Exploiting light-based 3D-printing for the fabrication of mechanically enhanced, patient-specific aortic grafts

Despite polyester vascular grafts being routinely used in life-saving aortic aneurysm surgeries, they are less compliant than the healthy, native human aorta. This mismatch in mechanical behaviour has been associated with disruption of haemodynamics contributing to several long-term cardiovascular complications. Moreover, current fabrication approaches mean that opportunities to personalise grafts to the individual anatomical features are limited. Various modifications to graft design have been investigated to overcome such limitations; yet optimal graft functionality remains to be achieved. This study reports on the development and characterisation of an alternative vascular graft material. An alginate:PEGDA (AL:PE) interpenetrating polymer network (IPN) hydrogel has been produced with uniaxial tensile tests revealing similar strength and stiffness (0.39 ± 0.05 MPa and 1.61 ± 0.19 MPa, respectively) to the human aorta. Moreover, AL:PE tubular conduits of similar geometrical dimensions to segments of the aorta were produced, either via conventional moulding methods or stereolithography (SLA) 3D-printing. While both fabrication methods successfully demonstrated AL:PE hydrogel production, SLA 3D-printing was more easily adaptable to the fabrication of complex structures without the need of specific moulds or further post-processing. Additionally, most 3D-printed AL:PE hydrogel tubular conduits sustained, without failure, compression up to 50% their outer diameter and returned to their original shape upon load removal, thereby exhibiting promising behaviour that could withstand pulsatile pressure in vivo. Overall, these results suggest that this AL:PE IPN hydrogel formulation in combination with 3D-printing, has great potential for accelerating progress towards personalised and mechanically-matched aortic grafts.

Outcomes of thoracic endovascular aortic repair with physician-manufactured partial micropore stent grafts for aortic arch pathologies

OBJECTIVE

Thoracic endovascular aortic repair (TEVAR) has been used extensively in the management of thoracic aortic diseases. Numerous efforts have been made to enhance clinical outcomes through the use of stent grafts. This study aimed to investigate the effectiveness and safety of physician-manufactured partial micropore stent grafts (PSMGs) in TEVAR.

METHODS

Between December 2017 and June 2022, data were collected from 56 patients who underwent TEVAR using physician-manufactured PSMGs. The evaluation encompassed technical success, perioperative and follow-up morbidity and mortality, stroke incidence, and branch artery patency.

RESULTS

In this investigation, 56 patients received treatment with physician-manufactured PSMGs. Of these patients, 46 were male, with a mean age of 62.1 ± 11.2 years. Aortic pathologies comprised aortic dissection (n = 31 [55.4%]), aortic aneurysms (n = 10 [17.9%]), penetrating aortic ulcer (n = 8 [14.3%]), and intramural hematoma (n = 7 [12.5%]). During a median follow-up of 18 months (interquartile range, 13-25 months), the stroke rate, supra-aortic branch patency rate, and endoleak rate were 0%, 100%, and 7.1%, respectively. There were no occurrences of all-cause mortality, stroke, or the necessity for open conversion.

CONCLUSIONS

TEVAR with physician-manufactured PSMGs is a viable alternative for addressing aortic arch pathologies in proficient medical centers. The approach demonstrates favorable branch patency, a low complication rate, and minimal postoperative mortality.

Outcomes Following Use of Bovine Pericardium (Xenoprosthetic) Grafts for Reconstruction of Mycotic Aortic Aneurysms and Infected Aortic Grafts: A Systematic Review and Meta-Analysis

BACKGROUND

Infected aortic grafts and mycotic aneurysms represent one of the most complex challenges faced by vascular surgeons. Treatment has progressed from extra-anatomical bypass to in situ reconstruction. Additionally, bovine pericardium reconstruction (BPR) has increased, due to accessibility and reduced lower limb morbidity. There remains, however, limited evidence for its use. The aim is to pool all known data to understand outcomes following BPR of mycotic aneurysms or infected vascular grafts.

