Mechanical characterisation of human ascending aorta dissection

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Materials Science

Background:

• Acute type A aortic dissection significantly alters aortic biomechanics.
• Understanding these changes is crucial for diagnosis and treatment.
• Previous studies have not fully characterized the mechanical response of dissected aortic tissue.

Purpose of the Study:

• To investigate the mechanical characteristics of healthy and dissected ascending aorta.
• To correlate in vitro mechanical properties with in vivo measurements and histological findings.
• To provide novel insights into the biomechanics of acute type A aortic dissection.

Main Methods:

• In vitro biaxial tensile testing of aortic tissue samples.
• In vivo measurements using transoesophageal echocardiography.
• Histological characterization of tissue microstructure, including collagen and elastin content.

Main Results:

• Dissected ascending aorta and healthy aorta exhibit nonlinear mechanical behavior, while the dissected intimomedial flap shows linear behavior.
• The healthy ascending aorta is stiffer longitudinally than circumferentially, correlating with fiber density.
• Acute type A aortic dissection leads to increased aortic stiffness, confirmed by both in vitro tests and in vivo stiffness indices (β, Ep).
• Histological analysis shows elastin degradation and increased collagen in dissected tissue.

Conclusions:

• Acute type A aortic dissection stiffens the ascending aorta.
• Mechanical alterations are linked to changes in extracellular matrix composition.
• This study provides the first report of biaxial tensile tests on dissected intimomedial flaps and in vivo stiffness measurements in human acute type A dissection.