Optimizing safety and efficacy of catheter ablation procedures

Abstract In this thesis new developments in the field of invasive electrophysiology are studied and discussed. The aim of this work is to find strategies to optimize safety and efficacy of catheter ablation procedures. The most important developments that are studied in this thesis are the magnetic navigation system, the use of contact force sensing catheters and the introduction of new gold-tip ablation catheters. ROBOTICS: In Part I of this thesis we discussed the use of the first available magnetic navigation system. CONTACT FORCE SENSING: In Part II of this thesis the use of contact force sensing catheters is studied. The success of catheter ablation procedures depends on accurate substrate localization, followed by optimal delivery of energy provided by good tissue contact. LESION FORMATION: The introduction of the irrigated-tip RF catheter was a great improvement for invasive electrophysiology and increased success rates for many arrhythmias compared to nonirrigated-tip catheters. FUTURE PERSPECTIVES: In this thesis new developments in the field of invasive electrophysiology are discussed to optimize safety and efficacy of catheter ablation procedures

The first human experience of a contact force sensing catheter for epicardial ablation of ventricular tachycardia

Contact force (CF) is one of the major determinants for sufficient lesion formation. CF-guided procedures are associated with enhanced lesion formation and procedural success.We report our initial experience in epicardial ventricular tachycardia (VT) ablation with a force-sensing catheter using a new approach with an angioplasty balloon. Two patients with arrhythmogenic right ventricular cardiomyopathy who underwent prior unsuccessful endocardial ablation were treated with epicardial VTablation. CF data were used to titrate force, power and ablation time

Extreme interatrial conduction delay and regularization of atrial arrhythmias in a subgroup of patients with hypertrophic cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) patients may develop interatrial activation delay, indicated by a complete separation of the right and left atrial activation on the ECG. This study aimed to determine the prevalence of interatrial activation delay and the relation to atrial tachycardia (AT) cycle length (CL) in HCM patients. Methods: 159 HCM patients were included (mean age 52±14y). In group I (n=15, 9%) patients had atrial arrhythmias and progressive ATCL. In group II (n=22, 14%) patients had a stable ATCL. In group III (n=122, 77%) HCM patients without AT were included. P wave morphology and change in P wave duration (δP and Pmax) and changes in ATCL (δATCL) were analyzed. Mean follow-up was 8.7±4.7years. Results: In group I 33% (n=5) had separated P waves. In group II no P wave separation was identified (OR 1.50 [1.05-2.15], p=0.007). In group I patients were older compared to group III (62.6±15.1 vs. 50.2±14.0y, p=0.002) and had longer follow-up (13.4±2.2 vs. 7.8±4.6y, p<0.001). In group III Pmax and δP were significantly lower (105.1±22.0ms and 8.9±13.2ms, both p<0.0001). Group I patients had an increased LA size compared to group II (61.1±11.6 vs. 53.7±7.5mm, p=0.028) and higher E/A and E/E prime ratios (p=0.007; p=0.037, respectively). In group I 93.3% of the identified mutations were typical Dutch founder mutations of the MYBPC3 gene. Conclusion: In HCM patients a unique combination of separated P waves and regularization of ATs is associated with larger atria, higher LA pressures and myosin binding protein mutations

Radiofrequency Ablation at Low Irrigation Flow Rates Using a Novel 12-Hole Gold Open-Irrigation Catheter