METHODS

A systematic review was conducted in November 2021 with subsequent computerized meta-analysis of the pooled results and a final search in March 2022. Three databases, Excerpta Medica dataBASE (EMBASE), Cumulative Index of Nursing and Allied Health Literature (CINAHL), and National Institutes of Health PubMed (PubMed), were searched for the search term "(bovine OR xenoprosthetic) AND (aneurysm)", according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

From 9 studies, there were 133 patients: 67% graft infections and 33% mycotic aneurysms. Fifty-seven percent of reconstructions were in the abdominal aorta and 33% were in the thoracic aorta. One hundred fifty-eight pathogens were identified, including Staphylococcus aureus (23%), Candida albicans (13%), and Escherichia coli (13%). In 12%, no microorganisms were identified. Thirty-day mortality was 19.14% (CI 10.83-28.71), late mortality was 19.08% (confidence interval [CI] 7.76-32.83), and overall mortality was 40.20% (CI 29.82-50.97). One patient died intraoperatively. There were a total of 151 in-hospital complications after 30 days postoperation. Common complications were acute renal failure (17%), pneumonia (14%), delirium (12%), respiratory insufficiency (11%) and renal insufficiency (7%). Lower limb ischemia was low, occurring in 5.66% (CI 0.54-13.82) of patients. Loss of graft patency leading to reintervention occurred in 1.20% (CI 0.00-7.71) of the grafts. Reinfection rate was 0.00% (CI 0.00-1.21).

CONCLUSIONS

This meta-analysis highlights low reinfection and high graft patency using BPR with medium-length follow-up; however, there remain limited long-term and comparative data regarding options for aortic reconstruction. As expected in this complex cohort, the complication rate and 30-day mortality remain high.

One-year follow-up after active aortic aneurysm sac treatment with shape memory polymer devices during endovascular aneurysm repair

OBJECTIVE

To determine the safety and efficacy of treating abdominal aortic aneurysm (AAA) sacs with polyurethane shape memory polymer (SMP) devices during endovascular aneurysm repair (EVAR), using a technique to fully treat the target lumen after endograft placement (aortic flow volume minus the endograft volume). SMP devices self-expand in the sac to form a porous scaffold that supports thrombosis throughout its structure.

METHODS

Two identical prospective, multicenter, single-arm studies were conducted in New Zealand and the Netherlands. The study population was adult candidates for elective EVAR of an infrarenal AAA (diameter of ≥55 mm in men and ≥50 mm in women). Key exclusion criteria were an inability to adequately seal a common iliac artery aneurysm, patent sac feeding vessels of >4 mm, and a target lumen volume of <20 mL or >135 mL. Target lumen volumes were estimated by subtracting endograft volumes from preprocedural imaging-based flow lumen volumes. SMP devices were delivered immediately after endograft deployment via a 6F sheath jailed in a bowed position in the sac. The primary efficacy end point was technical success, defined as filling the actual target lumen volume with fully expanded SMP at the completion of the procedure. Secondary efficacy outcome measures during follow-up were the change in sac volume and diameter, rate of type II endoleak and type I or III endoleaks, and the rate of open repair and related reinterventions, with data collection at 30 days, 6 months, and 1 year (to date). Baseline sac volumes and diameters for change in sac size analyses were determined from 30-day imaging studies. Baseline and follow-up volumes were normalized by subtraction of the endograft volume.

