TEVAR and EVAR, the unknown knowns of the cardiovascular hemodynamics; and the immediate and long-term consequences of fabric material on major adverse clinical outcome

Emerging Trends in the Care of Type B Aortic Dissections

Aortic dissection is the most common of the acute aortic syndromes. Acute aortic dissection remains a highly morbid and potentially lethal condition despite contemporary advances in medical and surgical care. Type B aortic dissection (TBAD) is classified as uncomplicated, uncomplicated with high-risk features, and complicated. The role of thoracic endovascular aortic repair (TEVAR) in uncomplicated TBAD remains uncertain and is the topic of ongoing clinical trials. In most complicated cases, TEVAR is effective at restoring visceral and extremity blood flow. TEVAR has also been shown to arrest hemorrhage in the setting of thoracic aortic rupture. TEVAR has been demonstrated to induce satisfactory remodeling in the covered segment of the thoracic aorta, but progressive enlargement of the visceral aorta has led to a variety of techniques designed to promote remodeling in the uncovered aortic segment. There is a need to better define high-risk features so that treatment can be tailored to specific clinical conditions.

Patient-specific compliant simulation framework informed by 4DMRI-extracted pulse wave Velocity: Application post-TEVAR

We introduce a new computational framework that utilises Pulse Wave Velocity (PWV) extracted directly from 4D flow MRI (4DMRI) to inform patient-specific compliant computational fluid dynamics (CFD) simulations of a Type-B aortic dissection (TBAD), post-thoracic endovascular aortic repair (TEVAR). The thoracic aortic geometry, a 3D inlet velocity profile (IVP) and dynamic outlet boundary conditions are derived from 4DMRI and brachial pressure patient data. A moving boundary method (MBM) is applied to simulate aortic wall displacement. The aortic wall stiffness is estimated through two methods: one relying on area-based distensibility and the other utilising regional pulse wave velocity (RPWV) distensibility, further fine-tuned to align with in vivo values. Predicted pressures and outlet flow rates were within 2.3 % of target values. RPWV-based simulations were more accurate in replicating in vivo hemodynamics than the area-based ones. RPWVs were closely predicted in most regions, except the endograft. Systolic flow reversal ratios (SFRR) were accurately captured, while differences above 60 % in in-plane rotational flow (IRF) between the simulations were observed. Significant disparities in predicted wall shear stress (WSS)-based indices were observed between the two approaches, especially the endothelial cell activation potential (ECAP). At the isthmus, the RPWV-driven simulation indicated a mean ECAP>1.4 Pa-1 (critical threshold), indicating areas potentially prone to thrombosis, not captured by the area-based simulation. RPWV-driven simulation results agree well with 4DMRI measurements, validating the proposed pipeline and facilitating a comprehensive assessment of surgical decision-making scenarios and potential complications, such as thrombosis and aortic growth.

Comparative study of acute kidney injury in pararenal aortic aneurysm: open surgical versus endovascular repair

Background

Pararenal abdominal aortic aneurysms (PR-AAA), constituting around 15%-20% of AAA patients, are defined as having no neck between the aneurysm and the renal arteries. Due to an insufficient sealing zone, open surgical repair (OSR) is the gold standard, while EVAR is reserved for those unfit for surgery. Renal outcomes disturb long-term survival, and they have massive socioeconomic and quality of life implications, especially if patients require dialysis.

Methods

This study aims to elucidate any difference between EVAR and OSR of PR-AAA, excluding suprarenal aneurysms, with specific emphasis on renal dysfunction over the short and long term. An existing database of PR-AAA between 2002 and 2023 was used to glean information regarding the therapeutic option used. Renal events were defined by the RIFLE criteria. Out of 1,563 aortic interventions, we identified 179 PR-AAA, of which 99 high-risk patients had an aortic neck of less than 10 mm with complete follow-up. We excluded patients with fenestrated EVAR (FEVAR), branched EVAR (BEVAR), or chimney EVAR (Ch-EVAR) and any patients requiring visceral artery reimplantation.

