Article

The Role of Three-dimensional Rotational Angiography in Atrial Fibrillation Ablation

Register or Login to View PDF Permissions
Permissions× For commercial reprint enquiries please contact Springer Healthcare: ReprintsWarehouse@springernature.com.

For permissions and non-commercial reprint enquiries, please visit Copyright.com to start a request.

For author reprints, please email rob.barclay@radcliffe-group.com.

  • Views: 1203

  • Likes: 0

  • Downloads: 3

  • Citations: 1

  • Read time: 15m
Average (ratings)
No ratings
Your rating

Abstract

Three-dimensional (3D) imaging became the cornerstone of catheter guidance in atrial fibrillation (AF) ablation procedures during the last few years. Multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) have been the technologies of choice for pre-procedural imaging of the left atrium (LA) and the pulmonary veins to make lesions more precisely set in a highly variable and difficult to understand 3D environment. These technologies have been used not only for pre-procedural orientation but have also been overlayed to fluoroscopic views in many fluoroscopy-guided ablation procedures. As image integration into non-fluoroscopic 3D imaging systems became available, 3D reconstructions of MSCT and MRI became the standard approach in many centres. However, 3D imaging is not a cornerstone during ablation as it is not indispensable and ablation can be performed without. Although rare, some very important and key centres do not routinely use 3D imaging during ablation. Being remote to the ablation procedure, these imaging technologies may have the disadvantage of not reflecting the current status of a variable LA volume and scheduling of an additional diagnostic procedure may complicate the workflow of AF ablation procedures. Intra-procedural imaging techniques are likely to overcome both issues. Beside others, rotational angiography has been introduced for proving highly actual imaging by intra-procedural acquisition of 3D shells suitable for overlay to fluoroscopy without need for registration and image integration into 3D mapping systems registered by point-by-point electroanatomical mapping or 3D echocardiographic imaging.

Keywords

Atrial fibrillation, pulmonary vein isolation, catheter ablation, intracardiac echocardiography, image integration, rotational angiography,

Disclosure:Georg Nölker received honoraria for lectures from Siemens AG and Biosense Webster, Inc. Klaus-Jürgen Gutleben received honoraria for proctorship from Biosense Webster, Inc. Dieter Horstkotte has no conflicts of interest to declare.

Received:

Accepted:

DOI:https://doi.org/10.15420/aer.2013.2.2.120

Correspondence Details:Georg Nölker, Department of Cardiology, Heart and Diabetes Center North Rhine-Westphalia, Ruhr University Bochum, Georgstrasse 11, 32545 Bad Oeynhausen, Germany. E: gnoelker@hdz-nrw.de

Copyright Statement:

The copyright in this work belongs to Radcliffe Medical Media. Only articles clearly marked with the CC BY-NC logo are published with the Creative Commons by Attribution Licence. The CC BY-NC option was not available for Radcliffe journals before 1 January 2019. Articles marked ‘Open Access’ but not marked ‘CC BY-NC’ are made freely accessible at the time of publication but are subject to standard copyright law regarding reproduction and distribution. Permission is required for reuse of this content.

Catheter ablation is an established treatment option for patients with symptomatic atrial fibrillation (AF).1-3 Pulmonary vein (PV) angiography has been the initial imaging tool in AF ablation and is still used by up to 50 % of leading electrophysiologists.3 PV angiography still plays a major role in balloon-based ablation techniques routinely performed without electroanatomical mapping (EAM). Some very experienced centres do not feel any need for three-dimensional (3D) imaging due to their ability to orientate in two-dimensional (2D) fluoroscopic views. 3D imaging is likely to better reflect relations between anatomic structures and ensures that all PVs are clearly identified. Therefore, it is not surprising that the majority of studies done on image integration of 3D shells into EAM show positive effects on radiation exposure, procedural and long-term success.4-6 In particular, results of large multicentre registries clearly show the benefit of image integration regarding freedom from AF7 in comparison with fluoroscopy-guided ablation. Integration of 3D reconstructions of pre-procedurally acquired data sets derived from multislice computed tomography (MSCT) or magnetic resonance imaging (MRI) into EAM systems has been introduced to guide left atrial (LA) ablation procedures.8-13 However, these remote imaging technologies may not perfectly reflect the status found during ablation due to changes in cardiac rhythm and preload, and their impact on the LA volume for example. Therefore, the search for an intra-procedural technology close to realtime imaging continued and led to the development of rotational angiography.

