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The architecture of the left ventricular myocytes relative to left ventricular systolic function


Dorri, Farshad; Niederer, Peter F; Lunkenheimer, Paul P; Anderson, Robert H (2009). The architecture of the left ventricular myocytes relative to left ventricular systolic function. European Journal of Cardio-Thoracic Surgery, 37(2):384-392.

Abstract

Objective: Mural thickening, combined with longitudinal and circumferential shortening, and apical along with basal twisting are critical components of the left ventricular systolic deformation that contribute to ventricular ejection. It is axiomatic that the spatial alignment of the actively contracting aggregates of myocytes must play a major role in the resulting ventricular deformation. The need to conserve functional global myocytic architecture, therefore, is an important aspect of the surgical manoeuvres affecting ventricular mass and geometry. To investigate the influence of the global alignment of the myocytes on ventricular contraction, we used a mathematical model simulating the large deformations produced by systolic contraction of the left ventricle of a human heart. Methods: The alignment and meshing of the myocytes within their supporting fibrous matrix cause mechanical anisotropy, which was included in the mathematical model in the form of a unit vector field, constructed from the measured trajectories of aggregated myocytes in an autopsied human heart. The relationship between ventricular structure and ventricular dynamics was assessed by analysing the influence of systematic deviations of the orientation of the myocytes from their original alignment, in longitudinal as well as radial directions, on the distribution of stress and strain within the myocardium, as well as on the ejection fraction. In addition, simplified idealised geometries were used to investigate the influence of the overall geometrical modifications. Results: Left ventricular function proved to be robust with respect to small-to-moderate rotational variations in myocytic alignment, up to 14°, a finding which we attribute to an equalising effect of the non-uniform anisotropic pattern found in a real heart involving substantial local irregularities in the architecture of the aggregated myocytes. Severe deterioration of function occurred only when deviations in alignment exceeded 30°. Conclusions: Our findings substantiate the concept of the myocardial walls representing a continuous three-dimensional meshwork, with the absence of any intermediate structures such as discrete bands or tracts extending over the ventricles, which could be destroyed surgically, thereby adversely affecting systolic function. With appropriate indications, they also support the validity of the surgical procedures performed to reduce ventricular radius and therefore to reduce mural stress

Abstract

Objective: Mural thickening, combined with longitudinal and circumferential shortening, and apical along with basal twisting are critical components of the left ventricular systolic deformation that contribute to ventricular ejection. It is axiomatic that the spatial alignment of the actively contracting aggregates of myocytes must play a major role in the resulting ventricular deformation. The need to conserve functional global myocytic architecture, therefore, is an important aspect of the surgical manoeuvres affecting ventricular mass and geometry. To investigate the influence of the global alignment of the myocytes on ventricular contraction, we used a mathematical model simulating the large deformations produced by systolic contraction of the left ventricle of a human heart. Methods: The alignment and meshing of the myocytes within their supporting fibrous matrix cause mechanical anisotropy, which was included in the mathematical model in the form of a unit vector field, constructed from the measured trajectories of aggregated myocytes in an autopsied human heart. The relationship between ventricular structure and ventricular dynamics was assessed by analysing the influence of systematic deviations of the orientation of the myocytes from their original alignment, in longitudinal as well as radial directions, on the distribution of stress and strain within the myocardium, as well as on the ejection fraction. In addition, simplified idealised geometries were used to investigate the influence of the overall geometrical modifications. Results: Left ventricular function proved to be robust with respect to small-to-moderate rotational variations in myocytic alignment, up to 14°, a finding which we attribute to an equalising effect of the non-uniform anisotropic pattern found in a real heart involving substantial local irregularities in the architecture of the aggregated myocytes. Severe deterioration of function occurred only when deviations in alignment exceeded 30°. Conclusions: Our findings substantiate the concept of the myocardial walls representing a continuous three-dimensional meshwork, with the absence of any intermediate structures such as discrete bands or tracts extending over the ventricles, which could be destroyed surgically, thereby adversely affecting systolic function. With appropriate indications, they also support the validity of the surgical procedures performed to reduce ventricular radius and therefore to reduce mural stress

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Item Type:Journal Article, refereed, original work
Communities & Collections:National licences > 142-005
Dewey Decimal Classification:610 Medicine & health
Scopus Subject Areas:Health Sciences > Surgery
Health Sciences > Pulmonary and Respiratory Medicine
Health Sciences > Cardiology and Cardiovascular Medicine
Language:English
Date:29 August 2009
Deposited On:24 Oct 2018 14:51
Last Modified:31 Jul 2020 02:06
Publisher:Oxford University Press
ISSN:1010-7940
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.ejcts.2009.07.010
Related URLs:https://www.swissbib.ch/Search/Results?lookfor=nationallicenceoxford101016jejcts200907010 (Library Catalogue)
PubMed ID:19717306

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