Results

In total, 63 patients underwent EVAR, and 36 required OSR. 17.46% of patients who underwent EVAR experienced acute kidney injury (AKI) compared with 36.11% of the OSR group (P = 0.037). The mean post-op creatinine for OSR was 109.88 µmol/L, and for EVAR was 127.06 µmol/L (P = 0.192). The mean difference between long-term (9-12 years) creatinine values in OSR was 14.29 µmol/L (P = 0.191), and the mean difference for EVAR was 25.05 µmol/L (P = 0.024). Furthermore, 27.8% of OSR patients who underwent Left Renal Vein Division and Ligation (LRVDL) experienced an AKI, while 50% who did not undergo LRVDL experienced an AKI (P = 0.382). Thirty-day morbidity in the EVAR group (20.97%) was significantly lower than in the OSR group (42.62%) (P = 0.022). Moreover, 3.17% in EVAR group and 7.14% in OSR group had aneurysm-related mortality (P = 0.584).

Conclusion

The rate of renal events for OSR is higher, while the rate of endovascular renal events was lower. Our study shows that PR-AAA undergoing OSR may benefit from endovascular repair.

The Utility of Three-Dimensional Printing in Physician-Modified Stent Grafts for Aortic Lesions Repair

Background: Three-dimensional (3D) printing is becoming increasingly popular around the world not only in engineering but also in the medical industry. This trend is visible, especially in aortic modeling for both training and treatment purposes. As a result of advancements in 3D technology, patients can be offered personalized treatment of aortic lesions via physician-modified stent grafts (PMSG), which can be tailored to the specific vascular conditions of the patient. The objective of this systematic review was to investigate the utility of 3D printing in PMSG in aortic lesion repair by examining procedure time and complications. Methods: The systematic review has been performed using the PRISMA 2020 Checklist and PRISMA 2020 flow diagram and following the Cochrane Handbook. The systematic review has been registered in the International Prospective Register of Systematic Reviews: CRD42024526950. Results: Five studies with a total number of 172 patients were included in the final review. The mean operation time was 249.95± 70.03 min, and the mean modification time was 65.38 ± 10.59 min. The analysis of the results indicated I2 of 99% and 100% indicating high heterogeneity among studies. The bias assessment indicated the moderate quality of the included research. Conclusions: The noticeable variance in the reviewed studies' results marks the need for larger randomized trials as clinical results of 3D printing in PMSG have great potential for patients with aortic lesions in both elective and urgent procedures.

Study Protocol of a Prospective, Monocentric, Single-Arm Study Investigating the Correlation of Endograft Properties with Aortic Stiffness in Abdominal Aortic Aneurysm Patients Subjected to Endovascular Aortic Repair

The number of endovascular aortic repairs (EVARs) has surpassed the number of open surgical repairs of abdominal aortic aneurysms (AAAs) worldwide. The available commercial endoprostheses are composed of materials that are stiffer than the native aortic wall. As a consequence, the implantation of stent-graft endoprostheses during EVAR increases aortic rigidity and thus aortic stiffness, resulting in a decrease in abdominal aorta compliance. EVAR has been found to have a possibly harmful effect not only on heart functions but also on other vascular beds, including kidney function, due to the decrease in aortic compliance that it causes. Aortic stiffness is measured by various hemodynamic indices like the pulse wave velocity (PWV), the central aortic pressure (CAP), and the augmentation index (AIx). In the literature, there are increasing numbers of studies investigating the properties of endografts, which are strongly related to increases in aortic stiffness. However, there is a lack of data on whether there is a correlation between the length of various endografts implanted during EVAR and the increase in the PWV, CAP, and AIx postoperatively compared to the preoperative values. The aim of this prospective, observational, monocentric, single-arm study is to investigate the correlation between endograft length and the postoperative increase in the PWV, CAP, and AIx in patients subjected to EVAR. Additionally, this study intends to identify other endograft properties related to increases in the PWV, CAP, and AIx. Other endpoints to be studied are the existence of immediate postoperative myocardial and kidney injury after EVAR. The prediction of cardiovascular events caused by endograft-related increased aortic stiffness could contribute to the improvement of various endograft properties so that the impact of endografts on the native aortic wall can be minimized.

