3D model-based catheter tracking for motion compensation in EP procedures

Two cases of radiation-induced skin injuries occurring after radiofrequency catheter ablation therapy for atrial fibrillation

Catheter ablation is widely accepted as the best remaining option for the treatment of atrial fibrillation if drug therapy fails. Ablation procedures can be guided by 3-D overlay images projected onto live fluoroscopic X-ray images. These overlay images are generated from either MR, CT or C-Arm CT volumes. As the alignment of the overlay is often compromised by cardiac and respiratory motion, motion compensation methods are desirable. The most recent and promising approaches use either a catheter in the coronary sinus vein, or a circumferential mapping catheter placed at the ostium of one of the pulmonary veins. As both methods suffer from different problems, we propose a novel method to achieve motion compensation for fluoroscopy guided cardiac ablation procedures. Our new method localizes the coronary sinus catheter. Based on this information, we estimate the position of the circumferential mapping catheter. As the mapping catheter is placed at the site of ablation, it provides a good surrogate for respiratory and cardiac motion. To correlate the motion of both catheters, our method includes a training phase in which both catheters are tracked together. The training information is then used to estimate the cardiac and respiratory motion of the left atrium by observing the coronary sinus catheter only. The approach yields an average 2-D estimation error of 1.99 ± 1.20 mm.KeywordsPulmonary VeinLeft AtriumRespiratory MotionAblation ProcedureMotion CompensationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Atrial fibrillation (AFib) has been identified as a major cause of stroke. Radiofrequency catheter ablation has become an increasingly important treatment option, especially when drug therapy fails. Navigation under X-ray can be enhanced by using augmented fluoroscopy. It renders overlay images from pre-operative 3-D data sets which are then fused with X-ray images to provide more details about the underlying soft-tissue anatomy. Unfortunately, these fluoroscopic overlay images are compromised by respiratory and cardiac motion. Various methods to deal with motion have been proposed. To meet clinical demands, they have to be fast. Methods providing a processing frame rate of 3 frames-per-second (fps) are considered suitable for interventional electrophysiology catheter procedures if an acquisition frame rate of 2 fps is used. Unfortunately, when working at a processing rate of 3 fps, the delay until the actual motion compensated image can be displayed is about 300 ms. More recent algorithms can achieve frame rates of up to 20 fps, which reduces the lag to 50 ms. By using a novel approach involving a 3-D catheter model, catheter segmentation and a distance transform, we can speed up motion compensation to 25 fps which results in a display delay of only 40 ms on a standard workstation for medical applications. Our method uses a constrained 2-D/3-D registration to perform catheter tracking, and it obtained a 2-D tracking error of 0.61 mm.

Background Data from the European Atrial Fibrillation (AF) Ablation Long-Term Registry suggest that there are significant differences in the volume of AF ablation procedures performed across different centers even in the same country. If these differences in AF ablation volume between centers reflect regional, socioeconomic, infrastructural/technical or other disparities has not been addressed till now. Purpose The aim of this study was to investigate patient and non-patient related differences among European AF ablation centers according to the volume of AF ablations performed. Methods Data for this analysis originate from the European AF Ablation Long-Term Study, a prospective registry designed to describe the clinical epidemiology of patients undergoing AF ablation. Based on 25th and 75th percentiles of AF ablation numbers performed, the participating centers were classified into high volume (HV) (≥250 procedures/year), medium volume (MV) (<250 and ≥58/year) and low volume (LV) (<58/year). Patient (demographics, comorbidities) and non-patient (center infrastructure, procedural characteristics) related differences were assessed. Results A total of 91 centers in 26 European countries enrolled 3368 patients. There were no significant differences concerning regional distribution, hospital/cardiology facilities or services provided among centers with the exception of electrophysiology procedures and labs which were more abundant in HV centers (p=0.02 and <0.001 respectively). HV and MV centers ablate twice more cases of long-standing persistent and persistent AF compared to LV centers, in which paroxysmal AF reaches 78.9% of all cases (Figure A). Accordingly, first AF ablation procedure was far more frequent in LV centers compared to MV and HV (85.8% vs 76.0% vs 76.1% respectively, p<0.001). Even though HV centers ablate significantly more high risk patients (CHA2DS2-VASc score ≥2 51.4% in HV vs 46.5% in MV vs 37.2% in LV, p<0.001) (Figure B) with accompanying comorbidities, applying more elaborate ablation techniques, fluoroscopy time and radiation dose were higher among patients undergoing AF ablation in LV centers (p<0.001 for all). Despite the above-mentioned dissimilarities, Kaplan-Meier survival analysis, based on adjusted data, demonstrated non-significant differences in complication rate (p=0.402) or AF recurrence rate (p=0.363) among HV, MV and LV centers. Conclusions Volume of AF ablations in a center is not correlated with regional or infrastructural characteristics. The higher volume in HV centers consists mainly by more long-term persistent AF and higher risk patients, suggesting that differences in volume reflect differences in experience and personnel's commitment towards AF ablation.

