12 research outputs found
In-Silico Data Based Machine Learning Technique Predicts Premature Ventricular Contraction Origin Coordinates
International audienc
A Patient-Specific Equivalent Dipole Model
International audienceSophisticated models for the electrocardiographic inverse problem are available, but their reliance on imaging data and large numbers of electrodes limit their use. Simple models such as the equivalent dipole model (EDM) therefore remain relevant. We developed a probabilistic approach to the equivalent unbounded uniform single dipole problem and developed a natural extension to the bounded nonuniform case that relies on a patientspecific statistical inference of the propagation mechanism between the location of the dipole and the electrode locations. The two models were tested on data simulated with a detailed heart-torso model with four different activation sequences and three different sets of tissue characteristics. We observed a throughout enhancement of the ability to reconstruct the ECG of the patient-specific model when compared to the uniform unbounded dipole model
Méthodes numériques d'apprentissage pour faciliter la localisation des arythmies ventriculaires lors d'une procédure d'ablation
Cardiovascular diseases are leading causes of death in the world. Among these diseases, ventricular arrhythmias are potentially serious pathologies that can lead to sudden cardiac death. A ventricular arrhythmia is an abnormality that affects the propagation of the electrical activation wavefronts through the ventricles, which normally coordinates the contraction of the ventricles such that they can optimally perform their role of pumping blood through the body. Of these arrhythmias, premature ventricular contraction (PVC) is the most benign. However, it can lead to tachycardia, which can induce fibrillation -- the most dangerous cardiac arrhythmia and fatal if not interrupted by a defibrillator.The challenge is therefore to treat PVCs if they are too frequent. To do this, cardiologists first use drugs that act on the electrical activity of the heart. However, sometimes these treatments are not sufficient. In this case, clinicians resort to a catheter ablation procedure. It proceeds by inserting a catheter into the patient's ventricular cavities, locating the areas of the heart responsible for the PVCs and then neutralizing them by applying a radiofrequency current that locally heats the tissue sufficiently to kill the cells. These procedures have a good success rate, but locating the areas responsible for PVC can be difficult for the cardiologist, and thus lengthen the intervention, which can last for several hours, and is unpleasant for the patient.The objective of this thesis is to create numerical tools that facilitate PVC localisation and that are easy to integrate in the clinical workflow. To do this, highly accurate simulations of the electrical activity of the heart were used.In the first part, an iterative pace-mapping method was proposed. This method, which uses only electrocardiogram signals, has been tested on simulated data.In the second part, a machine learning method was constructed, based on in-silico data generated with several realistic patient-specific heart-torso models, using both imaging and electrocardiogram signals. This method was trained on the simulated data and then tested on clinical data, from ablation procedures performed at the Bordeaux University Hospital.Les maladies cardiovasculaires sont les principales causes de dĂ©cĂšs dans le monde. Parmi ces maladies, les arythmies ventriculaires sont des pathologies potentiellement graves, pouvant engendrer la mort subite cardiaque. Une arythmie ventriculaire est une anomalie qui affecte la propagation des ondes Ă©lectriques parcourant les ventricules, ondes qui coordonnent la contraction de ceux-ci afin quâils puissent assurer leur rĂŽle de pomper le sang dans lâorganisme. Parmi ces arythmies, lâextrasystole ventriculaire est la