Therapy Efficacy of Idiopathic Ventricular Extrasystoles: A Real Life Study

Background

Ventricular extrasystoles (VESs) are common and often harmless in a healthy heart, but they can significantly affect the quality of life. If changes in lifestyle and antiarrhythmic medication are not enough, invasive and often curative catheter ablation can be considered. Better understanding of the conformation of VESs with a 12-lead ECG, as well as their precise localization, have increased their treatment with catheter ablation. Our goal was to determine whether the anatomical site of VES had an effect on procedure success. We also analyzed the safety of the procedure and patient-related factors affecting the results.

Materials and Methods

In this retrospective study, we analyzed the medical records of 63 consecutive patients with multiple idiopathic VESs treated by catheter ablation at Heart Hospital, Tampere University Hospital, during 2017 and 2018. Patients with structural heart disease were excluded. Ablation success was estimated with two endpoints, primary and follow-up success.

Results

The majority of the patients received treatment on the right ventricular outflow tract (66.7%), others on the left ventricle (17.5%), or the aortic cusp (9.5%). The site of origin remained unknown in four procedures (6.3% of patients). Primary success was observed in 48 procedures (76.2%). During the follow-up period of three months, the procedure was successful in 70.3% of the cases. The anatomical site of VES had no significant effect on either primary or follow-up success. Those with a successful follow-up result had a lower body mass index (BMI = 26.4) than those who had an unsuccessful result (BMI = 28.7; p=0.069); this did not reach statistical significance, potentially due to the small study population size. Complications were observed in three patients (4.5%). All of them were related to the catheter insertion site.

Conclusions

For a symptomatic patient, catheter ablation is an effective and often fully curative treatment. The success rate was similar regardless of the site of VESs. This suggests that catheter ablation should also be assessed early on for other cases besides classic right ventricular outflow tract VESs. A high BMI was the only factor associated with a poor procedure success rate. The procedure itself is safe, and adverse effects are rare. The radiation dose is also low partly due to the current magnetic navigation method.

The First Evaluation of Remote Magnetic Navigation-Guided Pediatric Ventricular Arrhythmia Ablation

Catheter ablation (CA) is an important treatment option for ventricular arrhythmias (VA) in pediatric cardiology. Currently, various CA techniques are available, including remote magnetic navigation (RMN)-guided radiofrequency (RF) ablation. However, no studies evaluate RMN-guided ablative therapy outcomes in children with VA yet. This study aimed to compare procedural and long-term outcomes between RMN-guided and manual (MAN)-guided VA ablation in children. This single-center, retrospective study included all CA procedures for VA performed in children with or without structural heart disease from 2008 until 2020. Two study groups were defined by CA technique: RMN or MAN. Primary outcome was recurrence of VA. Baseline clinical, procedural and safety data were also evaluated. This study included 22 patients, who underwent 30 procedures, with a median age of 15 (IQR 14-17; range 1-17) years and a mean weight of 57 ± 20 kg. In total, 14 procedures were performed using RMN and 16 using MAN (22 first and 8 redo procedures). Regarding first procedures, recurrence rates were significantly lower in RMN compared to MAN (20% versus 67%, P = 0.029), at a mean follow-up of 5.2 ± 3.0 years. Moreover, fluoroscopy dosages were significantly lower in RMN compared to MAN [20 (IQR 14-54) versus 48 (IQR 38-62) mGy, P = 0.043]. In total, 20 patients (91%) were free of VA following their final ablation procedure. This is the first study to investigate the use of RMN in pediatric VA ablation. RMN showed improved outcomes compared to MAN, resulting in lower VA recurrence and reduced fluoroscopy exposure.

Procedural and long-term outcome after catheter ablation of idiopathic outflow tract ventricular arrhythmias: comparing manual, contact force, and magnetic navigated ablation

Aims

Currently, comparative data on procedural and long-term clinical outcome of outflow tract (OT) idiopathic ventricular arrhythmia (IVA) ablation with manual (MAN), contact force (CF), and magnetic navigation system (MNS) ablation are lacking. The aim of this study was to compare the procedural and long-term clinical outcome of MAN, CF, and MNS ablation of OT IVAs.

