Thoracic Endovascular Aortic Repair: Review of Current Devices and Treatments Options

Implantation of ascyrus medical dissection stent, our first-hand experience

BACKGROUND

Acute type A aortic dissection is associated with high perioperative morbidity and mortality. Ascyrus Medical Dissection Stent (Cryolife, Kennesaw, USA) is a novel uncovered hybrid stent graft developed to be used as an adjunct to standard surgical approach to promote true lumen expansion and enhance aortic remodeling.

METHODS

From March 2021 to March 2022, four consecutive patients presented with acute Debakey type I aortic dissection and underwent emergent surgical repair with Tirone David procedure and implantation of Ascyrus Medical Dissection Stent. We reviewed patient's files retrospectively and described the perioperative outcomes.

RESULTS

All four device implantations were successful. Overall 30-day mortality was 0%. Malperfusion that was present in two patients pre-operatively improved after Ascyrus Medical Dissection Stent implantation. No aortic reinterventions were needed. No aortic injury related to the device was noted. Favourable changes in aortic true lumen and false lumen dimensions were found in most of our patients but the stent was compressed at the isthmus in one patient.

CONCLUSION

Ascyrus Medical Dissection Stent is a reliable and secure device. However, its benefits remain unclear when it comes to a positive remodeling and seems less likelihood comparable to a frozen elephant trunk. The main reason seems to be an insufficient radial force of the stent.

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.

Aortic haemodynamics and wall stress analysis following arch aneurysm repair using a single-branched endograft

Introduction

Thoracic endovascular aortic repair (TEVAR) of the arch is challenging given its complex geometry and the involvement of supra-aortic arteries. Different branched endografts have been designed for use in this region, but their haemodynamic performance and the risk for post-intervention complications are not yet clear. This study aims to examine aortic haemodynamics and biomechanical conditions following TVAR treatment of an aortic arch aneurysm with a two-component single-branched endograft.

Methods

Computational fluid dynamics and finite element analysis were applied to a patient-specific case at different stages: pre-intervention, post-intervention and follow-up. Physiologically accurate boundary conditions were used based on available clinical information.

Results

Computational results obtained from the post-intervention model confirmed technical success of the procedure in restoring normal flow to the arch. Simulations of the follow-up model, where boundary conditions were modified to reflect change in supra-aortic vessel perfusion observed on the follow-up scan, predicted normal flow patterns but high levels of wall stress (up to 1.3M MPa) and increased displacement forces in regions at risk of compromising device stability. This might have contributed to the suspected endoleaks or device migration identified at the final follow up.

Discussion

Our study demonstrated that detailed haemodynamic and biomechanical analysis can help identify possible causes for post-TEVAR complications in a patient-specific setting. Further refinement and validation of the computational workflow will allow personalised assessment to aid in surgical planning and clinical decision making.

Special Features of Polyester-Based Materials for Medical Applications

This article presents current possibilities of using polyester-based materials in hard and soft tissue engineering, wound dressings, surgical implants, vascular reconstructive surgery, ophthalmology, and other medical applications. The review summarizes the recent literature on the key features of processing methods and potential suitable combinations of polyester-based materials with improved physicochemical and biological properties that meet the specific requirements for selected medical fields. The polyester materials used in multiresistant infection prevention, including during the COVID-19 pandemic, as well as aspects covering environmental concerns, current risks and limitations, and potential future directions are also addressed. Depending on the different features of polyester types, as well as their specific medical applications, it can be generally estimated that 25-50% polyesters are used in the medical field, while an increase of at least 20% has been achieved since the COVID-19 pandemic started. The remaining percentage is provided by other types of natural or synthetic polymers; i.e., 25% polyolefins in personal protection equipment (PPE).

Haemodynamic Analysis of Branched Endografts for Complex Aortic Arch Repair

This study aims to investigate the haemodynamic response induced by implantation of a double-branched endograft used in thoracic endovascular aortic repair (TEVAR) of the aortic arch. Anatomically realistic models were reconstructed from CT images obtained from patients who underwent TEVAR using the RelayPlus double-branched endograft implanted in the aortic arch. Two cases (Patient 1, Patient 2) were included here, both patients presented with type A aortic dissection before TEVAR. To examine the influence of inner tunnel branch diameters on localised flow patterns, three tunnel branch diameters were tested using the geometric model reconstructed for Patient 1. Pulsatile blood flow through the models was simulated by numerically solving the Navier–Stokes equations along with a transitional flow model. The physiological boundary conditions were imposed at the model inlet and outlets, while the wall was assumed to be rigid. Our simulation results showed that the double-branched endograft allowed for the sufficient perfusion of blood to the supra-aortic branches and restored flow patterns expected in normal aortas. The diameter of tunnel branches in the device plays a crucial role in the development of flow downstream of the branches and thus must be selected carefully based on the overall geometry of the vessel. Given the importance of wall shear stress in vascular remodelling and thrombus formation, longitudinal studies should be performed in the future in order to elucidate the role of tunnel branch diameters in long-term patency of the supra-aortic branches following TEVAR with the double-branched endograft.

