after surgical ablation of atrial fibrillation. Activation and entrainment mapping is necessary for an accurate diagnosis.

Effect of Elimination of Noisy ECG Leads on the Noninvasive Localization of the Focus of Premature Ventricular Complexes

High frequency of the premature ventricular complexes (PVCs) can lead to the development of the left ventricular dysfunction. Preoperative noninvasive localization of the PVC focus can decrease the time of the invasive electrophysiological study and improve the success rate of the radiofrequency ablation. Body surface potential (BSP) maps, patient-specific inhomogeneous torso model and inverse solution in terms of single dipole model were used for noninvasive localization of the PVC focus in five patients. BSP maps were computed for the initial 20 ms time interval of the ventricular activation (QRS complex in the ECG) from five selected PVCs in each patient. The inhomogeneous torso model included surfaces of torso, lungs, heart cavities and outflow tracts. To investigate whether the exclusion of the noisy ECG leads improves the accuracy of the inverse solution, the leads with the signal-to-noise ratio (SNR) less than the defined threshold value were excluded from the inverse computations. Four levels of the SNR were defined: 10, 20, 30, 40 dB. Locations of the PVC foci were computed by the inverse solution and compared with the catheter positions during successful radiofrequency ablation performed within invasive electrophysiological study. Removal of noisy ECG leads did not improve the PVC localization when the noisy ECG leads were located in left anterior torso region.

Cost effectiveness analysis of out-patient and remote monitoring of patients after pacemaker replacement from the perspective of the health care payer

Objectives: To determine the cost effectiveness of remote vs. outpatient monitoring of patients with pacemaker after device replacement due to battery depletion. Background: Despite the fact that modern pacemakers can be checked remotely, most checkups are still carried out during outpatient visits. So far, a cost effectiveness analysis of remote monitoring has not been performed in the Czech Republic. Patients, methods: A retrospective analysis was done using the files of 217 patients that had undergone pacemaker replacement between 2002 and 2005. All visits from 2002 to 2015 were analyzed. Using a pharmacoeconomic model, a cost minimization analysis was made to compare the costs of outpatient visits relative to remote monitoring of pacemakers, from the perspective of the health care payer. Results: The costs for the out-patient follow-up of the analyzed group of patients were calculated to be 802,709 CZK. Remote management for the same group would have cost 6,398,631 CZK. Cost minimization analysis showed that remote monitoring would have cost 5,595,922 CZK more than current standard care. Conclusion: Remote monitoring, is from the perspective of the health care payer, not associated with costs reduction in patients after pacemaker replacement due to battery depletion compared to standard out-patient follow-up.

The absence of effect of ganglionated plexi ablation on heart rate variability parameters in patients after thoracoscopic ablation for atrial fibrillation

Background Hybrid ablation [thoracoscopic ablation (TA) of atrial fibrillation (AF) followed by catheter ablation (CA)] is an increasingly common method of the treatment for patients with AF. The aim of this study was to assess the response to ganglionated plexi (GP) ablation in patients with a previous TA (i.e., to assess whether TA had resulted in damage to the GP. Heart rate variability (HRV) was used as a marker of the autonomic response. Methods Twenty AF patients underwent pulmonary vein isolation (PVI) plus GP ablation (GP group) and 18 AF patients underwent CA including GP ablation as a part of hybrid ablation (i.e., all patients had undergone a previous TA; Hybrid group). In each group, a 5 min electrocardiogram (ECG) obtained before and after the CA were analyzed. Time and frequency domain parameters were evaluated. Results Vagal responses (VR) during CA were observed in 12 (60%) patients in the GP group; however, in the Hybrid group, VR was not observed in any of the patients during CA. The change in normalized power in the low frequency (LF) component and the ratio between the LF and high frequency (LF/HF ratio) components of the HRV spectra, before and after ablation, were statistically significant in the GP group (3.3±2.6 before vs. 1.8±1.9 after ablation) but unchanged, before or after CA, in the Hybrid group. Conclusions GP ablation in patients subsequent to TA has a little influence on HRV parameters, which could be explained by GP damage during the preceding TA.

Routine use of intracardiac echocardiography for atrial flutter ablation is associated with reduced fluoroscopy time, but not with a reduction of radiofrequency energy delivery time

Background The ablation of cavotricuspid-isthmus (CTI) atrial flutter (AFL) dependent atrial flutter could be difficult in patients with complex anatomy of the CTI.The aim of the study was to assess whether the use of intracardiac echocardiography (ICE) was associated with less fluoroscopy time and faster ablations of cavotricuspid isthmus dependent atrial flutter (CTI-AFL). Methods Patients with an indication for an ablation of a CTI-AFL were enrolled. Patients in which ablation of a CTI-AFLas part of an atrial fibrillation ablation were not included. Randomization was done using the envelope method. Standard techniques (i.e., coronary sinus, 20-polar halo catheter, and an ablation catheter), and criteria of success (bidirectional block through the CTI) were used. In patients randomized to the ablation with ICE, a 10F AcuNav ICE probe (Siemens, Germany)was used. Results Seventy-nine patients were enrolled; 40 were randomized to ablation with ICE and 39 without ICE. The X-ray exposure was shorter (3.29±2.6 vs. 5.94±3.43 min, p<0.001) and total X-ray dose was reduced (3.30±1.98 vs. 6.68±5.25 Gy.cm2, p<0.001) in the ICE group. However, the total RF energy ablation time was not different between groups (ICE group: 604.56±380.46sec vs. 585.82±373.39 sec, p=0.8). The procedure duration was slightly longer in the ICE group (82.0±20.8 vs. 72.1±19.0 min, p=0.03). Procedural success was 100% (40/40) in the ICE group and 95% (37/39) in the control group. Two control patients required crossover to ICE at a prespecified point to achieve bidirectional block. There were two femoral hematomas in the ICE group and one in the control group. Conclusion The use of ICE for atrial flutter ablation is associated with less fluoroscopy time and improved ability to achieve bidirectional block compared to traditional conventional flutter ablation methods. However, it is not asoociated with reduced ablation time or overall procedure duration.