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

  • similarities and differences in the arrangement of the Atrioventricular Conduction axis in the canine compared to the human heart
    Heart Rhythm, 2021
    Co-Authors: Marcos C De Almeida, J A Cabrera, Yolanda Macias, Damian Sanchezquintana, Justin T Tretter, Diane E Spicer, Robert H Anderson
    Abstract:

    Background Subtle differences exist between dog and human, despite use of the dog as a model for cardiac surgical and electrophysiological research. Objective The purpose of this study was to investigate the differences in the Atrioventricular Conduction axis and adjacent structures between dogs and humans. Methods We prepared 33 human and 5 canine hearts for serial histologic sections of the Atrioventricular Conduction axis, making correlations with gross anatomic findings. We additionally examined and photographed 15 intact normal human hearts obtained from infants undergoing autopsy. Furthermore, we interrogated a computed tomographic dataset from a human adolescent and from 2 autopsied canine hearts, both with normal cardiac anatomy. Results All canine hearts lacked an inferoseptal recess, with the noncoronary leaflet of the aortic valve and the right fibrous trigone having direct attachments to the septal surface of the left ventricular outflow tract. This correlated with an extensive nonbranching component of the ventricular Conduction axis, which skirted half of the noncoronary aortic sinus. This anatomic arrangement was observed in 2 of 15 of autopsied infant hearts. In the human hearts with an inferoseptal recess, the relatively shorter nonbranching bundle is embedded within the fibrous tissue forming its right wall. Conclusion We found a major difference between canine and the majority of human hearts, namely, the presence or absence of an inferoseptal recess. When this recess is absent, as in the canine heart and in some human hearts, a greater proportion of the Atrioventricular Conduction axis is found within the circumference of the subaortic outflow tract.

  • variable arrangement of the Atrioventricular Conduction axis within the triangle of koch implications for permanent his bundle pacing
    JACC: Clinical Electrophysiology, 2020
    Co-Authors: J A Cabrera, Robert H Anderson, Yolanda Macias, J Nevadomedina, Andreu Portasanchez, Jose Manuel Rubio, Damian Sanchezquintana
    Abstract:

    Abstract Objectives This study sought to describe, in detail, the angiographic, gross macroscopy, and histological dissection of the Conduction axis in humans. Background The recent upsurge of interest in specific pacing of the Atrioventricular Conduction axis has emphasized the need for precise knowledge of the location of the atrial and penetrating components of the Atrioventricular Conduction axis. Methods A total of 41 human hearts were studied by serial histological sectioning and an additional 3 hearts by gross dissection. One of the hearts studied histologically was also dissected to show the location of the Conduction axis prior to serial sectioning. The anatomical findings were then compared with the results of angiography undertaken in the catheter laboratory in 60 patients undergoing electrophysiological studies. Results Marked variation of the location of the transition from Atrioventricular Conduction axis to the penetrating Atrioventricular bundle, or the bundle of His, relative to the landmarks of the triangle of Koch was observed. In just over one-half of both the specimens and the patients, the site of penetration was on the atrial aspect of the hinge of the septal leaflet of the tricuspid valve, with further variation noted relative to the apex of the triangle of Koch. Based on measurements of the histological sections, marked variation in the dimensions of the axis and its adjacency to the right-sided endocardium were also found. In almost three-fifths of hearts, an interventricular component of the fibrous membranous septum was not able to be identified. The significance of these findings to those who seek to perform selective pacing of the Atrioventricular Conduction axis are discussed. Conclusions Marked variability of the location of the Conduction axis within the triangle of Koch is reported. In three-fifths of hearts, the interventricular component of the fibrous membranous septum is nonexistent.

