Bruno Schwagten

The magnetic navigation system allows safety and high efficacy for ablation of arrhythmias

Aims We aimed to evaluate the safety and long-term efficacy of the magnetic navigation system (MNS) in a large number of patients. The MNS has the potential for improving safety and efficacy based on atraumatic catheter design and superior navigation capabilities. Methods and results In this study, 610 consecutive patients underwent ablation. Patients were divided into two age- and sex-matched groups. Ablations were performed either using MNS (group MNS, 292) or conventional manual ablation [group manual navigation (MAN), 318]. The following parameters were analysed: acute success rate, fluoroscopy time, procedure time, complications [major: pericardial tamponade, permanent atrioventricular (AV) block, major bleeding, and death; minor: minor bleeding and temporary AV block]. Recurrence rate was assessed during follow-up (15 ± 9.5 months). Subgroup analysis was performed for the following groups: atrial fibrillation, isthmus dependent and atypical atrial flutter, atrial tachycardia, AV nodal re-entrant tachycardia, circus movement tachycardia, and ventricular tachycardia (VT). Magnetic navigation system was associated with less major complications (0.34 vs. 3.2%, P = 0.01). The total numbers of complications were lower in group MNS (4.5 vs. 10%, P = 0.005). Magnetic navigation system was equally effective as MAN in acute success rate for overall groups (92 vs. 94%, P = ns). Magnetic navigation system was more successful for VTs (93 vs. 72%, P < 0.05). Less fluoroscopy was used in group MNS (30 ± 20 vs. 35 ± 25 min, P < 0.01). There were no differences in procedure times and recurrence rates for the overall groups (168 ± 67 vs. 159 ± 75 min, P = ns; 14 vs. 11%, P = ns; respectively). Conclusions Our data suggest that the use of MNS improves safety without compromising efficiency of ablations. Magnetic navigation system is more effective than manual ablation for VTs.

Initial experience with catheter ablation using remote magnetic navigation in adults with complex congenital heart disease and in small children

Background: The improved outcomes and increased availability of surgery for congenital heart disease (CHD) over the last three decades have created a small but steadily increasing subset of patients with unique needs: children and adults with complex arrhythmias in the setting of structural cardiac abnormalities. Radiofrequency catheter ablation (RFCA) in these patients, and in small children with normal cardiac anatomy, is effective but challenging. An understanding of specific anatomical and electrophysiological characteristics of these patients and the technical challenges in addressing them are critical to the success of this therapy. Tools specifically designed for intracardiac diagnosis and therapy in anatomically complex and/or small hearts remain scarce.

Prevalence, Characteristics, and Predictors of Pulmonary Vein Narrowing After Isolation Using the Pulmonary Vein Ablation Catheter