RESULTS

Of 34 patients treated with SMP devices and followed per protocol, 33 patients were evaluable at 1 year. Preprocedural aneurysm volume was 181.4 mL (95% confidence interval [CI], 150.7-212.1 mL) and preprocedural aneurysm diameter was 60.8 mm (95% CI, 57.8-63.9 mm). The target lumen volume was 56.3 mL (95% CI, 46.9-65.8 mL). Technical success was 100% and the ratio of SMP fully expanded volume to estimated target lumen volume was 1.4 ± 0.3. Baseline normalized sac volume and diameter were 140.7 mL (95% CI, 126.6-154.9 mL) and 61.0 mm (95% CI, 59.7-62.3 mm). The adjusted mean percentage change in normalized volume at 1 year was -28.8% (95% CI, -35.3 to -22.3%; P < .001). The adjusted mean change in sac diameter at 1 year was -5.9 mm (95% CI, -7.5 to -4.4 mm; P < .001). At 1 year, 81.8% of patients (95% CI, 64.5%-93.0%) achieved a ≥10% decrease in normalized volume and 57.6% of patients (95% CI, 39.2%-74.5%) achieved a ≥5 mm decrease in diameter. No device- or study procedure-related major adverse events occurred through 1 year after the procedure.

CONCLUSIONS

Treatment of AAA sacs with SMP devices during EVAR resulted in significant sac volume and diameter regression at 1 year with an acceptable safety profile in this prospective study.

Total aortic arch replacement using a frozen elephant trunk device: Results of a 1-year US multicenter trial

OBJECTIVE

In this prospective US investigational device exemption trial, we assessed the safety and 1-year clinical outcomes of the Thoraflex Hybrid device (Terumo Aortic) for the frozen elephant trunk technique to repair the ascending aorta, aortic arch, and descending thoracic aorta.

METHODS

For the trial, which involved 12 US sites, 65 patients without rupture were recruited into the primary study group, and 9 patients were recruited into the rupture group. All patients underwent open surgical repair of the ascending aorta, aortic arch, and descending thoracic aorta in cases of aneurysm and/or dissection. The primary end point was freedom from major adverse events (MAE), defined as permanent stroke, permanent paraplegia/paraparesis, unanticipated aortic-related reoperation (excluding reoperation for bleeding), or all-cause mortality.

RESULTS

In the primary study group, 2 patients were lost to follow-up at 1 year. Freedom from MAE at 1 year was 81% (51/63). Seven patients (11%) died (including 2 before 30 days or discharge), 3 patients (5%) suffered permanent stroke, and 3 (5%) developed permanent paraplegia/paraparesis. Twenty-six patients (41%) underwent planned extension procedures, including 22 endovascular procedures within a median of 122 (interquartile range, 64-156) days. In the aortic rupture group, 2 patients were lost to follow-up at 1 year. Freedom from MAE at 1 year was 71% (5/7). One patient (14%) died, 2 patients (29%) had permanent stroke, and none had permanent paraplegia/paraparesis. No extension procedures were performed in the rupture group.

CONCLUSIONS

One-year results with the Thoraflex Hybrid device are acceptable. Long-term data are necessary to assess the durability of these repairs.

Three-year outcomes of the Dissected Aorta Repair Through Stent Implantation trial

OBJECTIVE

The study objective was to evaluate the clinical and radiographic outcomes of the Ascyrus Medical Dissection Stent in a prospective, nonrandomized, international study (Dissected Aorta Repair Through Stent Implantation) of patients with acute DeBakey type I aortic dissection.

METHODS

The Ascyrus Medical Dissection Stent was used in combination with the standard surgical management of acute DeBakey type I aortic dissection I to treat patients with (56.5%, 26/46) and without (43.5%, 20/46) preoperative clinical and radiographic malperfusion. All patients had a primary entry tear in the ascending aorta, and 97.8% (45/46) were treated with a hemiarch repair. Median follow-up was 3 years.

RESULTS

All 47 patients underwent emergency surgical repair with successful Ascyrus Medical Dissection Stent implantation. One patient was excluded from analysis due to use in iatrogenic dissection. Overall mortality at 30 days and 3 years was 13.0% (6/46) and 21.7% (10/46), respectively. Overall new stroke rate at 30 days was 15.2% (7/46). No devices were explanted at any time during the 3-year median follow-up. At 3 years, the total aortic diameter in zones 0, 1, and 2 decreased or remained stable in 91.7%, 72.7%, and 75.0%, respectively. The false lumen was completely or partially thrombosed in 90.5% in zone 0, 60.0% in zone 1, and 68.2% in zone 2 at 3 years.

