Case Report: A Novel Imaging Technique to Facilitate Radiofrequency Catheter Ablation of an Accessory Pulmonary Vein

In this case report, author James Armstrong, PA-C describes the use of three-dimensional atriography when performing catheter ablation for the treatment of atrial fibrillation. There is growing evidence to suggest that three-dimensional (3D) imaging is a key ingredient to improved outcomes of catheter ablation of atrial fibrillation (AF). Computed tomography (CT) with 3D reconstruction has been the traditional modality providing accurate anatomic replicas of the left atrium (LA) and its adjacent structures. However, this technology requires additional radiation, cost and scheduling in the radiology suite. Three-dimensional atriography (3DATG), on the other hand, is a novel imaging technique that combines the advantages of angiography with 3D reconstruction performed entirely in the electrophysiology (EP) laboratory. The images are easily obtained at the start of the EP procedure, are processed within minutes and provide anatomically accurate 3D guidance when performing radiofrequency ablation (RFA) of this complex arrhythmia.1,2 We report a case of a patient undergoing left atrial RFA with unusual pulmonary vein anatomy where a real-time, three-dimensional rendering of the LA was obtained and integrated with fluoroscopic images during catheter navigation to augment ablation. Case Description A 59-year-old male was referred to our EP laboratory for elective catheter-based radiofrequency ablation and pulmonary vein isolation (PVI) of the LA for symptomatic persistent AF. The patient’s arrhythmia was originally diagnosed in October 2008 when he was hospitalized with chief complaints of several hours of progressive exertional dyspnea and a severe headache of equal duration. A cardiac work-up yielded the causal diagnosis of atrial fibrillation with a rapid ventricular response, and the patient was placed on oral sotalol 80 mg three times daily with warfarin for stroke prevention. After six doses and confirmation of a normal QTc, prior to discharge he underwent synchronized direct current cardioversion, which successfully restored the patient’s rhythm to normal sinus. His sotalol was decreased during his one-month office follow-up to a twice daily regimen due to symptomatic bradycardia. Unfortunately, within a few weeks the patient reverted back to AF that again compromised his well-being. Alternative antiarrhythmic agents were considered but dismissed due to comorbid factors, including a prior history of chronic obstructive pulmonary disease, a recent increase in his serum creatinine and the patient’s overall reluctance to try these medications derived from his own research into their side effect profiles. The patient had also investigated the option of radiofrequency ablation, and thus requested a referral to our EP clinic for consideration six months after the initial diagnosis. After confirming that the patient’s symptomatic AF was now persistent despite continuation of the sotalol and upon discussing the risks and benefits of the procedure, the electrophysiologist agreed that RFA was indeed a viable therapeutic option and thus scheduled the patient for transeptal RFA/PVI of the LA. Our laboratory had traditionally used high-resolution CT scans with 3D reconstruction to provide an anatomical reference point for each case. However, we recently switched to 3DATG as a sole guide for AF ablation procedures after gaining experience with this technology and confirming its accuracy and ease of use.1,2 The process began by placing a pigtail catheter in the IVC a few centimeters inferior to the right atrium. An 80 cc injection of contrast was then delivered, followed by a timed (4-second count) 240-degree rotation of the C-arm. Simultaneously, the patient swallowed a 2 cc bolus of barium to illuminate the esophagus. This regimen took 15 minutes from the time femoral vein access was obtained. The resultant rotational angiogram was then digitally reconstructed and segmented into multiple still images that were subsequently registered into 3D renderings of the LA and adjacent structures via the Philips software (Philips Healthcare, Andover, MA). The process took an additional 15 minutes and was performed while transeptal access was obtained so as to maintain the workflow of the procedure. The 3D shell of the LA could then be superimposed onto live fluoroscopy via the EP Navigator software (Philips Healthcare) to provide anatomical guidance for catheter manipulation and ablation. Total radiation exposure to the patient for image acquisition was 2.3mSv, which is consistent with other experience with this technology and far less than that of CT (13.8 ± 2.4 mSv).2 During the rotational angiogram, we noticed the presence of an additional PV draining into the roof of the LA (Figures 1 and 2). Three-dimensional atriography initially demonstrated this variant and its anatomical relationship to the rest of the LA and other PVs, but the images were only suggestive. However, after obtaining the 3D images, the accessory vessel became more evident (Figures 3-5). We were then able to perform direct contrast injections into each of the PVs via a multipurpose catheter. Images of the selective injections were then combined digitally to illustrate the subtle differences in their ostial characteristics (Figure 6). The accessory vein proved to be the most arrhythmogenic focus as confirmed by the abundance of fractionated high frequency electrograms (EGMs) both within the antrum and beyond (Figure 7). We were successful in mitigating these EGMs after delivery of radiofrequency current (Figure 8). Subsequent ablation of the remaining four PVs assisted by 3DATG produced their successful isolation and organization of the arrhythmia into atrial flutter and finally conversion to sinus rhythm after IV ibutilide. The patient tolerated the procedure well and suffered no acute complications. In early three-month follow-up, the patient remains asymptomatic and in sinus rhythm. We attribute the success of this case to rotational angiography with 3D reconstruction, as it enhanced our ability to identify this unusual anatomic variant and proceed with a well-guided complex ablation. Conclusion In summary, 3DATG is a novel technique that allows attainment of real-time, anatomically accurate replicas of the LA (or other chambers if needed) to guide radiofrequency catheter ablation. The attractive features of this technology, including its availability to the EP operator, reduced radiation exposure as compared to CT, and simplification of overall workflow, are likely to enhance its popularity in the future.