Bipolar ablation – an inspiring past, a promising future

Although its idea has been known for more than 30 years, it is currently more widely used in clinical practice due to technical progress. Bipolar ablation may be the only practical alternative for a specific group of patients with heart rhythm disorders. Piotr Futyma, MD, PhD, Associate Professor at the University of Rzeszów and Cardiac Electrophysiologist at St. Joseph’s Heart Rhythm Center in Rzeszów, talks about the current position of this procedure and Polish scientific and technological projects.

Expert’s comment

We refer to bipolar ablation when we use a second ablation catheter located near the application site, connected to a radiofrequency (RF) generator instead of a dispersive patch. Our goal is to surround our predefined ablation target with two ablation catheters coupled into a single circuit to maximize the RF current near the area of interest. 

Bipolar ablation was, in fact, an original idea for performing ablation procedures. Publications from the early 1990s documented the first cases of accessory pathways treated with RF current delivered in bipolar fashion (1). At that time, the bipolar ablation appeared to be rather inconvenient. Firstly, it was necessary to provide full control over not only a single one but two separate ablation catheters. Secondly, the biophysics of RF application was not that well known back then. So, it was challenging to take into account and coordinate many parameters of both ablation catheters located in the patient’s heart. 

In the very first landmark paper on ablation in WPW syndrome, researchers led by Professor Warren Jackman switched to unipolar ablation after treating their first eight patients, ultimately with the bipolar technique. The unipolar ablation has been considered the classic ablation method since then. By using only one ablation catheter and a dispersion patch located at the patient’s body, it was easier to control RF delivery because it required parameters maintenance of a single ablation catheter only. It is worth mentioning that the use of RF current those days was an alternative to high-energy discharges performed with a direct current (2) – a method that is now returning to clinical electrophysiology as an irreversible electroporation, also called pulsed-field ablation. 

In the following years, RF current proved to be an optimal solution for sufficient control of effective ablation procedures in a broad spectrum of arrhythmias. Unipolar RF delivery has become an efficient therapy for ablation of accessory pathways and turned out to be highly effective for the treatment of atrioventricular nodal reentrant tachycardia. The next step was to use unipolar RF ablation to treat right and left ventricular outflow tract arrhythmias (3). In the last decade, RF ablation was established for the treatment of post-infarction ventricular tachyarrhythmias and pulmonary vein isolation for atrial fibrillation (4). 

In the early development of ablative electrophysiology, there was a brief intriguing return to the use of the bipolar method for some more complex cases. In the early 1990s at St George’s Hospital, the bipolar technique was used for the ablation of septal accessory pathways that could not be successfully eliminated using the classic approach (5). At the beginning of this century, single reports from Spain, the Czech Republic and the United States showed up demonstrating the possibility of effective ventricular arrhythmias treatment with the use of bipolar ablation (6). The first Polish reports appeared in the last decade; for instance, the first Polish publication concerning bipolar ablation came from our St. Joseph’s Center in Rzeszow and described the treatment of atrial flutter in a patient with an anatomical variant (7). Almost simultaneously, a team from Poznań led by Prof. Artur Baszko performed an emergency bipolar ablation of ventricular septal tachycardia (8), and several such procedures have been performed in Poznań since then. In Rzeszów, we focused mainly on bipolar ablation of arrhythmias from a relatively complex area of the heart, which is the left ventricular summit (9). Arrhythmias originating in the left ventricular ostium can sometimes cause significant difficulties for electrophysiologists, mainly due to unique anatomical relationships and tissue heterogeneity in this area. That’s why arrhythmic substrates located there are sometimes refractory to classical RF applications, either from the left ventricular outflow tract, from the aortic cusps or from the great cardiac vein. The long-term efficacy of classical ablation in the left ventricular summit area is also suboptimal (10). The first reports on the possibility of effective treatment of tachycardias originating from the left ventricular summit came from Poland, with the main participation of our center in Rzeszow (11,12), and this is what I am particularly proud of. Today, we have the honor and pleasure to share our knowledge and skills with colleagues from other centers in Poland and worldwide.

Possibilities for the use of bipolar ablation are significant. In particular, patients after multiple and extensive unsuccessful ablation attempts frequently appear to be good candidates for this procedure. Not only patients with refractory septal arrhythmic substrates may particularly benefit from bipolar ablation, but also relatively young patients with idiopathic arrhythmias, i.e., those without structural heart disease, with the emphasis on the left ventricular summit cases.

One of the most challenging patients was a male after six ventricular tachycardia (VT) ablations. After these unsuccessful attempts using the classic approach performed at four different expert centers, the decision was made that the patient would ultimately live with his recurrent VT or should be scheduled for heart transplantation. Together with Prof. Piotr Kulakowski in our center in Rzeszów, we’ve performed the 7th procedure, this time using the bipolar technique. The case lasted over five hours and required bipolar applications for a total duration of approximately 30 minutes – it was so difficult to get to the source of the arrhythmia. However, this challenging case was ultimately successful (13). Until this day, nearly five years after the procedure, the patient has no VT recurrence and remains symptom-free. Similar results are frequently observed in other patients treated with this method.

