Functional Evaluation of Embedded Modular Single-Branched Stent Graft: Application to Type B Aortic Dissection With Aberrant Right Subclavian Artery

The Prospective, Multiple Center Study of a Novel Embedded Modular Single-Branched Stent-Graft for Type B Aortic Dissection Involving the Left Subclavian Artery

OBJECTIVES

This study aimed to assess the midterm outcomes of a novel embedded modular single-branched stent-graft (EMSBSG) designed to preserve the left subclavian artery (LSA) of type B aortic dissection (TBAD).

METHODS

From December 2020 to November 2021, a total of 120 patients with TBAD treated with an EMSBSG were enrolled in a multicenter prospective clinical trial at 18 Chinese tertiary hospitals. Follow-up computed tomography angiography scanning was conducted at 1, 6, and 12 months postprocedure.

RESULTS

The technical success rate was 99.17% (n = 119/120), with only 1 technical failure attributed to aortic intimo-intimal intussusception. The 30-day mortality rate was 0.83% (n = 1). Thirty-day major complications included 2 cases (1.67%) of retrograde type A aortic dissection (RTAD), 3 cases (2.50%) of stroke, and 6 cases (5.22%) of Type Ia endoleaks. The median follow-up time was 12.84 (range, 11-16) months. The 1-year mortality rate was 4.17% (n = 5/120), and the follow-up patency rate of the branch section was 99.09% (n = 109/110). The overall 12-month reintervention rate was 4.17% (n = 5), including 3 RTAD cases, 2 Type I endoleaks, and 1 stent-induced new entry.

CONCLUSION

For patients with TBAD involving the LSA, the midterm outcomes are encouraging for EMSBSG as a relatively safe, effective, and noncustomized endovascular option. However, long-term outcomes warrant attention and further investigation.Clinical ImpactThe midterm outcomes indicate that EMSBSG offers a safe, and effective endovascular option for preserving the LSA in patients with TBAD. The EMSBSG achieves LSA preservation through a non-customized endovascular solution, making it particularly suitable for emergency procedures. The core innovation of EMSBSG lies in its flexible, modular Embedded design, which adapts to the anatomical characteristics of TBAD in patients.

Mechanisms of aortic dissection: From pathological changes to experimental and in silico models

Aortic dissection continues to be responsible for significant morbidity and mortality, although recent advances in medical data assimilation and in experimental and in silico models have improved our understanding of the initiation and progression of the accumulation of blood within the aortic wall. Hence, there remains a pressing necessity for innovative and enhanced models to more accurately characterize the associated pathological changes. Early on, experimental models were employed to uncover mechanisms in aortic dissection, such as hemodynamic changes and alterations in wall microstructure, and to assess the efficacy of medical implants. While experimental models were once the only option available, more recently they are also being used to validate in silico models. Based on an improved understanding of the deteriorated microstructure of the aortic wall, numerous multiscale material models have been proposed in recent decades to study the state of stress in dissected aortas, including the changes associated with damage and failure. Furthermore, when integrated with accessible patient-derived medical data, in silico models prove to be an invaluable tool for identifying correlations between hemodynamics, wall stresses, or thrombus formation in the deteriorated aortic wall. They are also advantageous for model-guided design of medical implants with the aim of evaluating the deployment and migration of implants in patients. Nonetheless, the utility of in silico models depends largely on patient-derived medical data, such as chosen boundary conditions or tissue properties. In this review article, our objective is to provide a thorough summary of medical data elucidating the pathological alterations associated with this disease. Concurrently, we aim to assess experimental models, as well as multiscale material and patient data-informed in silico models, that investigate various aspects of aortic dissection. In conclusion, we present a discourse on future perspectives, encompassing aspects of disease modeling, numerical challenges, and clinical applications, with a particular focus on aortic dissection. The aspiration is to inspire future studies, deepen our comprehension of the disease, and ultimately shape clinical care and treatment decisions.

