Cover Story

User Review: The New EnSite Precision Cardiac Mapping System

John D. Day, MD
Director, Intermountain Heart Rhythm Specialists
Murray, Utah

John D. Day, MD
Director, Intermountain Heart Rhythm Specialists
Murray, Utah

On December 19, 2016, an 88-year-old woman from Salt Lake City was the first person in the U.S. to experience the new EnSite Precision Cardiac Mapping System (Abbott). This next generation mapping system allowed me far better assessment of her atrial fibrillation (AF) than any previously available technology I have used by the company.

As the first user of this new technology in the U.S., I was asked by EP Lab Digest to share our initial experience with this next-generation 3D mapping system. This article highlights my 12 favorite mapping features of the EnSite Precision cardiac mapping system, and includes the two areas where I think improvement is still needed.

Highlights of the Technology

1. Better Resolution

Just as I love the high-resolution quality of my MacBook with Retina display, I also love having 27x better resolution with the EnSite Precision cardiac mapping system versus the previous generation Velocity mapping system. Even though my mapping time is now much faster than it used to be, 27x better resolution means tens of thousands of geometry points, rather than hundreds with the previous generation system. It goes without mention that better resolution means a much more lifelike 3D map.

2. “TurboMap”

With TurboMap, the EnSite AutoMap Module can be replayed at 10x the real-time speed to map multiple PVC morphologies or nonsustained tachycardias that are different from the original mapped tachycardia. This feature allows the operator to replay the same automatically recorded segment to map the secondary PVCs or tachycardias without having to manually move the catheter through the chamber again, and without having to wait for the PVCs or tachycardia to break through again. 

3. Magnetic Points

The next-generation EnSite Precision cardiac mapping system has married magnetic points to impedance points. However, how these magnetic points are used is different than Biosense Webster’s CARTO system.

Magnetic points are collected with several new magnet-enabled catheters. The purpose of these magnetic points is to correct impedance distortion and render a precise, accurate geometry model. Personally, I have found the 15-mm, fixed curve Advisor FL Circular Mapping Catheter (Abbott) to be my magnetic catheter of choice for AF cases at this time. 

However, I should point out that magnet-enabled catheters are not required to use the EnSite Precision cardiac mapping system. For example, I have not used magnet-enabled catheters for my supraventricular tachycardia or typical right atrial flutter cases. Likewise, in one AF ablation case where the fixed loop circular mapping catheter wasn’t working for me, I switched back to a traditional circular mapping catheter without sacrificing any key features of the EnSite Precision cardiac mapping system.

4. Better Map Stability

Long cases or cardioversions were the bane of the previous generation Velocity maps — they often required manual realignment of the map due to “impedance drift.”

Fortunately, with the EnSite Precision cardiac mapping system, the need for manual realignment of the map has been significantly reduced — not eliminated, but at least significantly reduced. For the most part, I have found that long cases or even multiple cardioversions have not affected the integrity of the map. 

This is mostly because of the redesign of the skin patches. Rather than the large patches that often wouldn’t stick very well by the end of the case, they are now much smaller and stickier. This means they are less prone to patient movement, sweating, etc., which translates to much better map stability.

5. RF Generator Parameters

Like many electrophysiologists, I have a bad neck. I suspect many of my neck problems can be traced back to wearing lead or having to crane my neck to see other monitors in the electrophysiology lab.

Fortunately, the radiofrequency (RF) generator parameters (e.g., impedance, power, temperature, and time) can all be displayed on the map of the EnSite Precision cardiac mapping system. Placement is entirely up to the user. 

Personally, I like this displayed near where I am ablating. By not having to crane my neck anymore, I feel much better at the end of a long day of doing ablation procedures.

6. A “OneMap” That Works

Conceptually, I always liked the OneMap feature with previous generations of the NavX mapping system. Being able to automatically generate activation maps while simultaneously collecting geometry points was a potential time saver.

The problem was that unless you went point-by-point through OneMap to fix erroneous points, the map was useless. This has now been fixed.

Using the threshold filters available in AutoMap, every OneMap I have created thus far with the EnSite Precision cardiac mapping system has been very accurate, with minimal editing of timing points required. The threshold filters include ECG score matching, speed limits, cycle length adjustability, contact force minimum and maximum values, and an adjustable signal-to-noise ratio filter. These filters eliminate the “bad” collection and annotation of beats that should be excluded. 

7. AutoMark Lesion Quality

In the past, I would ask my team to manually mark the quality of my lesions. Typically, we would often assign a different colored lesion marker to areas where we knew a quality lesion had been delivered. With the EnSite Precision cardiac mapping system, this is all now done automatically.

With the AutoMark lesion quality feature, you can set your parameters for temperature, time, force, impedance drop, or power. With these parameters in place, the EnSite Precision cardiac mapping system will then give you a different colored lesion marker depending on the parameters you have selected.