Bipolar ablation is a technique attracting increasing interest from clinicians and researchers. The 2019 expert consensus on ablation of ventricular arrhythmias includes a paragraph dedicated to bipolar ablation, highlighting some limitations of the procedure (14). There are regular publications, usually single-center or consisting of a relatively small group of patients from several centers, describing the effects of this therapy. We are currently waiting impatiently for the results of prospective studies. We are also aware of certain limitations and difficulties. The group of patients who may benefit most from bipolar ablation is a relatively challenging group in the view of clinical trials – these patients frequently underwent long-term antiarrhythmic drug treatment and many extensive ablations as well.

Technical issues are essential aspects of bipolar ablation. Centers often use customized equipment or available off-label connections in order to plug in ablation catheters into a bipolar circuit. The first models of RF generators capable of deriver energy in bipolar fashion have been recently developed. Here in Rzeszow, we’ve constructed a connection device dedicated for bipolar ablation based on my original project. This adapter allows to collect and track substantial information from the catheter plugged into the position of the return electrode connected instead of a dispersive patch, which results in reasonable control of bipolar ablation. 

Our adapter enables the delivery of the bipolar ablation as well as temperature measurements from the electrode tip, which allows avoiding overheating and subsequent formation of charring and related complications. Another functionality of the adapter is the ability to transfer signals from the catheter electrodes, which allows 3D reconstruction of the catheter in the electroanatomical mapping system and provides signal recordings obtained directly from the catheter electrodes. The device works with most of the available RF generators and with a spectrum of currently available ablation catheters.

After the device received a CE mark in 2020, we successfully implemented bipolar ablation in several leading European centers (15). Apart from the St. Joseph’s Heart Rhythm Center in Rzeszów, the bipolar ablation device is currently used in the main EP centers in Frankfurt, Cologne, Essen, Basel, Zurich, and London. The results of bipolar ablation with the use of the adapter and the feedback concerning the use of our tool are very satisfactory. In my opinion, this is an excellent proof that the original idea of using bipolar ablation was not a mistake. It is beneficial to develop technological concepts and ideas due to true clinical demands, and it is worth cooperating — exchanging views, experiences, sharing knowledge and skills. This way, we can help a number of challenging patients who just recently had barely any alternative.

Assoc. prof. Piotr Futyma, MD, PhD

Finalist in the Innovation Stage competition at the 2019 EHRA Congress in Lisbon. Member of the Heart Rhythm Society (HRS) Communications Committee. In 2021 accepted as a Fellow of ESC (FESC) and Fellow of EHRA (FEHRA). Author of 5 patent applications.

He participated in implementation bipolar ablation technique at several leading electrophysiology centres in Europe, including Cardioangiologisches Centrum Bethanien in Frankfurt, Germany, Universitatsspital Basel, Switzerland, Klinik Hirslanden in Zurich, Switzerland, St. Georges University Hospital in London, UK, and several others.

References :

