Age-dependent ascending aorta mechanics assessed through multiphase CT.

Area of Science:

• Cardiovascular Imaging and Mechanics
• Biomedical Engineering
• Gerontology

Background:

• Ascending aorta (AA) mechanical properties are crucial for cardiovascular health.
• Age-related changes in AA mechanics can predispose individuals to serious conditions like aneurysm and dissection.
• Understanding these age-specific changes is vital for early detection and intervention.

Purpose of the Study:

• To quantify age- and gender-specific in vivo mechanical characteristics of the ascending aorta (AA).
• To assess age-dependent changes in AA geometry, strain, and wall tension.
• To identify mechanical abnormalities beyond normal aging processes.

Main Methods:

• Reconstruction of 3D AA geometry from multiphase clinical CT scans of 45 male patients (ages 30-79).
• Measurement of AA circumference across 9-10 cardiac phases to determine diameter, strain, and wall tension.
• Calculation of the pressure-strain modulus for each patient.

Main Results:

• Older patients (69.0 ± 5.2 years) exhibited significantly larger mean diastolic AA diameters (33.2 ± 3.2 mm) compared to younger patients (42.6 ± 5.2 years; 29.9 ± 2.8 mm).
• Circumferential AA strain decreased with age (0.092 ± 0.03 in young vs. 0.056 ± 0.03 in old).
• The pressure-strain modulus doubled in older patients (162.0 ± 93.5 kPa) versus younger patients (68.4 ± 30.5 kPa), and systolic wall tension increased (304.9 ± 49.2 kPa in old vs. 268.5 ± 31.3 kPa in young).

Conclusions:

• The ascending aorta dilates and stiffens with advancing age.
• Increased AA wall tension in older individuals likely elevates the risk of aortic aneurysm and dissection.
• Quantifying these age-related mechanical changes aids in identifying pathological conditions.