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Research Papers

The Effect of Trabeculae Carneae on Left Ventricular Diastolic Compliance: Improvement in Compliance With Trabecular Cutting

[+] Author and Article Information
David L. Halaney, Daniel Escobedo

Department of Medicine,
The University of Texas Health Science
Center at San Antonio,
San Antonio, TX 78229;
Department of Veterans Affairs,
South Texas Veterans Health Care System,
San Antonio, TX 78229

Arnav Sanyal

Department of Mechanical Engineering,
University of Texas at San Antonio,
San Antonio, TX 78249

Navid A. Nafissi, G. Patricia Escobar

Department of Medicine,
The University of Texas Health Science
Center at San Antonio,
San Antonio, TX 78229

Martin Goros, Joel Michalek

Department of Epidemiology and Biostatistics,
The University of Texas Health Science
Center at San Antonio,
San Antonio, TX 78229

Pedro J. Acevedo

Department of Anatomy,
University of Environmental
and Applied Sciences U.D.C.A.,
Bogotá, Cundinamarca, Colombia

William Pérez

Department of Anatomy,
Faculty of Veterinary Medicine,
University of the Republic,
Montevideo 11200, Uruguay

Marc D. Feldman

Department of Medicine,
The University of Texas Health Science
Center at San Antonio,
San Antonio, TX 78229;
Department of Veterans Affairs,
South Texas Veterans Health Care System,
San Antonio, TX 78229
e-mail: feldmanm@uthscsa.edu

Hai-Chao Han

Fellow ASME
Department of Mechanical Engineering,
University of Texas at San Antonio,
San Antonio, TX 78249

1Corresponding author.

Manuscript received May 25, 2016; final manuscript received December 13, 2016; published online January 24, 2017. Assoc. Editor: Thao (Vicky) Nguyen.

J Biomech Eng 139(3), 031012 (Jan 24, 2017) (8 pages) Paper No: BIO-16-1225; doi: 10.1115/1.4035585 History: Received May 25, 2016; Revised December 13, 2016

The role of trabeculae carneae in modulating left ventricular (LV) diastolic compliance remains unclear. The objective of this study was to determine the contribution of trabeculae carneae to the LV diastolic compliance. LV pressure–volume compliance curves were measured in six human heart explants from patients with LV hypertrophy at baseline and following trabecular cutting. The effect of trabecular cutting was also analyzed with finite-element model (FEM) simulations. Our results demonstrated that LV compliance improved after trabecular cutting (p < 0.001). Finite-element simulations further demonstrated that stiffer trabeculae reduce LV compliance further, and that the presence of trabeculae reduced the wall stress in the apex. In conclusion, we demonstrate that integrity of the LV and trabeculae is important to maintain LV stiffness and loss in trabeculae leads to more LV compliance.

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References

Figures

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Fig. 1

Longitudinal cross section of a typical human LV illustrating the trabeculae (examples marked by arrowheads). A chordae tendineae is marked by the arrow.

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Fig. 2

Ex vivo experimental setup for human hearts. (a) A custom cap was attached to the heart above the mitral valve. A latex balloon was inserted through the cap into the LV chamber. The cap included a hemostasis valve to allow a high fidelity micromanometer pressure catheter to be placed within the balloon, and a luer lock for volume input. (b) Measurements of LV compliance were conducted with the heart suspended by the cap inside a custom housing chamber which was surrounded by 37 °C water circulation to mimic in vivo conditions.

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Fig. 3

Three-dimensional sectional view of the computational model of the left ventricle with three layers of trabeculae. All dimensions are in mm. The wall thickness is 13.5 mm at the equator and 5.5 mm at the apex.

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Fig. 4

A comparison of a typical LV wall region before (top panel) and after (bottom panel) trabecular cutting

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Fig. 5

Comparison of pressure–volume relationships of human hearts before and after trabecular cutting. Six human heart (a)–(f) and their average (G) pressure–lumen volume curves before (• = uncut) and after (○ = cut) trabecular cutting. For the average, volume was normalized to the highest volume measured for each heart. R2 values correspond to cubic fits in all panels. For all six cases, trabecular cutting increased the compliance of the left ventricle.

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Fig. 6

The pressure–volume relationship of control hearts without trabecular cutting. (a) Comparison of measurements of repeating saline filling in heart #7. The pressure measurement system remains in the LV during the tests. (b) Comparison of measurements after sham operation in heart #8. The pressure measurement system was removed from the heart after the first measurement, and trabecular cutting was mimicked with a blunt tool, but no trabeculae were cut. The pressure measurement system was then placed back into the heart for the second measurement. R2 values correspond to cubic fits of the pressure–volume data. In both cases, there was no significant change in compliance in the absence of trabecular cutting.

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Fig. 7

Pressure–volume relationship obtained from the FEM simulations of the LV model without trabeculae, with three layers of intact and normal trabeculae, with three layers of intact and stiffer trabeculae, and with one layer of intact and normal trabeculae. These results demonstrate that severing trabeculae increases LV compliance and the presence of stiffer trabeculae decreases LV compliance.

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Fig. 8

Color map of circumferential stress distribution obtained from FEM simulations of LV model during a chamber pressure of 10 mm Hg. The stress was obtained for the cases without trabeculae, with three layers of trabeculae, and with only one apical layer of trabeculae. Each color represents the range of stress shown in the scale.

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