Article
Experimental model of acute aortic rupture with porcine aortas
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Published: | April 26, 2013 |
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Introduction: Few is known about the pressure leading to rupture of normal aortic tissue. The aim of our study was to evaluate maximum pressures causing acute aortic ruptures and correlate these results with mechanical properties of the aortic wall using ex-vivo porcine aortic specimens.
Material and methods: Fresh porcine descending aortic specimens with a branchless length exceeding more than 35mm were included in our study. Characteristics as length, proximal and distal diameter and aortic thickness were gained. The specimens were filled with water, increasing the pressure continuously until rupture of the vessel occurred. The pressure curves were monitored and changes in length and diameter were recorded. Afterwards aortic stripes were created out of the ruptured specimens and a stress-strain-test was performed.
Results: A total of 51 experiments were performed. The mean rupture pressure was 1652±248 mmHg. We observed 37 transverse, 12 oblique and 2 longitudinal ruptures. Dissections occurred in 12 cases. The stress-strain-test revealed a 17.8% higher mean rupture pressure in the transverse stripes and 55.6% in the oblique stripes (2145±568 mmHg and 3763±643 mmHg) compared to the water experiment.
Conclusion: In contrast to recent calculated data we observed lower mean maximal pressures leading to acute aortic ruptures (1652 vs. 2500 mmHg). The descending aortas ruptured more often transversely than longitudinally. This observation may be explained by different anisotropic properties of the aortic tissue. Dissections occurred in 12 cases, being comparable to those observed in clinics and may be explained by different elasticity of aortic wall layers, leading to higher wall stress of the intima during distension. The unidirectional strip-strain-tests revealed higher rupture pressures than the water experiment and substantially overestimated the actual rupture pressure of aortic tissue. Our findings may serve as a basis for a broader understanding of aortic pathologies and lead to reconsideration of the validity of aortic strain-stress-tests.