Ryo Haraguchi

University of Hyogo · Graduate School of Information Science

Wolff‒Parkinson‒White (WPW) syndrome is characterized by an anomalous accessory pathway (AP) connecting the atrium and ventricle, leading to abnormal myocardial excitation and cardiac arrhythmias. The effective refractory period (ERP) of the AP is crucial for risk stratification. Building on previous research indicating the significance of the sour...

Congenital heart disease (CHD) involves structural abnormalities in blood vessels connected to the heart or in the heart itself, which are present since birth. Morphological abnormalities in CHD lead to abnormalities in blood flow and circulatory function. Education and training on cardiac morphology for medical students and cardiologists have trad...

Background Wolff‐Parkinson‐White (WPW) syndrome is characterized by an anomalous accessory pathway (AP) that connects the atrium and ventricles, which can cause abnormal myocardial excitation and cardiac arrhythmias. The morphological and electrophysiological details of the AP remain unclear. The size and conductivity of the AP may affect conductio...

Introduction: Although modulation of atrial fibrillation (AF) drivers and/or substrates has been proposed as one of the effective ablation strategies for non-paroxysmal AF (Non-PAF), previous meta-analyses showed that ablation, targeting complex fractionated atrial electrogram (CFAE) indirectly-reflecting Non-PAF drivers, had no additional benefit...

Background Detection of the fiber orientation pattern of the myocardium using diffusion tensor magnetic resonance imaging lags ≈12 weeks of gestational age (WGA) behind fetal myocardial remodeling with invasion by the developing coronary vasculature (8 WGA). We aimed to use diffusion tensor magnetic resonance imaging tractography to characterize th...

The underlying mechanism of Wolff-Parkinson-White (WPW) syndrome involves an accessory conduction pathway between the atria and ventricles. Since the accessory pathway cannot be visualized using clinical imaging modalities, WPW is usually diagnosed using an electrocardiogram. The treatment of WPW is radiofrequency catheter ablation. We have recentl...

Myocardial bundles working as accessory pathways in Wolff-Parkinson-White (WPW) syndrome are generally tiny tissues, so elucidating the culprit histology of atrioventricular (AV) myocardial connections requires careful serial sectioning of the AV junction. We performed a postmortem examination of accessory AV myocardial connections in an 84-year-ol...

Background Effects of nonparoxysmal atrial fibrillation (non‐PAF) ablation targeting complex fractionated atrial electrogram (CFAE) areas and/or low voltage areas (LVAs) are still controversial. Methods and Results A recently developed online real‐time phase mapping system (ExTRa Mapping) was used to conduct LVA mapping and simultaneous ExTRa and...

This study aimed to compare the visibility of formalin-fixed heart among various 3D MRI sequences and to clarify the optimal sequence for the computational modeling of congenital heart disease.

This chapter presents examples of medical image understanding algorithms using computational anatomy models explained in Chap. 2. After the introductory in Sect. 3.1, Sect. 3.2 shows segmentation algorithms for vertebrae, ribs, and hip joints. Segmentation algorithms for skeletal muscle and detection algorithms for lymph nodes are explained in Sect...

Background The atrioventricular (AV) node is the only compartment that conducts an electrical impulse between the atria and the ventricles. The main role of the AV node is to facilitate efficient pumping by conducting excitation slowly between the two chambers as well as reduce the ventricular rate during atrial fibrillation (AF). Methods Using co...

Vast macroscopic and histological specimens on cardiovascular diseases have been saved since its founding in National Cerebral and Cardiovascular Center Hospital (Japan). We conduct the project for contributing medical research and education by digitizing those specimens and developing novel cardiac computational models with congenital heart diseas...

The aim of this study was to elucidate the effects of myocardial fiber orientation on the deformation of the left ventricular (LV) wall. An LV wall model was constructed by modeling the myocardial fiber structure as an anisotropic hyperelastic material. The shapes of the endocardium and epicardium were assumed to be two spheroids. LV wall deformati...

Background: Recently, myocardial sheets consisting of human induced pluripotent stem cellderived cardiomyocytes (hiPSC-CM) have been used to clarify the mechanisms of inherited arrhythmias and to evaluate the efficacy of antiarrhythmic drugs. However, whether the electrophysiological properties of the hiPSC-CM are the same as those of the original...

