CT-guided cardiac electrophysiology

Recent advances in cardiac electrophysiology with revolutionary development of transcutaneous procedures have required electrophysiologists to have precise knowledge of the spatial anatomy of the heart, and thus, led to the increasing use of cardiac imaging procedures such as multidetector CT (MDCT). The introduction of 64-detector (and higher) scanners has made it possible to visualize the anatomic landmarks that are essential for both diagnostic and therapeutic cardiac procedures and, in selected cases, prevention of procedure-related complications. Future work with these emerging imaging techniques will further characterize how cardiac CT can aid cardiologists to dissect the microscopic anatomy of the heart, optimize success rates, and potentially minimize inherent risks of the cardiac interventions. In this review, we focus on the latest developments in the application of MDCT for electrophysiologic interventions.     

MRI for electrophysiology

Catheter ablation is a first-line treatment for many cardiac arrhythmias and is generally performed under x-ray fluoroscopy guidance. However, current techniques for ablating complex arrhythmias such as atrial fibrillation and ventricular tachycardia are associated with suboptimal success rates and prolonged radiation exposure. Pre-procedure three-dimensional (3-D) MRI has improved understanding of the anatomic basis of complex arrhythmias and is being used for planning and guidance of ablation procedures. A particular strength of MRI compared to other imaging modalities is the ability to visualize ablation lesions. Post-procedure MRI is now being applied to assess ablation lesion location and permanence, with the goal of indentifying factors leading to procedure success and failure. In the future, real-time MRI, together with the ability to image complex 3-D arrhythmogenic anatomy and target additional ablation to regions of incomplete lesion formation, may allow for more successful treatment of even complex arrhythmias without exposure to ionizing radiation.     

The electrophysiology of cluster headache

Cluster headache (CH) is a neurovascular headache disease characterized by recurrent, strictly unilateral, severe pain attacks. Despite its typical clinical features, including circadian rhythm of the attacks and ipsilateral autonomic dysfunction, the underlying pathophysiology of CH is still unclear. Electrophysiological data point to central disinhibition of the trigeminal nociceptive system as one of the key mechanisms of CH pain. Therefore, altered habituation pattern and changes within trigeminal-facial neuronal circuits due to central sensitization seem to be involved. One biochemical correlate is probably represented in dysfunctions of serotonergic raphe nuclei-hypothalamic pathways. Structural and functional imaging data show an alteration of hypothalamic structures in CH patients, supporting the hypothesis that the hypothalamus, according to its function as a circadian pacemaker, plays a pivotal role in CH pathology. Cortical and brainstem reflexes are reviewed to illuminate the pathophysiology of CH.     

Imaging techniques in cardiac electrophysiology

Modern cardiac electrophysiology procedures include catheter-based arrhythmia ablation and transvenous device implantation, which are highly dependent on accurate, real-time cardiac imaging. With the realization that anatomic structures are critical to successful electrophysiologic procedures, accurately defining a patient’s cardiac anatomy has become more important. Fluoroscopy allows for 2D imaging of cardiac structures in real-time, and is used to guide catheter and lead placement, but does not allow for visualization of soft tissues. Intracardiac echocardiography allows for both direct visualization of anatomic structures within the heart and real-time imaging during catheter placement. Despite advances in intracardiac echocardiography catheters that allow for larger windows, the ability to accurately delineate anatomic structures depends on the patient’s anatomy and operator experience. Neither of these techniques allows for electrical mapping of the heart; however, both anatomic and electrical intracardiac mapping can be achieved with advanced mapping systems. These systems allow for real-time catheter localization, help elucidate cardiac anatomy, evaluate electrical activation during arrhythmias and guide catheter placement for deliverance of radiofrequency current. More recently, 3D cardiac computed tomography has been used to accurately define intracardiac anatomy; however, catheter tracking and electrical mapping cannot be performed by computed tomography. Mapping systems are now being merged with computed tomography images to produce an accurate anatomic and electrical map of the heart to guide catheter ablations. The objective of this paper is to describe the current imaging and mapping techniques used in electrophysiologic procedures.     

