Fluoroless Cryoballoon Ablation for Atrial Fibrillation

Case Description

We present the case of a 60-year-old woman with systemic sclerosis manifesting with esophageal dysmotility and difficulty swallowing as well as pulmonary hypertension. The patient first developed atrial fibrillation 13 months prior to presentation. She underwent a direct current cardioversion and was started on oral anticoagulation. She was started on antiarrhythmic drug therapy with sotalol; however, she was not able to tolerate this drug due to symptomatic bradycardia. The arrhythmia recurred 2 weeks later, and another cardioversion was performed.

She was referred to the Atrial Fibrillation Clinic at the University of Washington. Symptoms experienced when in the arrhythmia include fatigue, shortness of breath, and palpitations. The symptoms were significantly limiting, and her quality of life was significantly improved while in sinus rhythm.

The patient did not have many modifiable risk factors as she was not overweight, did not drink alcohol, and did not smoke. There was no suspicion for sleep apnea. Catheter ablation was discussed as a therapeutic option that would give her a higher likelihood of maintaining sinus rhythm, and she was excited to move forward with this.

A cardiac MRI was obtained to evaluate for left atrial fibrosis (using late-gadolinium MRI hyperenhancement), as well as pulmonary vein size and overall cardiac anatomy (Figure 1, Video 1). The patient had two pulmonary veins on each side, and her overall left atrial fibrosis was determined to be 17%. Figure 1 illustrates the distribution of atrial fibrosis in the green color (Marrek, Inc.).

Based on the pulmonary vein anatomy and atrial fibrosis, it was decided to proceed with pulmonary vein isolation using cryoablation.

The patient presented for the procedure at the University of Washington Medical Center. The procedure was performed under general anesthesia. Ultrasound was used to guide central venous access in the femoral veins. Heparin was given in a bolus followed by an infusion to achieve a goal activated clotting time (ACT) of 350-450 seconds.

An intracardiac echocardiography (ICE) catheter was advanced from the left femoral vein and used throughout the procedure. An esophageal temperature probe was placed orally, and its position was verified posterior to the left atrium with ICE.

Next, the ICE catheter was retroflexed to visualize the lateral right atrial wall and superior vena cava (SVC) junction. An exchange length wire was advanced from the femoral vein and visualized with ICE as it went up in the SVC. Next, a long SL-0 sheath was advanced over the wire to the SVC and visualized with ICE. The ICE catheter was then returned to the neutral position and torqued clockwise to visualize the interatrial septum posteriorly at the level of the left pulmonary veins.

Next, a Brockenbrough needle (Medtronic) was advanced through the SL-0 dilator until 3 cm from the tip. A pressure line was used to transduce pressure from the needle. The needle and side arm of the sheath were lined up and torqued to about 5-6 o’clock (pointing down on the patient). The sheath, dilator, and needle system were pulled back slowly until the tip of the dilator was at the level of the fossa ovalis on the interatrial septum (Figure 2, Video 2). The needle was advanced and seen traversing the interatrial septum into the left atrium. The pressure line showed a mean left atrial pressure of 13 mm of mercury. The dilator and sheath were advanced over the needle into the left atrium. The needle and dilator were withdrawn, and the sheath was flushed and connected to a heparinized saline drip.

A circular multipolar mapping catheter was then advanced through the sheath into the left atrium, and an electroanatomical voltage map of the left atrium was obtained. This was registered with a three-dimensional model of the left atrium obtained from the cardiac MRI. (Figure 3)

Next, the mapping catheter was removed and a stiff exchange length wire was advanced through the sheath and placed in the left superior pulmonary vein under ICE guidance.