Background —The risk of pulmonary vein narrowing (PVN) after pulmonary vein isolation (PVI) using a novel multi-electrode ablation catheter (PVAC) is unknown. Methods and Results —Left atrial (LA) volume and PV diameters (PVD) were compared by computed tomography before and 3 months after PVI using duty-cycled phased RF energy (2:1 or 4:1 bipolar/unipolar ratio) in 50 patients. PVD was measured in a coronal and axial view at three levels (A=ostium, B=1cm more distal, C=2cm more distal). Moderate PVN was defined as a PVD reduction of 25-50%, severe PVN as > 50%. LA volume decreased by 12±12% (p<0.01). Axial PVD shortened by a median of 16% (IQR 28% to 5%) , 13% (IQR 25% to 5%) and 9% (IQR 21% to -3%) at level A, B and C respectively (p<0.01 for all); coronal PVD decreased by a median of 6% (IQR 24% to 7%), 11% (IQR 21% to 4%) and 8% (IQR 18% to -2%) (p<0.01 for all). Moderate PVN occurred in 30% of the PVs, in 78% of the patients; severe PVN occurred in 4% of the PVs, in 15% of the patients. PV diameter reduction was not related to changes in LA volume. Conclusions —PVAC ablation results in a consistent moderate reduction of the PV diameters predominantly at the ostium. Severe PVN in 15% of patients raises concerns about the risk for clinical PV stenosis.Background— The risk of pulmonary vein narrowing (PVN) after pulmonary vein isolation, using a novel multi-electrode ablation catheter, is unknown. Methods and Results— Left atrial volume and PV diameters were compared by computed tomography (CT) before and 3 months after pulmonary vein isolation using duty-cycled phased radio frequency energy (2:1 or 4:1 bipolar/unipolar ratio) in 50 patients. Pulmonary vein diameter was measured in a coronal and axial view at 3 levels (A, ostium; B, 1 cm more distal; C, 2 cm more distal). Moderate PVN was defined as a pulmonary vein diameter reduction of 25 to 50%, and severe PVN as >50%. Left atrial volume decreased by 12±12% (P<0.01). Axial pulmonary vein diameter shortened by a median of 16% (interquartile range [IQR] 28 to 5%), 13% (IQR 25 to 5%), and 9% (IQR 21 to −3%) at level A, B, and C, respectively (P<0.01 for all); coronal pulmonary vein diameter decreased by a median of 16% (IQR 24 to 7%), 11% (IQR 21 to 4%), and 8% (IQR 18 to −2%; P<0.01 for all). Moderate PVN occurred in 30% of the PVs, in 78% of the patients; severe PVN occurred in 4% of the PVs, in 15% of the patients. PV diameter reduction was not related to changes in left atrial volume. Conclusions— Isolation of the pulmonary veins using a multielectrode ablation catheter and duty cycled phased radiofrequency energy delivery results in a consistent moderate reduction of the PV diameters predominantly at the ostium. Severe PVN in 15% of patients raises concerns about the risk for clinical PV stenosis.

Prevalence, Characteristics and Predictors of Pulmonary Vein Narrowing after PVAC Ablation

Background —The risk of pulmonary vein narrowing (PVN) after pulmonary vein isolation (PVI) using a novel multi-electrode ablation catheter (PVAC) is unknown. Methods and Results —Left atrial (LA) volume and PV diameters (PVD) were compared by computed tomography before and 3 months after PVI using duty-cycled phased RF energy (2:1 or 4:1 bipolar/unipolar ratio) in 50 patients. PVD was measured in a coronal and axial view at three levels (A=ostium, B=1cm more distal, C=2cm more distal). Moderate PVN was defined as a PVD reduction of 25-50%, severe PVN as > 50%. LA volume decreased by 12±12% (p<0.01). Axial PVD shortened by a median of 16% (IQR 28% to 5%) , 13% (IQR 25% to 5%) and 9% (IQR 21% to -3%) at level A, B and C respectively (p<0.01 for all); coronal PVD decreased by a median of 6% (IQR 24% to 7%), 11% (IQR 21% to 4%) and 8% (IQR 18% to -2%) (p<0.01 for all). Moderate PVN occurred in 30% of the PVs, in 78% of the patients; severe PVN occurred in 4% of the PVs, in 15% of the patients. PV diameter reduction was not related to changes in LA volume. Conclusions —PVAC ablation results in a consistent moderate reduction of the PV diameters predominantly at the ostium. Severe PVN in 15% of patients raises concerns about the risk for clinical PV stenosis.Background— The risk of pulmonary vein narrowing (PVN) after pulmonary vein isolation, using a novel multi-electrode ablation catheter, is unknown. Methods and Results— Left atrial volume and PV diameters were compared by computed tomography (CT) before and 3 months after pulmonary vein isolation using duty-cycled phased radio frequency energy (2:1 or 4:1 bipolar/unipolar ratio) in 50 patients. Pulmonary vein diameter was measured in a coronal and axial view at 3 levels (A, ostium; B, 1 cm more distal; C, 2 cm more distal). Moderate PVN was defined as a pulmonary vein diameter reduction of 25 to 50%, and severe PVN as >50%. Left atrial volume decreased by 12±12% (P<0.01). Axial pulmonary vein diameter shortened by a median of 16% (interquartile range [IQR] 28 to 5%), 13% (IQR 25 to 5%), and 9% (IQR 21 to −3%) at level A, B, and C, respectively (P<0.01 for all); coronal pulmonary vein diameter decreased by a median of 16% (IQR 24 to 7%), 11% (IQR 21 to 4%), and 8% (IQR 18 to −2%; P<0.01 for all). Moderate PVN occurred in 30% of the PVs, in 78% of the patients; severe PVN occurred in 4% of the PVs, in 15% of the patients. PV diameter reduction was not related to changes in left atrial volume. Conclusions— Isolation of the pulmonary veins using a multielectrode ablation catheter and duty cycled phased radiofrequency energy delivery results in a consistent moderate reduction of the PV diameters predominantly at the ostium. Severe PVN in 15% of patients raises concerns about the risk for clinical PV stenosis.

