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Robert H. Anderson - One of the best experts on this subject based on the ideXlab platform.

  • Three‐dimensional visualization of the bovine cardiac conduction system and surrounding structures compared to the arrangements in the human heart
    Journal of anatomy, 2021
    Co-Authors: Marcos C. De Almeida, Shumpei Mori, Robert H. Anderson
    Abstract:

    In the human heart, the Atrioventricular node is located toward the apex of the triangle of Koch, which is also at the apex of the inferior pyramidal space. It is adjacent to the Atrioventricular portion of the membranous Septum, through which it penetrates to become the Atrioventricular bundle. Subsequent to its penetration, the conduction axis is located on the crest of the ventricular Septum, sandwiched between the muscular Septum and ventricular component of the membranous Septum, where it gives rise to the ramifications of the left bundle branch. In contrast, the bovine conduction axis has a long non-branching component, which penetrates into a thick muscular Atrioventricular Septum having skirted the main cardiac bone and the rightward half of the non-coronary sinus of the aortic root. It commonly gives rise to both right and left bundle branches within the muscular ventricular Septum. Unlike the situation in man, the left bundle branch is long and thin before it branches into its fascicles. These differences from the human heart, however, have yet to be shown in three-dimensions relative to the surrounding structures. We have now achieved this goal by injecting contrast material into the insulating sheaths that surround the conduction network, evaluating the results by subsequent computed tomography. The fibrous Atrioventricular membranous Septum of the human heart is replaced in the ox by the main cardiac bone and the muscular Atrioventricular Septum. The apex of the inferior pyramidal space, which in the bovine, as in the human, is related to the Atrioventricular node, is placed inferiorly relative to the left ventricular outflow tract. The bovine Atrioventricular conduction axis, therefore, originates from a node itself located inferiorly compared to the human arrangement. The axis must then skirt the non-coronary sinus of the aortic root prior to penetrating the thicker muscular ventricular Septum, thus accounting for its long non-branching course. We envisage that our findings will further enhance comparative anatomical research.

  • Solitary trunk from the right ventricle with a cleft mitral valve simulating the trifoliate left valve of an Atrioventricular septal defect with common Atrioventricular junction.
    Cardiology in the young, 2004
    Co-Authors: Geoffrey P. Sharratt, Robert H. Anderson
    Abstract:

    We report a case of a true cleft in the anterior leaflet of the mitral valve. The cleft, however, is directed toward the ventricular Septum, and the left ventricular papillary muscles have the same arrangement as seen in the setting of a common Atrioventricular orifice. The Atrioventricular Septum is intact. This appearance reflects the presence, in this patient, of right ventricular origin of a solitary arterial trunk, so that there was no outflow tract within the left ventricle to interpose between the mitral valve and the Septum.

  • The anatomy of interatrial communications – what does the interventionist need to know?
    Cardiology in the young, 2000
    Co-Authors: José Diogo Ferreira Martins, Robert H. Anderson
    Abstract:

    Increasingly, the interventional cardiologist is seeking to close interatrial communications by inserting devices by means of catheterisation. So as to optimise these procedures, it is advantageous to have a firm grasp of the anatomy of the normal atrial septal structures, this then providing the basis to understand the morphology of the holes which can exist between the chambers, not all of which are true septal defects. A true septal structure can be removed without exiting from the cavities of the heart. It is the flap valve of the oval fossa, along with the anterior rim of the fossa, which fulfill this criterion. The remainder of the extensive rim of the normal fossa is no more than an infolding between the walls of the right and left atria and their venous tributaries, and has different dimensions at various points around the circumference. The so-called muscular Atrioventricular "Septum" is a sandwich incorporating a layer of epicardial fibro-adipose tissue. True defects of the atrial Septum, therefore, exist because of deficiency, perforation, or absence of the flap valve. Most of these defects will prove suitable for interventional closure, but potential caveats include multiple defects, aneurysm of the flap valve, or adjacency of the fossa to the venous orifices. The other interatrial communications, namely the sinus venosus, coronary sinus, and "ostium primum" defects are outside the confines of the oval fossa. Recognition of this feature is the key to their diagnosis, and their differentiation from true atrial septal defects. Of these defects, only the coronary sinus defect is likely to be suitable for device closure, and then only in the very rare circumstances when it is seen in isolation.

  • Mechanisms of Deficient Cardiac Septation in the Mouse With Trisomy 16
    Circulation research, 1999
    Co-Authors: Sandra Webb, Robert H. Anderson, Wouter H. Lamers, Nigel A. Brown
    Abstract:

    Abstract—It used to be thought that the Atrioventricular Septum was predominantly the product of the Atrioventricular endocardial cushions. In a previous study, we have shown that multiple developmental primordia are of importance in its formation. With this in mind, we have evaluated cardiac morphogenesis in the mouse with trisomy 16, an animal model with a high incidence of Atrioventricular septal defects. Normal and trisomic fetuses from an Rb(11.16)2H/Rb(16.17)7Bnr×C57BL/6J cross were collected on days 10 to 15 of gestation and examined by scanning electron microscopy and histological serial sectioning. No evidence was found to suggest that Atrioventricular septal defect could be explained simply on the basis of “failure of fusion” between the Atrioventricular endocardial cushions. Rather, our findings supported two other developmental elements as being important in the genesis of Atrioventricular septal defect. The first is an alteration in the configuration of the heart tube, with inadequate remodel...