BACKGROUND: High irrigation rates during radiofrequency (RF) ablation may cause fluid overload and limit lesion size. This in vivo animal study assessed the safety and efficacy of RF ablation at low irrigation rates using a novel 12-hole gold catheter. METHODS: A total of 103 lesions, created on the thigh of five mongrel dogs, were analyzed. Lesions were created using a 12-hole irrigated gold-tip (Au) and a six-hole irrigated platinum-iridium (PtIr) catheter (both 7F/3.5-mm electrode; BIOTRONIK SE & CO, KG, Berlin, Germany) in parallel and perpendicular orientation. RF current was delivered for 60 seconds at 30 W using 8 mL/min and 15 mL/min irrigation. Electrode temperature, steam pops, lesion dimensions, and coagulum formation were recorded. RESULTS: Electrode temperatures were lower for Au compared to PtIr in parallel (8 mL/min: 38.1 +/- 1.7 degrees C vs 48.0 +/- 4.8 degrees C, P < 0.0001; 15 mL/min: 36.0 +/- 1.5 degrees C vs 46.9 +/- 5.4 degrees C, P < 0.0001) and perpendicular position (15 mL/min: 35.5 +/- 1.2 degrees C vs 38.4 +/- 2.5 degrees C, P = 0.003). The number of steam pops between Au and PtIr was comparable for parallel (8 mL/min: 14% vs 27%, P = 0.65; 15 mL/min: 14% vs 43%, P = 0.21) and perpendicular orientation (8 mL/min: 25% vs 17%, P = 1.00; 15 mL/min: 18% vs 0%, P = 0.48). Au created larger volumes than PtIr at 8 mL/min irrigation (861 +/- 251 mm3 vs 504 +/- 212 mm3 , P = 0.004); however, for 15 mL/min, volumes were comparable (624 +/- 269 mm3 vs 768 +/- 466 mm3 , P = 0.46). No coagulum formation was observed for any of the catheters on the surface and catheter tip. CONCLUSION: RF ablation at low flow rate using a novel 12-hole irrigation Au catheter is safe and results in larger lesions than with a PtIr electrode

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. Published on behalf of the European Society of Cardiology. All rights reserved

High-volume lesions using a new second-generation open irrigation radiofrequency catheter are associated with the development of inhomogeneous lesions

BACKGROUND: After catheter ablation there is often a discrepancy between acute and chronic success rates. We aimed to evaluate major determinants for lesion quality and understand different manifestations of lesion structures. METHODS: In a canine thigh muscle model radiofrequency (RF) current was delivered for 60 seconds at 30 W (n = 39) or 50 W (n = 18) with 15-g contact force. A second-generation 12-hole gold open irrigation catheter (SGIT) and a first-generation six-hole platinum-iridium catheter (FGIT; Biotronik, Berlin, Germany) were used. Electrode and tissue temperatures (at the surface and 3.5-mm and 7-mm depth) were recorded and lesion dimensions were measured. Lesions with steam pops were excluded. Histological examination was performed to evaluate homogeneity of the lesions. Inhomogeneity was defined as a visual multiband lesion pattern indicating different histological characteristics. RESULTS: In total 57 lesions were created. Seventeen lesions were excluded (steam pops) and 40 lesions were analyzed. A total number of 11 homogeneous and 29 inhomogeneous lesions were identified. Using the SGIT catheter 16.7% of the lesions was homogeneous and 83.3% inhomogeneous; for FGIT it was 43.8% and 56.2% (P = 0.065), respectively. Homogeneous lesions had lower volumes as compared to inhomogeneous lesions (514.0 +/- 198.8 vs 914.8 +/- 399.1 mm, P = 0.003). Multiple logistic regression analysis indicated that the SGIT catheter is a significant predictor for inhomogeneous lesions (odds ratio 6.5, 95% confidence interval 1.1-38.8; P = 0.040) independent from power setting and flow rate. CONCLUSIONS: The development of inhomogeneous lesions after acute RF ablation is associated with higher lesion volumes and the use of the second-generation irrigation gold-tip catheter

Haemolysis as a first sign of thromboembolic event and acute pump thrombosis in patients with the continuous-flow