  • the ox Atrioventricular Conduction axis compared to human in relation to the original investigation of sunao tawara
    Clinical Anatomy, 2020
    Co-Authors: Marcos C De Almeida, Damian Sanchezquintana, Nelson Davis, Friedwilde R Charles, Alfred Chikweto, Wayne Sylvester, Marios Loukas, Robert H Anderson
    Abstract:

    It was Sunao Tawara who, in 1906, established the foundations for knowledge of the arrangement of the Atrioventricular Conduction axis in man and other mammals. Study of the hearts of ungulates was a central part in his investigation, which assessed other species, including man. He described several subtle differences between the mammals. We have now ourselves studied the cardiac Conduction tissue of the ox heart, comparing our findings with our knowledge of the arrangement in man, and providing new insights into the differences illustrated by Tawara. It is, perhaps, surprising that these differences, although subtle, have not attracted more attention. We show that the major difference is the fact that the noncoronary aortic sinus in the ox heart is mainly supported by the myocardium of the ventricular septum, whereas in the human heart the sinus, and its leaflet, are in fibrous contiguity with the aortic leaflet of the mitral valve. It is this feature that determines the difference in the arrangement of the Conduction axis between the species. We also show that the emergence of the left bundle branch on the left ventricular aspect of the muscular septum is more variable than previously described. Clin. Anat. 33:383-393, 2020. © 2019 Wiley Periodicals, Inc.

  • visualization and quantification of the Atrioventricular Conduction axis in hearts with ventricular septal defect using phase contrast computed tomography
    The Journal of Thoracic and Cardiovascular Surgery, 2020
    Co-Authors: Shuichi Yoshitake, Robert H Anderson, Yukihiro Kaneko, Kiyozo Morita, Masato Hoshino, Yoshihiro Oshima, Masashi Takahashi, Shuichi Oshitake, Hiroyuki Morishita, Gen Shinohara
    Abstract:

    Abstract Objective To visualize and quantify the Atrioventricular Conduction axis in the setting of ventricular septal defect using phase contrast computed tomography. Methods We used the SPring-8 synchrotron radiation facility in Hyogo prefecture in Japan, processing and reconstructing the data with 3-dimensional software. Results We studied 8 hearts obtained from patients known to have had ventricular septal defects, aged from 6 to 150 days, with a median of 24.5 days. None of the individuals, however, had undergone corrective surgery. The penetrating bundle was found at a median of 1.43 mm from the septal crest, with a range of 0.99 to 1.54 mm. The distance to the nonbranching bundle to the right ventricular endocardium was 1.10 mm, with a range from 0.49 to 2.49 mm, to the origin of the left bundle branch was 2.46 mm, with a range from 1.7 to 3.18 mm, and to the origin of the right bundle branch was 2.34 mm, with a range from 0.50 to 2.59 mm. The median distance from the edge of the caudal limb of the septomarginal trabeculation to the right bundle branch was 1.04 mm, with a range from 0.81 to 1.16 mm. Conclusions We were able to show the precise location of the axis, with our findings suggesting that longitudinal sutures placed along the posteroinferior rim should be effective in avoiding iatrogenic injury, but sutures should not be placed in the valley between the limbs of the septomarginal trabeculation.

  • the anatomy development and evolution of the Atrioventricular Conduction axis
    Journal of Cardiovascular Development and Disease, 2018
    Co-Authors: Robert H Anderson, Damian Sanchezquintana, Diane E Spicer, Shumpei Mori, Bjarke Jensen
    Abstract:

    It is now well over 100 years since Sunao Tawara clarified the location of the axis of the specialised myocardium responsible for producing coordinated ventricular activation. Prior to that stellar publication, controversies had raged as to how many bundles crossed the place of the Atrioventricular insulation as found in mammalian hearts, as well as the very existence of the bundle initially described by Wilhelm His Junior. It is, perhaps surprising that controversies continue, despite the multiple investigations that have taken place since the publication of Tawara's monograph. For example, we are still unsure as to the precise substrates for the so-called slow and fast pathways into the Atrioventricular node. Much has been done, nonetheless, to characterise the molecular make-up of the specialised pathways, and to clarify their mechanisms of development. Of this work itself, a significant part has emanated from the laboratory coordinated for a quarter of a century by Antoon FM Moorman. In this review, which joins the others in recognising the value of his contributions and collaborations, we review our current understanding of the anatomy, development, and evolution of the Atrioventricular Conduction axis.

M Peter D Wenaweser - One of the best experts on this subject based on the ideXlab platform.