Total Arch Replacement Versus Hemiarch Replacement in Hemodynamic Performance: A Simulation Study

Acute type A aortic dissection (ATAAD) is a life-threatening aortic emergency with high mortality. Currently, hemiarch replacement (HAR) and total arch replacement (TAR) are the primary surgeries for ATAAD, but their long-term outcomes remain debated, possibly due to the influence of clinical factors in multicenter studies. This study aims to evaluate the long-term outcomes of HAR and TAR by in silico analysis, mitigating the impact of clinical factors. A personalized model was reconstructed to simulate HAR and TAR by altering the material properties at the replacement regions, obtaining hemodynamic and wall response parameters through two-way fluid-structure interaction analysis. HAR exhibits a higher increase in von Mises stress at the anastomosis compared to pre-operation levels (HAR: 4.39 times normal, TAR: 2.42 times normal), increasing the risk of pseudoaneurysm formation. TAR induced more severe streamline absence in the arch branches, potentially resulting in intermittent blood flow to the upper limbs and brain. HAR poses a higher risk of pseudoaneurysm formation at the anastomosis, while TAR carries increased risks of upper limb and cerebral ischemia. Enhanced monitoring of the anastomosis in HAR patients and vigilance for upper limb fatigue and cerebral ischemic events in TAR patients are recommended. This study offers effective guidance for managing postoperative HAR and TAR patients, contributing to the prevention of complications and enhancing their postoperative quality of life.

Long-Term Longitudinal Computational Study of a Marfan Syndrome Patient After Hybrid Repair of Aortic Arch Dissection With Parallel Stent-Grafts

Hybrid repair is a valuable alternative treatment for aortic arch disease in Marfan syndrome patients after proximal aorta replacement. This study aimed to investigate the long-term durability of this technique with the use of parallel stent-grafts and evaluate strategies to prevent abdominal aortic dilation. One Marfan syndrome patient who underwent hybrid aortic repair with parallel stent-grafts for arch dissection after the Bentall procedure was admitted. Five patient-specific three-dimensional models were reconstructed based on preoperative and follow-up computed tomography angiography scans. Three hypothetical models addressing the closure of an endoleak or reentry tears were created. Hemodynamic parameters were assessed using computational fluid dynamics. Postoperatively, increased blood flow into the descending aorta and rising abdominal aortic pressure were observed. During the 5-year follow-up, no new thoracic aorta-related adverse events occurred. One early type III endoleak persisted, and three reentry tears were identified in the descending aorta. The abdominal aorta dilated from 31 to 49 mm. Simultaneously addressing both the endoleak and reentry tears was more effective in reducing false lumen pressure and flow velocity in the abdominal aorta and expanding the high-value relative residence time region. Longitudinal follow-up imaging demonstrated the long-term durability of hybrid aortic arch repair with parallel stent-grafts in a Marfan syndrome patient after ascending aorta replacement. The increased pressure resulting from blood flow redistribution was associated with downstream aortic dilation. Furthermore, computational fluid dynamics simulations can offer predictive analyses for optimizing intervention strategies in the treatment of distal aneurysmal degeneration.

In situ fenestration (ISF) versus single-branched stent graft (SBSG) implantation in the management of acute Stanford type B aortic dissection involving the left subclavian artery

Background

With the advances in medical technology and materials, thoracic endovascular aortic repair has become the mainstay of treatment for aortic dissection. In situ fenestration (ISF) and single-branch stent graft (SBSG) implantation are commonly used methods, with each having its own advantages and disadvantages. The study aimed to compare the perioperative outcomes and one-year follow-up results of patients who underwent ISF or SBSG in the treatment of acute Stanford type B aortic dissection involving the left subclavian artery (LSA).

Methods

From January 2018 to December 2022, consecutive patients with Stanford type B aortic dissection were retrospectively recruited and divided into ISF group and SBSG group according to the type of surgery. The patient's aortic physiology was evaluated by computed tomography angiography at 1, 3, 6, and 12 months after discharge.

Results

This study included 67 patients in the SBSG group and 21 patients in the ISF group. The baseline and preoperative indices were similar between the groups. The success rate of perioperative treatment was 100%, and no adverse consequences occurred in either group. No spinal cord ischemia, stroke, or paraplegia occurred in either group during the one-year follow-up. The rate of endoleak in the SBSG group was significantly lower (3%, all type I endoleaks) than that in the ISF group (9.5% type I and 14.3% type II endoleaks) (P=0.005). Type II endoleak mainly occurred in the LSA. In addition, complete thrombosis of the false lumen was achieved in 95.5% of the SBSG group versus 81.0% of the ISF group, but this was not a significant difference (P=0.091). The maximum diameter of the true lumen increased significantly in the ISF (P<0.001) and SBSG (P<0.001) groups. Meanwhile, the maximum diameter of the false lumen was significantly reduced in the ISF (P<0.001) and SBSG (P<0.001) groups, but the difference in the maximum diameter change of the true or false lumen between the two groups was not statistically significant (P>0.05).

