Conventional Mapping Systems Research Articles

A novel noncontact high-resolution charge density mapping system to guide ablation of complex atrial arrhythmias: overview of device technology and application

ABSTRACT Introduction: Despite advances in imaging technology to guide ablative therapies, catheter ablation of more complex arrhythmias continues to be a challenge in part due to suboptimal mechanistic understanding of these arrhythmias by conventional mapping systems. A novel noncontact charge density mapping system has been designed to overcome some of these limitations. Areas covered: Hereby, we present an overview of this novel, charge density-based global chamber mapping approach. We initially highlight the concept of charge density, describe further the device technology and finally summarize the clinical application of this system. Expert opinion: Noncontact charge density mapping provides a more localized, high-resolution global panoramic assessment of cardiac activation. This might contribute to uncover the mechanisms of more complex arrhythmias such as persistent atrial fibrillation or unstable atrial tachycardias with the ultimate goal to guide the ablation therapy.

Novel three-dimensional imaging approach for cryoballoon navigation and confirmation of pulmonary vein occlusion.

Cryoballoon apposition is crucial for durable pulmonary vein isolation (PVI) in atrial fibrillation, yet the balloon is difficult to visualize by conventional mapping systems, and pulmonary venography may miss small or out-of-plane leaks. We report a novel imaging system that offers real-time 3D navigation of the cryoballoon within atrial anatomy that may circumvent these issues. A novel overlay guidance system (OGS) registers already-acquired segmented atrial cardiac tomography (CT) with fluoroscopy, enabling real-time visualization of the cryoballoon within tomographic left atrial imaging during PVI. Phantom experiments in a patient-specific 3D printed left atrium showed feasibility for confirming PV apposition and leaks. We applied OGS prospectively to 68 PVs during PVI in 17 patients. The cryoballoon was successfully reconstructed in all cases, and its apposition was compared to concurrent PV venography. The OGS uncovered leaks undetected by venography in nine veins (eight cases), which enabled repositioning, confirming apposition in remaining 68 veins. Concordance of OGS to venography was 83.8% (χ2 , P<.01) CONCLUSIONS: We report a new system for real-time imaging of cryoballoon catheters to ensure PV apposition within the tomography of the left atrium. While providing high concordance with other imaging modalities for confirming balloon apposition or leak, the system also identified leaks missed by venography. Future studies should determine if this tool can provide a new reference for cryoballoon positioning.

Comparison of ablation outcomes of the second ablation procedure for recurrent atrial fibrillation using an ultra‐high‐resolution mapping system and conventional mappings system

BackgroundThe utility of an ultra‐high‐resolution electroanatomical mapping system (UHR‐EAM, Rhythmia) for repeat atrial fibrillation (AF) ablation has not been evaluated.HypothesisA second AF ablation procedure performed using UHR‐EAM may demonstrate different outcomes compared with that using a conventional electroanatomical mapping system (C‐EAM, CARTO3).MethodThis observational study enrolled consecutive patients who underwent a second AF ablation procedure using UHR‐EAM (n = 103) and C‐EAM (n = 153). The second ablation procedure included re‐isolation of reconnected pulmonary veins (PVs) and elimination of clinical or induced non‐PV AF triggers and atrial tachycardia (AT). Other empirical ablations were additionally conducted at the discretion of the operators.ResultsRe‐isolation of PVs was achieved in 196 patients who had ≥1 left atrial‐PV reconnection. The elimination rate of AT was higher in the UHR‐EAM group than the C‐EAM group (87% vs 65%, P = .040), while that of non‐PV AF triggers was similar (63% vs 63%, P = 1.00). The UHR‐EAM demonstrated shorter radiofrequency application time (21.8 ± 16.8 vs 28.0 ± 21.3 minutes, P = .017), but longer fluoroscopic time (26.2 ± 12.6 vs 21.4 ± 9.3 minutes, P = .0001). No severe complication developed. The total 1‐year AF/AT‐free survival rates were similar between the two groups (off AADs, 59.2% vs 56.2%, P = .62; on AADs, 65.0% vs 69.3%, P = .49).ConclusionThe efficacy and safety outcomes of repeat AF ablation using UHR‐EAM was comparable to those using C‐EAM.

