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Free-running Purkinje fibers. A. Gross findings. B. OCM findings. C. Histology. Some Purkinje bundles are free running without attaching with ventricular surface or directly connect between trabeculae and the papillary muscle. The Purkinje fibers are seen at most of the false tendon at the apical part of the septum. Only Purkinje cells without cardiac myocytes are in these false tendons.
Source publication
Background:
The distribution and connection of ventricular Purkinje fibers are known to be associated with idiopathic left ventricular arrhythmias. Unusual anatomy is one of the important factors associated with catheter ablation success rate. With the widefield high-speed, swept-source optical coherence microscopy (OCM) and light microscope, we v...
Contexts in source publication
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... left bundle, which was separated from the His bundle, runs in the apical direction like a waterfall emerging from the myocardial perimembranous septal wall ( Figure 4A). The direction of this bundle is different from that of working myocardium in the endocardial area (Supplementary Figure 5). In the bundle ( Figure 4B), each fiber splits into a thinner fascicle according to its destination (Supplementary Figure 6). ...
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... the bundle ( Figure 4B), each fiber splits into a thinner fascicle according to its destination (Supplementary Figure 6). Some of them are free-running and lead directly to papillary muscles ( Figure 5). ...
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... cardiac Purkinje cells run on the crest of the trabeculae, but the basal part of the groove between trabeculae is free of the Purkinje cells or less populated. Free-standing bundles of Purkinje fibers were observed at the false tendon as seen by OCM ( Figure 5C). The most distal Purkinje cells merged with the myocardial cells predominantly at the mid-and apical myocardium but this transition was also found at the basal part. ...
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... left bundle, which was separated from the His bundle, runs in the apical direction like a waterfall emerging from the myocardial perimembranous septal wall ( Figure 4A). The direction of this bundle is different from that of working myocardium in the endocardial area (Supplementary Figure 5). In the bundle ( Figure 4B), each fiber splits into a thinner fascicle according to its destination (Supplementary Figure 6). ...
Context 5
... the bundle ( Figure 4B), each fiber splits into a thinner fascicle according to its destination (Supplementary Figure 6). Some of them are free-running and lead directly to papillary muscles ( Figure 5). ...
Context 6
... cardiac Purkinje cells run on the crest of the trabeculae, but the basal part of the groove between trabeculae is free of the Purkinje cells or less populated. Free-standing bundles of Purkinje fibers were observed at the false tendon as seen by OCM ( Figure 5C). The most distal Purkinje cells merged with the myocardial cells predominantly at the mid-and apical myocardium but this transition was also found at the basal part. ...
Citations
... The fact that Van Herendael et al. employed intracardiac ultrasound for a substantial number of patients is intriguing, as this was cited as a key factor in accurately identifying the papillary muscles as the sites of origin for the triggering PVCs. However, one caveat is the distinction between Purkinje-mediated and papillarymuscle-originating ectopy may not be black and white, given reports of Purkinje fibers extending into the papillary muscles [74]. ...
Sudden cardiac death (SCD) represents approximately 50% of all cardiovascular mortality in the United States. The majority of SCD occurs in individuals with structural heart disease; however, around 5% of individuals have no identifiable cause on autopsy. This proportion is even higher in those <40 years old, where SCD is particularly devastating. Ventricular fibrillation (VF) is often the terminal rhythm leading to SCD. Catheter ablation for VF has emerged as an effective tool to alter the natural history of this disease among high-risk individuals. Important advances have been made in the identification of several mechanisms involved in the initiation and maintenance of VF. Targeting the triggers of VF as well as the underlying substrate that perpetuates these lethal arrhythmias has the potential to eliminate further episodes. Although important gaps remain in our understanding of VF, catheter ablation has become an important option for individuals with refractory arrhythmias. This review outlines a contemporary approach to the mapping and ablation of VF in the structurally normal heart, specifically focusing on the following major conditions: idiopathic ventricular fibrillation, short-coupled ventricular fibrillation, and the J-wave syndromes—Brugada syndrome and early-repolarization syndrome.
... It is necessary to choose different equipment types and distribution system types or choose to build in different stages of network development. e following is an analysis of the general business needs of users in different buildings or in different scenarios [16]. ...
With the continuous development of network communication technology, the domestic network has covered the homes of ordinary people, but the indoor coverage system of the network cable network needs to be further improved. The optical fiber distribution system is a signal coverage system integrating GSM, TD-SCDMA, and other standards. It is mainly composed of system access unit, system expansion unit, and system remote unit. Wireless network is an important communication technology, which is easy to use and can be connected wirelessly over long distances. The purpose of this paper is to study an optical fiber distribution system for indoor coverage design of wireless networks, so as to achieve faster and more efficient coverage. In this paper, a wireless network signal processing algorithm is proposed, and a systematic method for designing the wireless network indoor coverage of the optical fiber distribution system is proposed, and the algorithms are compared and tested. The test results in this paper show that the signal strength obtained by the algorithm in this paper is −54.83 dB, while the traditional artificial design algorithm is only −45.97 dB. In addition, the wireless network base point of the algorithm in this paper is also 3 lower than the traditional one. Moreover, the coverage rate achieved by the algorithm in this paper is 3.17% higher than that of the network cable network base point layout given by the genetic algorithm, and the average received signal strength is 3.34 dB higher. In addition, the algorithm in this paper takes 9.1 s, 11.2 s, and 5.3 s for the three scenarios of underground parking lot, large shopping mall, and residential residential area, while the traditional manual design algorithm takes 87.9 s, 108.8 s, and 51.7 s, respectively. The algorithm in this paper is only about 1/10 of the traditional artificial design algorithm. Therefore, it can be concluded that the coverage effect of the wireless network indoor coverage system of the optical fiber distribution system designed in this paper is significantly improved.