  • Formation of the Atrioventricular Septal Structures in the Normal Mouse
    Circulation research, 1998
    Co-Authors: Sandra Webb, Nigel A. Brown, Robert H. Anderson
    Abstract:

    Abstract —It is sometimes thought that formation of the Atrioventricular Septum is equated with fusion of the endocardial cushions and that failure of fusion can explain all deficiencies of Atrioventricular septation. Clearly, this is simplistic, but the exact contribution of different primordia to Atrioventricular septation is not well understood. To clarify this, we studied normal mouse embryos (days 10 to 15 of gestation), which were serially sectioned and examined by light microscopy. Another group of embryos was examined by scanning electron microscopy after microdissection. Our results show that development of the Atrioventricular septal area is highly complex. Proper formation requires the following: remodeling of the inner heart curvature, rotation of the horns of the systemic venous sinus around the pulmonary portal, expansion of the right Atrioventricular junction, formation of the muscular atrial and ventricular septa, bridging by the dextrodorsal outflow ridge and the superior endocardial cushion, fusion with the inferior margins of the venous valves, and formation of the mouth of the coronary sinus from the cranial muscular wall of the left sinus horn. Multiple primordia contribute to a central mesenchymal mass (the “Septum intermedium”), including the mesenchyme on the leading edge of the primary atrial Septum, the Atrioventricular endocardial cushions, and the cap of mesenchyme on the spina vestibuli. Fusion of these components closes the ostium primum, completing atrial and Atrioventricular septation. Additionally, the spina vestibuli has a mesodermal core, which contributes to the muscularization of the lower margin of the oval fossa. This contrasts with the formation of the upper rim, which occurs as a result of an infolding of the atrial wall itself.

Fernando Alfonso - One of the best experts on this subject based on the ideXlab platform.

  • Atrioventricular Septum Pseudoaneurysm As Late Complication After Repeated Mitral Valve Replacement
    The Annals of thoracic surgery, 2017
    Co-Authors: Pilar Agudo-quilez, Eduardo Pozo, Amparo Benedicto, Guillermo Reyes, María José Olivera, Paloma Caballero, Luis Jesús Jiménez-borreguero, Fernando Alfonso
    Abstract:

    We report the case of a pulsatile mass found in a patient who presented for a routine echocardiogram. The mass turned out to be an exceedingly rare mitral-subannular pseudoaneurysm involving the membranous Atrioventricular Septum with systolic expansion protruding into right atrium, discovered late after repeated multiple valve replacement surgery. Although these pseudoaneurysms may present asymptomatically, surgical intervention might be indicated because of the risk of rupture. This report describes this rare finding, discusses possible pathophysiological mechanisms, and underscores the importance of multimodality imaging to achieve correct identification and delimitation to guide surgical intervention in such cases.

Samuel J. Asirvatham - One of the best experts on this subject based on the ideXlab platform.

  • Synchronous ventricular pacing without crossing the tricuspid valve or entering the coronary sinus--preliminary results.
    Journal of cardiovascular electrophysiology, 2009
    Co-Authors: Benhur D. Henz, Paul A. Friedman, Charles J. Bruce, Yasuo Okumura, B B S Susan Johnson, Andrew J. Danielsen, Douglas L. Packer, Samuel J. Asirvatham
    Abstract:

    Background: Right ventricular apical (RVA) pacing promotes tricuspid regurgitation (TR), electromechanical dyssynchrony, and ventricular dysfunction. We tested a novel intramyocardial bipolar lead to assess whether stimulation of the Atrioventricular Septum (AVS) produces synchronous ventricular activation without crossing the tricuspid valve (TV). Methods: A lead with an active external helix and central pin was placed on the AVS and the RVA in three dogs. High-density electroanatomic (EA) mapping was performed of both ventricles endocardially and epicardially. Intracardiac echocardiography was used to access ventricular synchrony. Results: The lead was successfully deployed into the AVS in all cases with consistent capture of the ventricular myocardium without atrial capture or sensing. The QRS duration was less with AVS compared with RVA pacing (89 ± 4 ms vs. 100 ± 11 ms [P < 0.0001, GEE P = 0.03]). There was decreased delay between color Doppler M-mode visualized peak contraction of the Septum and the mid left ventricular free wall with AVS compared with RVA pacing (89 ± 91 ms vs. 250 ± 11 ms [P < 0.0001, GEE P = 0.006]). Activation time between the mid Septum and mid free wall was shorter with AVS versus RVA pacing (20.4 ± 7.7 vs. 30.8 ± 11.6 [P = 0.01, GEE P = 0.07]). The interval between QRS onset to earliest free wall activation was shorter with AVS vs. RVA pacing (19.2 ± 6.4 ms vs. 31.1 ± 11.7 ms [P = 0.005, GEE P = 0.02]). Conclusion: The AVS was successfully paced in three dogs resulting in synchronous ventricular activation without crossing the TV.