Our research group has conducted many computer simulation studies over the past years, in order to comprehensively understand the electrophysiological phenomena in the heart. By developing high performance computing techniques and visualization technology and by integrating the multilevel knowledge obtained through basic studies from the ion channe...

The Purkinje fiber network is one of the specialized excitation conduction systems that ensure coordinated contraction of the ventricles due to faster excitation conduction than other regions of the heart. A recent study identified a mutation in connexin 40 (Cx40), a gap junction isoform predominantly expressed in the His-Purkinje system, in patien...

A shape matching dynamics (SMD) is a robust and efficient elastic model based on geometric constraints. This article introduces our study [1] that adopts SMD to visual simulation of cardiac beating motion. In our technique, a heart is represented by a tetrahedral mesh model and a local region is defined at each vertex by connecting its immediate ne...

To improve clinical research efficiency, it is necessary to utilize various information systems, including electronic data capture (EDC) systems. However, it is difficult to appropriately manage EDC systems in an academic institution because commercial EDC systems are often cost-prohibitive, and to safely and effectively manage EDC systems, network...

Background Cardiomyocytes located at the ischemic border zone of infarcted ventricle are accompanied by redistribution of gap junctions, which mediate electrical transmission between cardiomyocytes. This ischemic border zone provides an arrhythmogenic substrate. It was also shown that sodium (Na+) channels are redistributed within myocytes located...

Recently, arrhythmia studies have been attempted to use myocardial sheets consisting of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). However, whether the electrophysiological property of hiPSC-CM is consistent with that of original human cardiomyocytes (hCM) is still unclear. In the present study, in silico myocardial shee...

The Purkinje network is one of the electrical excitation conduction systems in the heart and represents the most distal portion of the ventricular conduction system. Gap junction channels provide a pathway for electrical signaling between cells. A recent study identified a mutation that reduces the gap junction conductance in patients with ventricu...

Previously, we developed of an online support system for persons with metabolic syndrome. In this study, we investigated the possibility of enhancing our system for applications in ischemic heart disease (IHD) and heart failure (HF). The main causes of IHD are obesity, hypertension, arteriosclerosis, hyperglycemia and other metabolic disorders. The...

The atrioventricular (AV) node, which is located between the atria and ventricles of the heart, acts as important roles in cardiac excitation conduction between the two chambers. Although there are multiple conduction pathways in the AV node, the structure of the AV node has not been clarified. In this study, we constructed a one-dimensional model...

In recent years, echocardiography is a common tool for diagnosing congenital heart disease because it is non-invasive and it provides real-time imaging. However, it is necessary to have specialized knowledge and experience to analyze the three-dimensional anatomical structure of the heart from 2-D echocardiography. Currently, experts on echocardiog...

The World Health Organization reported that ischemic heart disease is the most common cause of death worldwide in 2008. The main causes of ischemic heart disease are obesity, hypertension, arteriosclerosis and other metabolic abnormalities. These conditions are related to lifestyle issues, such as diet and exercise. We developed a system to support...

Computer simulation techniques for cardiac beating motions potentially have many applications and a broad audience. However, most existing methods require enormous computational costs and often show unstable behavior for extreme parameter sets, which interrupts smooth simulation study and make it difficult to apply them to interactive applications....

A basic interface of our prototype system. This video shows a basic interface for modifying local contraction rate and timing, and our real-time simulation result. (WMV)

Left ventricle ejection fraction of a simulated whole heart. This video shows simulated whole heart motions with three different maximum contraction rates. (WMV)

Three interaction tools. This video shows our three interaction tools, a cutting tool, a peeling tool, and a direct deformation tool. (WMV)

Comparison between our method and a physics-based method. This video shows simulation results generated with our method and the physics based method side-by-side. (WMV)

This paper proposes a 3-D cardiovascular modeling system based on neonatal echocardiographic images. With the system, medical doctors can interactively construct patient-specific cardiovascular models, and share the complex topology and the shape information. For the construction of cardiovascular models with a variety of congenital heart diseases,...