Catheter Ablation of Ventricular Tachycardias Using Remote Magnetic Navigation: A Consecutive Case–Control Study

Remote Magnetic Navigation for VT Ablation. Background: This study aimed to compare acute and late outcomes of VT ablation using the magnetic navigation system (MNS) to manual techniques (MAN) in patients with (SHD) and without (NSHD) structural heart disease.

Usefulness of remote magnetic navigation for ablation of ventricular arrhythmias originating from outflow regions

Monomorphic ventricular tachycardia (VT) and symptomatic monomorphic PVCs originating from the region of the right and left outflow tracts are increasingly treated by radiofrequency (RF) catheter ablation. Technical difficulties in catheter manipulation to access these outflow tract areas, very accurate mapping and reliable catheter stability are key issues for a successful treatment in this vulnerable region. VT ablation from the aortic sinus cusp (ASC) in particular carries a significant risk of perforation, of creating left coronary artery injury and of damage to the aorta and the aortic valve.This case series describes RF ablation of VT originating in the outflow region using the remote magnetic navigation system (MNS). Potential advantages of the MNS are catheter flexibility, steering accuracy and reproducibility to navigate to a desired location with a low probability of perforating the myocardium. This report supports the idea of using advanced MNS technology during RF ablation in regions which are difficult to reach and thin walled, such as parts of the outflow tract and the ASC. (Neth Heart J 2009;17:245–9.)

Cryoablation: how to improve results in atrioventricular nodal reentrant tachycardia ablation?

Ablation for atrioventricular nodal reentry tachycardia is very effective, with a potential for damage to the normal conduction system. Cryoablation is an alternative, as it allows cryomapping, which permits assessment of slow pathway elimination at innocent freezing temperatures, avoiding permanent damage to the normal conduction system. It is associated with shorter radiation times and the absence of heart block in all published data. We discuss in this overview different approaches of cryoenergy delivery (focusing on spot catheter ablation), and how lesion formation is influenced by catheter tip size, application duration, and freezing rate. Some advantages of cryoenergy are explained. Whether these features also apply for an approach with a cryoballoon, e.g. for atrial fibrillation is unclear.

Effect of magnetic navigation system on procedure times and radiation risk in children undergoing catheter ablation.

Transcatheter ablation is an effective method to eliminate the arrhythmogenic substrate in symptomatic children with various types of arrhythmias. A reduction in the procedure and fluoroscopy time would decrease the hazardous effects of the ablation procedures. The magnetic navigation system (MNS) uses atraumatic catheters and facilitates accurate catheter placement in all regions of the heart for mapping and therapy delivery. We compared the efficacy and safety between a manual and MNS-guided approach for mapping and ablation of arrhythmias in a general pediatric arrhythmia population and in a subgroup of young children aged <10 years old. A total of 58 pediatric patients (mean age 12.2 +/- 3.2 years) were included in the present study. Of the 58 consecutive patients, 29 were treated with the MNS and 29 underwent conventional manual ablation. No demographic differences were present between the 2 groups. Acute success was achieved in 26 of 29 patients and 27 of 29 patients (p = NS). The mean procedure and fluoroscopy times were comparable in both study groups (168 +/- 56 minutes vs 183 +/- 52 minutes, p = NS; and 22 +/- 59 minutes vs 30 +/- 29 minutes, p = NS). In young children (aged <10 years), the success rate did not differ between the 2 groups (10 of 11 vs 6 of 8, p = NS). However, significant decreases in the procedure and fluoroscopy times were achieved (139 +/- 57 minutes vs 204 +/- 49 minutes and 13 +/- 7 minutes vs 31 +/- 28 minutes, respectively; p = 0.01 and p = 0.04). In conclusion, our data have strongly suggested that using the MNS for treating young children is advantageous, because it significantly reduced the procedure and fluoroscopy times without compromising efficacy.