forme la plus bĂ©nigne de cette catĂ©gorie, mais elle peut entraĂźner une tachycardie capable de dĂ©clencher une fibrillation, forme la plus dangereuse, et mĂȘme mortelle si elle nâest pas interrompue par un dĂ©fibrillateur.Lâenjeu est donc de parvenir Ă soigner les extrasystoles si elles sâavĂšrent trop frĂ©quentes. Pour cela, les cardiologues ont dâabord recours Ă des mĂ©dicaments permettant dâagir sur lâactivitĂ© Ă©lectrique cardiaque. NĂ©anmoins, il arrive que ces traitements ne soient pas suffisants. Les cliniciens procĂšdent alors Ă une procĂ©dure dâablation par radiofrĂ©quence : cela consiste Ă introduire un cathĂ©ter dans les cavitĂ©s ventriculaires du patient, de localiser les zones du tissu cardiaque responsables des extrasystoles, puis de les neutraliser via ce cathĂ©ter en chauffant Ă une tempĂ©rature suffisante pour tuer les cellules malades. Ce type de procĂ©dure a un bon taux de rĂ©ussite, cependant la localisation des zones responsables des extrasystoles peut sâavĂ©rer difficile pour le cardiologue, et ainsi rallonger le temps dâintervention, qui peut sâĂ©tendre sur plusieurs heures, ce qui est inconfortable pour le patient. Câest en particulier le cas lorsque les extrasystoles sont rares au moment de lâintervention.Lâobjectif de cette thĂšse est de crĂ©er des outils numĂ©riques permettant de faciliter la localisation des extrasystoles ventriculaires, outils qui sâintĂšgrent facilement dans le procĂ©dĂ© clinique. Pour cela, des simulations trĂšs prĂ©cises de la propagation Ă©lectrique dans le cĆur ont Ă©tĂ© utilisĂ©es.Dans la premiĂšre partie, une mĂ©thode itĂ©rative de guidage, basĂ©e sur des stimulations successives via cathĂ©ter, a Ă©tĂ© proposĂ©e. Cette mĂ©thode, qui utilise uniquement les signaux des Ă©lectrocardiogrammes, a Ă©tĂ© testĂ©e sur des donnĂ©es simulĂ©es.Dans la seconde partie, une mĂ©thode dâapprentissage automatique a Ă©tĂ© construite sur des donnĂ©es simulĂ©es gĂ©nĂ©rĂ©es sur plusieurs modĂšles de patients rĂ©alistes, en utilisant lâimagerie ainsi que les signaux des Ă©lectrocardiogrammes. Cette mĂ©thode a Ă©tĂ© entraĂźnĂ©e sur les donnĂ©es simulĂ©es puis a pu ĂȘtre testĂ©e sur des donnĂ©es cliniques, rĂ©cupĂ©rĂ©es de procĂ©dures dâablation rĂ©alisĂ©es au CHU de Bordeaux
Méthodes numériques d'apprentissage pour faciliter la localisation des arythmies ventriculaires lors d'une procédure d'ablation
Cardiovascular diseases are leading causes of death in the world. Among these diseases, ventricular arrhythmias are potentially serious pathologies that can lead to sudden cardiac death. A ventricular arrhythmia is an abnormality that affects the propagation of the electrical activation wavefronts through the ventricles, which normally coordinates the contraction of the ventricles such that they can optimally perform their role of pumping blood through the body. Of these arrhythmias, premature ventricular contraction (PVC) is the most benign. However, it can lead to tachycardia, which can induce fibrillation -- the most dangerous cardiac arrhythmia and fatal if not interrupted by a defibrillator.The challenge is therefore to treat PVCs if they are too frequent. To do this, cardiologists first use drugs that act on the electrical activity of the heart. However, sometimes these treatments are not sufficient. In this case, clinicians resort to a catheter ablation procedure. It proceeds by inserting a catheter into the patient's ventricular cavities, locating the areas of the heart responsible for the PVCs and then neutralizing them by applying a radiofrequency current that locally heats the tissue sufficiently to kill the cells. These procedures have a good success rate, but locating the areas responsible for PVC can be difficult for the cardiologist, and thus lengthen the intervention, which can last for several hours, and is unpleasant for the patient.The objective of this thesis is to create numerical tools that facilitate PVC localisation and that are easy to integrate in the clinical