CONCLUSIONS

The use of the Ascyrus Medical Dissection Stent in the treatment of acute DeBakey type I aortic dissection I holds promise as a simple technology that enables repair of the aortic arch and proximal descending aorta, while promoting positive aortic remodeling. Ongoing follow-up of the Dissected Aorta Repair Through Stent Implantation trial will provide long-term, prospective, clinical outcomes and radiographic data on positive remodeling of the aortic arch.

Prospective evaluation of upper extremity access and total transfemoral approach during fenestrated and branched endovascular repair

OBJECTIVE

Total transfemoral (TF) access has been increasingly used during fenestrated-branched endovascular aortic repair (FB-EVAR). However, it is unclear whether the potential decrease in the risk of cerebrovascular events is offset by increased procedural difficulties and other complications. The aim of this study was to compare outcomes of FB-EVAR using a TF vs upper extremity (UE) approach for target artery incorporation.

METHODS

We analyzed the clinical data of consecutive patients enrolled in a prospective, nonrandomized clinical trial in two centers to investigate the use of FB-EVAR for treatment of complex abdominal aortic aneurysms (CAAA) and thoracoabdominal aortic aneurysms (TAAA) between 2013 and 2022. Patients were classified into TF or UE access group with a subset analysis of patients treated using designs with directional branches. End points were technical success, procedural metrics, 30-day cerebrovascular events defined as stroke or transient ischemic attack, and any major adverse events (MAEs).

RESULTS

There were 541 patients (70% males; mean age, 74 ± 8 years) treated by FB-EVAR with 2107 renal-mesenteric TAs incorporated. TF was used in175 patients (32%) and UE in 366 patients (68%) including 146 (83%) TF and 314 (86%) UE access patients who had four or more TAs incorporated. The use of a TF approach increased from 8% between 2013 and 2017 to 31% between 2018 and 2020 and 96% between 2021 and 2022. Compared with UE access patients, TF access patients were more likely to have CAAAs (37% vs 24%; P = .002) as opposed to TAAAs. Technical success rate was 96% in both groups (P = .96). The use of the TF approach was associated with reduced fluoroscopy time and procedural time (each P < .05). The 30-day mortality rate was 0.6% for TF and 1.4% for UE (P = .67). There was no early cerebrovascular event in the TF group, but the incidence was 2.7% for UE patients (P = .035). The incidence of MAEs was also lower in the TF group (9% vs 18%; P = .006). Among 237 patients treated using devices with directional branches, there were no significant differences in outcomes except for a reduced procedural time for TF compared with UE access patients (P < .001).

CONCLUSIONS

TF access was associated with a decreased incidence of early cerebrovascular events and MAEs compared with UE access for target artery incorporation. Procedural time was decreased in TF access patients irrespective of the type of stent graft design.

Use of physician-modified inverted limb in conjunction with Zenith fenestrated stent graft to rescue failed previous endovascular and open repair

OBJECTIVE

To evaluate outcomes and performance of inverted limbs (ILs) when used in conjunction with Zenith fenestrated stent grafts (Zfens) to treat patients with short distance between the lowest renal artery (RA) and aortic or graft bifurcation (A/GB).

METHODS

This study was a multicenter, retrospective review of prospectively maintained database of patients with complex aortic aneurysms, failed endovascular aneurysm repair (EVAR), or open surgical repair (OSR) with short distance between LRA and A/GB treated using a combination of Zfen and an IL between 2013 and 2023. Endpoints included technical success, aneurysm sac regression, long-term device integrity, and target vessel patency. We defined technical success as implantation of the device with no endoleak, conversion to an aorto-uni-iliac or OSR.