Principles of Rotational Angiography 
Different protocols of this technique have been introduced over time14-19 having in common the principle of a C-arm run around the patients' region of interest (in case of AF ablation the LA) with acquisition of X-ray images with a certain rate of frames per second using a flat panel detector (see Figure 1). To enhance cardiac structures, contrast media is administered into the right atrium or the pulmonary artery and C-arm run is started after a delay reflecting the pulmonary transition time. Individual pulmonary transition time can be estimated by a bolus injection of contrast media into the pulmonary artery. This compensates for delayed enhancements due to low cardiac output. Alternatively, direct injection into the LA is performed and the C-arm run is started with a short delay. A more intense contrast of the LA may be seen after direct injection. However, contrast injection into the LA may lead to an artificial enlargement of its image. For enhancement of the oesophagus the patient is asked to swallow contrast paste. All these approaches provide data sets that allow for measurements in virtually unlimited planes and 3D reconstruction of the LA, PV, aorta and the oesophagus applying software on different specialised computer systems (e.g. Syngo X-Workplace, Siemens, Forchheim, Germany and EP Navigator, Philips, Best, The Netherlands).

Accuracy in Comparison with Multislice Computed Tomography 
Accuracy is a critical point of imaging during AF ablation as ablating too far ostially bears the risk of inducing PV stenosis and of missing antral foci, and overseeing small PVs may lead to ineffectiveness of the procedure. Furthermore, suboptimal orientation may lead to perforation and other avoidable complications. The gold standard of 3D imaging in AF ablation is MSCT. Two studies have compared accuracy of MSCT with rotational angiography. In our study,16 planes from pre-procedural MSCT and DynaCT Cardiac (Siemens AG, Forchheim, Germany) were automatically parallelised and cross-sectional diameters of PVs, LA appendage and LA and aorta were correlated. In our series we found an overall correlation of diameter of 0.99 and no significant difference in diameters derived from rotational angiography and MSCT. However, although not being significantly different between the two modalities, correlation between pre- and intra-procedural volumes of the LA was less good (0.86). This may be due to the remoteness of MSCT as discussed above. In addition, the position of the oesophagus may also vary significantly between a pre-procedural and thereby remote imaging and an intra-procedural rotational angiography supporting the assumption that higher actuality of imaging is relevant. However, intra-procedural changes of structures and positions remain a domain of realtime imaging technologies. Kriatselis and co-workers20 showed later that acceptable imaging in comparison with MSCT can also be achieved with a smaller detector. In their data set a correlation of 0.82-0.92 for the PVs and 0.80-0.87 for the LA volume was found.
 

Image Aquisition in Rotational Angiography
 

Section of a 3D Reconstruction Derived from a Rotational Angiography
 

Three-dimensional Reconstructions of Rotational Angiography as an Overlay to Fluoroscopic Views 
Having a 3D reconstruction of the LA and the PV available for pre-procedural orientation was found to be helpful but was only a stepping stone towards image integration. The first step of image integration was to superimpose 3D reconstructions to fluoroscopic views during the ablation (see Figure 2). Technologies are available to make the superimposed 3D shell automatically follow moves of the C-arm to provide a continuous 3D guidance to the operator (e.g. Syngo iPilot dynamic, Siemens, Forchheim, Germany). As image acquisition by rotational angiography is performed with the patient at the same place where ablation is done, no registration or adjustment of the reconstruction is needed as long as the patient does not move.16 In case of need for registration due to movements, protocols have been introduced to facilitate this based on the position of the LA related to the spinal column and the trachea and mainstem bronchi.21

A limitation of the overlay technology still is the missing compensation for respiration. However, the overlay technique can be used as a single navigation tool in AF ablation17 with an acceptable short-term outcome and low complication rates. Meanwhile, superimposition of ablation points to fluoroscopy and rotational angiography has been integrated into software of different manufacturers. This may reduce the need for EAM systems furthermore, as long as advanced functionality like activation mapping is not required. Ablation then is fully fluoroscopy-based and by this radiation exposure due to long fluoroscopy times may be high.17,22

Image Integration of Rotational Angiography into Three-dimensional Mapping Systems 
Image integration of 3D shells into EAM-systems has lots of theoretical advantages over overlay techniques. In particular, activation mapping in case of transformation of AF into atrial tachycardias is possible; navigation in a 3D environment can be performed without or with a minimal amount of additional radiation and parameters like contactforce can be related to ablation points in the EAM. Moreover, it has been shown that integration of 3D reconstructions into EAM may improve the outcome.13