How to leverage local impedance to guide effective ablation strategy: A case series

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with significant morbidity and mortality. Pharmacological agents are not very effective in the management of AF. Therefore, ablation procedures have become the mainstay of AF management. The irregular and seemingly chaotic atrial activity in AF is caused by one or more meandering spiral waves. Previously, we have shown the presence of sudden rhythm organization during ablation of persistent AF. We hypothesize that the observed transitions from a disorganized to an organized rhythm is a critical phase transition. Here, we explore this hypothesis by simulating ablation in an anatomically-correct 3D AF model. In 722 out of 2160 simulated ablation, at least one sudden transition from AF to an organized rhythm (flutter) was noted (33%). They were marked by a sudden decrease in the cycle length entropy and increase in the mean cycle length. At the same time, the number of reentrant wavelets decreased from 2.99 ± 0.06 in AF to 1.76 ± 0.05 during flutter, and the correlation length scale increased from 13.3 ± 1.0 mm to 196.5 ± 86.6 mm (both P < 0.0001). These findings are consistent with the hypothesis that transitions from AF to an anatomical flutter behave as phase transitions in complex non-equilibrium dynamical systems with flutter acting as an absorbing state. Clinically, the facilitation of phase transition should be considered a novel mechanism of ablation and may help to design effective ablation strategies.

Aim: To evaluate efficacy of endocardial radiofrequency catheter ablation (RFA) in atrial fibrillation (AF) in Maze regimen, to assess patients’ health status with a European Quality of Life Questionnaire (EQ-5D) and cardiovascular mortality in patients after the intervention taking anticoagulants. Materials and methods: 391 patients with AF (247 of them males) aged from 18 to 77 years (mean age 54.9 ± 10.1 years) were examined and got treatment. All patients underwent RFA, including pulmonary vein isolation, linear ablations of the posterior wall, left atrial roof and mitral isthmus. Their health status was assessed according to efficacy of the intervention and data from EQ-5D questionnaires. Results: At 3 and 36 months after the intervention, RFA efficacy in patients with paroxysmal AF was 92% and 83.3%, respectively, and in patients with persistent AF, 89.7% and 72.4%. According to EQ-5D “thermometer”, after 36 months patients with successful catheter ablation assessed their health status as being approximately at the same level as during initial hospitalization, i.e., in patients with paroxysmal AF this scale scored at 79.74% and 81.4%, and in patients with persistent AF, at 79.94% and 81.06%, respectively. However, if the endocardial Maze procedure was unsuccessful, there was a deterioration of health status from 80.8% to 70.14% in patients with paroxysmal AF and from 77.82% to 69.46% in those with persistent AF. The same trend was observed in the analysis of other EQ-5D items. All-cause cardiovascular mortality in the subgroup with successful RFA was lower than in the subgroup with unsuccessful RFA, irrespective of AF form (p < 0.001). A 36-month mortality rate in patients with paroxysmal AF after a successful RFA was 2.1% and in patients with persistent AF, 1.2%, after unsuccessful RFA the corresponding values being 13.4% and 9.6%. Causes of death in patients with successful and unsuccessful RFA were different. After successful RFA for paroxysmal AF, the main cause of death was myocardial infarction (80%), and only 1 patient (20%) died of hemorrhagic stroke. The main cause of death after unsuccessful ablation in paroxysmal AF was ischemic stroke (83%), and only 1 patient (17%) died of myocardial infarction. In patients with persistent AF and successful RFA, there was only 1 death at 24 months after the intervention due to acute myocardial infarction. In the subgroup with unsuccessful RFA, the single cause of death in all patients who died was ischemic stroke. Conclusion: Maze RFA showed high efficacy in patients with paroxysmal and persistent AF, being somewhat lower in those with persistent AF. Maintenance of sinus rhythm in addition to medical treatment allows for a substantial reduction of cardiovascular mortality compared to anticoagulation only within the rate control strategy.

