Locating atrial fibrillation (AF) focal and rotor sources can help improve target ablation therapy for AF. However, it remains unclear how to use the information provided by multi-polar diagnostic catheters (MPDC) to locate AF sources. Our aim was to develop a catheter-guidance algorithm to locate AF focal and rotor sources using a conventional MPDC. We simulated a 10 cm x 10 cm atrial tissue with focal and rotor sources using the Nygren et al. ionic model. We modeled a Lasso MPDC with 20-unipole electrodes placed with a spacing of 4.5-1-4.5 mm (diameter, d=15 mm) along a circle to obtain 10-bipole electrograms. Staring from an initial location, the algorithm, which was blinded to the location and type of the AF source, iteratively advanced the MPDC by moving its center to the location of the first activated bipole (FAB). The algorithm located an AF source if a stopping condition for either source was satisfied using bipole electrogram characteristics extracted from the MPDC placement. We tested the algorithm for a single rotor and focal source for all possible initial positions on the simulated tissue and repeated it for a random placement with a maximum of 20 possible placements at every trial. The algorithm located the AF source for 100% of trials and on average required 5.99 ± 1.92 placements to an AF source. This algorithm may be used to iteratively direct an MPDC towards an AF source and allow the AF source to be localized for customized AF ablation.

Introduction: Targeting repeating-pattern atrial fibrillation (AF) sources (reentry or focal drivers) can help in patient-specific ablation therapy for AF; however, the development of reliable and accurate tools for locating such sources remains a major challenge. We describe an iterative catheter navigation (ICAN) algorithm to locate AF drivers using a conventional circular Lasso catheter. Methods and Results: At each step, the algorithm analyzes 10 bipolar electrograms recoded at a given catheter location and the history of previous catheter movements to determine if the source is inside the catheter loop. If not, it calculates new coordinates and selects a new position for the catheter. The process continues until a source is located. The algorithm was evaluated in a computer model of atrial tissue with various degrees of fibrosis under a broad range of arrhythmia scenarios. The latter included slow and fast reentry, macroreentry, figure-of-eight reentry, and fibrillatory conduction. Depending on the initial distance of the catheter from the source and scenario, it took about 3–16 steps to localize an AF source. In 94% of cases, the identified location was within 4mm from the source, independently of the initial position of the catheter. The algorithm worked equally well in the presence of patchy fibrosis, low-voltage areas, fragmented electrograms, and dominant-frequency gradients. Conclusions: AF repeating-pattern sources can be localized using circular catheters without the need to map the entire tissue. The proposed algorithm has the potential to become a useful tool for patient-specific ablation of AF sources located outside the pulmonary veins.

Atrial fibrillation (AF) is an irregular heart rhythm that can lead to stroke and other heart-related complications. Catheter ablation has been commonly used to destroy triggering sources of AF in the atria and consequently terminate the arrhythmia. However, efficient and accurate localization of the AF sustaining sources known as rotors is a major challenge in catheter ablation. In this paper, we developed a novel probabilistic algorithm that can adaptively guide a Lasso diagnostic catheter to locate the center of a rotor. Our algorithm uses a Bayesian updating approach to search for and locate rotors based on the characteristics of electrogram signals collected at every catheter placement. The algorithm was evaluated using a 10 × 10 cm 2D atrial tissue simulation of the Nygren human atrial cell model and was able to successfully guide the catheter to the rotor center in 3.37±1.05 (mean±std) steps (including placement at the center) when starting from any location on the tissue. Our novel automated algorithm can potentially play a significant role in patient-specific ablation of AF sources and increase the success of AF elimination procedures.

Simulations are excellent tools for assessing new therapeutic strategies and are often conducted before implementing new therapy options in a clinical practice. For patients suffering from a heart arrhythmia, the main source of information comes from an intracardiac catheter. One of the common catheters is a Lasso multi-pole diagnostic catheter, which is a catheter that has 20 electrodes in a circular pattern. In this paper, we developed algorithm and simulation software that allows the users to place a multi-pole catheter on the atrial endocardial surface and record electrograms. In 3D atrial tissue, the plane of principal curvature is determined using eigenvectors of catheter vertices, from where the normals are projected and registered to the surface using 3D geodesic distance. This tool provides a platform for performing customized virtual cardiac experiments.

Purpose of the study. To reveal the relationship between the serum concentration of vascular endothelial growth factor and the structural and functional state of the myocardium in patients in the post-infarction period at the stage of rehabilitation. Materials and methods. We examined 94 patients at the outpatient stage of rehabilitation after ad hoc stenting 6 weeks after myocardial infarction, 10 healthy volunteers without somatic pathology. All participants in the study underwent standard transthoracic echocardiography with assessment of thickness of epicardial fat, assessment of the concentration of vascular endothelial growth factor (VEGF) in peripheral blood by ELISA. Results and discussion. VEGF values above the median values were associated with lower left ventricular ejection fraction and left ventricular fraction shortening, which indirectly may indicate a more pronounced expression of VEGF in patients with left ventricular systolic dysfunction. Assessing the parameters of LV diastolic dysfunction in groups with different levels of VEGF, no significant differences were found in patients after myocardial infarction. Correlation relationships between the content of VEGF and the thickness of epicardial adipose tissue were not found either among patients or in the control group. Conclusions. Elevated VEGF values in patients with coronary artery disease at the 6th week of rehabilitation were accompanied by left ventricle systolic dysfunction, in contrast to diastolic dysfunction. There was no direct correlation between the thickness of epicardial fat and the concentration of VEGF in the blood serum in patients with coronary artery disease.