Pre-procedural MRI and MSCT scans can be accurately registered to EAM-systems and integration of these has been the gold standard of image integration for a long time. Integration of the rotational angiography-based reconstructions is likely to have the same advantages of MRI/MSCT integration and may be even superior because of its high degree of actuality and its seamless integration into the workflow in the electrophysiology laboratory. 3D reconstructions of the rotational (see Figure 3) angiography can be transferred to both the EnSite (St Jude Medical) and the Carto® (Biosense Webster, Inc) system either directly online via hospital networks or via hard copies in terms of a compact disc (CD). Image integration of rotational angiography then follows the same steps well-known for MSCT/MRI, and accuracy of imaging compared with MSCT has been demonstrated to be acceptable with a deviation between EAM and rotational angiography of 2.2 ± 0.4 millimetres (mm).23 3D reconstructions of intracardiac echo may serve as an alternative to EAM for integration of rotational angiography. This can be done before LA access and thereby LA dwelling time is reduced and inaccuracy of EAM due to pushing a mapping catheter against the LA wall may be reduced.24 This technique is also very accurate in registration of an intra-procedural shell by another one and additional EAM points do not improve registration accuracy.
 

3D Reconstruction of a Rotational Angiography of the Left Atrium and Pulmonary Veins
 

Radiation Exposure by Rotational Angiography 
Rotational angiography as an X-ray-based imaging system is potentially harmful for the operator and the patients. Radiation exposure has been reported to be 2.2 ± 0.2 to 6.6 ± 1.8 millisievert (mSv) based on estimations from the dose-area product.18,20,25 The huge variety of values may be traced back to different ways of estimation applied and to the different protocols used for image acquisition. However, comparisons to MSCT by some groups18,20 showed a significantly lower effective radiation dose in rotational angiography compared with MSCT. This is confirmed by our own unpublished data, finding 15.5 ± 10.1 mSv in patients with MSCT image integration compared with 9.0 ┬▒ 4.2 mSv in patients with rotational angiography (p<0.0003) in terms of total procedural and pre-procedural effective doses. For sure, radiation exposure of MRI would have been zero and more recent MSCT protocols have demonstrated to save a lot of radiation. However, low-dose protocols for rotational angiography are under way. Radiation exposition to the operator can be minimised by initialising the C-arm run from the control room, this reduces the time of exposure to the time needed for placing the pigtail catheter and isocentering of the patient.

Time and Costs 
In times of limited financial resources for healthcare even in the Western European and North American countries, besides its benefits, costs are a relevant matter of discussion. One group has calculated the costs of rotational angiography in terms of technical fee without personal costs and resulted in €91-95 per examination compared with €100-125 caused by a MSCT.20 These are rough estimations and differences in workload will have an impact as well as variations in costs of different systems. However, rotational angiography does not seem to be costly in comparison with MSCT.

The time required for acquisition and segmentation of rotational angiography varies a little between different groups: Li et al.18 spent 14.4 ± 3.2 minutes and Kriatselis et al.17 reported on 6.0 ± 3.0 minutes for preparation and performance, 4.0 ± 2.0 minutes for 3D reconstruction and 5.0 ± 3.0 minutes and of a total time for acquisition and reconstruction of 13.0 ± 5.0 minutes in another series20 being close to the times reported by Li et al. Our acquisition and reconstruction time seems to be shorter (7.0 ± 5.0 minutes) with a larger detector (30 x 40 centimetres [cm]; Siemens, Forchheim, Germany) at a frame rate of 60 per second, which is likely to improve imaging quality and thereby may reduce reconstruction time at the price of higher radiation exposure.16

Ways to Improve Imaging Quality in Rotational Angiography
Although X-ray systems with capability of rotational angiography have been installed in many electrophysiology laboratories in the last few years, use of these systems is still limited. This may be at least partly due to a learning curve in application of this novel technology, which may be shortened when a few key points are kept in mind.

Isocentering is of critical importance especially when a small detector is used. With a 20 x 20 cm detector, two landmarks may help the operator to isocenter:

  • The tracheal bifurcation is always found some millimetres superior to the roof of the LA and closer to the right than to the left superior pulmonary vein in a posterior-anterior projection.
  • The vertebral column is always at the back of the posterior wall of the LA in a lateral view and when half of it is depicted in the 20 x 20 cm detector in a lateral projection the LA is centred well.