Treatment Site Does Not Affect Changes in Pulse Wave Velocity but Treatment Length and Device Selection Are Associated With Increased Pulse Wave Velocity After Thoracic Endovascular Aortic Repair

Background: Endovascular treatment of aortic aneurysm is associated with an increase in pulse wave velocity (PWV) after surgery. However, the effect of different types of endovascular devices on PWV at different sites of the thoracic aorta remains unclear.

Objectives: The purposes of this study were (1) to investigate the changes in PWV after endovascular treatment of thoracic aortic aneurysm; (2) to evaluate whether there is a difference in the changes in PWV at different treatment sites; and (3) to evaluate the effect of treatment length on changes in PWV.

Methods: From July 2008 to July 2021, 276 patients underwent endovascular treatment of the true thoracic aortic aneurysm. Of these patients, 183 patients who underwent preoperative and postoperative PWV measurement within 1 year of surgery were included in the study. The treatment length index was calculated by treatment length divided by the height of the patients.

Results: Five different types of endovascular devices were used (Najuta, Kawasumi Laboratories, Inc., Tokyo, Japan; TAG, W.L. Gore & Associates, Inc., AZ, USA; Relay, Bolton Medical, Inc., FL, USA; Talent/Valiant, Medtronic, MN, USA; and Zenith, Cook Medical, IN, USA). There was no significant change in PWV in patients receiving Najuta (Before: 2,040 ± 346.8 cm/s vs. After: 2,084 ± 390.5 cm/s, p = 0.14). However, a significant increase was observed in other devices: TAG (Before: 2,090 ± 485.9 cm/s vs. After: 2,300 ± 512.1 cm/s, p = 0.025), Relay (Before: 2,102 ± 465.3 cm/s vs. After: 2,206 ± 444.4 cm/s, p = 0.004), Valiant (Before: 1,696 ± 330.2 cm/s vs. After: 2,186 ± 378.7 cm/s, p < 0.001), and Zenith (Before: 2,084 ± 431.7 cm/s vs. After: 2,321 ± 500.6 cm/s, p < 0.001). There was a significant increase in PWV in patients treated from aortic arch (Before: 2,006 ± 333.7 cm/s vs. After: 2,132 ± 423.7 cm/s, p < 0.001) and patients treated from descending thoracic aorta (Before: 2,116 ± 460.9 cm/s vs. After: 2,292 ± 460.9 cm/s, p < 0.001). Multivariate analysis showed that treatment site was not an independent factor associated with changes in PWV. However, Najuta (Coef −219.43, 95% CI −322.684 to −116.176, p < 0.001) and treatment index (Coef 147.57, 95% CI 24.826 to 270.312, p = 0.019) were independent factors associated with changes in PWV.

Conclusion: Najuta did not show a significant increase in PWV, while other commercially available devices showed a significant increase. The treatment site did not have a different effect on PWV. However, the treatment length was an independent factor associated with an increase in PWV.

Malpositioned pedicle screw in spine deformity surgery endangering the aorta: report of two cases, review of literature, and proposed management algorithm

STUDY DESIGN

Case reports and review of the literature with a proposed management algorithm.

OBJECTIVES

To report two cases of a potential vascular complication due to an incorrectly placed pedicle screw (PS) during spine deformity surgery. Relevant literature regarding the management of vascular complications is reviewed, and an evidence-based management algorithm is proposed. Aortic lesions represent a rare but potentially life-threatening complications with spine deformity and revision surgery, significantly increasing the risk. A management algorithm for an aortic lesion in the case of a malpositioned PS has not yet been published.

METHODS

Case 1: An 18-year-old female with proximal thoracic spinal non-instrumented fusion underwent a revision corrective procedure due to a progressive right-sided thoracolumbar compensatory curve. However, postoperative computed tomography (CT) performed to evaluate the position of the PS revealed malposition of the left T9 PS, which was abutting the descending aorta with CT angiography excluding the perforation of the aorta. Case 2: A 17-year-old male was scheduled for correction of Lenke 3-C-N adolescent idiopathic scoliosis. Postoperative routine evaluation with low-dose CT revealed a left T9 PS paravertebral malposition, and subsequent CTA demonstrated that the thread of the PS was in contact with the descending thoracic aorta and an unlikely hemodynamically significant vessel injury.

RESULTS

Successful removal of both malpositioned PS was performed. In the first case, a cardiovascular surgeon attended the operation if an urgent thoracotomy was needed, and in the second case, additional video-assisted thoracoscopic control of the aorta was performed during PS removal.

CONCLUSIONS

Preoperative imaging in spinal surgery is essential to avoid major vascular and other complications when placing PS, especially in thoracic deformities. When a potential major vessel complication emerges, an interdisciplinary approach and an appropriate management algorithm are mandatory to make the best clinical decisions.

LEVEL OF EVIDENCE

4.