Modified Convergent Procedure for Refractory Atrial Fibrillation Using Intraoperative 3D Epicardial Voltage Mapping

In this video, the authors demonstrate a modified convergent procedure for refractory atrial fibrillation using intraoperative three-dimensional epicardial voltage mapping. The patient is a seventy-four-year-old man who presented with recurrent symptomatic atrial fibrillation despite maximal medical therapy and three prior catheter ablations.

3D voltage maps from the patient’s most recent preoperative catheter ablation are shown in the video. The red areas indicate successful ablation and total isolation of the posterior wall. However, in the upper, pre-ablation image, the purple areas indicate recovery in conduction anterior to the left atrial appendage and along the superior vena cava and cavotricuspid isthmus since previous ablations. Therefore, at the time of this ablation, additional lesions were delivered in these areas, as shown by the red and white circles in the lower post-ablation image. The areas that were once purple are now red, indicating that transmural lesions were achieved.

Despite what seems to be electrical isolation of the left atrium in the lower image, the patient presented with recurrent symptomatic atrial fibrillation. Therefore, the decision was made to proceed with a modified epicardial convergent procedure and left atrial appendage closure.

The materials used for this procedure include an esophageal temperature probe with placement confirmed by fluoroscopy, transesophageal echocardiography, defibrillator pads, two robotic Cadiere graspers, a robotic vessel sealer, an endoscopic grasper, two endoscopic cigar sponges, an Abbot Advisor mapping device, and an AtriCure EPI-Sense ST radiofrequency ablation probe.

After induction of general anesthesia and double lumen endotracheal intubation, the patient was positioned supine with the left shoulder elevated on a bump. The bump under the left shoulder elevated the left chest relative to the left arm. This positioning allowed placement of the ports as posterior as possible so that the instruments would not collide with the left arm or shoulder.

The skin was then marked for port placement. Three 8 mm ports were placed in the third, fifth, and seventh intercostal spaces—two instrument ports and a camera port. A 12 mm assistant port was placed in the eighth intercostal space posteriorly. The assistant port was placed last, only after the chest was insufflated to allow placement in the trajectory of the left atrial appendage. A transesophageal echocardiogram confirmed no left atrial appendage thrombus.

With thoracoscopic ports in place and the robot docked, the pericardium was opened posterior to the phrenic nerve and pericardial vein from the aorta down to the level of the diaphragm. The Abbott Advisor cardiac mapping device was then introduced through the assistant port for preablation epicardial 3D voltage mapping. As the probe was moved along the epicardial surface, it generated a 3D voltage map.

Before showing the real-time preablation 3D voltage map for the patient, surgeons oriented themselves with this blank schematic which was oriented posteriorly, as if they were looking at the left atrium from behind. In other words, the left pulmonary veins were to the left of the screen, and the right pulmonary veins were to the right of the screen.

Surgeons then positioned the ablation probe for each lesion. The first lesions formed a line along the roof of the left atrium on the transverse sinus and extended to the left atrial appendage. Marshall’s ligament was also ablated at this time. The ablation probe was then advanced through the assistant port and placed longitudinally along the left atrium for serial epicardial lesions. The line of dots was oriented upward, indicating that the head of the probe was also oriented up against the surface of the atrium. Moving the ablation probe to one of the instrument ports instead of the assistant port is sometimes necessary to achieve the appropriate angle.

The next lesion was a line anterior to the left pulmonary veins. Here, surgeons pulled gently on the pericardium to clearly expose the left pulmonary veins and then serially reposition the ablation probe anterior to the veins. Additional lesions to the posterior wall were performed with the probe through the assistant port. Again, keeping in mind the orientation and depth of the line of black dots.

Finally, the floor line was created as a line connecting the inferior pulmonary veins along the posterior wall. Here, it was necessary to move the camera to the assistant port and the probe to the camera port. Approximately 23 epicardial lesions were completed in total to accomplish this final lesion set.
The Abbott Advisor cardiac mapping device was again used to confirm electrical isolation and transmurality of each lesion. There was a gap on the postablation map showing residual activity along the posterior wall near right superior pulmonary vein. Based on this map, additional lesions were delivered to these areas at different angles and, eventually, total isolation of the posterior atrium was achieved.

Next, a 45 mm AtriClip was advanced through the assistant port to be placed at the base of the LAA within 1 cm of the lateral ridge without occluding or kinking the left circumflex. With the clip clamped but not deployed, TEE was used to confirm appropriate placement, absent flow in the appendage, and a patent left circumflex artery. The clip was then deployed. The patient was extubated in the operating room in sinus rhythm and was discharged home on postoperative day three.

In summary, this video demonstrated a modified convergent procedure with intraoperative 3D epicardial voltage mapping guidance. This hybrid approach may be more effective than a convergent procedure alone because of the ability to simultaneously confirm transmurality and complete electrical isolation.

References

1. DeLurgio DB, Gill JS, Ahsan S, Kaba RA, Plasseraud KM, Halkos ME. Hybrid Convergent Procedure for the Treatment of Persistent and Long-standing Persistent Atrial Fibrillation. Arrhythm Electrophysiol Rev. 2021 Oct;10(3):198-204.
2. DeLurgio DB, Crossen KJ, Gill J, et al. Hybrid convergent procedure for the treatment of persistent and long-standing persistent atrial fibrillation: results of CONVERGE clinical trial. Circ Arrhythm Electrophysiol. 2020; 13:e009288.
3. Crandall, B., Kanuri, S., Cutler, M., et al. High power ultra short duration ablation with HD Grid improves freedom from atrial fibrillation and redo procedures compared to circular mapping catheter. Journal of Atrial Fibrillation. 2020;13.2.

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