Methods and results

Seventy-three patients (31 MAN, 17 CF, and 25 MNS patients; consecutive per group) with OT IVA, who underwent catheter ablation in our centre were analysed. Procedural success rates (success at the end of the procedure), procedural data and long-term follow-up data were compared. Baseline patient demographics were comparable. Procedural success rates were similar (MAN 81%, 71% CF, and MNS 92%; P = 0.20). Median fluoroscopy time was shorter in the MNS group: MAN 29 (16-38), CF 37 (21-46), and MNS 13 (10-20) min (P = 0.002 for MNS vs. CF and MAN). The overall complication rate was: MAN 10%, CF 0%, and MNS 0% (P = 0.12). Median follow-up was: MAN 2184 (1672-2802), CF 1721 (1404-1913), and MNS 3031 (2524-3286) days (P <0.001). Recurrences occurred in MAN 46%, CF 50%, and MNS 46% (P = 0.97). Repeat procedures were performed in MAN 20%, CF 40%, and MNS 33% (P = 0.32).

Conclusion

Procedural and long-term clinical outcome of OT IVA ablation are equal for MAN, CF, and MNS. MNS has a favourable procedural safety profile due to the shorter fluoroscopy time compared with MAN and CF.

Ventricular Arrhythmias in the Patient with a Structurally Normal Heart

Ventricular arrhythmias (VAs) are among the most common cardiac rhythm disturbances encountered in clinical practice. Patients presenting with frequent ventricular ectopy or sustained ventricular tachycardia represent a challenging and worrisome clinical scenario for many practitioners because of concerning symptoms, frequent associated acute hemodynamic compromise, and the adverse prognostic implications inherent to these cases. While an underlying structural or functional cardiac abnormality, metabolic derangement, or medication toxicity is often readily apparent, many patients have no obvious underlying condition, despite a comprehensive diagnostic evaluation. Such patients are diagnosed as having an idiopathic VA, which is a label with specific implications regarding arrhythmia origin, prognosis, and potential for pharmacologic and invasive management. Further, a subset of patients with otherwise benign idiopathic ventricular ectopy can present with polymorphic ventricular tachycardia and ventricular fibrillation, adding a layer of complexity to a clinical syndrome previously felt to have a benign clinical course. Thus, this review seeks to highlight the most common types of idiopathic VAs with a focus on their prognostic implications, underlying electrophysiologic mechanisms, unique electrocardiographic signatures, and considerations for invasive electrophysiologic study and catheter ablation. We further address some of the data regarding idiopathic ventricular fibrillation with respect to the heterogeneous nature of this diagnosis.

Remote Magnetic Navigation: A Focus on Catheter Ablation of Ventricular Arrhythmias

VT ablation is based on percutaneous catheter insertion under fluoroscopic guidance to selectively destroy (i.e., ablate) myocardial tissue regions responsible for the initiation or propagation of ventricular arrhythmias. Although the last decade has witnessed a rapid evolution of ablation equipment and techniques, the control over catheter movement during manual ablation has remained largely unchanged. Moreover, the procedures are long, and require ergonomically unfavorable positions, which can lead to operator fatigue. In an attempt to overcome these constraints, several technical advancements, including remote magnetic navigation (RMN), have been developed. RMN utilizes a magnetic field to remotely manipulate specially designed soft-tip ablation catheters anywhere in the x, y, or z plane inside the patient's chest. RMN also facilitates titration of the contact force between the catheter and the myocardial tissue, which may reduce the risk of complications while ensuring adequate lesion formation. There are several non-randomized studies showing that RMN has similar efficacy to manual ablation, while complication rates and total radiation exposure appears to be lower. Although these data are promising, larger randomized studies are needed to prove that RMN is superior to manual ablation of VT.

Remote Navigation for Complex Arrhythmia

Magnetic navigation has been established as an alternative to conventional, manual catheter navigation for invasive electrophysiology interventions about a decade ago. Besides the obvious advantage of radiation protection for the operator who is positioned remotely from the patient, there are additional benefits of steering the tip of a very floppy catheter. This manuscript reviews the published evidence from simple arrhythmias in patients with normal cardiac anatomy to the most complex congenital heart disease. This progress was made possible by the introduction of improved catheters and most importantly irrigated-tip electrodes.

Outcomes of repeat catheter ablation using magnetic navigation or conventional ablation

AIMS

After initial catheter ablation, repeat procedures could be necessary. This study evaluates the efficacy of the magnetic navigation system (MNS) in repeat catheter ablation as compared with manual conventional techniques (MANs).