  • Innovation Focus: the Patient with Arrhythmia
    Journal of Cardiovascular Translational Research, 2008
    Co-Authors: Samuel J. Asirvatham
    Abstract:

    Great strides have been made over the last two decades in the management of patients with rhythm disorders. Despite this, however, the remaining critical problems of stroke related to atrial fibrillation or as a result of radiofrequency ablation require innovative solutions to fully realize the potential of these recent advances. Similarly, implanted cardiac devices have revolutionized the care of patients with bradyrhythmias and tachyarrhythmias. Dyssynchronus ventricular pacing associated with present devices; however, results in heart failure, tricuspid regurgitation, and inappropriate device therapy once again create a demand for creative solutions. While not technically an arrhythmia, epilepsy management today is riddled with many of the problems that plagued cardiac arrhythmia management previously, and thus an appreciation of the similarities in requirement for investigative solutions may yield groundbreaking solutions. In this paper, we describe some novel methods to reduce complications associated with rhythm disorders and their treatment and apply the lessons learned from cardiovascular arrhythmia management to the brain. These include: a method to reduce coagulum formation and thus subsequent thromboembolism with indwelling catheters specifically during radiofrequency ablation procedures; a technique to ligate the left atrial appendage through percutaneous subxiphoid pericardial access; development and testing of a novel intramyocardial pace-sense lead, particularly used in a unique anatomic location (the Atrioventricular Septum) to allow pacing the ventricles in a relatively synchronous manner without crossing the tricuspid valve or entering the coronary sinus; finally, novel modifications of the cardiovascular mapping and ablation techniques used for the management of the central nervous system disorders primarily via the venous drainage of the brain. Innovative and potential solutions to treat the patient with arrhythmia are presented.

Shengli Jiang - One of the best experts on this subject based on the ideXlab platform.

  • Inferior Vena Cava Filter Broken and Migrated to Left Ventricle With Destruction of Mitral Valve.
    The Annals of thoracic surgery, 2020
    Co-Authors: Shixiong Wei, Huimin Cui, Zekun Feng, Zhiyun Gong, Bing Liu, Shengli Jiang
    Abstract:

    Inferior vena cava filters are used for patients with pulmonary embolism or those with risk of embolization. Here we present a case of a 38-year-old man who underwent placement of an inferior vena cava filter because of deep vein thrombosis. The operating arm fractured and embolized to the posteromedial papillary muscle of mitral valve and the posterior inferior wall of the left ventricle through right atrium and Atrioventricular Septum, leading to large symptomatic mitral and tricuspid insufficiency and pericardial tamponade. Here we report a rare case where the filter migrated to the left ventricle and destroyed the mitral valve.

Chwan-jau Luo - One of the best experts on this subject based on the ideXlab platform.

  • Aneurysm of the Atrioventricular Septum between the left ventricle and right atrium without septal defect
    American Heart Journal, 1993
    Co-Authors: Li-jen Lin, Jyh-hong Chen, Yu-jen Yang, Liang-miin Tsai, Chi-ming Kwan, Jeng-kai Teng, Chwan-jau Luo
    Abstract:

    partly separated this layer from the thinned outer muscular wall, which had ruptured at a point close to the left superior pulmonary vein. There was a large hematoma at this site that had presumably not progressed to full-blown tamponade because of the presence of pericardial adhesions. No intracardiac thrombus was evident. The left atria1 dissection was repaired and the Carpentier-Edwards xenograft was excised and was replaced with a 31 mm St. Jude Medical prosthesis (St. Jude Medical, Inc., St. Paul, Minn.). Postoperatively the patient remained extremely ill and she died in cardiogenic shock 36 hours later. Consent for a postmortem examination was refused by her family. Pulmonary edema in patients with mitral valve prostheses is usually caused by thrombotic occlusion of mechanical prostheses,’ ball valve thrombotic occlusion of the mitral anulus, acute degeneration of bioprostheses,2 acute arrhythmias, or poor left ventricular function as a result of associated coronary artery disease or coronary embolism. All these syndromes result in acute elevation of left atria1 pressure. In contrast, left atrial dissection may result in pulmonary edema caused by compression of the pulmonary veins and elevation of pulmonary venous pressure without increased left atria1 pressure. We suggest that this possibility be borne in mind in the differential diagnosis if a patient presenting with pulmonary edema appears to have satisfactory mitral valve function. Transesophageal echocardiography, although not performed in this instance, should be useful in assessing such patients. REFERENCES