Mechanical behavior of the porcine coronary artery
Citation for published version (APA):Broek, van den, C. N., Rutten, M. C. M., & Vosse, van de, F. N. (2008). Mechanical behavior of the porcine coronary artery. In Biomechanics in vascular disease (pp. 1-).
Document status and date: Published: 01/01/2008 Document Version:
Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:
• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.
• The final author version and the galley proof are versions of the publication after peer review.
• The final published version features the final layout of the paper including the volume, issue and page numbers.
Link to publication
General rights
Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain
• You may freely distribute the URL identifying the publication in the public portal.
If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement:
www.tue.nl/taverne Take down policy
If you believe that this document breaches copyright please contact us at: openaccess@tue.nl
providing details and we will investigate your claim.
Mechanical behavior of the porcine coronary artery
Chantal N. van den Broek, Marcel C.M. Rutten, Frans N. van de Vosse
Biomedical Engineering: Cardiovascular Biomechanics, Eindhoven University of Technology, The Netherlands Introduction
Knowledge of mechanical properties of living arteries is important to understand vascular function in arterial pathologies and different treatments. We have developed an ex vivo model in which a porcine coronary artery can be kept at physiological circumstances, while enabling measurement of its mechanical behavior. Arterial mechanical behavior was determined for segments of the porcine left anterior descending coronary artery (LAD) during dynamic loading at different axial strains. Also, the physiological axial strain of the LAD was determined, based on the hypothesis that the in vivo axial strain of an artery is the strain at which the axial force is relatively insensitive to changes in pressure1.
Methods
Figure 1: Definition of different segment lengths for which P-D & P-Fax behavior were determined.
An approximately 4 cm proximal segment of a porcine LAD was excised, fixed in the ex vivo model, immersed in a Krebs solution with 10-4 M papaverin and kept at 38.5 °C. The segment was loaded with a pulsatile pressure varying from 0-120 mmHg max. Pressure-diameter and pressure-axial force (P-D & P-Fax) behavior was measured twice at lev, lheart, lphys, lmin & lplus (fig. 1) with a pressure and force
sensor and an ultrasound system (ART.LAB, Esaote Europe, NL). lphys was the hypothesized
physiological segment length at which the axial force change during a pressure cycle was minimized.
Results
Mechanical behavior was measured successfully for 8 porcine LAD segments. Successive measurements were reproducible and little hysteresis is present (fig. 2a&b). P-D curves show the typical arterial stiffening behavior at higher pressures and all P-Fax curves show the typical cross-over
point at which the derivative of the Fax-P curve changes from negative to positive. The physiological
axial stretch at this cross-over point (λphys) was 1.38±0.05 (n=12, fig. 2c). The stretch of the segment
when it was still fixed to the heart (λheart) was 1.21±0.03 (n=12, fig. 2c).
Figure 2: Typical example of a) P-D and b) P-Fax behavior of a porcine LAD at different axial stretches (measurement 1&2, solid & dashed line resp.). c) Average axial stretches of the porcine LAD (n=12).
Conclusions
We have succeeded in performing reproducible measurements of the mechanical behavior of the porcine LAD in our ex vivo model. The arterial segments show the expected stiffening behavior and reveal a clear cross-over point with respect to the P-Fax measurements. The stretch at this point was
hypothesized to correspond to the physiological stretch of the segment and was found to be 1.38 on average. The hypothesized physiological axial strain of the LAD will be validated in an isolated beating heart experiment in which a porcine heart is loaded physiologically. The mechanical behavior will be fitted with the model developed by Driessen2 and Holzapfel3, to determine mechanical parameters. 1. Weizsacker, H.W. et al. (1983) J Biomech, 16, p. 703-715.
2. Driessen, N.J.B. et al. (2005) J Biomech Eng, 127, p. 494-503. 3. Holzapfel, G.A. et al. (2000) J Elasticity, 61, p. 1- 48.
ev i i