Contrast can be improved by direct injection of contrast medium into the LA. This may have the disadvantage of longer LA dwelling time and will require either rapid ventricular pacing or adenosine to avoid an immediate washout of the dye. Both of these have their own disadvantages like induction of arrhythmias, need for general anaesthesia and others. In addition, administration of 50-60 millilitres (mL) of contrast medium into the LA while rapid ventricular pacing and/ or adenosine is applied may lead to an artificial enlargement resulting in an overestimation of the LA volume by rotational angiography. Higher enhancing contrast medium may be another option to increase contrast (e.g. Imeron 400 MCT, Bracco Imaging, Konstanz, Germany with 400 milligram [mg] Iodine per mL). Any cables and skin electrodes have disturbing effects on X-ray imaging, removal of all these before image acquisition or use of X-ray transparent material improves imaging quality. A pigtail catheter filled with contrast medium after injection leads to imaging artifacts. This can be avoided by withdrawing the catheter after contrast medium administration or flushing the catheter with a few millilitres of saline. In case of working in a magnetic laboratory, the pigtail catheter can also be removed remotely by the Cardiodrive Catheter Advancement System (Stereotaxis Inc, St Louis, MO, US).

Limitations
In case of right-sided contrast injection, estimation of pulmonary transition time is of critical importance and may induce a learning period until this can be done properly.

Rotational angiography will always add a certain amount of radiation exposure to the procedure bearing a risk of inducing malignant diseases. Contrast enhancement is necessarily associated with administration of contrast media. This may be an issue in patients with impaired renal function as well as in those suffering from severe congestive heart failure or thyroid dysfunctions. Finally, there is an undeniable but certainly very limited risk of anaphylactic reaction.

Conclusion and Perspective
Rotational angiography introduced as an imaging technology in AF ablation is highly accurate in displaying crucial structures for PV isolation comparable with MSCT. Furthermore, being an intra-procedural imaging technique, it provides a high level of actuality and may improve workflows when scheduling of an additional imaging procedure can be avoided. Image-integration of 3D reconstructions based on rotational angiography into EAM is feasible, accurate and fast. Therefore, rotational angiography may replace other imaging technologies for AF ablation.

