Three-dimensional image integration guidance for cryoballoon pulmonary vein isolation procedures

BACKGROUND

We present a new, easily applicable approach for the guidance of cryoballoon (CB) pulmonary vein isolation (PVI) procedures that use the combination of a 3D-mapping system image integration module and computed tomographic (CT)-derived anatomy. The aim of this retrospective, nonrandomized study was to investigate: (a) an alternative use for an established radiofrequency image integration module for cryo procedures; (b) a guidance technology for cryo PVI based on integrated CT anatomy; and (c) its clinical impact.

METHODS AND RESULTS

CT left atrium-angiography was performed in 50 consecutive patients before a CB PVI procedure, and a 3D reconstruction of the cardiac anatomy was segmented. A total of 25 patients were treated using conventional fluoroscopy; 25 patients were treated using the 3D image integration technique. In the image integration group, the CARTO3 UNIVU (Biosense Webster) module was used for image integration of 3D anatomy and fluoroscopic imaging. Transseptal puncture and cryo PVI were guided by 3D-overlay imaging. Procedures were feasible without complications in all patients and cryo PVI procedures were successfully guided using the image integration technique. The intraprocedural time needed to perform image integration was 37 ± 10 seconds. Fluoroscopy time was 31.7 ± 11.7 minutes in the conventional group and 20.1 ± 7.9 minutes in the image integration group (P < .001), procedure time was 116.3 ± 29.0 minutes in the conventional group vs 101.2 ± 20.9 minutes in the 3D group (P = .04).

CONCLUSION

3D-overlay guidance of CB PVI is feasible, safe, and applicable in real time with minimal effort. It may significantly reduce radiation exposure by introducing 3D information, known from electroanatomic mapping systems, into cryo PVI procedures.

First experience with zero-fluoroscopic ablation for supraventricular tachycardias using a novel impedance and magnetic-field-based mapping system

AIMS

Zero- and near-zero-fluoroscopic ablation techniques reduce the harmful effects of ionizing radiation during invasive electrophysiology procedures. We aimed to test the feasibility and safety of a zero-fluoroscopic strategy using a novel integrated magnetic and impedance-based electroanatomical mapping system for radiofrequency ablation (RFA) of supraventricular tachycardias (SVTs).

METHODS

We retrospectively studied 92 consecutive patients undergoing electrophysiology studies with/without RFA for supraventricular tachycardia (SVT) performed by a single operator at a single center. The first 42 (Group 1) underwent a conventional fluoroscopic-guided approach and the second 50 (Group 2) underwent a zero-fluoroscopic approach using the Ensite Precision^™ 3-D magnetic and impedance-based mapping system (Abbott Inc).

RESULTS

Group 1 comprised 14 AV-nodal re-entrant tachycardia (AVNRT), 12 typical atrial flutter, 4 accessory pathway (AP), 2 atrial tachycardia (AT), and 9 diagnostic EP studies (EPS). Group 2 comprised 16 AVNRT, 17 atrial flutter, 6 AP, 3 AT, 2 AV-nodal ablations, and 7 EPS. A complete zero-fluoroscopic approach was achieved in 94% of Group 2 patients. All procedures were acutely successful, and no complications occurred. There was a significant reduction in fluoroscopy dose, dose area product, and time (p < 0.0001, for all), with no difference in procedure times. Ablation time for typical atrial flutter was shorter in Group 2 (p = 0.006).

CONCLUSIONS

A zero-fluoroscopic strategy for diagnosis and treatment of SVTs using this novel 3D-electroanatomical mapping system is feasible in majority of patients, is safe, reduces ionizing radiation exposure, and does not compromise procedural times, success rates, or complication rates.

Reducing radiation exposure during procedures performed in the electrophysiology laboratory

INTRODUCTION

Expert societies recently published strong recommendations to reduce the exposure of patients and staff to ionizing radiation (IR) during interventional and electrophysiology (EP) procedures. However, adherence to these guidelines remains difficult and the impact of implementing such recommendations is poorly characterized.

METHODS AND RESULTS

We conducted a single-center cohort study to quantify radiation exposure over time in three EP laboratories at the Montreal Heart Institute during 5,546 consecutive procedures from 2012 to 2015 by 11 primary operators. Overall, 2,618 (47.2%) procedures were catheter-based and 2,928 (52.8%) were device interventions. Interventions to reduce radiation exposure included educational initiatives to raise awareness (i.e., limiting cine acquisition, patient position, table height), slower frame rate, lower radiation dose per pulse, collimation, and integration with 3-D mapping systems and/or MediGuide technology. An 85% reduction in IR exposure was observed from 2012 to 2015, with the mean dose-area-product (DAP) decreasing from 7.65 ± 0.05 Gy·cm² to 1.15 ± 0.04 Gy·cm² (P < 0.001). This was true for catheter-based procedures (mean DAP 16.99 ± 0.08 to 2.00 ± 0.06 Gy·cm² , P < 0.001) and device interventions (mean DAP 4.18 ± 0.06 to 0.64 ± 0.05 Gy·cm² , P < 0.001). The median effective dose of IR recorded per quarter by 282 cervical dosimeters on EP staff decreased from 0.57 (IQR 0.18, 1.03) mSv in 2012 to 0.00 (IQR 0.00, 0.19) mSv in 2015, P < 0.001.