High-density Mapping Guided Pulmonary Vein Isolation for Treatment of Atrial Fibrillation - Two-year clinical outcome of a single center experience

Pulmonary vein isolation (PVI) as interventional treatment for atrial fibrillation (AF) aims to eliminate arrhythmogenic triggers from the PVs. Improved signal detection facilitating a more robust electrical isolation might be associated with a better outcome. This retrospective cohort study compared PVI procedures using a novel high-density mapping system (HDM) with improved signal detection vs. age- and sex-matched PVIs using a conventional 3D mapping system (COM). Endpoints comprised freedom from AF and procedural parameters. In total, 108 patients (mean age 63.9 ± 11.2 years, 56.5% male, 50.9% paroxysmal AF) were included (n = 54 patients/group). Our analysis revealed that HDM was not superior regarding freedom from AF (mean follow-up of 494.7 ± 26.2 days), with one- and two-year AF recurrence rates of 38.9%/46.5% (HDM) and 38.9%/42.2% (COM), respectively. HDM was associated with reduction in fluoroscopy times (18.8 ± 10.6 vs. 29.8 ± 13.4 min; p < 0.01) and total radiation dose (866.0 ± 1003.3 vs. 1731.2 ± 1978.4 cGy; p < 0.01) compared to the COM group. HDM was equivalent but not superior to COM with respect to clinical outcome after PVI and resulted in reduced fluoroscopy time and radiation exposure. These results suggest that HDM-guided PVI is effective and safe for AF ablation. Potential benefits in comparison to conventional mapping systems, e.g. arrhythmia recurrence rates, have to be addressed in randomized trials.

Impact of nonfluoroscopic MediGuide™ tracking system on radiation exposure in radiofrequency ablation procedures (LESS-RADS registry)—an initial experience

Radiation exposure in the electrophysiology (EP) lab is a major concern to most electrophysiologists. A new technology, MediGuide™ nonfluoroscopic catheter tracking system, has been used for the first time in the USA recently. We intended to evaluate the efficacy of this novel catheter tracking system in reducing radiation exposure. We performed a prospective observational study by comparing the radiation exposure with MediGuide™ system to that of conventional mapping systems. The first 45 EP procedures performed with the MediGuide™ system were compared to 45 matched patients undergoing similar procedures during the same time frame using conventional mapping systems (CARTO and NavX) and fluoroscopy. We collected and compared baseline characteristics, procedural variables including fluoroscopic exposure between both groups. Forty-five patients underwent EP procedures using the MediGuide™ technology. They were matched with an equal number of patients with conventional mapping systems. Of the 45 patients included in the study, 33 underwent right atrial flutter ablations, 5 underwent atrioventricular nodal reentrant tachycardia ablations, 4 underwent ablation of Wolf-Parkinson-White syndrome, and 3 underwent EP studies with no ablation. There were no differences in mean age, gender distribution, and body mass index between the groups. Procedure duration in the MediGuide™ group was significantly lower than the duration in the conventional group (103 vs. 142min, p = 0.03). The fluoroscopic time was significantly less during the procedures performed with the MediGuide™ technology when compared to the control group (8 vs. 21min, p < 0.001). No major complications occurred during the procedures in either group. MediGuide™, a new nonfluoroscopic catheter tracking system, is associated with more than a 50% reduction in fluoroscopic time when compared to conventional mapping systems.

Radiofrequency Catheter Ablation of Hemodynamically Unstable Ventricular Tachycardia Associated with Systemic Sclerosis

Systemic sclerosis (SS) is a connective tissue disease and cardiac involvement is common. Primary cardiac involvement such as conduction system disturbances and arrhythmias can also occur. However, reports of sustained ventricular tachycardia (VT) are rare. We report a case of catheter ablation of sustained ventricular tachycardia in a patient with systemic sclerosis using a conventional mapping system. A 64-yr-old woman with a 10-yr history of SS was referred for management of her ventricular tachycardia. There was no structural abnormality in cardiac chambers. However, electrophysiologic study revealed electrical substrate of ventricular tachycardia which could be ablated with pacemapping and substrate mapping. This case demonstrated successful conventional mapping and catheter ablation in a hemodynamically unstable patient with SS.