Arterial Stiffness and Aortic Aneurysmal Disease - A Narrative Review

It has been documented that large-artery stiffness is independently associated with increased cardiovascular risk and may potentially lead to heart and kidney failure and cerebrovascular disease. A systematic review of studies investigating changes in arterial stiffness in patients undergoing endovascular repair of aortic disease was conducted. In addition, a review of the available literature was performed, analyzing findings from studies using the cardio-ankle vascular index (CAVI) as a marker of arterial stiffness. Overall, 26 studies were included in the present analysis. Our research revealed a high heterogeneity of included studies regarding the techniques used to assess the aortic stiffness. Aortic stiffness was assessed by pulse wave velocity (PWV), elastic modulus (Ep), and augmentation index (AI). Currently a few studies exist investigating the role of CAVI in patients having an aortic aneurysm or undergoing endovascular aortic repair. The majority of studies showed that the treatment of an abdominal aortic aneurysm (AAA) either with open repair (OR) or endovascular aortic repair (EVAR) reduces aortic compliance significantly. Whether EVAR reconstruction might contribute a higher effect on arterial stiffness compared to OR needs further focused research. An increase of arterial stiffness was uniformly observed in studies investigating patients following thoracic endovascular aortic repair (TEVAR), and the effect was more pronounced in young patients. The effects of increased arterial stiffness after EVAR and TEVAR on the heart and the central hemodynamic, and an eventual effect on cardiac systolic function, need to be further investigated and evaluated in large studies and special groups of patients.

MRI detects increased aortic stiffening and myocardial dysfunction after TEVAR of blunt injury in young patients

Background: Thoracic endovascular aortic repair (TEVAR) is a well-established technique for the management of blunt thoracic aortic injury (BTAI). Despite improvements in vascular imaging, graft material properties, and implant techniques, stent-graft deployment artificially induces aortic stiffening. This study aimed to evaluate the midterm effect of thoracic endovascular aortic repair after blunt thoracic aortic injury on aortic stiffness and cardiac function in young patients using cardiovascular magnetic resonance (CMR) imaging. Patients and methods: From all patients who underwent TEVAR for BTAI between 2009 and 2019 in a single institution, 10 patients with no other comorbidities affecting arterial stiffness were sex-, age-, height-, and body surface area-matched to 10 healthy controls. Comprehensive CMR examination was performed in all controls and patients. The mean follow-up period was 5.4±1.8 years; the mean age at the time of TEVAR was 30.3±8.7 years. Results: Four patients who underwent TEVAR developed arterial hypertension. 4D flow CMR-based analysis demonstrated higher global pulse wave velocity (PWV) in TEVAR patients than in controls (p=0.012). Segmental analysis showed a higher PWV in the descending and abdominal aorta. The indexed diameter of the ascending aorta was larger in TEVAR patients than in controls (p=0.007). The CINE acquisitions demonstrated increased left ventricular myocardial thickness (p<0.001). The 3D global diastolic strain rate and diastolic longitudinal velocity (e') decreased, and the A-wave velocity increased. Native myocardial T1 values were significantly higher in TEVAR patients (p=0.037). Conclusions: Young patients with TEVAR after BTAI are at an increased risk of developing vascular and myocardial dysfunction due to increased aortic stiffness. CMR follow-up allows for a comprehensive and radiation-free evaluation of vascular stiffness and associated myocardial changes, especially at the early and subclinical stages.

Abdominal Aortic Endograft Implantation Immediately Induces Vascular Stiffness Gradients That May Promote Adverse Aortic Neck Dilatation: Results of A Porcine Ex Vivo Study

PURPOSE

Endovascular aortic repair (EVAR) is the method of choice for most abdominal aortic aneurysm (AAA) patients requiring intervention. However, chronic aortic neck dilatation (AND) following EVAR progressively weakens the structural seal between vessel and endograft and compromises long-term results of the therapy. This experimental ex vivo study seeks to investigate mechanisms of AND.

