With the aim of optimizing catheter ablation, we believe new tools for the assessment of cardiac excitation patterns are needed to help determine the underlying mechanisms, and to improve the identification of the appropriate targets. Moreover, there are indications that AFL and AF could be expressions of a single arrhythmogenic substrate, which would make it significant to fine-tune the concept of “curing” AFL (Cosio et al., 2006).
If an incorrect target is ablated, the patient will certainly not be cured and, due to scarring with an ineffective ablation procedure, there is an additional risk that a new arrhythmia may be induced (Chugh et al., 2005 Deisenhofer et al., 2006). Successful ablation is dependent on identification of a critical isthmus in the reentrant circuit, which can be interrupted either with a line, or focal point of ablation (Lee et al., 2012). Computerized mapping systems are of crucial importance for delineating the more complex circuits of atypical AFL (particularly in the context of abnormal atrial anatomy, multiple circuits, and regions with scars). Also, the presence of AFL usually suggests an underlying predisposition to AF, which is a more complex arrhythmia (Waldo and Feld, 2008).Īblation approaches guided by activation maps obtained from three-dimensional (3D) electro-anatomical mapping systems try to localize and target atrial arrhythmia drivers. Although AFL is not directly related to death, it affects life quality due to the higher ventricular activation rate, and it can cause significant complications such as heart failure and stroke (Biblo et al., 2001). In these cases, an electrophysiological (EP) study is the most common way to unveil the mechanisms causing the arrhythmia and plan a proper ablation (Gerstenfeld et al., 2004). Atypical AFL is often associated with structural heart disease, especially in patients that have undergone cardiac surgery or extensive catheter ablation for the treatment of atrial fibrillation (AF). Depending on the obstacle, AFL is usually classified as “typical”, if the re-entry is around the tricuspid valve, or “atypical” if the tricuspid valve is not involved (Saoudi et al., 2001 Bun et al., 2015). Generally, these arrhythmias respond poorly to antiarrhythmic drugs and after many years of technological advances in cardiac electrophysiology, catheter ablation is today recognized as the treatment of choice (Lee et al., 2012).Ītrial flutter (AFL) is a common supraventricular arrhythmia characterized by a reentrant circuit around a central obstacle, which can be a fixed anatomical structure or a functional electrophysiological line of block (Cosio et al., 2006). Further investigations are needed to assess the reliability of the method in different clinical scenarios.Ītrial arrhythmias include many diverse rhythm disturbances for which a wide range of different arrhythmia mechanisms are responsible. Directed network mapping represents an innovative tool that showed promising results in identifying AFL mechanisms in an automatic fashion.
The other two cases presented a poor mapping quality or a major complexity related to previous ablations, large areas of fibrotic tissue, etc. Regarding the AFL cases, arrhythmia mechanisms were either totally or partially identified in most of the cases (8 out of 10), i.e., cycles around the mitral valve, tricuspid valve and figure-of-eight reentries. The algorithm correctly detected the electrical propagation of both sinus rhythm cases and in-silico simulations. The method was tested on two subjects in sinus rhythm, six in an experimental model of in-silico simulations, and 10 subjects diagnosed with AFL who underwent a catheter ablation. Using directed network mapping, we employed a cycle-finding algorithm to detect all cycles in the network, resembling the main propagation pattern of AFL. The main advantage of NT is the large number of available algorithms that can efficiently analyze the network.
In this study, we modeled the electrical propagation pattern of AFL (measured during mapping) using network theory (NT), a well-known field of research from the computer science domain. However, the identification of rotational activities is not straightforward, and requires an intense effort during the first phase of the electrophysiological (EP) study, i.e., the mapping phase, in which an anatomical 3D model is built and electrograms (EGMs) are recorded. It is usually treated with catheter ablation. Atrial flutter (AFL) is a common atrial arrhythmia typically characterized by electrical activity propagating around specific anatomical regions.
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