Electrogram-based catheter ablation, targeting complex fractionated atrial electrograms (CFAEs), is empirically known to be effective in halting persistent/permanent atrial fibrillation (AF). However, the mechanisms underlying CFAEs and electrogram-based ablation remain unclear. Because atrial fibrosis is associated with persistent/permanent AF, we...

Advanced clinical diagnosis of a cardiac function requires quantitative evaluation of myocardium deformation. It is however still challenging to quantify myocardium deformations due to noises caused by entire cardiac movements and limits of imaging modalities. Here, we propose a novel method for gaining strain rates of myocardium with better spatio...

This paper presents a lightweight sketching system that enables interactive illustration of complex fluid systems. Users can sketch on a 2.5-dimensional (2.5D) canvas to design the shapes and connections of a fluid circuit. These input sketches are automatically analyzed and abstracted into a hydraulic graph, and a new hybrid fluid model is used in...

This paper presents a lightweight sketching system that enables interactive illustration of complex fluid systems. Users can sketch on a 2.5-dimensional (2.5D) canvas to design the shapes and connections of a fluid circuit. These input sketches are automatically analyzed and abstracted into a hydraulic graph, and a new hybrid fluid model is used in...

The gap junction and voltage-gated Na(+) channel play an important role in the action potential propagation. The purpose of this study was to elucidate the roles of subcellular Na(+) channel distribution in action potential propagation. To achieve this, we constructed the myocardial strand model, which can calculate the current via intercellular cl...

Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Rate control to limit conduction from the atrium to the ventricle during AF is one of the important treatments clinically. However, the ionic basis underlying the rate control is not clear. In this study, we have investigated the effect of antiarrhythmic drugs on ventricula...

Background: We have recently demonstrated in computer simulations that rotational anisotropy of ventricular fiber orientation decreases the sustainability of ventricular fibrillation (VF) even under the large transmural dispersion of repolarization (TDR). However, how the rotational anisotropy restrains VF is still unclear. Methods: To clarify this...

Cardiac sodium (Na+) channels play critical roles in initiating and propagating action potentials in myocardium. We have recently reported that the action potential propagation was greatly affected by the subcellular distribution of Na+ channels in a physiologically-relevant myofiber model, where myocytes were electrically coupled with both gap-jun...

Background: We have recently demonstrated in computer simulations that electrotonic interactions between atrial myocytes and heterogeneously-distributed fibroblasts result in the genesis of complex fractionated atrial electrograms (CFAEs) during chronic atrial fibrillation (AF). However, previous research has not provided sufficient evidence that a...

Background: There are many studies to investigate mechanisms of induction and maintenance of ventricular fibrillation (VF); however, the mechanisms have not been clarified yet. It is known that the thickness of ventricular wall varies with time during VF; i.e., thickness of left ventricular wall is increased whereas that of right ventricular wall i...

Ventricular tachyarrhythmia is the leading cause of sudden cardiac death, and scroll wave re-entry is known to underlie this condition. Class III antiarrhythmic drugs are commonly used worldwide to treat ventricular tachyarrhythmias; however, these drugs have a proarrhythmic adverse effect and can cause Torsade de Pointes or ventricular fibrillatio...

The heart is important internal organs for the human body, and it is known by doing a very efficient systole-diastole movement. It is thought that the twist movement of the heart and the twist arrangement of cardiac muscle fiber influence to an efficient movement of the heart, so various studies are studied. The Phase-Contrast method of MRI can mea...

Ventricular fibrillation (VF) is the major cause of sudden cardiac death by lethal arrhythmia. Regional abnormalities such as myocardial infarction are regarded as the cause of VF; however, VF is clinically caused without the organic heart disease. Then we hypothesized that a human heart equips a protective mechanism against VF and thus the breakdo...

The Purkinje fibers are located in the ventricular walls of the heart, just beneath the endocardium and conduct excitation from the right and left bundle branches to the ventricular myocardium. Recently, anatomists succeeded in photographing the Purkinje fibers of a sheep, which clearly showed the mesh structure of the Purkinje fibers. In this stud...