As pulmonary vein reconnection is the main determinant of whether an AF ablation will be successful or not, you can now quickly identify areas that may require additional ablation to prevent AF from recurring. 
I have found this feature also works well for typical right atrial flutter ablations. With AutoMark lesion quality, I can quickly identify a gap in my cavotricuspid isthmus ablation line.

8. “SparkleMaps”

SparkleMaps are cool — not just the name, but how propagation is displayed with this feature.

SparkleMaps allow you to see activation over voltage maps. SparkleMaps have identified gaps in my lesion sets with complex flutter cases. 

The best part is that this map can be gathered in the background, even while I am ablating. Thus, no extra time is required to create this map.

We are currently evaluating the utility of this feature in mapping AF wavefronts for patients with persistent atrial fibrillation. In time, we will know if this feature improves our ablation success rates.

9. Template Score Matching

I believe premature ventricular complex (PVC) ablations are much easier with the EnSite Precision cardiac mapping system, because the technology automatically scores surface electrograms individually and provides a composite score analysis of PVCs. This precisely eliminates PVCs that are not of interest or captures every matching PVC with automatically annotated timing points. 

For example, while collecting geometry points, if the patient happens to have a spontaneous clinical PVC, you can automatically collect the timing of your ablation catheter to the PVC. This allows you to get your ablation catheter to the PVC site of earliest activation much quicker than you could with Velocity.

10. Real-Time PVC Pace Map Scoring

Years ago, I loved Bard’s real-time pace map scoring feature of their EP recording system. This was especially helpful in PVC cases, where the PVCs were few and far between.

Once you identified the 12-lead of your PVC of interest, you could then pace map and the EP recording system would tell you your percent match to the PVC template. The EnSite Precision cardiac mapping system now offers this same feature.

By pacing in the general area of where you think the PVC is originating, you can quickly see how close your pacing is to the PVC of interest. In our experience, once your percent match is above 95%, you are getting extremely close to the source. As with the auto electrogram analysis for PVCs, these two features alone have the potential for a much more accurate and quicker PVC ablation procedure. 
A new mapping template automatically creates a percentage color map while pace mapping. 

11. Latest Activation Maps for VT

One of the biggest challenges with ventricular tachycardia (VT) ablation has to do with mapping. As most VTs cause hemodynamic instability, substrate mapping approaches are often preferred.

One neat feature of the EnSite Precision cardiac mapping system is the ability to perform latest activation maps for VT. This mapping feature thus facilitates identification of late potential electrograms for ablation. Whether or not these PVC mapping technologies improve PVC ablation success rates will be seen with time.

12. Auto Fractionation and CFAE Maps

Auto fractionation and complex fractionated electrogram (CFAE) maps are probably my favorite features of the EnSite Precision cardiac mapping system. While recent studies have largely discredited CFAE mapping, I suspect this is likely because CFAE mapping went after the wrong target.

For example, we have long observed that CFAEs often correlated with healthy atrial tissue. Thus, it came as no surprise to us that ablating healthy tissue didn’t improve AF ablation success rates.

However, if you can adjust the auto fractionation and/or CFAE collection parameters in conjunction with a voltage map, then you just may be able to see and map AF rotors and drivers. Currently, we are using the EnSite Precision cardiac mapping system to identify areas of high frequency with long electrograms, in areas of low voltage, as potential targets. We are optimistic that pulmonary vein isolation, in conjunction with electrogram substrate-guided ablation, will improve persistent AF ablation success rates.

Areas of Improvement

Despite these new changes, there are still a few areas that could be improved upon in the next version of the EnSite Precision cardiac mapping system. For example, the following features would be preferable in future versions:

  1. EnSite Precision cardiac mapping system not integrated with EnSite Array balloon mapping catheter. The 64-pole non-contact EnSite Array catheter (Abbott) is a great tool to map tachycardias with just one beat. It is also beneficial for mapping conduction velocity or conduction direction of atrial fibrillation. However, this tool is still not integrated with EnSite Precision. Thus, if you want to use the Array Catheter, you can’t use EnSite Precision. You are forced to choose one or the other.
  2. Inability to map conduction velocity and direction with the EnSite Precision cardiac mapping system. Mapping the source of atrial fibrillation remains the “Holy Grail” of AF ablation. Unfortunately, the EnSite Precision cardiac mapping system doesn’t get us any closer to this goal. Hopefully, future upgrades will allow mapping of AF drivers and rotors through conduction velocity and conduction direction mapping. Seeing the AF wavefront propagation could be very helpful in identifying the source of persistent AF.

Disclosure: The author has no conflicts of interest to report regarding the content herein. Outside the submitted work, Dr. Day reports he is a consultant with Abbott, Boston Scientific, and BIOTRONIK.