Trends in Hospital Admissions, Operative Approaches, and Mortality Related to Abdominal Aortic Aneurysms in England Between 1998 and 2020

Strain Patterns With Ultrasound for Assessment of Abdominal Aortic Aneurysm Vessel Wall Biomechanics

BACKGROUND

Abdominal aortic aneurysms (AAAs) are an important cause of death. Small AAAs are surveyed with ultrasound (US) until a defined diameter threshold, often triggering a computer tomography scan and surgical repair. Nevertheless, 5%-10% of AAA ruptures are below threshold, and some large AAAs never rupture. AAA wall biomechanics may reveal vessel wall degradation with potential for patient-centred risk assessment. This clinical study investigated AAA vessel wall biomechanics and deformation patterns, including reproducibility.

METHODS

In 50 patients with AAA, 183 video clips were recorded by two sonographers. Prototype software extracted AAA vessel wall principal strain characteristics and patterns. Functional principal component analysis (FPCA) derived strain pattern statistics.

RESULTS

Strain patterns demonstrated reduced AAA wall strains close to the spine. The strain pattern "topography" (i.e., curve phases or "peaks" and "valleys") had a 3.9 times lower variance than simple numeric assessment of strain amplitudes, which allowed for clustering in two groups with FPCA. A high mean reproducibility of these clusters of 87.6% was found. Median pulse pressure-normalised mean principal strain (PPPS) was 0.038%/mm Hg (interquartile range: 0.029-0.051%/mm Hg) with no correlation to AAA size (Spearman's ρ = 0.02, false discovery rate-p = 0.15). Inter-operator reproducibility of PPPS was poor (limits of agreement: ±0.031%/mm Hg).

DISCUSSION

Strain patterns challenge previous numeric stiffness measures based on anterior-posterior-diameter and are reproducible for clustering. This study's PPPS aligned with prior findings, although clinical reproducibility was poor. In contrast, US-based strain patterns hold promising potential to enhance AAA risk assessment beyond traditional diameter-based metrics.

Anatomy of the aortic segmental arteries-the fundamentals of preventing spinal cord ischemia in aortic aneurysm repair

Objective

Spinal cord ischemia due to damage or occlusion of the orifices of aortic segmental arteries (ASA) is a serious complication of open and endovascular aortic repair. Our study aims to provide detailed descriptions of the proximal course of the ASAs and metric information on their origins.

Materials and methods

Initially, 200 randomly selected, embalmed cadavers of human body donors were anatomically dissected and systematically examined. On macroscopic inspection, 47 showed severe pathologies and were excluded. Of the remaining 153, 73 were males and 80 females.

Results

In total, 69.9% of the aortae showed 26-28 ASA orifices. In 59.5% the most proximal ASA, at least unilaterally, was the third posterior intercostal artery, which originated from the descending aorta at approximately 10% of its length. In 56.2%, the left and right ASAs had a common origin in at least one body segment. This mainly affected the abdominal aorta and L4 in particular (54.2%). The ASAs of lumber segments 1-3 originated strictly segmentally. In contrast, in 80.4%, at least one posterior intercostal artery originated from a cranially or caudally located ipsilateral ASA. Such an arrangement was seen along the entire thoracic aorta. Further descriptions of variants and metric data on ASA orifices are presented.

Conclusion

Our large-scale study presents a detailed topographic map of ASAs. It underscores the value of preoperative CT councils and provides crucial information for interpreting the results. Furthermore, it aids in planning and conducting safe aortic intervention and assists in deciding on single- or two-staged stent graft procedures.