workflow. To do this, highly accurate simulations of the electrical activity of the heart were used.In the first part, an iterative pace-mapping method was proposed. This method, which uses only electrocardiogram signals, has been tested on simulated data.In the second part, a machine learning method was constructed, based on in-silico data generated with several realistic patient-specific heart-torso models, using both imaging and electrocardiogram signals. This method was trained on the simulated data and then tested on clinical data, from ablation procedures performed at the Bordeaux University Hospital.Les maladies cardiovasculaires sont les principales causes de dĂ©cĂšs dans le monde. Parmi ces maladies, les arythmies ventriculaires sont des pathologies potentiellement graves, pouvant engendrer la mort subite cardiaque. Une arythmie ventriculaire est une anomalie qui affecte la propagation des ondes Ă©lectriques parcourant les ventricules, ondes qui coordonnent la contraction de ceux-ci afin quâils puissent assurer leur rĂŽle de pomper le sang dans lâorganisme. Parmi ces arythmies, lâextrasystole ventriculaire est la forme la plus bĂ©nigne de cette catĂ©gorie, mais elle peut entraĂźner une tachycardie capable de dĂ©clencher une fibrillation, forme la plus dangereuse, et mĂȘme mortelle si elle nâest pas interrompue par un dĂ©fibrillateur.Lâenjeu est donc de parvenir Ă soigner les extrasystoles si elles sâavĂšrent trop frĂ©quentes. Pour cela, les cardiologues ont dâabord recours Ă des mĂ©dicaments permettant dâagir sur lâactivitĂ© Ă©lectrique cardiaque. NĂ©anmoins, il arrive que ces traitements ne soient pas suffisants. Les cliniciens procĂšdent alors Ă une procĂ©dure dâablation par radiofrĂ©quence : cela consiste Ă introduire un cathĂ©ter dans les cavitĂ©s ventriculaires du patient, de localiser les zones du tissu cardiaque responsables des extrasystoles, puis de les neutraliser via ce cathĂ©ter en chauffant Ă une tempĂ©rature suffisante pour tuer les cellules malades. Ce type de procĂ©dure a un bon taux de rĂ©ussite, cependant la localisation des zones responsables des extrasystoles peut sâavĂ©rer difficile pour le cardiologue, et ainsi rallonger le temps dâintervention, qui peut sâĂ©tendre sur plusieurs heures, ce qui est inconfortable pour le patient. Câest en particulier le cas lorsque les extrasystoles sont rares au moment de lâintervention.Lâobjectif de cette thĂšse est de crĂ©er des outils numĂ©riques permettant de faciliter la localisation des extrasystoles ventriculaires, outils qui sâintĂšgrent facilement dans le procĂ©dĂ© clinique. Pour cela, des simulations trĂšs prĂ©cises de la propagation Ă©lectrique dans le cĆur ont Ă©tĂ© utilisĂ©es.Dans la premiĂšre partie, une mĂ©thode itĂ©rative de guidage, basĂ©e sur des stimulations successives via cathĂ©ter, a Ă©tĂ© proposĂ©e. Cette mĂ©thode, qui utilise uniquement les signaux des Ă©lectrocardiogrammes, a Ă©tĂ© testĂ©e sur des donnĂ©es simulĂ©es.Dans la seconde partie, une mĂ©thode dâapprentissage automatique a Ă©tĂ© construite sur des donnĂ©es simulĂ©es gĂ©nĂ©rĂ©es sur plusieurs modĂšles de patients rĂ©alistes, en utilisant lâimagerie ainsi que les signaux des Ă©lectrocardiogrammes. Cette mĂ©thode a Ă©tĂ© entraĂźnĂ©e sur les donnĂ©es simulĂ©es puis a pu ĂȘtre testĂ©e sur des donnĂ©es cliniques, rĂ©cupĂ©rĂ©es de procĂ©dures dâablation rĂ©alisĂ©es au CHU de Bordeaux
Numerical learning methods to facilitate ventricular arrhythmias localisation during ablation procedures
