Kriatselis.qxp 25/7/08 02:22 Page 92
Arrhythmia Management
(see Figure 1). The resulting single image supports catheter/ operators should always question the possibility that the anatomical
device navigation during specified procedures. This helps physicians information they are viewing is not entirely accurate.
to navigate through the heart during complex procedures. The EP
Navigator instantly indicates the position of any catheter, including the Rotational Angiography
ablation catheter, with respect to complex 3D cardiac anatomy (see Rotational angiography is an imaging method involving rotating a
Figure 2). The design of the EP Navigator is intended to allow users to fluoroscopy system around an anatomy, taking angiographic images at
reach ablation points and perform complex procedures when there is different angles in rapid sequence. This technique can produce high-
no access to mapping. resolution images of the cardiac anatomy, such as the left atrium and
pulmonary veins, which are clearly defined in both left and right atrial
Each patient undergoes a pre-procedural multislice CT scan, which is then orientations in the majority of patients. The German Heart Institute in
transferred to the EP Navigator. Data are then selected by the operator for Berlin has used rotational angiography in over 100 patients and all
3D reconstruction and a segmented volume of the desired cardiac structures ancillary pulmonary veins were clearly identified. This technique does not
is created. X-ray images are acquired at multiple angles; the 3D volumes are involve separate registration of images. The acquired 3D rotational scan
overlaid onto the X-ray images, and the user manipulates the 3D volumes automatically corresponds directly to the anatomy of the patient at the
to optimise registration of both images. In realtime the registered image time of the procedure. Rotational angiography is simple to perform and
shows the position of the catheter in relation to the 3D cardiac anatomy. To is time-saving since images are acquired in only five to seven minutes. The
optimise the visualisation of the anatomy, the composite 3D image will technique also has lower radiation exposure than conventional CT scans
automatically rotate to follow the movement of the X-ray system in order to and negligible costs, and no safety issues have arisen to date. Therefore,
track the catheter. The German Heart Institute in Berlin has been using the it has potential for use in the future for AF ablation procedures.
EP Navigator system for over a year and has reported extremely pleasing
results on its use in catheter ablation procedures. Summary
AF is the most common arrhythmia and is associated with high rates of
Limitations to Image Integration morbidity and mortality. AF ablation procedures are necessary for patients
There are limitations to the use of image integration in AF ablation with highly symptomatic or persistent AF. In ablation procedures 3D
procedures. To achieve high-resolution 3D images of the left cardiac electroanatomical mapping systems are useful for guidance. However,
geometry using conventional mapping systems, the catheter has to be chamber reconstruction with these guidance systems is not able to
sequentially placed at many different sites in the left atrium; this can replicate the highly complex anatomy of the heart and accurately represent
be very time-consuming and does not always show all anatomical the variable pulmonary vein and left atrium anatomy. Therefore, the
details of the left atrium. CT and MRI images take time to produce, alignment of pre-procedural CT and MRI images is a new focus in catheter
increasing both the administrative burden of scheduling and the ablation in AF procedures and may enhance the efficacy and safety of the
financial burden. Radiation exposure is also an important issue during procedure. CartoMerge is currently the most widely used image integration
the imaging procedure. system that registers pre-procedural MRI and CT images of the cardiac
anatomy with realtime maps. CT–fluoroscopy guidance systems such as the
In addition, static images of the registered MRI/CT reconstructions are in EP Navigator may offer advantages in terms of ease of use during
general taken at least one day before the ablation procedure, and in the procedure. Both of these systems have enhanced the efficacy and
some cases weeks before; therefore, physiological differences in volume safety of AF ablation, although they have limitations such as exposure to
status, heart rhythm and rate and respirations are inevitable. As a result, radiation, expense and procedure length. Rotational angiography may
fusion of CT/MRI images with fluoroscopy can give a false impression of offer an alternative imaging system to pre-procedural MRI or CT. Direct
the real anatomy during the procedure. This may be misleading and in comparisons between the two devices have not been completed and will
most cases a perfect match is not possible, hence before ablating a site be necessary to compare the clinical benefits of each. ■
1. Fuster V, Rydén LE, Cannom DS, et al.; Task Force on Practice 5. Haissaguerre M, Sanders P, Hocini M, et al., Catheter ablation conventional pulmonary venography and study of
Guidelines, American College of Cardiology/American Heart of long lasting persistent atrial fibrillation: critical structures for reproducibility, Eur Radiol, 2004;14:369–74.
Association; Committee for Practice Guidelines, European termination, J Cardiovasc Electrophysiol, 2005;16:1125–37. 11. Shan F, Liu SW, Zhang ZY, Value of pulmonary venography by
Society of Cardiology; European Heart Rhythm Association; 6. Dong J, Calkins H, Technology insight: Catheter ablation of multislice computed tomography in radiofrequency catheter
Heart Rhythm Society, ACC/AHA/ESC 2006 guidelines for the the pulmonary veins in the treatment of atrial fibrillation, Nat ablation of atrial fibrillation, Radiol Practice (Chin), 2007;22:
management of patients with atrial fibrillation—executive Clin Pract Cardiovasc Med, 2005;2:159–66. 641–3.
summary: a report of the American College of 7. Jongbloed MR, Bax JJ, Lamb HJ, et al., Multislice computed 12. Dong J, Calkins H, Solomon SB, et al., Integrated
Cardiology/American Heart Association Task Force on practice tomography versus intracardiac echocardiography to evaluate electroanatomic mapping with three-dimensional computed
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Framingham study, Neurology, 1978;28(10):973–7. imaging, Circulation, 2003;107:2004–10. 14. Tang K, Zhang J, Zhang JY, et al., A randomized prospective
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of pooled data from five randomized controlled trials, Arch electro-anatomical mapping to guide radiofrequency catheter paroxysmal atrial fibrillation, Chin Med J,
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4. Cappato R, Calkins H, Chen SA, et al., Worldwide survey on 10. Maksimovic R, Cademartiri F, Scholten M, et al., Sixteen-row 15. Sra J, Narayan G, Krum D, et al., Computed tomography
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