RESULTS

During this time, 52 patients underwent endovascular rescue of failed repair. Twenty (38.5%) of them required relining of the failed repairs using IL due to lowest RA to A/GB length restrictions. Two patients had undergone rescue with a fenestrated cuff alone but developed type III endoleaks. One patient with no previous implant had a short distance between the lowest RA and aortic bifurcation to accommodate the bifurcated distal device, and two patients had failed OSR or anastomotic pseudoaneurysms. The majority (94%) were men with a mean age of 76.8 ± 6.1 years. The mean aortic neck diameter and aneurysm size were 32 ± 4 cm and 7.2 ± 1.3 cm, respectively. The median time laps between initial repair and failure was 36 months (interquartile range [IQR], 24-54 months). Sixteen patients (80%) were classified as American Society of Anesthesiologists class III, whereas four were class IV. Seventy-eight vessels were targeted and successfully incorporated. Technical success was 100%, and median estimated blood loss was 100 mL (IQR, 100-200 mL). Mean fluoroscopy time and dose were 61 ± 18 minutes and 2754 ± 1062 mGy, respectively. Average hospital length of stay was 2.75 ± 2.15 days. Postoperative complication occurred in one patient who required lower extremity fasciotomy for compartment syndrome. At a median follow-up of 50 months (IQR, 18-58 months), there were no device migration, components separation, aneurysmal related mortality, and type I or type III endoleak. Aneurysm sac regression (95%) or stabilization (5%) was observed in all patients, including in four patients (25%) with type II endoleak.

CONCLUSIONS

The use of IL in conjunction with Zfen to treat patients with short distance between the lowest RA and A/GB is safe, effective, and has excellent long-term results. The technique expands the indication of Zfen, especially in patients with failed previous EVAR.

Hemodynamics and Wall Mechanics of Vascular Graft Failure

Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.

Inflammation in aortic surgery: postoperative evolution of biomarkers according pathologies and segments of the aorta

OBJECTIVES

Aortic pathologies often present with elevated inflammatory biomarkers due to the nature of the disease. Open aortic surgery causes significant trauma to the body due to often mandatory ischemic periods, long cardiopulmonary bypass times and polytransfusion. We aim to determine postoperative trends on inflammation biomarkers for different aortic pathologies and type of surgery in different segments of the aorta.

METHODS

Retrospective review of prospectively collected data of 193 consecutive patients who underwent aortic surgery in our centre between 2017 and 2021, grouped according to the type of aortic intervention: (1) Type A aortic dissection (AD) repair with ascending aorta/hemiarch replacement, (2) Aortic root replacement (ARR), (3) Aortic arch + Frozen elephant trunk (FET), (4) Descending thoracic aorta (DTA)/Thoraco-Abdominal aortic repair (TAA). Primary outcomes were daily values of white blood cells (WBC) and C-Reactive Protein (CRP) during the first 15 postoperative days.

RESULTS

All groups had a similar inflammatory peak in the first 2-4 days (WBC 12-15 × 109 c/L). AD and FET groups show similar trends with WBC and CRP peaks on days 2 and 10. The ARR group didn't experience the 2nd peak as most patients were already discharged. DTA/TAA patients experienced a more prolonged inflammatory response, reaching a plateau by day 5-10. AD group shows the highest WBC levels and the DTA/TAAA group the highest CRP levels. CRP levels remain elevated (100-200 mg/L) in all groups after 15 postoperative days.

CONCLUSIONS

Inflammatory biomarkers show different postoperative trends depending on the clinical presentation and complexity of the aortic procedure performed. Further understanding of the inflammatory response to different aortic pathologies and surgical procedures will permit reduction on the liberal use of antibiotics that this cohort of patients are usually exposed to. An earlier version of the data included in this manuscript was presented as Oral Abstract in the UK Society of Cardiothoracic Surgery Annual meeting in 2021.