Les maladies cardiovasculaires sont les principales causes de dĂ©cĂšs dans le monde. Parmi ces maladies, les arythmies ventriculaires sont des pathologies potentiellement graves, pouvant engendrer la mort subite cardiaque. Une arythmie ventriculaire est une anomalie qui affecte la propagation des ondes Ă©lectriques parcourant les ventricules, ondes qui coordonnent la contraction de ceux-ci afin quâils puissent assurer leur rĂŽle de pomper le sang dans lâorganisme. Parmi ces arythmies, lâextrasystole ventriculaire est la forme la plus bĂ©nigne de cette catĂ©gorie, mais elle peut entraĂźner une tachycardie capable de dĂ©clencher une fibrillation, forme la plus dangereuse, et mĂȘme mortelle si elle nâest pas interrompue par un dĂ©fibrillateur.Lâenjeu est donc de parvenir Ă soigner les extrasystoles si elles sâavĂšrent trop frĂ©quentes. Pour cela, les cardiologues ont dâabord recours Ă des mĂ©dicaments permettant dâagir sur lâactivitĂ© Ă©lectrique cardiaque. NĂ©anmoins, il arrive que ces traitements ne soient pas suffisants. Les cliniciens procĂšdent alors Ă une procĂ©dure dâablation par radiofrĂ©quence : cela consiste Ă introduire un cathĂ©ter dans les cavitĂ©s ventriculaires du patient, de localiser les zones du tissu cardiaque responsables des extrasystoles, puis de les neutraliser via ce cathĂ©ter en chauffant Ă une tempĂ©rature suffisante pour tuer les cellules malades. Ce type de procĂ©dure a un bon taux de rĂ©ussite, cependant la localisation des zones responsables des extrasystoles peut sâavĂ©rer difficile pour le cardiologue, et ainsi rallonger le temps dâintervention, qui peut sâĂ©tendre sur plusieurs heures, ce qui est inconfortable pour le patient. Câest en particulier le cas lorsque les extrasystoles sont rares au moment de lâintervention.Lâobjectif de cette thĂšse est de crĂ©er des outils numĂ©riques permettant de faciliter la localisation des extrasystoles ventriculaires, outils qui sâintĂšgrent facilement dans le procĂ©dĂ© clinique. Pour cela, des simulations trĂšs prĂ©cises de la propagation Ă©lectrique dans le cĆur ont Ă©tĂ© utilisĂ©es.Dans la premiĂšre partie, une mĂ©thode itĂ©rative de guidage, basĂ©e sur des stimulations successives via cathĂ©ter, a Ă©tĂ© proposĂ©e. Cette mĂ©thode, qui utilise uniquement les signaux des Ă©lectrocardiogrammes, a Ă©tĂ© testĂ©e sur des donnĂ©es simulĂ©es.Dans la seconde partie, une mĂ©thode dâapprentissage automatique a Ă©tĂ© construite sur des donnĂ©es simulĂ©es gĂ©nĂ©rĂ©es sur plusieurs modĂšles de patients rĂ©alistes, en utilisant lâimagerie ainsi que les signaux des Ă©lectrocardiogrammes. Cette mĂ©thode a Ă©tĂ© entraĂźnĂ©e sur les donnĂ©es simulĂ©es puis a pu ĂȘtre testĂ©e sur des donnĂ©es cliniques, rĂ©cupĂ©rĂ©es de procĂ©dures dâablation rĂ©alisĂ©es au CHU de Bordeaux.Cardiovascular diseases are leading causes of death in the world. Among these diseases, ventricular arrhythmias are potentially serious pathologies that can lead to sudden cardiac death. A ventricular arrhythmia is an abnormality that affects the propagation of the electrical activation wavefronts through the ventricles, which normally coordinates the contraction of the ventricles such that they can optimally perform their role of pumping blood through the body. Of these arrhythmias, premature ventricular contraction (PVC) is the most benign. However, it can lead to tachycardia, which can induce fibrillation -- the most dangerous cardiac arrhythmia and fatal if not interrupted by a defibrillator.The challenge is therefore to treat PVCs if they are too frequent. To do this, cardiologists first use drugs that act on the electrical activity of the heart. However, sometimes these treatments are not sufficient. In this case, clinicians resort to a catheter ablation procedure. It proceeds by inserting a catheter into the patient's ventricular cavities, locating the areas of the heart responsible for the PVCs and then neutralizing them by applying a radiofrequency current that locally heats the tissue sufficiently to kill the cells. These procedures have a good success rate, but locating the areas responsible for PVC can be difficult for the cardiologist, and thus lengthen the intervention, which can last for several hours, and is unpleasant for the patient.The objective of this thesis is to create numerical tools that facilitate PVC localisation and that are easy to integrate in the clinical workflow. To do this, highly accurate simulations of the electrical activity of the heart were used.In the first part, an iterative pace-mapping method was proposed. This method, which uses only electrocardiogram signals, has been tested on simulated data.In the second part, a machine learning method was constructed, based on in-silico data generated with several realistic patient-specific heart-torso models, using both imaging and electrocardiogram signals. This method was trained on the simulated data and then tested on clinical data, from ablation procedures performed at the Bordeaux University Hospital