Characterization of atrial histology in a patient with hypertrophic cardiomyopathy: Possible evidence of a primary atrial myopathy

Atrial fibrillation is the most common sustained arrhythmia in the general population, and circumferential pulmonary vein isolation has emerged as a cornerstone in the treatment of drug-resistant atrial fibrillation. However, there is a paucity of data regarding the CHA2DS2-VASc and SAMe-TT2R2 scores as predictors of outcomes among patients with nonvalvular atrial fibrillation on vitamin K antagonists after radiofrequency catheter ablation (RFCA). The current prospective observational study enrolled 304 consecutive patients with atrial fibrillation who underwent RFCA. Warfarin was maintained for at least 3 months after RFCA. The 1-year atrial fibrillation recurrence rate was documented. Persistent atrial fibrillation (P = 0.003), heart failure (P < 0.001), an enlarged left atrium (P = 0.003), current smoking (P < 0.001), the CHA2DS2-VASc score (P = 0.001), and the SAMe-TT2R2 score (P < 0.001) were univariate associated with recurrent atrial fibrillation. Cutoff analysis showed that a CHA2DS2-VASc score at least 3 (areas under the curve = 0.612; 95% confidence interval 0.537-0.687) and a SAMe-TT2R2 score at least 5 (areas under the curve = 0.642, 95% confidence interval 0.575-0.708) had the highest predictive value for atrial fibrillation recurrence. Patients with a CHA2DS2-VASc score at least 3 (P < 0.001) and a SAMe-TT2R2 score at least 5 (P = 0.001) had a higher probability of experiencing atrial fibrillation recurrence after RFCA compared with patients with a CHA2DS2-VASc score less than 3 and a SAMe-TT2R2 score less than 5. CHA2DS2-VASc and SAMe-TT2R2 scores were associated with 1-year recurrence of atrial fibrillation in patients on vitamin K antagonists after RFCA. For CHA2DS2-VASc and SAMe-TT2R2 scores, a cutoff value of at least 3 and at least 5 had the highest predictive value for atrial fibrillation recurrence, respectively.

Nerve sprouting induced by radiofrequency catheter ablation in dogs

Rationale, considerations, and goals for atrial fibrillation centers of excellence: A Heart Rhythm Society perspective

PO-01-032 CLINICAL AND PHYSIOLOGIC OUTCOMES OF COMPUTED TOMOGRAPHY-GUIDED CARDIONEUROABLATION VERSUS STANDARD ABLATION FOR ATRIAL FIBRILLATION

ABSTRACTIntroductionData regarding safety and long‐term outcome of very high‐power‐short duration (vHPSD) ablation in adult congenital heart disease (ACHD) patients with paroxysmal or persistent atrial fibrillation (AF) are lacking.MethodsRetrospective observational single‐center study. The data of 66 consecutive ACHD patients (mean age 60 ± 12.8 years, 46% male) with mild (69.7%), moderate (22.7%), or complex (7.6%) congenital heart disease (CHD) who underwent ablation for paroxysmal (40.9%) or persistent AF (59.1%) were analyzed. Circumferential PVI was performed in all patients and additional substrate ablation in 79,4% of persistent AF patients using irrigated RF energy with vHPSD settings of 70 W/5–7 s or 60 W/7–10 s.ResultsMean procedure time was 123.6 ± 42 min with a mean RF time of 18.19 ± 10 min. No technique related adverse events occurred. Vascular access complications were detected in seven patients (10.6%) requiring intervention in four patients (6%). A median follow‐up time of 491 days (IQR: 194–1054 days). Freedom from any atrial arrhythmia off antiarrhythmic drugs (AAD) at 1 year was present in 58% of patients (77.8% with paroxysmal AF, 43.6% with persistent AF).ConclusionvHPSD for ablation of paroxysmal or persistent AF in ACHD patients is safe and effective. Regardless of CHD complexity, no vHPSD ablation modality related complications occurred. Long‐term outcome for paroxysmal AF after one ablation was excellent whereas results for persistent AF were limited.

Obstructive Sleep Apnoea in Patients Having Atrial Fibrillation Ablation: Prevalence, Severity and Association with Arrhythmia Phenotype

Long-term clinical outcomes in patients after catheter ablation for atrial fibrillation or atrioventricular node ablation: A French nationwide cohort study