Elastic properties of the ascending aorta in patients with α1-antitrypsin deficiency (Z homozygotes)

Objective and design α1-Antitrypsin deficiency (AATD) is a genetic disorder that may be a pathogenic factor in vascular aneurysms and dissection. The aim of this study was to measure the diameters of the Valsalva sinuses (VS), sinotubular junction (STJ), ascending aorta (AA) and aortic arch (AAr) and elastic properties of the AA (distensibility, stiffness and tissue Doppler imaging (TDI strain)) in AATD subjects.

Patients 33 AATD subjects (all Z-homozygous, 17 male, 16 female) were examined. Aortic elastic properties, namely, distensibility and stiffness index, were calculated from the echocardiographically-derived thoracic aortic diameters and TDI strain was measured on the wall of the AA 3 cm above the aortic valve. The results were compared with those obtained in healthy controls matched for age, sex and body mass index.

Results AATD subjects had larger aortic diameters (VS: 3.5±0.5 vs 3.2±0.5 cm, p<0.05; STJ 2.7±0.4 vs 2.4±0.4 cm, p<0.01; AA 3.3±0.5 vs 2.9±0.4 cm, p<0.01; AAr 2.3±0.3 vs 2.1±0.3 cm, p=0.05); greater aortic stiffness 14.9±11.9 versus 7.4±4.4 (pure numbers, p<0.005); and less aortic distensibility 2.4±1.8 versus 4.0±2.6 10⁻⁶×cm²×dyne⁻¹, p<0.005. Peak systolic (S) and diastolic (E and A) waves of the aortic wall TDI were similar in patients and controls (S wave: 5.4±1.6 vs 5.9± 2.3 cm/s; E wave: −4.8±2.2 vs −4.5±2.2 cm/s; A wave: −6.1±2.2 vs −6.2±2.4 cm/s) while TDI strain of the aortic wall was lesser in patients than controls (−14.7±8.0% vs −28.3±7.1%, p<0.001).

Conclusions AATD subjects have a larger AA with abnormal elastic properties as compared to controls. The increase in stiffness, decrease in distensibility and abnormal strain of the aortic wall may all reflect pathological changes in its elastic tissue.