... Furthermore, there was frequent electrogram evidence of both fascicular and myocardial disease in and around VA foci. Purkinje tissue is abundant on and around PM [46]. Such Purkinje involvement may occur in parallel to papillary muscle injury from repetitive papillary stretch secondary to prolapse, or diastolic interaction of mitral leaflets or cords with surrounding endocardium. ...
Sudden cardiac death (SCD) from ventricular fibrillation (VF) can occur in mitral valve prolapse (MVP) in the absence of other comorbidities including mitral regurgitation, heart failure or coronary disease. Although only a small proportion with MVP are at risk, it can affect young, otherwise healthy adults, most commonly premenopausal women, often as the first presentation of MVP. In this review, we discuss arrhythmic mechanisms in MVP and mechanistic approaches for sudden death risk assessment and prevention. We define arrhythmogenic or arrhythmic MVP (AMVP) as MVP associated with complex and frequent ventricular ectopy, and malignant MVP (MMVP) as MVP with high risk of SCD. Factors predisposing to AMVP are myxomatous, bileaflet MVP and mitral annular disjunction (MAD). Data from autopsy, cardiac imaging and electrophysiological studies suggest that ectopy in AMVP is due to inflammation, fibrosis and scarring within the left ventricular (LV) base, LV papillary muscles and Purkinje tissue. Postulated mechanisms include repetitive injury to these regions from systolic papillary muscle stretch and abrupt mitral annular dysmotility (excursion and curling) and diastolic endocardial interaction of redundant mitral leaflets and chordae. Whereas AMVP is seen relatively commonly (up to 30%) in those with MVP, MVP-related SCD is rare (2–4%). However, the proportion at risk (i.e., with MMVP) is unknown. The clustering of cardiac morphological and electrophysiological characteristics similar to AMVP in otherwise idiopathic SCD suggests that MMVP arises when specific arrhythmia modulators allow for VF initiation and perpetuation through action potential prolongation, repolarization heterogeneity and Purkinje triggering. Adequately powered prospective studies are needed to assess strategies for identifying MMVP and the primary prevention of SCD, including ICD implantation, sympathetic modulation and early surgical mitral valve repair. Given the low event rate, a collaborative multicenter approach is essential.
... We have previously used micro-CT to visualise and reconstruct the Purkinje fibre network in the intact normal human heart (Stephenson et al. 2017) and heart failure rabbits (Logantha et al. 2021). A previous study used optical coherence microscopy and light microscope to visualise the Purkinje fibre network of the left ventricle of the sheep heart (Cha et al. 2020). Other studies have used MRI to visualise the Purkinje fibre network in the left ventricle of pig heart (Magat et al. 2021) and whole rabbit heart (Hwang et al. 2011). ...
Research purpose
The cardiac conduction system (CCS) regulates electrical impulses across the heart and cardiac arrhythmias cause structural remodelling of the CCS. Since its discovery over a century ago, the precise anatomy and differences between the human CCS in healthy, aged, and obese human hearts has remained relatively unknown. Using iodine potassium-iodide (I2KI) and graphene oxide (GO) as contrast agents for high-resolution micro-computed tomography (micro-CT), we explored and identified the anatomies of whole healthy, aged, and obese hearts, including their CCS.
Basic procedures
Human specimens were obtained from 5 post-mortem hearts, under local ethical rules and stored in the Dobrzynski laboratory, under the Human Tissue Act 2004. Specimens were stained with I2KI or GO contrast agents before scanning with micro-CT. Data obtained from micro-CT was uploaded onto Amira v6.5 software for analysis, 3-dimensional reconstructions, and segmentation of relevant structures. Following micro-CT analyses, tissue blocks were cryosectioned and stained for histological assessments.
Main findings
There are obvious anatomical structural differences between the healthy, aged and obese hearts. Compared to the healthy heart, the aged heart and obese heart had larger chambers; thicker myocardial walls; thicker blood vessels; more extensive nodal regions and connective tissue; more epicardial fat; and fewer Purkinje fibres.
Our use of I2KI and GO as contrast agents for high-resolution micro-CT scanning contribute to - and expands - the current understanding of CCS structural variations between healthy, aged and obese human hearts.These current and novel techniques can have key impacts on our anatomical understandings for current treatments for cardiovascular disease and the development of mathematical models of aged and diseased hearts. Thus ultimately aiding in the reduction of cardiac morbidities and reduction of patient death rate.