Acute and long-term results of PVI at antrum using a novel high-density mapping catheter without help of 3D electro-anatomic mapping in patients with paroxysmal and chronic atrial fibrillation

Multi-electrode circumferential mapping catheters have been developed by several manufacturers to facilitate catheter ablation procedures for atrial fibrillation (AF). We tested the effectiveness and safety of a conventional, fully endocardial electrogram-guided circumferential antrum isolation (PVI) with a novel mapping device. The study enrolled 250 consecutive patients with paroxysmal or chronic AF. High-density (HD) mapping of the pulmonary veins was performed with the HD Mesh Mapper (HDMM; Bard Electrophysiology, Lowell, MA, USA). The device was not constructed for radiofrequency energy delivery. Antral PVI was performed by irrigated radiofrequency application around the HDMM. Entry and exit conduction block, as well as decreased local electrode amplitude, were endpoints for acute successful ablation. Primary endpoint of the study was the AF free event probability during follow-up. As secondary endpoints, the acute results and related complications were determined. In 984 of 1,002 pulmonary vein (PV, 98.2%), signals were characterized as PV potentials by mapping the proximal part of the PV and the antrum. We achieved a complete antrum ablation in front of the 25-mm ring of the MESH Mapper in 95% of the PV in all patients. In difficult anatomic relationships, the repositioning of the mapping catheter could be necessary. The median follow-up time was 20.8 and 15.6 months in patients with paroxysmal and chronic AF, respectively. Log Rang test revealed a probability to be free from AF episodes of 71.2% and 49.4% after one ablation procedure and improved in chronic AF after a second procedure (71.1%). Our study demonstrates satisfactory success rate regarding the safety and long-term results in patients both with paroxysmal and persistent AF when a 3D mapping system is not being implemented. The study underlines the importance of a continuous signal analysis during the ablation procedure even with a conventional mapping system.

Catheter Ablation of Tachycardias After Undergoing a Surgical Atriotomy Using a Multipolar Electrode Catheter

A variety of supraventricular tachyarrhythmias may occur in patients after undergoing a surgical atriotomy. The purpose of this study was to characterize them and determine the role of conventional mapping. In 45 patients after a surgical atriotomy, 68 atrial tachyarrhythmias were observed. A conventional mapping system with a 20-pole electrode catheter used in the electrophysiological study detected 39 atrial tachycardias (ATs). Type 1 atrial flutter (AFL) was observed in 23 and reverse type 1 AFL in 4. AT was classified into 3 subgroups, namely, incisional macroreentrant AT (n=31), incisional focal AT (n=1) and non-incisional AT (n=7). In the patients with incisional macroreentrant AT after the standard right atriotomy, the 20-pole electrode catheter placed on the incision could easily record the entire sequence of the atrial activation. Successful catheter ablation was achieved in all patients with incisional reentrant AT. The ablation site of incisional reentrant AT was the isthmus between the incision and the superior vena cava cannulation scar in 4, between the incision and the inferior vena cava cannulation scar in 22, and the area at the septal incision in 3. The remaining 2 incisional ATs were left atrial AT and right atrial transincisional AT. The conventional mapping system is still very useful for making an electrophysiological diagnosis in patients after a standard right atriotomy.

Wide-Field Low-Frequency Imaging with the VLA

The 330 MHz observing system at the VLA is a potentially powerful survey system. It can map fields many degrees in size quickly and at high sensitivity. However imaging characteristics unique to this data pose excessive computational burdens on conventional mapping systems. Hence while data acquisition is quick and efficient, data reduction has been difficult and slow. Here we describe how powerful new scalable processing algorithms have been used to generate the first full resolution 330 MHz images, demonstrating also that lower resolution survey work is now a tractable problem.

SMALL FORMAT AERIAL SURVEYS FROM LIGHT AND MICROLIGHT AIRCRAFT

AbstractSmall format (SF) cameras, fitted to light or microlight aircraft, can provide an economic and convenient alternative to the more expensive conventional mapping systems. Further advantages accrue from the use of wider aperture lenses, an extensive range of easily available films and simplijed processing. These advantages can be exploited by employing light aircraft for small survey missions, such as map revision, and desktop photogrammetric systems dedicated to handling SF imagery. In this paper, an account is given of a research study involving SF map revision survey photography, using a modern microlight aircraft and a 70 mm metric camera.

Operational concepts of topographic mapping in developing countries-an appeal for a more efficient and integrated approach to an urgent problem

Considering the slow progress in topographic mapping in vast areas of the world, it becomes evident that a new outlook to this problem is necessary and that new means have to be found to solve it. The author attempts first to analyse the prevailing requirements and environmental circumstances which have to be considered in designing national mapping programmes. Based on the results of this analysis a proposal is made for a topographic mapping system in phases, which is then compared with the conventional mapping system. The proposed system seems to meet the actual requirements in a better way by adhering more to the environmental circumstances encountered in developing countries.