Background Despite advances in pump technology, thromboembolic events/acute pump thrombosis remain potentially life-threatening complications in patients with continuous-flow left ventricular assist devices (CF-LVAD). We sought to determine early signs of thromboembolic event/ pump thrombosis in patients with CF-LVAD, which could lead to earlier intervention. Methods We analysed all HeartMate II recipients (n = 40) in our centre between December 2006 and July 2013. Thromboembolic event/pump thrombosis was defined as a transient ischaemic attack (TIA), ischaemic cerebrovascular accident (CVA), or pump thrombosis. Results During median LVAD support of 336 days [IQR: 182–808], 8 (20%) patients developed a thromboembolic event/pump thrombosis (six TIA/CVA, two pump thromboses). At the time of the thromboembolic event/pump thrombosis, significantly higher pump power was seen compared with the no-thrombosis group (8.2 ± 3.0 vs. 6.4 ± 1.4 W, p = 0.02), as well as a trend towards a lower pulse index (4.1 ± 1.5 vs. 5.0 ± 1.0, p = 0.05) and a trend towards higher pump flow (5.7 ± 1.0 vs. 4.9 ± 1.9 L m, p = 0.06). The thrombosis group had a more than fourfold higher lactate dehydrogenase (LDH) median 1548 [IQR: 754– 2379] vs. 363 [IQR: 325–443] U/L, p = 0.0001). Bacterial (n = 4) or viral (n = 1) infection was present in 5 out of 8 patients. LDH > 735 U/L predicted thromboembolic events/ pump thrombosis with a positive predictive value of 88%. Conclusions In patients with a CF-LVAD (HeartMate II), thromboembolic events and/or pump thrombosis are associated with symptoms and signs of acute haemolysis as manifested by a high LDH, elevated pump power and decreased pulse index, especially in the context of an infection

Clinical outcome of ablation for long-standing persistent atrial fibrillation with or without defragmentation

Objective To assess the outcome and associated risks of atrial defragmentation for the treatment of long-standing persistent atrial fibrillation (LSP-AF). Methods Thirty-seven consecutive patients (60.4±7.3 years; 28 male) suffering from LSP-AF who underwent pulmonary vein isolation (PVI) and linear ablation were compared. All patients were treated with the Stereotaxis magnetic navigation system (MNS). Two groups were distinguished: patients with (n =20) and without (n =17) defragmentation. The primary endpoint of the study was freedom of AF after 12 months. Secondary endpoints were AF termination, procedure time, fluoroscopy time and procedural complications. Complications were divided into two groups: Major (infarction, stroke, major bleeding and tamponade) and minor (fever, pericarditis and inguinal haematoma). Results No difference was seen in freedom of AF between the defragmentation and the non-defragmentation group (56.2 % vs. 40.0%, P=0.344). Procedure times in the defragmentation group were longer; no differences in fluoroscopy times were observed. No major complications occurred. A higher number of minor complications occurred in the defragmentation group (45.0 % vs. 5.9 %, P=0.009). Mean hospital stay was comparable (4.7±2.2 vs. 3.4±0.8 days, P=0.06). Conclusion Our study suggests that complete defragmentation using MNS is associated with a higher number of minor complications and longer procedure times and thus compromises efficiency without improving efficacy

Cardiac allograft vasculopathy and donor age affecting permanent pacemaker implantation after heart transplantation

AIMS: The need for permanent pacemakers (PMs) after heart transplantation (HT) is increasing. The aim was to determine the influence of cardiac allograft vasculopathy (CAV), donor age, and other risk factors on PM implantations early and late after HT and its effect on survival. METHODS AND RESULTS: A retrospective, single‐centre study was performed including HTs from 1984 to July 2018. Early PM was defined as PM implantation ≤90 days and late PM as PM > 90 days. Risk factors for PM and survival after PM were determined with (time‐dependent) multivariable Cox regression. Out of 720 HTs performed, 62 were excluded (55 mortalities ≤30 days and 7 retransplantations). Of the remaining 658 patients, 95 (14%) needed a PM: 38 (6%) early and 57 (9%) late during follow‐up (median 9.3 years). Early PM risk factors were donor age [hazard ratio (HR) 1.06, P < 0.001], ischaemic time (HR 1.01, P < 0.001), and in adults amiodarone use before HT (HR 2.02, P = 0.045). Late PM risk factors were donor age (HR 1.03, P = 0.024) and CAV (HR 3.59, P < 0.001). Late PM compromised survival (HR 2.05, P < 0.001), while early PM did not (HR 0.77, P = 0.41). CONCLUSIONS: Risk factors for early PM implantation were donor age, ischaemic time, and in adults amiodarone use before HT. Late PM implantation risk factors were donor age and CAV. Late PM diminished survival, which is probably a surrogate marker for underlying progressive cardiac disease