Estimation of cardiac electrical activity by invasive and non-invasive mapping techniques
- Autores: Ismael Hernández-Romero
- Directores de la Tesis: Batiste Andreu Martínez Climent (dir. tes.), Carlos Figuera Pozuelo (codir. tes.)
- Lectura: En la Universidad Rey Juan Carlos ( España ) en 2019
- Idioma: español
- Materias:
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- Resumen
Cardiovascular Diseases (CD) constitute a serious health problem worldwide. Almost one third of the mortality is associated to cardiovascular diseases and their sanitary cost in industrialized countries overcomes that dedicated to any other disease. Most common pathologies among the CD are cardiac arrhythmias, which are cardiac rhythm alterations provoked by modifications in the electrical activity governing heart functioning. Nowadays, the most effective treatment for complex arrhythmias is based on invasive processes by radiofrequency ablation. This procedure allows eliminating the areas of the cardiac tissue responsible for the maintenance of the arrhythmia. Before initiating these ablation procedures, it is necessary to use cardiac mapping techniques from intracavitary electrical signals for the characterization of the electrical activity in-situ.
Characterization of the regions prone to keep arrhythmias remains today as a major challenge for improving diagnosis, and is key for the effective treatment of cardiac arrhythmias. With the goal of providing a more detailed picture of the spatio-temporal characteristics of arrhythmias, electrocardiography imaging (ECGI) has been developed in recent years. ECGI allows obtaining cardiac electrical activity non-invasively, building tridimensional maps that represent arrhythmic characteristics. With these data, the exact mechanism of a certain arrhythmia could be reconstructed. This could provide key information for deciding the future treatment and for the planning of the surgical intervention if needed, therefore reducing its duration and costs.
Due to the emerging nature of this non-invasive system for diagnosis, this technology still lacks of technical resources for the obtaining of parameters that allow the stratification of cardiac substrate and the characterization of the initiation and maintenance of arrhythmias. Therefore, the goal of this thesis is to generate a new methodology applicable to ECGI which is capable of obtaining stratification parameters that provide the spatio-temporal cardiac characteristics and owns the versatility to work under a variety of arrhythmic scenarios. To achieve that, a novel methodology to measure conduction velocity in simple and fibrillatory patterns of cardiac activity, together with complex 3D geometries, has been developed. This methodology was later applied to characterize and describe different arrhythmic mechanisms of varying nature using mathematical models, animal experimental models and clinical data.
In the first place, the methodology was designed to measure conduction velocity in fibrillatory functional and re-entrant patterns, as in atrial fibrillation, which is the arrhythmia with most prevalence worldwide and with current treatments of limited efficacy. The proposed methodology was validated with the use of synthetic, simple and realistic 3D models. Moreover, its utility to characterize regions of remodelled tissue was illustrated in realistic 3D models and clinical data.
Later on, it was studied the sequence of events prior to the initiation of functional re-entries that can be produced in cases of sudden cardiac death due to ventricular fibrillation. In this case, an animal experimental model of initiation of ventricular fibrillation was used to obtain the electrophysiological tendencies previous to the unleashing of the arrhythmia. In addition to that, an antiarrhythmic drug was applied to investigate its effect in this scenario.
The next goal was the identification of the arrhythmic mechanisms of quiescent cardiac substrates, studying possible hypothesis related to the appearance of cardiac diseases under specific environmental conditions. In this case, the manifestation of Brugada pattern under hyperkalemic environment was studied employing clinical data and mathematical realistic models to test the different hypothesis proposed.
The results obtained from these data illustrate the utility of this developed methodology to further investigate arrhythmic mechanisms, potentiate the utility of ECGI technique and help to develop new therapies and treatment strategies. This Thesis contributes to the improvement in knowledge for decision making in real pathologies of diverse nature but with common factors.
