Physician-Modified Stent-Grafts Created in the Three-Dimensionally Aortic Template Have Better Reliability and Greater Alignment With the Target Vessels Than Stent-Grafts Modified Based on Measurements From Computed Tomography

PURPOSE

Physician-modified stent-grafts (PMSG) are widely used, especially when a patient's condition precludes waiting for a custom-made device. In recent years, the modification process has been upgraded using 3-dimensional (3D) aortic templates. Nonetheless, the reliability of PMSG and accuracy of fenestration alignment with the target vessel are not known. Thus, the study is aimed to fulfill the gap in current knowledge.

MATERIALS AND METHODS

Ten computed tomographic (CT) scans of aortic aneurysm previously treated with the fenestrated endovascular repair were selected to 3D-print aortic templates and elastic vessel phantoms. Two vascular surgeons performed fenestrations using the 3D template and modification plan based on CT measurements. Two operators each performed 10 fenestrated stent-grafts in the aortic template and 10 using CT measurements, for a total of 40 fenestrated stent-grafts. Then, stent-grafts were implanted in elastic vessel phantoms, which served to evaluate fenestration alignment with the target vessel. The alignment was judged in a 5-point scale: 0%, 1% to 25%, 26% to 50%, 51% to 75%, and 76% to 100%. The distances between fenestrations served to calculate interobserver variability for both methods. The measurements were processed as interclass correlation coefficient (ICC), Pearson and Spearman correlation, and Bland-Altman plots.

RESULTS

PMSG created with a 3D template had higher interclass correlation coefficient values and Pearson/Spearman correlation than fenestrations created from CT measurements. The rate of fenestration alignment with the target vessel was higher for PMSG created with a 3D template (p=0.007).

CONCLUSIONS

PMSGs created with a 3D template are more reliable and have better fenestration alignment with the target vessel than PMSGs created based on CT measurements.

International Multi-Institutional Experience with Presentation and Management of Aortic Arch Laterality in Aberrant Subclavian Artery and Kommerell's Diverticulum

BACKGROUND

Aberrant subclavian artery (ASA) with or without Kommerell's diverticulum (KD) is a rare anatomic aortic arch anomaly that can cause dysphagia and/or life-threatening rupture. The objective of this study is to compare outcomes of ASA/KD repair in patients with a left versus right aortic arch.

METHODS

Using the Vascular Low Frequency Disease Consortium methodology, a retrospective review was performed of patients ≥18 years old with surgical treatment of ASA/KD from 2000 to 2020 at 20 institutions.

RESULTS

288 patients with ASA with or without KD were identified; 222 left-sided aortic arch (LAA), and 66 right-sided aortic arch (RAA). Mean age at repair was younger in LAA 54 vs. 58 years (P = 0.06). Patients in RAA were more likely to undergo repair due to symptoms (72.7% vs. 55.9%, P = 0.01), and more likely to present with dysphagia (57.6% vs. 39.1%, P < 0.01). The hybrid open/endovascular approach was the most common repair type in both groups. Rates of intraoperative complications, death within 30 days, return to the operating room, symptom relief and endoleaks were not significantly different. For patients with symptom status follow-up data, in LAA, 61.7% had complete relief, 34.0% had partial relief and 4.3% had no change. In RAA, 60.7% had complete relief, 34.4% had partial relief and 4.9% had no change.

CONCLUSIONS

In patients with ASA/KD, RAA patients were less common than LAA, presented more frequently with dysphagia, had symptoms as an indication for intervention, and underwent treatment at a younger age. Open, endovascular and hybrid repair approaches appear equally effective, regardless of arch laterality.

The accuracy and reliability of 3D printed aortic templates: a comprehensive three-dimensional analysis

Background

Advances in 3D printing technology allow us to continually find new medical applications. One of them is 3D printing of aortic templates to guide vascular surgeons or interventional radiologists to create fenestrations in the stent-graft surface for the implantation procedure called fenestrated endovascular aortic aneurysm repair. It is believed that the use of 3D printing significantly improves the quality of modified fenestrated stent-grafts. However, the accuracy and reliability of personalized 3D printed models of aortic templates are not well established.

Methods

Thirteen 3D printed templates of the visceral aorta and sixteen of the aortic arch and their corresponding computer tomography of angiography images were included in this accuracy study. The 3D models were scanned in the same conditions on computed tomography (CT) and evaluated by three physicians experienced in vascular CT assessment. Model and patient CT measurements were performed at key landmarks to maintain quality for stent-graft modification, including side branches and aortic diameters. CT-scanned aortic templates were segmented, aligned with sourced patient data, and evaluated for the Hausdorff matrix. Next, Bland-Altman plots determined the degree of agreement.

Results

The Intraclass Correlation Coefficients values were more than 0.9 for all measurements of aortic diameters and aortic branches diameter in all landmark locations. Therefore, the reliability of the aortic templates was considered excellent. The Bland-Altman plots analysis indicated measurement biases of 0.05 to 0.47 for aortic arch templates and 0.06 to 0.38 for reno-visceral aortic templates. The arithmetic mean of Hausdorff's mean distances of the aortic arch templates was 0.47 mm (SD =0.06) and ranged from 0.34 to 0.58. The mean metrics for abdominal models was 0.24 mm (SD =0.03) and ranged from 0.21 to 0.31.

Conclusions

The printed models of 3D aortic templates are accurate and reliable, thus can be widely used in endovascular surgery and interventional radiology departments as aortic templates to guide the physician-modified fenestrated stent-graft fabrication.

A 3-Dimensional Printed Aortic Arch Template to Facilitate the Creation of Physician-Modified Stent-Grafts

PURPOSE

To demonstrate the utility of a 3-dimensional (3D) printed template of the aortic arch in the construction of a fenestrated and scalloped physician-modified stent-graft (PMSG).

CASE REPORT

A 73-year-old woman with descending thoracic aneurysm was scheduled for thoracic endovascular aortic repair after being disqualified for open surgery. Computed tomography angiography (CTA) revealed no proximal landing zone as the aneurysm began from the level of the left subclavian artery, so a fenestrated/scalloped PMSG was planned. To facilitate accurate placement of the openings in the graft, a 3D printed aortic arch template was prepared from the CTA data and gas sterilized. In the operating room, a Valiant stent-graft was inserted into the 3D printed template and deployed. Using ophthalmic cautery, a fenestration and a scallop were created; radiopaque markers were added. The PMSG was successfully deployed with no discrepancy between the openings and the target vessels.

CONCLUSION

A 3D printed aortic arch template facilitates handmade fenestrations and scallops in PMSGs and may improve accuracy and quality.