A challenging case of emergency redo surgery for acute type A aortic dissecting aneurysm of ascending and aortic arch with frozen elephant trunk following aortic root replacement

Redo ascending and aortic arch surgeries following previous cardiac or aortic surgery are associated with high risk of morbidity and mortality due to multiple factors included sternal re-entry injury, extensive aortic arch surgery, emergency aortic surgery, prolonged cardiopulmonary bypass duration, poor heart function, and patients with older age. Therefore, appropriate surgical strategies are important. We report a case of a 72-year-old gentleman with previous surgery of aortic root replacement who presented with acute Type A aortic dissecting aneurysm of ascending and aortic arch complicated with left hemothorax, which was successfully treated by emergency redo aortic surgery with frozen elephant trunk (FET) technique.

Safety and efficacy of the novel Alpha stent for the treatment of intracranial wide-necked aneurysm

The Alpha stent is an intracranial closed-cell stent with a unique mesh design to enhance wall apposition. It recently underwent structural modifications to facilitate easier stent deployment. This study aimed to evaluate the safety and efficacy of stent-assisted coil embolization for unruptured intracranial aneurysms using the Alpha stent. Between January 2021 and November 2021, 35 adult patients with 35 unruptured intracranial aneurysms in the distal internal carotid artery were prospectively enrolled. For efficacy outcomes, magnetic resonance angiography at the 6-month follow-up was evaluated using the Raymond-Roy occlusion classification (RROC). The safety outcome evaluated the occurrence of symptomatic procedure-related neurological complications up to 6 months postoperatively. Technical success was achieved in 34/35 (97.1%). Six months postoperatively, aneurysm occlusion showed RROC I in 32/35 (91.4%) and RROC II in 3/35 (8.6%) patients. Procedure-related neurologic complications occurred in one patient (2.9%) who experienced hemiparesis due to acute lacunar infarction, which resulted in a 6-month mRS score of 1. The Alpha stent demonstrated excellent efficacy and safety outcomes in stent-assisted coil embolization of unruptured distal ICA aneurysms. The recent structural modifications allowed for easier stent delivery and deployment.Clinical trial registration number: KCT0005841; registration date: 28/01/2021.

Surgeon-modified fenestrated endovascular grafts and thoracoscope-assisted fixation for treatment of thoraco-abdominal aortic aneurysms

BACKGROUND

Total endovascular technique with fenestrated endovascular graft might be hampered for the late dilatation of proximal landing zone, which may cause endografts migration. We describe a successful urgent hybrid procedure for extent III thoracoabdominal aortic aneurysm with aortic intramural hematoma.

CASE PRESENTATION

A 55-year-old female with thoracoabdominal aortic aneurysm was considered at high surgical risk and unfit for open repair due to multiple comorbidities. Therefore, a hybrid procedure of surgeon-modified fenestrated endovascular graft combined with thoracoscope-assisted Transaortic epicardial fixation of endograft was finally chosen and performed in the endovascular operating room. A 3-port technique was performed through a left video-assisted thoracoscopic approach. After the first tampering stent-graft was deployed, a double-needle suture was penetrated both the aortic wall and stent-graft to fixate it in the proximal descending aorta. Then the second endograft, which had been fenestrated on table, was introduced and oriented extracorporeally by rotating superior mesenteric artery and left renal artery fenestration radiopaque markers and deployed with perfect apposition between the fenestrations and target visceral artery. Each vessel was sequentially stented using Viabahn self-expandable stent to finish target vessel stenting. An Ankura cuff stent was deployed in the distal abdominal aortic artery.

CONCLUSION

Surgeon-modified fenestrated endovascular graft combined with thoracoscope-assisted fixation may be an innovative and viable alternative for selected high-risk patients with extent III thoracoabdominal aortic aneurysm. A longer follow-up is needed to ascertain the success of this approach.