MATERIALS AND METHODS

Porcine abdominal aortas (n=20) were harvested from slaughterhouse pigs and connected to a mock circulation. A commercially available endograft was implanted (n=10) or aortas were left untreated as controls (n=10). Vascular circumferential strain was assessed via ultrasound in defined aortic segments as a parameter of aortic stiffness. Histology and aortic gene expression analysis were performed to investigate potential changes of aortic wall structure and molecular differences due to endograft implantation.

RESULTS

We found that endograft implantation acutely induces a significant stiffness gradient directly at the interface between stented and unstented aortic segments under pulsatile pressure. Comparing stented aortas with unstented controls, we detected increased aortic expression levels of inflammatory cytokines (Il6 and Ccl2) and matrix metalloproteinases (Mmp2 and Mmp9) after 6 hours of pulsatile pressurization. This effect, however, was abolished when repeating the same experiment under 6 hours of static pressure.

CONCLUSIONS

We identified endograft-induced aortic stiffness gradients as an early trigger of inflammatory aortic remodeling processes that might promote AND. These results highlight the importance of adequate endograft designs to minimize vascular stiffness gradients and forestall late complications, such as AND.

CLINICAL IMPACT

AND may compromise the long-term results following endovascular aortic repair. However, the mechanisms behind the underlying detrimental aortic remodeling are still unclear. In this study we find that endograft-induced aortic stiffness gradients induce an inflammatory aortic remodeling response consistent with AND. This novel pathomechanistic insight may guide the design of new aortic endografts that minimize vascular stiffness gradients and forestall late complications such as AND.

Management of acute aortic syndrome with evolving individualized precision medicine solutions: Lessons learned over two decades and literature review

Background

Thoracoabdominal acute aortic syndrome is associated with high morbidity and mortality. We aim to scrutinize our evolving strategies for acute aortic syndrome (AAS) management using minimally invasive and adaptive surgical techniques over two decades.

Methods

This is a longitudinal observational study at our tertiary vascular centre from 2002 to 2021. Out of 22,349 aortic referrals, we performed 1,555 aortic interventions over twenty years. Amongst 96 presented with symptomatic aortic thoracic pathology, 71 patients had AAS. Our primary endpoint is combined aneurysm-related and cardiovascular-related mortality.

Results

There were 43 males and 28 females (5 Traumatic Aortic Transection (TAT), 8 Acute Aortic Intramural Hematoma (IMH), 27 Symptomatic Aortic Dissection (SAD) and 31 Thoracic Aortic Aneurysm (TAA) post-SAD) with a mean age of 69. All the patients with AAS received optimal medical therapy (OMT), but TAT patients underwent emergency thoracic endovascular aortic repair (TEVAR). Fifty-eight patients had an aortic dissection, of which 31 developed TAA. These 31 patients with SAD and TAA received OMT initially and interval surgical intervention with TEVAR or sTaged hybrId sinGle lumEn Reconstruction (TIGER). To increase our landing area, we performed a left subclavian chimney graft with TEVAR in twelve patients. The average follow-up duration was 78.2 months, and eleven patients (15.5%) had combined aneurysm and cardiovascular-related mortality. Twenty-six percentage of the patients developed endoleaks (EL), of which 15% required re-intervention for type II and III. Four patients who had paraplegia (5.7%) and developed renal failure died. None of our patients had a stroke or bowel ischaemia. Twenty patients had OMT, eight of these were patients with acute aortic hematoma, and all eight died within 30 days of presentation.

Conclusion

Acute aortic hematoma is a sinister finding, which must be closely monitored, and consideration is given to early intervention. Paraplegia and renal failure result in an increased mortality rate. TIGER technique with interval TEVAR has salvaged complex situations in young patients. Left subclavian chimney increases our landing area and abolishes SINE. Our experience shows that minimally invasive techniques could be a viable option for AAS.