The presence of extensive atrial scars hinders the differential diagnosis of focal or macroreentrant atrial tachycardias in patients with complex congenital heart disease

AIMS Atrial tachycardias (ATs) frequently develop in patients with congenital heart defects (CHDs). This study aimed to evaluate the effects of extensive atrial scar formation on the total atrial activation time (TAAT) and its relation to the tachycardia cycle length (CL) to classify AT. METHODS AND RESULTS Seventy-one patients were included and divided into two groups: patients without CHD (Group I, 35 patients) and with CHD (Group II, 36 patients). All patients underwent CARTO electroanatomical activation mapping. Two subgroups were created: centrifugal (CAT) or macroreentrant AT (MRAT). Total atrial activation time, CL, and mean bipolar signal amplitude (BiSA) were analysed. In Group I, 18 patients (51.4%) had CAT and 17 (48.6%) MRAT. The mean BiSA for Group I was 1.30 ± 0.32 mV. Total atrial activation time/CL ratios were different between CAT and MRAT (28.4 ± 16.9 vs. 66.6 ± 14.3%, P < 0.001). In Group II, 18 patients (50%) had CAT and 18 patients (50%) MRAT. The mean BiSA was 0.94 ± 0.50 mV and was not different for CAT and MRAT subgroups (1.04 ± 0.64 vs. 0.85 ± 0.29, P = 0.243). Total atrial activation time/CL ratios were comparable between CAT and MRAT patients (69.0 ± 40.4 vs. 83.6 ± 8.3%, P = 0.243). A significant lower BiSA was found for CAT with TAAT/CL ratios above 40% (0.62 ± 0.11 vs. 1.90 ± 0.18 mV, P < 0.001). A strong negative correlation was identified between the BiSA and the TAAT/CL ratio in patients with CAT in Group II (-0.742; P < 0.001). CONCLUSION Low mean BiSA values in CHD patients are associated with altered impulse propagation, making TAAT- and CL-based diagnostic tools inaccurate. Further diagnostic tests are needed to determine the correct mechanism of ATs.

Baffle puncture guided by transoesophageal echocardiography in a patient with dextrocardia and Mustard correction

A baffle puncture is a challenging procedure but can be safely done using direct visualization of the region of interest. To our knowledge, however, it has never been performed in a patient with dextrocardia. We present a 62-year-old male with dextrocardia, right isomerism, congenitally corrected transposition of the great arteries, persistent left-sided superior and inferior caval veins, atrial septum defect, and pulmonary valve stenosis. The atrial septum defect was surgically closed with a Teflon patch, a variant Mustard operation was performed, and also a prosthetic tricuspid valve was implanted. The patient developed multiple episodes of atrial tachycardia leading to acute heart failure on many occasions. An electrophysiological study was undertaken in order to create a bi-atrial electro-anatomical map. Owing to the presence of a prosthetic tricuspid valve, the femoral venous access was used and a baffle puncture was performed using continuous monitoring with fluoroscopy and transoesophageal echocardiography (TEE). The baffle puncture was successful and the tachycardia was ablated in the systemic venous atrium. To our knowledge, we present the very first case report demonstrating a successful baffle puncture in a patient with dextrocardia and Mustard correction. Direct imaging using TEE seems to be a very useful tool for guiding the puncture.