Towards patient-specific modelling of lesion formation during radiofrequency catheter ablation for atrial fibrillation

Abstract

Radiofrequency catheter ablation procedures are a first-line method of clinical treatment for atrial fibrillation. However, they suffer from suboptimal success rates and are also prone to potentially serious adverse effects. These limitations can be at least partially attributed to the inter-and intrapatient variations in atrial wall thickness, and could be mitigated by patient-specific approaches to the procedure.In this study, a modelling approach to optimising ablation procedures in subject-specific 3D atrial geometries was applied. The approach enabled the evaluation of optimal ablation times to create lesions for a given wall thickness measured from MRI. A nonliner relationship was revealed between the thickness and catheter contact time required for fully transmural lesions. Hence, our approach based on MRI reconstruction of the atrial wall combined with subject-specific modelling of ablation can provide useful information for improving clinical procedures. I IntroductionAtrial fibrillation (AF) is the most common cardiac arrhythmia. Effects of AF include a decreased quality of life and more serious morbidities including the increased risk of stroke [1]. While the underlying mechanisms of AF are not completely understood, the arrhythmia is known to arise from irregular electrical activity in the atria. Ultimately, clinical treatments of AF aim to target this irregular activity.Radiofrequency catheter ablation (RFCA) procedures are one such treatment. An ablation catheter is used to produce electrically inert, transmural lesions in the myocardium to isolate or remove areas contributing to the generation or maintenance of the activity sustaining AF. However, RFCA procedures are not always effective in treating AF. Thus, when considering paroxysmal AF, the success rates for pulmonary vein isolations (PVI) are between 38-70% after a single procedure, or 65-90% after repeated procedures [2]. For persistent cases of AF, PVI alone is not sufficient and further areas of the atrial wall are targeted. Moreover, RFCA procedures are not without risks, and major complications have been found to occur in 4.5% of patients [3].High inter-and intra-patient variations in atrial wall thickness (AWT) presents a major issue when creating the transmural lesions required for effective RFCA treatments. Patientspecific knowledge of AWT could provide clinicians with useful information to optimise the Europe PMC Funders Group Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts ablation procedure by using the minimal amount of RF energy, thereby improving the efficacy of the procedure by ensuring the optimal catheter contact time to achieve lesion transmurality. Furthermore, patient-specific knowledge could also reduce the risk of complications. For example, PV stenosis can be avoided by minimising catheter contact time at target areas of the atrial wall to ensure temperatures stay below noted risk levels [4].Such a patient-specific approach requires information of the AWT variations throughout the atr...

Left atrial wall thickness of the pulmonary vein reconnection sites during atrial fibrillation redo procedures

“…Importing the LAWT map derived from the MDCT into the navigation system allows for real‐time knowledge of the atrial WT in contact with the catheter tip. This feature might be useful in different settings, as for instance in adapting energy delivery to avoid excessive application in thinned wall segments improving safety or delivering more energy in thicker regions in order to obtain more durable lesions 16 ; allowing to focus mapping at the thicker points looking for reconnections in the ablation line during AF‐redo procedures; and personalizing sites of RF application when drawing ablation lines to avoid thicker segments. Thus, this new imaging tool, opens the door for future diagnostic and therapeutic strategies using the integration of 3D LAWT maps into the navigation system.…”

Modeling Left Atrial Flow, Energy, Blood Heating Distribution in Response to Catheter Ablation Therapy

“…Thermal processes during CA were modeled using a modified version of the Pennes bioheat equation (Soor et al, 2016):…”

“…The increased risk of heart failure and stroke in AF patients have been associated with higher residence times of blood in the fibrillating LA (Camm et al, 2012; Soor et al, 2016). In the healthy atria, blood forms high-speed vortices, while in AF these structures merge into a single slow-moving vortex, contributing to blood stasis and potential thromboembolism formation (Fyrenius, 2001; Fluckiger et al, 2013; Koizumi et al, 2015; Gülan et al, 2017).…”

Development of a Deep Learning Method to Predict Optimal Ablation Patterns for Atrial Fibrillation

“…Despite of the current data volume limitations, this work allowed us to highlight the importance of a patient-specific approach to AF therapy, which is being increasingly recognised [19]- [21]. Moreover, we identified CNNs as a new tool to investigate different patterns for optimal CA therapy.…”