1. Jackman WM, Wang XZ, Friday KJ, Roman CA, Moulton KP, Beckman KJ, McClelland JH, Twidale N, Hazlitt HA, Prior AL, et al. Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current. N Engl J Med. 1991 Jun 6;324(23):1605-11. Doi: 10.1056/NEJM199106063242301. PMID: 2030716.
2. Chen SA, Tsang WP, Hsia CP, Wang DC, Chiang CE, Yeh HI, Chen JW, Ting CT, Kong CW, Wang SP, et al. Catheter ablation of accessory atrioventricular pathways in 114 symptomatic patients with Wolff-Parkinson-White syndrome – a comparative study of direct-current and radiofrequency ablation. Am Heart J. 1992 Aug;124(2):356-65. Doi: 10.1016/0002-8703(92)90598-p. PMID: 1636579.
3. Zhu DW, Maloney JD, Simmons TW, Nitta J, Fitzgerald DM, Trohman RG, Khoury DS, Saliba W, Belco KM, Rizo-Patron C, et al. Radiofrequency catheter ablation for management of symptomatic ventricular ectopic activity. J Am Coll Cardiol. 1995 Oct;26(4):843-9. Doi: 10.1016/0735-1097(95)00287-7. PMID: 7560606.
4. Andrade JG, Champagne J, Dubuc M, Deyell MW, Verma A, Macle L, Leong-Sit P, Novak P, Badra-Verdu M, Sapp J, Mangat I, Khoo C, Steinberg C, Bennett MT, Tang ASL, Khairy P; CIRCA-DOSE Study Investigators. Cryoballoon or Radiofrequency Ablation for Atrial Fibrillation Assessed by Continuous Monitoring: A Randomized Clinical Trial. Circulation. 2019 Nov 26;140(22):1779-1788. Doi: 10.1161/CIRCULATIONAHA.119.042622. Epub 2019 Oct 21. PMID: 31630538.
5. Bashir Y, Heal’ SC, O’Nunain S, Katritsis D, Camm AJ, Ward DE. Radiofrequency current delivery by way of a bipolar tricuspid annulus-mitral annulus electrode configuration for ablation of posteroseptal accessory pathways. J Am Coll Cardiol. 1993 Aug;22(2):550-6. Doi: 10.1016/0735-1097(93)90063-7. PMID: 8335828.
6. Koruth JS, Dukkipati S, Miller MA, Neuz’l P, d’Avila A, Reddy VY. Bipolar irrigated radiofrequency ablation: a therapeutic option for refractory intramural atrial and ventricular tachycardia circuits. Heart Rhythm. 2012 Dec;9(12):1932-41. Doi: 10.1016/j.hrthm.2012.08.001. Epub 2012 Aug 2. PMID: 22863684.
7. Futyma P, Futyma M, Maciołek M, Kułakowski P. Bipolar Radiofrequency Ablation of Typical Atrial Flutter. J Cardiovasc Electrophysiol. 2016 Jul;27(7):874-5. Doi: 10.1111/jce.12908. Epub 2016 Feb 4. PMID: 27405451.
8. Baszko A, Telec W, Kałmucki P, Iwachów P, Kochman K, Szymański R, Kłopocki J, Ożegowski S, Szyszka A, Siminiak T. Bipolar irrigated radiofrequency ablation of resistant ventricular tachycardia with a septal intramural origin: the initial experience and a description of the method. Clin Case Rep. 2016 Aug 25;4(10):957-961. Doi: 10.1002/ccr3.648. PMID: 27761246; PMCID: PMC5054470.
9. Futyma P, Wysokińska A, Sander J, Futyma M, Kułakowski P. Bipolar Endo-Epicardial Radiofrequency Ablation of Arrhythmia Originating from the Left Ventricular Summit. Circ J. 2018 May 25;82(6):1721-1722. Doi: 10.1253/circj. CJ-17-0782. Epub 2017 Oct 18. PMID: 29046505.
10. Chung FP, Lin CY, Shirai Y, Futyma P, Santangeli P, Lin YJ, Chang SL, Lo LW, Hu YF, Chang HY, Marchlinski FE, Chen SA. Outcomes of catheter ablation of ventricular arrhythmia originating from the left ventricular summit: A multicenter study. Heart Rhythm. 2020 Jul;17(7):1077-1083. Doi: 10.1016/j.hrthm.2020.02.027. Epub 2020 Feb 28. PMID: 32113894.
11. Futyma P, Sander J, Ciąpała K, Głuszczyk R, Wysokińska A, Futyma M, Kułakowski P. Bipolar radiofrequency ablation delivered from coronary veins and adjacent endocardium for treatment of refractory left ventricular summit arrhythmias. J Interv Card Electrophysiol. 2020 Sep;58(3):307-313. Doi: 10.1007/s10840-019-00609-9. Epub 2019 Aug 11. PMID: 31402415.
12. Futyma P, Santangeli P, Pürerfellner H, Pothineni NV, Głuszczyk R, Ciąpała K, Moroka K, Martinek M, Futyma M, Marchlinski FE, Kułakowski P. Anatomic approach with bipolar ablation between the left pulmonic cusp and left ventricular outflow tract for left ventricular summit arrhythmias. Heart Rhythm. 2020 Sep;17(9):1519-1527. Doi: 10.1016/j.hrthm.2020.04.029. Epub 2020 Apr 26. PMID: 32348845.
13. Futyma P, Głuszczyk R, Futyma M, Kułakowski P. Right atrial position of a return electrode for bipolar ablation of the left posterosuperior process ventricular tachycardia. Pacing Clin Electrophysiol. 2019 Apr;42(4):474-477. Doi: 10.1111/pace.13554. Epub 2018 Dec 9. PMID: 30461031.
14. Cronin EM, Bogun FM, Maury P, Peichl P, Chen M, Namboodiri N, Aguinaga L, Leite LR, Al-Khatib SM, Anter E, Berruezo A, Callans DJ, Chung MK, Cuculich P, d’Avila A, Deal BJ, Della Bella P, Deneke T, Dickfeld TM, Hadid C, Haqqani HM, Kay GN, Latchamsetty R, Marchlinski F, Miller JM, Nogami A, Patel AR, Pathak RK, Sáenz Morales LC, Santangeli P, Sapp JL, Sarkozy A, Soejima K, Stevenson WG, Tedrow UB, Tzou WS, Varma N, Zeppenfeld K; ESC Scientific Document Group. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias. Europace. 2019 Aug 1;21(8):1143-1144. doi: 10.1093/europace/euz132. Erratum in: Europace. 2019 Aug 1;21(8):1144. Erratum in: J Arrhythm. 2020 Jan 12;36(1):214. Erratum in: Europace. 2020 Mar 1;22(3):505. PMID: 31075787; PMCID: PMC7967791.
15. CorSystem announces first use of Bipolar Ablation Adapter. Cardiac Rhythm News, 10th March 2021