Conclusions

SBSG was associated with a significantly lower incidence of endoleak than was ISF. However, there were no differences observed in complete thrombosis of the false lumen. Further studies with larger sample sizes are needed to definitively establish which treatment is superior in terms of complete thrombosis of the false lumen.

Stent-induced new entry and device migration associated with hemodynamic stress after thoracic endovascular aortic repair for type B chronic aortic dissection using computational fluid dynamics analysis: a case report

BACKGROUND

Stent graft-induced new entry (SINE) after thoracic endovascular aortic repair (TEVAR) is a serious adverse event which leads to stent graft migration and rupture. SINE is known to be more frequent in cases of chronic dissection and oversizing. However, few studies have evaluated the influence of hemodynamic stress on SINE in patients with chronic dissection. Here, we report a rare case of TEVAR for chronic dissection with a dissection stent, inducing SINE 6 years after the first surgery. In addition, we analyze the hemodynamic stress for the aortic event using computational fluid dynamics (CFD) analysis.

CASE PRESENTATION

A 69-year-old male underwent TEVAR with left subclavian artery debranching for chronic type B aortic dissection, using a stent graft and dissection stent. The postoperative course was uneventful, but follow-up computed tomography (CT) showed that the stent graft and bare-metal stent had dislodged 4 years after surgery. The gap between the bare-metal stent and the stent graft increased over time, and the proximal edge of the bare-metal stent led to SINE at the descending aorta 6 years after surgery. We performed reintervention to cover the SINE. The patient recovered well and was discharged at 6 days postoperatively. He is currently in good condition 6 months after reintervention. CFD analysis of the patient's CT image suggested that the local change in wall shear stress at the stent graft and dissection stent might be related to the aortic event.

CONCLUSION

Hemodynamic stress is a factor affecting SINE and device migration. CFD may be useful for evaluating patient-specific risk of aortic events.

Thoracic endovascular aortic repair for type B aortic dissection with aberrant right subclavian artery: a single-center retrospective study

Objective

To evaluate the outcomes of thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD) with aberrant right subclavian artery (ARSA).

Methods

A retrospective analysis was conducted on patients with TBAD and ARSA who underwent TEVAR between the period of January 2017 and December 2022. Patient demographics, computed tomography angiography (CTA) measurements, surgical procedures, and postoperative outcomes were reviewed.

Results

A total of 9 patients (6 males and 3 females) were included in the study. 4 ARSA were reconstructed, 3 by periscope technique and 1 by in vitro fenestration technique. 3 left subclavian arteries (LSA) were reconstructed, 1 by the chimney technique and 2 by the single-branched stent technique. 2 patients underwent reconstruction of both ARSA and LSA. The overall technical success rate was 100%, with no occurrences of stroke, paraplegia, or mortality within 30 days. 1 patient experienced immediate type Ia endoleak, which resolved after 3 months. 1 patient developed weakness in the right upper limb, while 1 patient presented mild subclavian steal syndrome (SSS); both cases showed recovery during follow-up. The average follow-up duration was 35.6 ± 11.1 months, during which no reinterventions, deaths, or strokes were observed.

Conclusion

Our limited experience involving 9 patients demonstrates that early and mid-term outcomes of TEVAR for the treatment of TBAD with ARSA are satisfactory.

Evaluating Short-Term and Long-Term Risks Associated with Renal Artery Stenosis Position and Severity: A Hemodynamic Study

Background: Moderate renal artery stenosis (50-70%) may lead to uncontrolled hypertension and eventually cause irreversible damage to renal function. However, the clinical criteria for interventional treatment are still ambiguous in this condition. This study investigated the impact of the position and degree of renal artery stenosis on hemodynamics near the renal artery to assess the short-term and long-term risks associated with this disease. Methods: Calculation models with different degrees of stenosis (50%, 60%, and 70%) located at different positions in the right renal artery were established based on the computed tomography angiography (CTA) of a personalized case. And computational fluid dynamics (CFD) was used to analyze hemodynamic surroundings near the renal artery. Results: As the degree of stenosis increases and the stenosis position is far away from the aorta, there is a decrease in renal perfusion. An analysis of the wall shear stress (WSS)-related parameters indicated areas near the renal artery (downstream of the stenosis and the entrance of the right renal artery) with potential long-term risks of thrombosis and inflammation. Conclusion: The position and degree of stenosis play a significant role in judging short-term risks associated with renal perfusion. Moreover, clinicians should consider not only short-term risks but also independent long-term risk factors, such as certain regions of 50% stenosis with adequate renal perfusion may necessitate prompt intervention.