CONCLUSION

Enforcing good clinical practices with simple measures and low-dose fluoroscopy settings are highly effective in reducing IR exposure in the EP lab. These promising results should encourage other EP labs to adopt similar protective measures.

Non-fluoroscopic catheter tracking for fluoroscopy reduction in interventional electrophysiology

A technological platform (MediGuide) has been recently introduced for non-fluoroscopic catheter tracking. In several studies, we have demonstrated that the application of this non-fluoroscopic catheter visualization system (NFCV) reduces fluoroscopy time and dose by 90-95% in a variety of electrophysiology (EP) procedures. This can be of relevance not only to the patients, but also to the nurses and physicians working in the EP lab. Furthermore, in a subset of indications such as supraventricular tachycardias, NFCV enables a fully non-fluoroscopic procedure and allows the lab staff to work without wearing lead aprons. With this protocol, we demonstrate that even complex procedures such as ablations of atrial fibrillation, that are typically associated with fluoroscopy times of >30 min in conventional settings, can safely be performed with a reduction of >90% in fluoroscopy exposure by the additional use of NFCV.

Reduction of Radiation Exposure in Atrial Fibrillation Ablation Using a New Image Integration Module: A Prospective Randomized Trial in Patients Undergoing Pulmonary Vein Isolation

INTRODUCTION

Recently, a new image integration module (IIM, CartoUnivu™ Module) has been introduced to combine and merge fluoroscopy images with 3-dimensional-(3D)-electroanatomical maps (Carto® 3 System) into an accurate 3D view. The aim of the study was to investigate the influence of IIM on the fluoroscopy exposure during pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) in a prospective randomized trial.

METHODS AND RESULTS

Between June and November 2014, a total of 60 patients with PAF (73.3% male, 64.0 ± 9.2 years), who underwent PVI with the endpoint of unexcitability of the ablation line, were randomized to either a conventional 3D mapping system (Carto® 3 System) or to an additional IIM on the basis of an assumed reduction of fluoroscopy exposure by the use of IIM. There were no significant differences in baseline characteristics. The median ablation procedure time was identical in both groups (140.7 ± 27.8 minutes vs. 140.8 ± 39.5 minutes; P = 0.851). A significant decrease of mean fluoroscopy time from 11.9 ± 2.1 to 7.4 ± 2.6 minutes (P < 0.0006) and median fluoroscopy dose from 882.9 to 476.5 cGycm(2) (P < 0.001) was achieved. The main reduction of radiation could be realized during creation of the 3D-map. No major complications occurred during the procedures. After a median follow-up of 125.7 ± 45.6 days 80% of the patients were free from any atrial arrhythmias.

CONCLUSION

CartoUnivu™ module easily integrates into the workflow of PVI with the endpoint of unexcitability of the ablation line without prolonging the procedure time. It is associated with a marked reduction in fluoroscopic dose when compared to a conventional 3D mapping system.

Feasibility of Transseptal Puncture Using a Nonfluoroscopic Catheter Tracking System

BACKGROUND

Radiation exposure in the electrophysiology lab is a major occupational hazard to the electrophysiologists. A catheter localization system (MediGuide Technology, St. Jude Medical Inc., St. Paul, MN, USA) allows the integration of electroanatomical mapping and x-ray imaging, and has been shown to be effective in reducing radiation exposure during several electrophysiological procedures. We intended to evaluate the feasibility of this catheter tracking system to guide transseptal (TS) access.

METHODS

The feasibility of performing TS puncture with MediGuide (MDG) was assessed in a prospective observational study in 16 patients undergoing radiofrequency ablation for atrial fibrillation. These patients were compared to 16 matched patients undergoing similar procedures during the same time frame using conventional approach. There were no differences in mean age, gender distribution, and body mass index between the two groups. Total duration of fluoroscopic exposure during TS puncture was compared between the two groups.

RESULTS

All patients underwent successful TS puncture. Fluoroscopy time for double TS puncture using the MDG system was significantly lower than the control group (0.48 ± 0.17 minutes vs. 5.9 ± 0.65 minutes; P < 0.0001). No major complications occurred during the procedures in either group.

CONCLUSIONS

TS puncture can be successfully performed using MDG, and results in significant reduction in radiation exposure.