We propose a sketch-based interface for modeling the myocardial fiber orientation required in the electrophysiological simulation of the heart, especially the ventricles. The user can create a volumetric vector field that represents the myocardial fiber orientation in two steps. First, a depth field over the three-dimensional (3D) ventricular model...

Selecting a region of interest (ROI) within unsegmented volume data is one of the fundamental operations in volume data processing and analysis, yet it is difficult to perform the task efficiently This paper proposes several simple and intuitive sketching user interface tools for the selection task, in which the user can directly click or draw a st...

The aim of this study was to investigate whether bipolar electrode potentials (BEPs) reflect local myocardial repolarization dynamics, using computer simulation. Simulated action potential and BEP mapping of myocardial tissue during fibrillation was performed. The BEP was modified to make all the fluctuations have the same polarity. Then, the modif...

This article proposes a sketch-based interface for modeling muscle fiber orientation of a 3D virtual heart model. Our target was electrophysiological simulation of the heart and fiber orientation is one of the key elements to obtaining reliable simulation results. We designed the interface and algorithm based on the observation that fiber orientati...

We previously developed an electrophysiological heart simulator. However, it was tedious and time-consuming to create the heart models for the simulation. In this study, we newly developed the graphical interface for modeling an excitation map and setting up some physiological parameters. Utilizing our interface enables us to save the labor for rep...

We developed an experimental system of Cardiac Arrhythmia Risk Evaluation (CARE) based on electrophysiological computer simulation. The system can evaluate a risk of tachyarrhythmia by the electrophysiological simulation with premature stimulation to many sites in the ventricular model, and users can browse the results on the Web page with the visu...

This paper introduces a pen-based interface for the graphical reporting of findings in cardiac catheterization. The user can interactively draw, erase, move, and deform coronary arteries as well as record stenoses on them. The location and degree of each stenosis is represented visually and the doctor can record various treatments such as bypasses...

We present an electrophysiological heart simulator equipped with sketchy 3-D modeling interface. It has been tedious and time-consuming to create the shape of heart for use it in the simulator. In this study, we developed a new simulator that is combined with a sketch-based 3-D modeling interface for the shape transformation. We also developed a se...

In cardiac catheter test and treatment process, it is much effective to utilize schemata in writing a patient's record. To support this process, we present an intuitive interface system for finding report and treatment planning, such as in coronary angiograms. Using the system, a user can comprehensively draw such as stenosis, blood vessel and bypa...

This paper deals with a new method of three dimensional reconstruction of coronary arteries, by using the texture-mapping technique on a myocardial nuclear image. The bi-plane CAG images are texture-mapped onto a LV surface model which is pre-determined on a nuclear 3D image. By maximizing a matching degree between two mapped CAG images, registrati...

We reported at the former CiC conference a method of superimposing a coronary arterial tree on a bull's eye map of SPECT. In the method, the left ventricular epicardial surface model (LV surface model) was constructed from SPECT data. Coronary images corresponding to the bull's eye map was obtained by mapping bi-plane coronary angiograms (CAG) onto...

This paper deals with a method of registration and superimposition of a coronary arterial tree on a myocardial SPECT (Single Photon Emission Computed Tomography) image. We can grasp the myocardial function more easily in connection with the shape of the coronary arterial tree. The superimposed image is easily obtainable through some manual pointing...

Deals with a method of generating a CAT's Eye Image, in which the coronary arterial tree is superimposed on bull's eye map of SPECT. One can grasp the myocardial function more easily in connection with the shape of the coronary artery. The CAT's eye image is easily obtainable through some manual pointing on coronary angiograms (CAG) followed by an...

To assist in understanding a relationship between stenotic change in coronary arteries and change in myocardial function, we are developing a method of registration and superimposed display of the coronary arterial tree on a myocardial SPECT (Single Photon Emission Tomography). Firstly we introduce a fully 3-dimensional registration and display met...

This paper proposes a sketch-based interface for modeling muscle fiber orientation of a 3D virtual heart model. Our current target is electrophysiological simulation of heart and fiber orientation is one of the key elements to obtain faithful simulation results. The interface and algorithm are designed based on the observation that fiber orientatio...