Time-dependent mechanical behaviour of the aortic chronic dissection flap

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Tissue Mechanics

Background:

• The transition from acute to chronic aortic dissection is not well understood.
• Chronic dissection tissues exhibit altered mechanical and biochemical properties.

Purpose of the Study:

• To investigate the time-dependent mechanical behavior and biochemical properties of chronic aortic dissection tissues.
• To compare the characteristics of the false lumen (FL), true lumen (TL), and flap (FP) tissues.

Main Methods:

• Aortic samples from 14 patients with chronic dissected aneurysms (3 months to 15 years post-dissection) were analyzed.
• Tissue elastic modulus and deformation were measured using a custom-indentation technique.
• Collagen, elastin, and glycosaminoglycan levels were quantified, and elastin fragmentation was graded histologically.

Main Results:

• The flap (FP) tissue was stiffer and exhibited less deformation than TL and FL tissues.
• FP tissue had lower collagen concentration and a lower collagen:elastin ratio compared to TL and FL.
• Significant elastin loss was observed in FL tissues, while FP and TL tissues showed aligned collagen fibers.

Conclusions:

• The aortic dissection flap (FP) displays unique mechanical and biochemical properties compared to TL and FL tissues.
• These distinct characteristics of FP are consistent across different connective tissue disorders and anatomical locations.