Dimensions and mechanical properties of porcine aortic segments determined by combined impedance planimetry and high-frequency ultrasound

Storkholm, Jan Henrik; Villadsen, Gerda Elisabeth; Krogh, Klaus; Jørgensen, Claus; Gregersen, Hans

doi:10.1007/bf02510387

Cited by 9 publications

(5 citation statements)

References 24 publications

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“…The accuracy of the ultrasound measurements also has to be considered. Regarding the latter, measurements using high-frequency ultrasound correlated well with histologic measures of wall thickness in the intestinal wall [23]. The ultrasound equipment used in this work was found to agree with wall thickness measurements based on histology and density [14,24].…”

Section: Methodsmentioning

confidence: 62%

“…A-mode ultrasound technique is a 1-dimensional type of pulsed ultrasound in which the processed signal shows the time history of a sound wave impulse along a particular path. The sound velocity was set at 1540 m/s −1 , which is the average sound velocity in soft tissues [23]. The transducer had a center frequency of 20 MHz, a focal distance of 20 mm, a beam width of 0.24 mm, and a maximum tissue penetration range of 13.1 mm.…”

Section: Methodsmentioning

confidence: 99%

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Biomechanical Remodeling of the Chronically Obstructed Guinea Pig Small Intestine

et al. 2007

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Small intestinal obstruction is a frequently encountered clinical problem. To understand the mechanisms behind obstruction and the clinical consequences, data are needed on the relation between the morphologic and biomechanical remodeling that takes place in the intestinal wall during chronic obstruction. We sought to determine the effect of partial obstruction on mechanical and morphologic properties of the guinea pig small intestine. Partial obstruction was created surgically in 2 groups of animals living for 2 and 4 weeks. Controls were sham operated and lived for 4 weeks. A combined impedance planimetry-high-frequency ultrasound system was designed to measure the luminal cross-sectional area and wall thickness. These measures were used to compute the circumferential stress and strain of the excised intestinal segments. The incremental elastic modulus was obtained by using nonlinear fitting of the stress-strain curve. Histologic analysis and the measurements of total wall collagen were also performed. The luminal cross-sectional area, wall thickness, and elastic modulus in circumferential direction increased in a time-dependent manner proximal to the obstruction site (P < 0.01), whereas no differences in these parameters were found distal to the obstruction site (P > 0.25). The circumferential stress-strain curves of the proximal segments in 2- and 4-week groups shifted to the left, indicating the intestinal wall became stiffer. Histologic examination revealed a massive increase in the thickness of the muscle layer especially the circular smooth muscle layer (P < 0.05). The collagen content proximal to the obstruction site was significantly larger in the partially obstructed animals compared to controls (P < 0.05). No difference was found distal to the obstruction site. Strong correlation was found between the collagen content and the elastic modulus at stress levels of 70 kPa stress (P < 0.01) and 10 kPa (P < 0.05) proximal to the obstruction site suggesting that the alteration of collagen has great impact on the mechanical remodeling. The morphologic and biomechanical remodeling likely influence the function of the intestine affected by partial obstructed intestine.

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Section: Methodsmentioning

confidence: 62%

Section: Methodsmentioning

confidence: 99%

Biomechanical Remodeling of the Chronically Obstructed Guinea Pig Small Intestine

et al. 2007

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“…For example, Storkholm et al (1997) found an incremental elastic modulus of 110 kPa at a strain of 15% for pig thoracic aortas. The incremental elastic modulus of human ascending aorta at a strain of 15% was determined by Okamoto et al (2002) and reached 45 kPa.…”

Section: Discussionmentioning

confidence: 97%

Characterization of fracture toughness exhaustion in pig aorta

Chu

Gaillard

Mongrain

et al. 2013

Journal of the Mechanical Behavior of Biomedical Materials

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“…The data were sampled at a frequency of 20 Hz and were amplified, analog-to-digital (A/D) converted, and stored on a personal computer (PC) for later analysis. The dynamic characteristics of the pressure recording system were evaluated using a test chamber [18,19], and it was characterized as an overdamped second-order system. The damping ratio was 0.71 and the undamped resonant frequency was 4.5 Hz.…”

Section: Pressure Recordingsmentioning

confidence: 99%

Spontaneous and Bolus-induced Motility in the Chronically Obstructed Guinea-Pig Small Intestine In vitro

2007

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Partial obstruction of the small intestine results in dysmotility and morphometric changes proximal to the site of obstruction. However, our understanding of the relation between the morphometric remodeling and change in the motility pattern during chronic obstruction is sparse. The aim of this study was to investigate the effect of partial chronic intestinal obstruction on motility, morphology, and collagen content proximal and distal to the site of obstruction. Twenty guinea-pigs with partial intestinal obstruction and eight sham-operated controls lived for four weeks. Spontaneous and bolus-induced motility was recorded in isolated intestinal segments proximal and distal to the site of obstruction using a perfused low-compliance pressure-measuring system in vitro. After the motility experiments, the specimens were fixed at 2 kPa luminal distension pressure and sampled for histomorphometric determination of luminal radius, layer thickness, and wall thickness. Total wall collagen was also determined. The area under the curve (AUC) of spontaneous contractions and the amplitude, frequency, and AUC for the bolus-induced motility were higher in the proximal segments of the banded animals compared to distal segments and to the intestinal segments in the control animals (P < 0.05). The radius-to-thickness ratio was lowest in the proximal segments of the obstructed animals (P < 0.01). The collagen content was three times higher proximal to the site of obstruction when compared to distal locations and to the controls (P < 0.01). The AUC at 2 ml bolus injections plotted against the radius-to-thickness ratio showed a strong association (r = 0.97 for control, and r = 0.99 for obstruction, P < 0.01). No correlation was found between the collagen content and AUC. In conclusion, partial intestinal obstruction in guinea pigs caused pronounced changes in morphology and motility. An association was found between the radius-to-thickness ratio and bolus-induced motility.

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Dimensions and mechanical properties of porcine aortic segments determined by combined impedance planimetry and high-frequency ultrasound

Cited by 9 publications

References 24 publications

Biomechanical Remodeling of the Chronically Obstructed Guinea Pig Small Intestine

Biomechanical Remodeling of the Chronically Obstructed Guinea Pig Small Intestine

Characterization of fracture toughness exhaustion in pig aorta

Spontaneous and Bolus-induced Motility in the Chronically Obstructed Guinea-Pig Small Intestine In vitro

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