References

  1. Fuster V, Ryd├®n LE, Cannom DS, et al. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation (full text): a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 guidelines for the management of patients with atrial fibrillation) developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Europace 2006;8:651-745.
    Crossref | Pubmed
  2. Camm AJ, Kirchhof P, Lip GY, et al. Guidelines for the management of atrial fibrillation. the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J 2010;31:2369-429.
    Crossref | Pubmed
  3. Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. Heart Rhythm 2012;9:632-96.
    Crossref | Pubmed
  4. Kistler PM, Rajappan K, Jahngir M, et al. The impact of CT image integration into an electroanatomical mapping system on clinical outcomes of catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2006;17:1093-101.
    Crossref | Pubmed
  5. Kistler PM, Earley MJ, Harris S, et al. Validation of threedimensional cardiac image integration: use of integrated CT image into electroanatomic mapping system to perform catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2006;17:341-8.
    Crossref | Pubmed
  6. Martinek M, Nesser HJ, Aichinger J, et al. Impact of integration of multislice computed tomography imaging into threedimensional electroanatomic mapping on clinical outcomes, safety, and efficacy using radiofrequency ablation for atrial fibrillation. Pacing Clin Electrophysiol 2007;30:1215-23.
    Crossref | Pubmed
  7. Bertaglia E, Bella PD, Tondo C, et al. Image integration increases efficacy of paroxysmal atrial fibrillation catheter ablation: results from the CartoMerge Italian Registry. Europace 2009;11:1004-10.
    Crossref | Pubmed
  8. Tops LF, Bax JJ, Zeppenfeld K, et al. Fusion of multislice computed tomography imaging with three-dimensional electroanatomic mapping to guide radiofrequency catheter ablation procedures. Heart Rhythm 2005;2:1076-81.
    Crossref | Pubmed
  9. Dong J, Calkins H, Solomon SB, et al. Integrated electroanatomic mapping with three-dimensional computed tomographic images for real-time guided ablations. Circulation 2006;113:186-94.
    Crossref | Pubmed
  10. Dong J, Dickfeld T, Dalal D, et al. Initial experience in the use of integrated electroanatomic mapping with threedimensional MR/CT images to guide catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2006;17:459-66.
    Crossref | Pubmed
  11. Malchano ZJ, Neuzil P, Cury RC, et al. Integration of cardiac CT/MR imaging with three-dimensional electroanatomical mapping to guide catheter manipulation in the left atrium: implications for catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2006;17:1221-9.
    Crossref | Pubmed
  12. Tang K, Ma J, Ma FS, et al. Initial experience with circumferential pulmonary vein ablation guided by fusion of magnetic resonance imaging with three-dimensional electroanatomic mapping. Chin Med J (Engl) 2006;119:1047-52.
    Pubmed
  13. Bertaglia E, Brandolino G, Zoppo F, et al. Integration of three-dimensional left atrial magnetic resonance images into a real-time electroanatomic mapping system: validation of a registration method. Pacing Clin Electrophysiol 2008; 31:273-82.
    Crossref | Pubmed
  14. Orlov MV, Hoffmeister P, Chaudhry GM, et al. Threedimensional rotational angiography of the left atrium and esophagus -- A virtual computed tomography scan in the electrophysiology lab? Heart Rhythm 2007;4:37-43.
    Crossref | Pubmed
  15. Thiagalingam A, Manzke R, D'Avila A, et al. Intraprocedural volume imaging of the left atrium and pulmonary veins with rotational X-ray angiography: Implications for catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol 2008;19;293-300.
    Crossref | Pubmed
  16. N├Âlker G, Gutleben KJ, Marschang H, et al. Three-dimensional left atrial and esophagus reconstruction using cardiac C-arm computed tomography with image integration into fluoroscopic views for ablation of atrial fibrillation: accuracy of a novel modality in atrial fibrillation ablation in comparison with multislice computed tomography. Heart Rhythm 2008;5:1651-7.
    Crossref | Pubmed
  17. Kriatselis C, Tang M, Nedios S, et al. Intraprocedural reconstruction of the left atrium and pulmonary veins as a single navigation tool for ablation of atrial fibrillation: a feasibility, efficacy, and safety study. Heart Rhythm 2009;6:733-41.
    Crossref | Pubmed
  18. Li JH, Haim M, Movassaghi B, et al. Segmentation and registration of three-dimensional rotational angiogram on live fluoroscopy to guide atrial fibrillation ablation: a new online imaging tool. Heart Rhythm 2009;6:231-7.
    Crossref | Pubmed
  19. Ector J, De Buck S, Nuyens D, et al. Adenosine-induced ventricular asystole or rapid ventricular pacing to enhance three-dimensional rotational imaging during cardiac ablation procedures. Europace 2009;11:751-62.
    Crossref | Pubmed
  20. Kriatselis C, Nedios S, Akrivakis S, et al. Intraprocedural imaging of left atrium and pulmonary veins: a comparison study between rotational angiography and cardiac computed tomography. Pacing Clin Electrophysiol 2011;34:315-22.
    Crossref | Pubmed
  21. Orlov MV. How to perform and interpret rotational angiography in the electrophysiology laboratory. Heart Rhythm 2009;6:1830-6.
    Crossref | Pubmed
  22. Knecht S, Wright M, Akrivakis S, et al. Prospective randomized comparison between the conventional electroanatomical system and three-dimensional rotational angiography during catheter ablation for atrial fibrillation. Heart Rhythm 2010;7:459-65.
    Crossref | Pubmed
  23. N├Âlker G, Asbach S, Gutleben KJ, et al. Image-integration of intraprocedural rotational angiography-based 3D reconstructions of left atrium and pulmonary veins into electroanatomical mapping: accuracy of a novel modality in atrial fibrillation ablation. J Cardiovasc Electrophysiol 2010;21:278-83.
    Crossref | Pubmed
  24. N├Âlker G, Gutleben KJ, Asbach S, et al. Intracardiac echocardiography for registration of rotational angiographybased left atrial reconstructions: a novel approach integrating two intraprocedural three-dimensional imaging techniques in atrial fibrillation ablation. Europace 2011;13:492-8.
    Crossref | Pubmed
  25. Wielandts JY, De Buck S, Ector J, et al. Three-dimensional cardiac rotational angiography: effective radiation dose and image quality implications. Europace 2010;12:194-201.
    Crossref | Pubmed
Previous Volume Article Next Volume Article