METHODS AND RESULTS

The results of 163 repeat ablation procedures were analysed. Ablations were performed either using MNS (n = 84) or conventional manual ablation (n = 79). Procedures were divided into four groups based on the technique used during the initial and repeat ablation procedure: MAN-MAN (n = 66), MAN-MNS (n = 31), MNS-MNS (n = 53), and MNS-MAN (n = 13). Three subgroups were analysed: supraventricular tachycardias (SVTs, n = 68), atrial fibrillation (AF, n = 67), and ventricular tachycardias (VT, n = 28). Recurrences were assessed during 19 ± 11 months follow-up. Overall, repeat procedures using MNS were successful in 89.0% as compared with 96.2% in the MAN group (P = ns). The overall recurrence rate was significantly lower using MNS (25.0 vs. 41.4%, P = 0.045). Acute success and recurrence rates for the MAN-MAN, MAN-MNS, MNS-MNS, and MNS-MAN groups were comparable. For the SVT subgroup a higher acute success rate was achieved using MAN (87.9 vs. 100.0%, P = 0.049). The use of MNS for SVT is associated with longer procedure times (205 ± 82 vs. 172 ± 69 min, P = 0.040). For AF procedure and fluoroscopy times were longer (257 ± 72 vs. 185 ± 64, P = 0.001; 59.5 ± 19.3 vs. 41.1 ± 18.3 min, P < 0.001). Less fluoroscopy was used for MNS-guided VT procedures (22.8 ± 14.7 vs. 41.2 ± 10.9, P = 0.011).

CONCLUSION

Our data suggest that overall MNS is comparable with MAN in acute success after repeat catheter ablation. However, MNS is related to fewer recurrences as compared with MAN.

Radiofrequency catheter ablation of idiopathic right ventricular outflow tract arrhythmias

Idiopathic ventricular arrhythmias (VA) consist of various subtypes of VA that occur in the absence of clinically apparent structural heart disease. Affected patients account for approximately 10% of all patients referred for evaluation of ventricular tachycardia (VT). Arrhythmias arising from the outflow tract (OT) are the most common subtype of idiopathic VA and more than 70-80% of idiopathic VTs or premature ventricular contractions (PVCs) originate from the right ventricular (RV) OT. Idiopathic OT arrhythmias are thought to be caused by adenosine-sensitive, cyclic adenosine monophosphate (cAMP) mediated triggered activity and, in general, manifest at a relatively early age. Usually they present as salvos of paroxysmal ventricular ectopic beats and are rarely life-threatening. When highly symptomatic and refractory to antiarrhythmic therapy or causative for ventricular dysfunction, ablation is a recommended treatment with a high success rate and a low risk of complications.

Safety and efficacy of the remote magnetic navigation for ablation of ventricular tachycardias--a systematic review

Objective

Remote magnetic navigation (RMN) is considered to be a solution for mapping and ablation of several arrhythmias. In this systematic review we aimed to assess the safety and efficacy of RMN in ablation of ventricular tachycardia (VT).

Methods

The National Library of Medicine’s PubMed database was searched for articles containing any of a predetermined set of search terms that were published prior to November 1, 2011. Quality of evidence was rated using the GRADE system.

Results

The database search resulted in 11 relevant articles evaluating the usefulness of RMN. Three groups of VTs were studied: VT in patients with ischemic cardiomyopathy (ICMP), non-ischemic cardiomyopathy (NICMP) and structurally normal hearts (SNH). The use of RMN in patients with ICMP has been associated with success rates ranging from 71 to 80%. RMN has been shown to be a feasible and effective method for ablation of VT in NICMP and SNH patients. Success rates between 50% and 100% have been reported in NICMP populations. Rates ranging from 86% to 100% have been reported for SNH patients. The lowest rates of arrhythmia recurrence are reported for SNH patients (0–17%). In ICMP and NICMP, recurrence rates of 0–30% and 14–50%, respectively, have been reported. One patient experienced total heart block, and one patient experienced a thromboembolic event after RMN catheter ablation procedures.

Conclusions

RMN has been shown to be an effective and safe method for ablation of VT in various patient populations with low recurrence and complication rates. However, more comparative and randomized studies are necessary, and therefore the true value of RMN for VT ablation remains still unknown.

Detection of Curved Robots using 3D Ultrasound

Three-dimensional ultrasound can be an effective imaging modality for image-guided interventions since it enables visualization of both the instruments and the tissue. For robotic applications, its realtime frame rates create the potential for image-based instrument tracking and servoing. These capabilities can enable improved instrument visualization, compensation for tissue motion as well as surgical task automation. Continuum robots, whose shape comprises a smooth curve along their length, are well suited for minimally invasive procedures. Existing techniques for ultrasound tracking, however, are limited to straight, laparoscopic-type instruments and thus are not applicable to continuum robot tracking. Toward the goal of developing tracking algorithms for continuum robots, this paper presents a method for detecting a robot comprised of a single constant curvature in a 3D ultrasound volume. Computational efficiency is achieved by decomposing the six-dimensional circle estimation problem into two sequential three-dimensional estimation problems. Simulation and experiment are used to evaluate the proposed method.