Determination of biomechanical properties in guinea pig esophagus by means of high frequency ultrasound and impedance planimetry

J. E. Assentoft, H. Gregersen, W. D. O'brien

Research output: Contribution to journalArticlepeer-review

Abstract

Impedance planimetry and high-frequency ultrasound were used to determine circumferential stress and strain from measurements of luminal cross-sectional area and wall thickness during balloon distension of the guinea pig esophagus in vitro (N = 30). The excised esophagus was mounted on two plastic tubes in an organ bath containing oxygenated calcium-free Krebs-Ringer solution with 10-2 M MgCl2 to abolish smooth muscle contractile activity. One of the plastic tubes was movable in order to stretch the esophagus longitudinally by 15% (elongated state). The impedance planimetry probe was placed with the balloon inside the lumen of the esophagus. A 20-MHz ultrasound transducer was mounted above the esophagus and provided scans in the transverse and longitudinal directions. The luminal cross-sectional area at the highest applied pressure of 2.9 kPa was 13.3 ± 0.3 mm2 in the resting state. In the elongated state the luminal cross-sectional area at the highest pressure was 12.5 ± 0.1 mm2 (P < 0.02). The wall thickness decreased from 990 ± 21 μm at 0 kPa to 640 ± 9 μm at 2.9 kPa at in vitro length. In the elongated state, the values were 940 ± 32 μm to 480 ± 13 μm (P < 0.01). The stress-strain relation was exponential (σ = α(e(βε) - 1), r2 > 0.98, P < 0.01). The circumferential elastic modulus calculated at a Green strain of 0.95 was 44.5 ± 10.5 kPa in the in vitro state and 81.7 ± 13.1 kPa in the elongated state. The elastic modulus differed between the resting and elongated states (P < 0.02).

Original languageEnglish (US)
Pages (from-to)1260-1266
Number of pages7
JournalDigestive Diseases and Sciences
Volume45
Issue number7
DOIs
StatePublished - 2000

Keywords

  • Biomechanical properties
  • Esophagus
  • Impedance planimetry
  • Ultrasound

ASJC Scopus subject areas

  • Physiology
  • Gastroenterology

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