Thoracic Endovascular Aortic Repair: Literature Review With Emphasis on the Role of Multidetector Computed Tomography

Rule of four: an anatomic and value-based approach to stent-graft inventory for blunt thoracic aortic injury

PURPOSE

As blunt thoracic aortic injury (BTAI) treatment has shifted from open to thoracic endovascular aortic repair (TEVAR), logistical challenges exist in creating and maintaining inventories of appropriately sized stent-grafts, including storage demands, shelf-life management and cost. We hypothesized that most injured aortas can be successfully repaired with a narrow range of stent-graft sizes and present a value-based anatomic approach to optimizing inventory.

METHODS

CT-scans of all patients with BTAI admitted to our Level I trauma center from Apr 2010-Dec 2018 were reviewed. Patients with anatomy incompatible with TEVAR were excluded. For each patient, after aortic sizing a set of two stent-grafts most likely to be utilized was selected from a list of twenty commercially available GORE conformable TAG endografts based on manufacturer instructions. Stent-graft sizes were then ranked based on the number of cases they would be suitable for. MATLAB was utilized to determine the combinations of stent-grafts which would cover the most patients.

RESULTS

Twenty-eight patients with BTAI were identified and three were excluded based on iliac diameter. Most patients were male (68%), mean age 42.3 ± 20.2 years, mean ISS 37.0 ± 9.8. Overall mortality was 25%. Of the 20 available stent-graft options, a combination of four stent-grafts would successfully treat 100% of the patients in this series.

CONCLUSIONS

Based on actual CT-scan aortic measurements, we demonstrated that an inventory of four sent-graft sizes was sufficient to treat 100% of patients with BTAI. These data can be utilized as a value-based anatomic approach to aortic stent-graft institutional inventory creation and maintenance.

Thoracic Aortic Strain is Irrelevant Regarding Endograft Sizing in Most Young Patients

BACKGROUND

The introduction of electrocardiogram gating in computed tomography (CT) angiography imaging of aortic disease raised questions whether diameters measured on diastolic images can lead to the undersizing of aortic endografts. As previous studies suggested that young patients may have the highest risk of an unintended undersize, the aim of our study was to analyze the strain of the thoracic aorta in a young patient cohort.

METHODS

We assessed the descending aorta of 52 patients (35 men, mean age 41.1 ± 7.3 years) who underwent coronary CT angiography (CCTA) with suspected coronary artery disease. To reduce radiation dose, native calcium score scans triggered on late systole were compared with diastolic phase CCTA images. Cross-section areas were measured, and effective diameters were derived at 3 levels of the visible segment of the descending aorta (P1, P2, and P3) in systole and diastole. Aortic pulsatility (mm, d_systolic-d_diastolic) and strain (%, [d_systolic-d_diastolic]/d_diastolic) were calculated at each level. All measurements were performed 3 times by 2 independent readers to evaluate interreader and intrareader reproducibility.

RESULTS

A total of 936 measurements were performed. Significant differences were found between systolic and diastolic diameters at each location (all P < 0.001). Average aortic pulsatility was 1.5 ± 0.6 mm at P1, 1.6 ± 0.7 mm at P2, and 1.7 ± 0.7 mm at P3, with a corresponding aortic strain of 6.7 ± 3.1% at P1, 7.4 ± 3.5% at P2, and 8.1 ± 3.6% at P3. The differences between the strain of the measurement levels were not significant (P = 0.344). Aortic strain and pulsatility did not show significant correlation with pulse pressure (P = 0.693), patient age (P = 0.649), or other anamnestic data. Intraclass correlation coefficient was in the range of 0.95-0.96 for interobserver and in the range of 0.95-0.97 for intraobserver analysis.

CONCLUSIONS

This study shows that descending aortic strain can be measured precisely and reliably on images of routine CCTA examinations with native scans acquired during systole. We demonstrated that young adults have an aortic strain of 6.7-8.1%. As the average thoracic aortic strain was still lower than the recommended prosthesis oversize of 10%, routine use of systolic phase imaging cannot be recommended: it has no clinical benefit for the vast majority of the patients but increases the risk of motion artefacts. We also demonstrated that large interindividual differences are present in the scale of thoracic aortic strain, a phenomenon that needs further investigations to be fully understood.

Hybrid treatment of penetrating aortic ulcer

Penetrating atherosclerotic aortic ulcer is a rare entity with poor prognosis in the setting of acute aortic syndrome. In the literature, cases like the present one, located in the aortic arch, starting with chest pain and evolving with dysphonia, are even rarer. The present report emphasizes the role played by computed tomography in the diagnosis of penetrating atherosclerotic ulcer as well as in the differentiation of this condition from other acute aortic syndromes. Additionally, the authors describe a new therapeutic approach represented by a hybrid endovascular surgical procedure for treatment of the disease.