A Novel Approach to Cardiac 3D Mapping

Case Description

A 63-year-old female with symptomatic persistent atrial fibrillation (AFib) was referred for a second opinion. She had a history of chronic kidney disease (stage III), moderate COPD, hypertension, obesity, and sleep apnea. Echocardiogram showed normal LVEF with left ventricular hypertrophy and a dilated left atrium (left atrial volume index of 47.4 ml/m². The patient had undergone unsuccessful DC cardioversion. She was started on sotalol, and repeat cardioversion also failed. The patient wanted aggressive rhythm control, so catheter ablation was offered. 

Under general anesthesia, regular vascular access was obtained. Pulmonary vein isolation (PVI) was performed using the cryoballoon. The Navik 3D (APN Health) mapping system was used. Atrial fibrillation continued after all veins were isolated. Navik 3D provided the exact location of every vein ostium (Figure 1). An Achieve catheter (Medtronic) was used to map and ablate other non-pulmonary vein triggers in the left atrium. The left superior ganglionic plexus (GP) area was recorded with highly fractionated activity. It was decided to use the cryoballoon for ablation, since Navik 3D offers unique property of mapping and tracking the balloon, and all its previous locations and cryo applications. Right anterior and right inferior GP areas were also active and thus ablated using cryo. All balloon locations were marked and tracked with Navik 3D. 

Using same technique, posterior wall ablation was performed with the cryoballoon. With ablation of the posterior wall, the AFib terminated and converted into a stable flutter (Figure 2). Coronary sinus activation indicated possible roof-dependent flutter. One more cryoballoon application applied along the roof terminated the flutter into sinus rhythm (Figure 3). Multiple attempts to induce AFib with and without isoproterenol failed. A high dose of isoproterenol (20 mcg/min) for 30 minutes also failed to induce atrial fibrillation. Follow-up with a 30-day implantable loop recorder data showed no recurrence. 

About the Technology

Navik 3D (Figure 4) is a novel cardiac electroanatomic three-dimensional mapping system. This innovative technology was developed by medical device company APN Health and its creative team, including Dr. Jasbir Sra (founder) and myself, both electrophysiologists at Aurora Health Care. The system uses a complex, proprietary mathematical formula and fast processor calculations to locate any opaque object in 3D within regular X-ray fluoroscopy, such as EP catheters and the cryoballoon. With this, it turns regular fluoroscopy into a three-dimensional map. 

After undergoing development and testing, APN Health received U.S. FDA clearance to market the Navik 3D in 2016. The system is now commercially available; the first clinical use was in March 2018 at Advocate Aurora St. Luke’s Medical Center in Milwaukee. 

Navik 3D creates and displays real-time three-dimensional maps of the cardiac chamber during catheter-based EP procedures performed on cardiac arrhythmia patients. Navik 3D processes real-time, two-dimensional, single-plane fluoroscopic images, along with body surface ECG data and intracardiac electrogram signals, to create a synchronized, real-time visual map. The device does not require any hardware attachment to the patient, and no patches or dedicated catheters are necessary. 

The system integrates easily in the current workflow in most labs. Navik 3D can integrate with any single-plane fluoroscopy system and patient recording and monitoring systems. Navik 3D’s integrated use of an EP lab’s existing equipment does not add any burden on these systems, which would require additional maintenance beyond standard levels of care. The technology is intended to be used as a complimentary resource to existing EP lab equipment. The live images and signals from each of these individual standalone systems remain completely available for operators without interference from the Navik 3D processing and display activities. The operator can decide at any time to use the mapping system, even in the middle of the case, without having to set up or having to move the patient to attach patches. 

As such, it is very cost effective, as it does not require a significant investment upfront. Instead, a modest amount that covers a small computer that houses the system — the hospital pays a flat fee for any number of cases they want for a period of time.

About Atrial Fibrillation

Atrial fibrillation is the most common arrhythmia encountered in clinical practice. It is estimated that about 9% of people 65 year or older have AFib.

The pulmonary veins are considered the trigger sites for most paroxysmal AFib patients, and the cryoballoon is one of the ablation strategies used for PVI. Navik 3D uses a patented algorithm to identify the 3D location of the cryoballoon along with temperature probes and other catheters such as the coronary sinus catheter (Figures 5 and 6). This technique allows the user to identify and see in real time the locations where ablation has occurred using the cryoballoon, and to determine the relationship of the cryoballoon to the esophageal temperature probe in 3D to avoid esophageal injury. The algorithm allows for fast initial 3D map creation using only a few points taken from fixed catheters (Figure 7).

Three-dimensional localization also allows the user to visualize the prior and current locations of the cryoballoon, thus creating a roadmap and allowing the user to adjust as needed (Figure 6).
This has the added benefit of potentially allowing the physician to create additional lines of block.

The second-generation Navik 3D system has advanced capabilities such as Artificial Intelligence for fast and accurate detection of catheter tips; Quick Map with creation and depiction of accurate 3D maps using only a few points; 3D localization of the cryoballoon, temperature probe, and other catheters; and the ability to create ultra-fast maps with minimal fluoroscopic exposure.

Conclusion

Since FDA clearance a few months ago, the Navik 3D mapping system has been used at Advocate Aurora St. Luke’s Medical Center (Milwaukee) with excellent results. The technology is set to be a breakthrough in cardiac 3D mapping technology for arrhythmia therapy with a promising future. The performance, accessibility, and affordability of this technology will not only reduce costs, but also potentially save millions of lives across the globe. ν

Disclosure: Dr. Hani has no conflicts of interest to report regarding the content herein. He reports that he serves as a non-paid clinical consultant with an insignificant (<1%) share.