Endovascular repair of an abdominal aortic aneurysm with external iliac artery occlusion using VBX as the contralateral leg via axillary delivery: A case report

RATIONALE

A hostile iliac access route is an important consideration when enforcing endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAA). Herein, we report a case of AAA with unilateral external iliac artery occlusion, for which bifurcated EVAR was successfully performed using a single femoral and brachial artery access.

PATIENT CONCERNS

A 76-year-old man who had undergone surgery for lung cancer 4.5 years prior was diagnosed AAA by computed tomography (CT).

DIAGNOSIS

Two and a half years before presentation, CT revealed an infrarenal 48 mm AAA, which had enlarged to 57 mm by 2 months preoperatively. CT identified occlusion from the right external iliac artery to the right common femoral artery, with no observed ischemic symptoms in his right leg. The right external iliac artery, occluded and atrophied, had a 1 to 2 mm diameter.

INTERVENTION

Surgery was commenced with the selection of a Zenith endovascular graft (Cook Medical) with an extended body length. Two Gore Viabahn VBX balloon expandable endoprosthesis (VBX; W.L. Gore & Associate) were delivered from the right axilla as the contralateral leg.

OUTCOMES

CT scan on the 2nd day after surgery revealed no endoleaks.

LESSONS

While the long-term results remain uncertain, this method may serve as an option for EVAR in patients with unilateral external iliac artery occlusion.

Endovascular Repair With Triple Inner-Branch Endograft for Aberrant Subclavian Artery Aneurysm: A Case Report

BACKGROUND

Endovascular repair of the thoracic aorta (TEVAR) is the preferred option for the treatment of the distal arch and descending thoracic aorta. Fenestrated and branched TEVAR have become an option to treat pathologies of the aortic arch, avoiding sternotomy and cardiopulmonary arrest as well as total surgical debranching. We describe here the case of a symptomatic patient with an arteria lusoria aneurysm associated with Kommerel diverticulum who underwent total endovascular repair with a triple-branched TEVAR.

CASE REPORT

A 66-year-old male patient was treated for a symptomatic arteria lusoria artery associated with a Kommerel diverticulum, resulting in difficulty swallowing and choking. We used a custom-made triple inner-branch endograft (Cook Medical, Bloomington, Indiana) following implantation of a right-sided carotid-subclavian (C-S) bypass. The C-S bypass occluded in the interval time between the 2 procedures and required recanalization and stent-graft placement during the aortic arch procedure. The arteria lusoria was embolized with a vascular plug. No complications occurred and postoperative tomography showed exclusion and thrombosis of the Kommerel diverticulum and perfusion of the supra-aortic vessels.

CONCLUSIONS

Treatment of arteria lusoria aneurysms can be performed with total endovascular arch inner-branch repair, avoiding increased risk of morbidity and mortality caused by open or hybrid procedures.

Design and implementation of mechanical property testing equipment for thoracic aortic stent grafts

The mechanical properties of the stent graft are important factors influencing the outcome of TEVAR treatment and the occurrence of postoperative complications. The aim of this study is to improve and design a mechanical performance testing equipment for thoracic aortic stent grafts. The mechanical performance testing equipment consists of a radial force testing equipment of the stent graft designed by the wire compression grip method and a dynamic straightening force testing device with stable and controllable test conditions and continuously variable test angles. By constructing the testing equipment to physically measure the stent specimen, the experimental results reflect the trend of change and the simulation results are basically consistent, i.e. the mechanical properties of the thoracic aortic stent designed in this study is feasible and the measured data are valid. The testing equipment can provide the basis and reference direction for the quality testing of stent graft products, optimisation of mechanical properties of stent grafts and R&D innovation.