Imaging techniques in cardiac electrophysiology

Modern cardiac electrophysiology procedures include catheter-based arrhythmia ablation and transvenous device implantation, which are highly dependent on accurate, real-time cardiac imaging. With the realization that anatomic structures are critical to successful electrophysiologic procedures, accurately defining a patient's cardiac anatomy has become more important. Fluoroscopy allows for 2D imaging of cardiac structures in real-time, and is used to guide catheter and lead placement, but does not allow for visualization of soft tissues. Intracardiac echocardiography allows for both direct visualization of anatomic structures within the heart and real-time imaging during catheter placement. Despite advances in intracardiac echocardiography catheters that allow for larger windows, the ability to accurately delineate anatomic structures depends on the patient's anatomy and operator experience. Neither of these techniques allows for electrical mapping of the heart; however, both anatomic and electrical intracardiac mapping can be achieved with advanced mapping systems. These systems allow for real-time catheter localization, help elucidate cardiac anatomy, evaluate electrical activation during arrhythmias and guide catheter placement for deliverance of radiofrequency current. More recently, 3D cardiac computed tomography has been used to accurately define intracardiac anatomy; however, catheter tracking and electrical mapping cannot be performed by computed tomography. Mapping systems are now being merged with computed tomography images to produce an accurate anatomic and electrical map of the heart to guide catheter ablations. The objective of this paper is to describe the current imaging and mapping techniques used in electrophysiologic procedures.     

网球运动发球动作过程中肌肉电生理变化

背景:目前,国内利用肌电技术对网球运动过程中肌肉电生理变化数据的研究开展的较少.目的:运用肌电测试系统记录网球发球动作的肌肉用力规律,对各主要关节肌肉活动状态进行分析.设计、时间及地点:网球运动发球动作过程肌电测试系统现场描记分析.实验于1986-12/1988-12在北京体育大学完成.对象:选择中国现役网球国家队的男运动员6名,年龄(20.8±2.5)岁,身高(180.3±4.8) cm,体质量(69.1±5.8) kg,训练年限(6.6±2.9)年.方法:运用肌电测试系统并结合关节角度分析仪对现场描记国内网球运动发球动作,并通过专门的软件分析肌肉用力顺序和用力情况.主要观察指标:发球动作解剖分析、各肌肉活动顺序比较、各肌肉发力持续时间和关节角度比较、各肌肉发力大小比较.结果:在网球发球过程中,击球时三角肌和斜方肌最先参与肌肉发力,持续时间较其他的肌肉长,是发球过程中的主要用力肌肉;斜方肌、胫骨前肌和腓肠肌最先参与整个动作发力,持续时间均较其他肌肉时间长;肌肉按照肌电活动持续的时间长短排列顺序为胸大肌、腹直肌、背阔肌、腓肠肌、腹外斜肌、股直肌、肱二头肌、胫骨前肌、肱桡肌、斜方肌、三角肌,其中三角肌和斜方肌的肌电活动持续时间最长,而胸大肌和腹直肌的肌电活动持续时间最短;个体差异不同肌肉的肌电积分值是不一样的,其所对应的肌肉力量大小也不一样,发挥出的肌肉占最大肌肉力量的比例存在很大的差异.结论:表面肌电测试可以应用于网球运动动作肌肉运动过程中科学合理性的判断分析.     

Cardiovascular magnetic resonance guided electrophysiology studies

The pericardium and pericardial diseases in particular have received, in contrast to other topics in the field of cardiology, relatively limited interest. Today, despite improved knowledge of pathophysiology of pericardial diseases and the availability of a wide spectrum of diagnostic tools, the diagnostic challenge remains. Not only the clinical presentation may be atypical, mimicking other cardiac, pulmonary or pleural diseases; in developed countries a shift for instance in the epidemiology of constrictive pericarditis has been noted. Accurate decision making is crucial taking into account the significant morbidity and mortality caused by complicated pericardial diseases, and the potential benefit of therapeutic interventions. Imaging herein has an important role, and cardiovascular magnetic resonance (CMR) is definitely one of the most versatile modalities to study the pericardium. It fuses excellent anatomic detail and tissue characterization with accurate evaluation of cardiac function and assessment of the haemodynamic consequences of pericardial constraint on cardiac filling. This review focuses on the current state of knowledge how CMR can be used to study the most common pericardial diseases.     

超声心动图在心脏电生理中的应用

心脏的泵血过程涉及3种生理活动:(1)心肌兴奋,为电学活动,包括细胞膜除极-复极周期性规律,形成心电周期;(2)心肌舒缩,为机械运动,包括肌纤维收缩-舒张周期性规律,形成心动周期;(3)心腔血液流场分布,属血流动力学范畴。     