Ablation of typical atrial flutter using a non-fluoroscopic catheter tracking system vs. conventional fluoroscopy--results from a prospective randomized study

AIMS

Reduction of radiation exposure using a sensor-based non-fluoroscopic catheter tracking (NFCT) system (MediGuide™, St Jude Medical, Inc.) was recently demonstrated by retrospective comparisons. We aimed to prospectively compare the effects of using NFCT vs. standard fluoroscopy on procedural parameters in patients undergoing radiofrequency ablation of typical atrial flutter.

METHODS AND RESULTS

We prospectively randomized 40 patients undergoing cavotricuspid isthmus ablation for typical atrial flutter to either NFCT (n = 20) or conventional fluoroscopy (CONV, n = 20). Procedural parameters such as fluoroscopy time, radiation dose, and procedure duration, as well as periprocedural complications were compared. There were no statistically significant differences in baseline characteristics between the two groups. Bidirectional isthmus block was achieved in all patients. Fluoroscopy time was significantly reduced in the NFCT group {0.3 [inter-quartile range (IQR) 0.2; 0.48] min} when compared with CONV [5.7 (IQR 4.2; 11.5) min] (P < 0.001). This resulted in a significant reduction in radiation dose in patients randomized to NFCT [17.4 (IQR 11; 206.6) cGy cm(2)] vs. the CONV group [418.4 (IQR 277; 812.2) cGy cm(2)] (P < 0.001). There were no significant differences in procedure duration between the NFCT group [49.5 (IQR 37; 65) min] when compared with the CONV group [33.5 (IQR 26.3; 55.5) min] (P = 0.053). No adverse events were recorded. Freedom from atrial flutter at 6 months of follow-up was 19/20 (95%) in the NFCT and 18/20 (90%) in the CONV group (n.s.).

CONCLUSION

In this first prospective randomized study, by comparing NFCT with standard fluoroscopy in patients undergoing radiofrequency ablation of typical atrial flutter, NFCT significantly reduced both radiation dose and fluoroscopy time with no effects on procedural duration. These findings support the incorporation of NFCT in routine clinical use.

MediGuide-impact on catheter ablation techniques and workflow

Since the introduction of percutaneous intervention in modern medical science, specifically cardiovascular medicine fluoroscopy has remained the gold standard for navigation inside the cardiac structures. As the complexity of the procedures continue to increase with advances in interventional electrophysiology, the procedural times and fluoroscopy times have proportionately increased and the risks of radiation exposure both to the patients as well as the operator continue to rise. 3D electroanatomic mapping systems have to some extent complemented fluoroscopic imaging in improving catheter navigation and forming a solid platform for exploring the electroanatomic details of the target substrate. The 3D mapping systems are still limited as they continue to be static representations of a dynamic heart without being completely integrated with fluoroscopy. The field needed a technological solution that could add a dynamic positioning system that can be successfully incorporated into fluoroscopic imaging as well as electroanatomic imaging modalities. MediGuide is one such innovative technology that exploits the geo-positioning system principles. It employs a transmitter mounted on the X-ray panel that emits an electromagnetic field within which sensor-equipped diagnostic and ablation catheters are tracked within prerecorded fluoroscopic images. MediGuide is also integrated with NavX mapping system and helps in developing better 3D images by field scaling-a process that reduces field distortions that occur from impedance mapping alone. In this review, we discuss about the principle of MediGuide technology, the catheter ablation techniques, and the workflow in the EP lab for different procedures.

The Unique MediGuide Technology For CRT Lead Placement And Catheter Ablation

Electrophysiologic procedures such as catheter ablation and/or cardiac resynchronization therapy (CRT) are usually performed under fluoroscopic guidance alone. Currently, we are witnessing the birth of a new era in which many patients can be safely and effectively treated without the use of fluoroscopy. Using MediGuide technology continuous fluoroscopy is no longer required to ascertain the position of the device/catheter, which minimizes the radiation exposure for both the physician and patient, with a further benefit by minimal need for contrast agent. This novel system provides real time tracking of devices projected into live fluoroscopy or pre-recorded cine-angiography. MediGuide technology is an important step forward facilitating complex ablation procedures such as AF ablation and CRT implantation.

Atrial Flutter Ablation Using MediGuideTM Non-fluoroscopic Catheter Tracking System: A Novel Technology to Reduce Radiation Exposure

We describe the first case of cardiac arrhythmia ablation with the novel MediGuide^TM non-fluoroscopic catheter tracking system in North America. This new technology uses electromagnetic field to track sensor integrated intracardiac electrophysiology catheters which are projected on pre-recorded fluoroscopy cine loops. This new technology permits catheter tracking in virtual biplane fluoroscopy and enhances spatial resolution of conventional 3D mapping systems while drastically reducing radiation exposure.