The SL-0 sheath was removed, and a cryoballoon delivery sheath was advanced over the wire into the left atrium under ICE guidance. After proper sheath flushing, the cryoballoon catheter and circular catheter (Achieve, Medtronic) were advanced into the left atrium through the sheath. The Achieve was first placed in the left superior pulmonary vein (LSPV), with pulmonary vein potentials recorded. The balloon was inflated and advanced to the pulmonary vein ostium under ICE guidance. Color flow Doppler imaging was used to verify a good seal (Video 3). A cryoballoon application was delivered, resulting in isolation of the LSPV 60 seconds from the start of the application. Another 120-second application was delivered to the LSPV. The balloon was then moved to the left inferior pulmonary vein (LIPV) (Figure 4), and the same process was repeated, resulting in isolation of the LIPV (Figure 5).

Next, the decapolar catheter was withdrawn from the coronary sinus and advanced into the SVC. High-output pacing resulted in capture of the right phrenic nerve, evidenced by strong right diaphragm contractions. The balloon and Achieve catheters were then positioned in the right superior pulmonary vein (RSPV) and vein ostium, respectively. Cryoballoon application resulted in electrical isolation, while pacing confirmed right phrenic nerve capture.

Lastly, the process was repeated for the right inferior pulmonary vein (RIPV). Next, the cryoballoon catheter was removed and the circular mapping catheter was re-inserted. Repeat mapping showed dissociated pulmonary vein potentials without evidence of electrical conduction into the pulmonary veins (entrance block). Pacing from each of the pulmonary veins showed local capture without conduction to the atrium (exit block).

With these findings, the catheters and sheath were withdrawn from the left atrium. The decapolar catheter was placed across the tricuspid valve, and atrioventricular conduction intervals were measured to be normal. The procedure was concluded without using any fluoroscopy to guide vascular access or catheter manipulation. The patient emerged from anesthesia without difficulty, and was observed in the hospital overnight before she was discharged the next day. She had a smooth post-procedural healing period and continues to do well, with no recurrence of arrhythmia at 7-month follow-up.

Discussion

Cryoballoon ablation was shown to be equally effective in long-term maintenance of sinus rhythm compared to radiofrequency ablation in the FIRE AND ICE Trial, which enrolled mostly paroxysmal atrial fibrillation patients similar to ours.¹ Cryoballoon ablation typically involves the use of contrast and more patient x-ray exposure for dye injections. Cryoballoon ablation was also associated with a higher risk of phrenic nerve palsy. Esophageal thermal injury, even though uncommon in the FIRE AND ICE Trial, can occur with the cryoballoon. We used pacing to monitor for phrenic nerve injury and esophageal temperature monitoring to check for esophageal thermal injury. Most importantly, our case demonstrates that cryoballoon ablation can be performed using ICE guidance without contrast or x-ray exposure.

Atrial fibrillation is the most common pathologic arrhythmia in adult clinical practice, and its prevalence is expected to increase in the coming decades. Catheter ablation is currently the most effective therapeutic method for long-term maintenance of sinus rhythm. In this case, we demonstrated the safe and effective performance of a cryoballoon ablation guided completely by intracardiac echo and prior cardiac imaging with MRI, which also does not expose the patient to any ionizing radiation or nephrotoxic contrast. Our lab is well versed in minimal and fluoroless catheter ablation cases. With maturation and widespread adoption of this technique, electrophysiology lab team members (physicians, nurses, technicians) would also minimize both their exposure to x-ray as well as the periods of time when wearing protective lead is important. This would be expected to increase job satisfaction and physical well-being, while also delivering the best possible care for the patient. 

Acknowledgements. We would like to thank the entire Cardiac Electrophysiology team at the University of Washington (Figure 6). Each member, even those not directly involved with this particular patient, had a valuable contribution to make it possible.

Disclosures: The authors have no conflicts of interest to report regarding the content herein.    

1. Kuck KH, Brugada J, Furnkranz A, et al; FIRE AND ICE Investigators. Cryoballoon or Radiofrequency Ablation for Paroxysmal Atrial Fibrillation. N Engl J Med. 2016;374(23):2235-2245.