An Improved Iterative Pace-Mapping Algorithm to Detect the Origin of Premature Ventricular Contractions
International audiencePremature ventricular contraction (PVC) is one of the mechanisms that induce Ventricular Tachycardia (VT) or Ventricular Fibrillation (VF). A way to cure PVC is to ab-late the origin with an endocardial catheter. But it can be difficult, and sometimes impossible, to localize this exit site accurately enough. We propose to accelerate catheter ablation using an automatic method to guide the catheter towards the PVC origin. This method uses the QRS complex integrals of the 8-lead ECGs of the PVC and a sequence of beats paced at known locations. The method was tested using 7 realistic heart-torso models with PVCs in endocardial, epicardial, and intramural tissue. With 10 pacing sites, 95 % of the targets had been approximated to less than 5 mm. We conclude that although the convergence is sometimes erratic, the proposed method does converge to the origin, often within the radius of an ablation lesion
In-Silico Evaluation of an Iterative Pace-Mapping Technique to Guide Catheter Ablation of Ventricular Ectopy
Ventricular tachychardia (VT) is one of the mechanisms that induce sudden cardiac death. A way to cure VT is to ablate the exit site with an endocardial catheter. But it can be difficult, and sometimes impossible, to localize this exit site accurately enough. We propose a process to accelerate catheter ablation using an automatic method to guide the catheter towards the exit site. The proposed process uses the QRS complex integral of the 12-lead ECG. The method was tested using a realistic numerical forward model with pacing sites in endocardial, epicardial, and mid-myocardial tissue. With 12 pacing sites, 6 targets had been approximated to less than 1 mm. Five more were within 5 mm distance, and one was at 10 mm distance. We conclude that although the convergence is sometimes erratic, the proposed method does converge to the exit site, often within the radius of an ablation lesion
Deep Learning for Model Correction in Cardiac Electrophysiological Imaging
International audienceImaging the electrical activity of the heart can be achieved with invasive catheterisation. However, the resulting data are sparse and noisy. Mathematical modelling of cardiac electrophysiology can help the analysis but solving the associated mathematical systems can become unfeasible. It is often computationally demanding, for instance when solving for different patient conditions. We present a new framework to model the dynamics of cardiac electrophysiology at lower cost. It is based on the integration of a low-fidelity physical model and a learning component implemented here via neural networks. The latter acts as a complement to the physical part, and handles all quantities and dynamics that the simplified physical model neglects. We demonstrate that this framework allows us to reproduce the complex dynamics of the transmembrane potential and to correctly identify the relevant physical parameters, even when only partial measurements are available. This combined model-based and data-driven approach could improve cardiac electrophysiological imaging and provide predictive tools
In-Silico Data Based Machine Learning Technique Predicts Premature Ventricular Contraction Origin Coordinates
Plateforme multi-modale d'exploration en cardiologieElectrostructural Tomography - Towards Multiparametric Imaging of Cardiac Electrical Disorder