两套视觉电生理检查系统的比较

目的:对比国特GT-2000NV与RETIscan两套视觉电生理检查系统对正常青年人检查的结果。方法:20例正常军校学员用国特和RETIscan两套系统进行图形视觉诱发电位(PVEP)、视网膜电图(ERG)、多焦视网膜电图(mERG)的检测,两套系统的各相应参数调整至相同或相近。结果:两套系统所检测各结果中除Max-ERGa波幅值外,PVEP和常规ERG的其余各值及mERG在两套系统中差异均有显著性意义。PVEPP100峰时、Rod-ERGa波幅值、Rod-ERGb波峰时、Cone-ERGb波峰时在两套系统的测量中,在α=0.05水准上无相关性,而PVEPP100幅值和常规ERG其余结果在两套系统中均表现为正相关,其中Rod-ERGb波幅值、Max-ERGb波幅值、峰时、Cone-ERGb波幅值、Flick-ERGP2波幅值的相关系数分别为0.679,0.832,0.702,0.756,0.766。mERG环形p波功率密度及各象限p波功率密度及峰时在两套系统中均为正相关,环形p波峰时在α=0.05水准上第1,2,3环无相关性,而第4、5环在α=0.05水准上为正相关。其中环形第1,2,3,4,5环功率密度的相关系数分别为0.443,0.627,0.591,0.592,0.739,其峰时的相关系数分别为0.292,0.269,0.302,0.432,0.810。两套系统在mERG测量中,p波功率密度及峰时的变化具有相同的趋势。结论:国特和RETIscan两套系统在视觉电生理的测量中,其各结果的正常值     

Evaluation of Fetal Growth and Fetal Well-Being

This article reviews the actual knowledge and future developments of ultrasound techniques for the evaluation of fetal growth and well-being. Sonography allows the visualization of the fetus in utero and is utilized worldwide for the evaluation of fetal growth and well-being. Fetal biometry assessment is performed in the second half of pregnancy when deviations of fetal growth can be best recognized through alterations of fetal abdominal circumference growth. Doppler velocimetry of utero-placental vessels identifies alterations of placental perfusion and is valuable in the assessment of fetal brain, heart, and liver perfusion, thus being utilized in the timing of delivery. Recently, three-dimensional ultrasound evaluation of fetal organs and placenta is being developed.     

心内超声在心脏介入电生理学中的作用

近几年心内超声(ICE)在国外已得到很大的发展.本文综述了最近几年ICE在心脏介入电生理中的应用和发展.研究发现,ICE能在检查过程中准确清晰地显示解剖部位和导管位置,与其他方法相比,ICE心内超声用于心脏介入电生理中有更高的安全性和可靠性.     

Advances in cardiac electrophysiology and pacing.

Significant advances have been made in the management of cardiac arrhythmias. New technology has enhanced the ability to understand and treat a variety of tachycardias. Excitement and caution surround ablative approaches for atrial fibrillation. The role of ICDs and class III antiarrhythmic drugs in the management of patients at risk for sudden cardiac death has been clarified. A new indication for cardiac pacing is evolving as a supplemental treatment for patients with refractory congestive heart failure. These and other advances provide numerous exciting options for management of cardiac patients.     

Atrial electrophysiology and mechanisms of atrial fibrillation

Atrial fibrillation is the most common cardiac arrhythmia in clinical practice, and its management remains challenging. A solid understanding of the scientific basis for atrial fibrillation therapy requires insight into the mechanisms underlying the arrhythmia, about which an enormous amount has been learned over the past 10 years. The basic information presently available about atrial fibrillation mechanisms is reviewed. The particular properties of normal atrial electrophysiology are discussed, including salient ionic determinants of the atrial action potential and key anatomic features. Reviewed are three crucial arrhythmia mechanisms long held to be involved in atrial fibrillation: 1) rapid ectopic activity, 2) single-circuit reentry with fibrillatory conduction, and 3) multiple-circuit reentry. The determinants of each and the evidence for their involvement in clinical and/or experimental atrial fibrillation are noted. The physiological consequences, various contributing mechanisms, and clinical implications of the role of atrial-tachycardia remodeling are analyzed. Atrial-tachycardia remodeling links the potential mechanisms of atrial fibrillation, since atrial fibrillation beginning by any mechanism is likely to cause tachycardia-remodeling and thus promote the maintenance of atrial fibrillation by multiple-circuit reentry. Atrial structural remodeling is discussed as a paradigm of atrial fibrillation in which the classic features required for reentry (reduced refractory period and reentrant wavelength) may be lacking. Finally, the importance of recent insights into potential genetic determinants of atrial fibrillation is reviewed. The classic understanding of atrial fibrillation pathophysiology saw the different possible mechanisms as being alternative and opposing hypotheses. We now consider the multiple potential mechanisms as contributing to the pathophysiology of the arrhythmia to a different extent in different clinical settings and interacting with each other in a dynamic way at various stages of the natural history in many patients. It is hoped that this improved mechanistic understanding will lead to the development of improved therapeutic options.