Kenichi Sugimoto - One of the best experts on this subject based on the ideXlab platform.

Stephan Windecker - One of the best experts on this subject based on the ideXlab platform.

  • the conundrum of permanent pacemaker implantation after transcatheter aortic valve implantation
    Circulation-cardiovascular Interventions, 2017
    Co-Authors: Anna Franzone, Stephan Windecker
    Abstract:

    Transcatheter aortic valve implantation (TAVI) has matured into the preferred treatment modality for patients with severe aortic stenosis at extreme or high risk for conventional surgery and a valuable alternative for those at intermediate risk in view of similar or superior clinical outcomes and decreased rates of periprocedural adverse events.1–3 In this context, it remains unclear whether other procedure-related events—including Atrioventricular Conduction disturbances that require permanent pacemaker (PPM) implantation—are of prognostic relevance. See Article by Mohananey et al In the natural history of aortic stenosis, variable degrees of heart block may occur with calcium deposits expanding progressively from the left ventricular outflow tract to the Atrioventricular Conduction system. As matter of fact, a PPM is already present in ≈10% to ≈20% of patients with severe aortic stenosis at the time of transcatheter or surgical intervention.4 Because of its proximity to the aortic root, iatrogenic injury to the Atrioventricular Conduction system also occurs after surgical bioprosthesis implantation, with comparable PPM rates for TAVI and surgery reported in the PARTNER trials (Placement of Aortic Transcatheter Valves).2,5 Several patient- and procedure-related factors have been associated with PPM implantation after TAVI and include advanced age, male gender, atrial fibrillation, calcification of aortic and mitral annulus, small left ventricular outflow tract, pre-procedural or intraprocedural Conduction disorders, balloon pre-dilation, and depth of prosthesis implantation.6,7 In addition, the type of transcatheter bioprosthesis plays an important role with rates of PPM implantation progressively increasing from balloon-expandable prostheses over self-expanding prostheses to mechanically deployed prostheses.8 Along this line, outer skirts and adaptive seals surrounding the inflow portion, designed to reduce paravalvular leaks, as well as features that allow for repositionability of the device within the aortic annulus, may modify the risk of Atrioventricular Conduction disturbances after TAVI. Despite …

Michael J Silka - One of the best experts on this subject based on the ideXlab platform.

  • late recovery of Atrioventricular Conduction after pacemaker implantation for complete heart block associated with surgery for congenital heart disease
    The Journal of Thoracic and Cardiovascular Surgery, 2003
    Co-Authors: Anjan S Batra, Winfield J Wells, Kathy W Hinoki, Robert Stanton, Michael J Silka
    Abstract:

    Abstract Objectives Pacemaker implantation is a standard recommendation for patients with persistent complete heart block following surgery for congenital heart disease. This study was performed to determine the incidence and clinical significance of late recovery of Atrioventricular Conduction following pacemaker implantation. Methods Between 1990 and 2001, 5662 open cardiac procedures for congenital heart defects were performed at our institution. The postoperative course of all patients with complete heart block in whom a permanent pacemaker was implanted was followed on a monthly basis, by either clinical or transtelephonic follow-up. Results A total of 72 patients with persistent postoperative complete heart block underwent pacemaker implantation. After insertion of the pacemaker, recovery of Atrioventricular Conduction was recognized in 7 of 72 patients (9.6%) at a median of 41 days (18-113 days) after the initial cardiac operation. These included 3 patients with ventricular septal defect, 2 with ventricular inversion or single ventricle, and 1 each with left ventricular outflow tract obstruction and Atrioventricular septal defect. During a mean follow-up of 4.4 ± 2.6 years, there was no late recurrence of heart block. Three patients had residual right bundle branch block and 1 had first-degree Atrioventricular block. Conclusions Atrioventricular Conduction may return in a small but significant percentage of patients following pacemaker implantation for complete heart block associated with congenital heart surgery. When recovery of Atrioventricular Conduction occurs within the first months after surgery it appears reliable, which suggests that lifelong cardiac pacing may not be necessary in these individuals. 20,24