Fabrication and biomechanical characterization of a spider silk reinforced fibrin-based vascular prosthesis

With fibrin-based vascular prostheses, vascular tissue engineering offers a promising approach for the fabrication of biologically active regenerative vascular grafts. As a potentially autologous biomaterial, fibrin exhibits excellent hemo- and biocompatibility. However, the major problem in the use of fibrin constructs in vascular tissue engineering, which has so far prevented their widespread clinical application, is the insufficient biomechanical stability of unprocessed fibrin matrices. In this proof-of-concept study, we investigated to what extent the addition of a spider silk network into the wall structure of fibrin-based vascular prostheses leads to an increase in biomechanical stability and an improvement in the biomimetic elastic behavior of the grafts. For the fabrication of hybrid prostheses composed of fibrin and spider silk, a statically cast tubular fibrin matrix was surrounded with an envelope layer of Trichonephila edulis silk using a custom built coiling machine. The fibrin matrix was then compacted and pressed into the spider silk network by transluminal balloon compression. This manufacturing process resulted in a hybrid prosthesis with a luminal diameter of 4 mm. Biomechanical characterization revealed a significant increase in biomechanical stability of spider silk reinforced grafts compared to exclusively compacted fibrin segments with a mean burst pressure of 362 ± 74 mmHg vs. 213 ± 14 mmHg (p < 0.05). Dynamic elastic behavior of the spider silk reinforced grafts was similar to native arteries. In addition, the coiling with spider silk allowed a significant increase in suture retention strength and resistance to external compression without compromising the endothelialization capacity of the grafts. Thus, spider silk reinforcement using the abluminal coiling technique represents an efficient and reproducible technique to optimize the biomechanical behavior of small-diameter fibrin-based vascular grafts.

Case Series on Double-Barrel Stenting for the Renal Arteries Associated With Fenestrated Repair (FEVAR) of Complex Anatomy Aortic Aneurysms

The double-barrel stenting (DBS) is a technique in which 2 parallel stents are simultaneously deployed through the same reinforced fenestration, into 2 adjacent target vessels. Prior reports describe the application of this technique for the treatment of superior mesenteric artery dissection with aneurysmal degeneration, coronary artery bifurcations, aortic arch branches, and intracranial aneurysms. The DBS technique is particularly useful in the context of fenestrated repair (FEVAR) of complex anatomy aortic aneurysms when the origin of visceral arteries branch off the aorta very close to each other or present early branches. We herein describe a case series including 7 patients who underwent a FEVAR procedure for thoracoabdominal and juxtarenal aortic aneurysms in which the presence of accessory renal arteries (ARA) or early renal branches was the reason for the application of this technique. Technical success was 100% and all stents were patent in the last follow-up CT scan (follow-up range: 1.8-62.8 months). There was only 1 small endoleak from indetermined source potentially related to the DBS, but the aneurysm sac decreased in size during follow-up and no secondary intervention was needed. Therefore, the DBS technique is a viable option for the incorporation of ARA or early renal branches to a fenestrated repair of aortic aneurysms with complex anatomy.

Water-Induced Expanded Bilayer Vascular Graft with Good Hemocompatibility and Biocompatibility

Shape memory polymer (SMP) vascular grafts are promising interventional vascular grafts for cardiovascular disease (CAD) treatment; However, hemocompatibility and biocompatibility, which are the critical issues for the SMP vascular grafts, are not systematically concerned. Furthermore, the water-induced SMP grafts are more convenient and safer than the thermally induced ones in case of the bioapplication. Herein, in this work, the new water-induced expanded bilayer vascular graft with the inner layer of crosslinked poly(ε-caprolactone) (cPCL) and the outer layer of water-induced SMP of regenerated chitosan/polyvinyl alcohol (RCS/PVA) are prepared by hot pressing and programming approaches. The results show that the inner and outer layer surfaces of the prepared grafts are smooth, and they exhibit good interfacial interaction properties. The bilayer grafts show good mechanical properties and can be expanded in water with a diameter expansion of ≈30%. When compared with commercial expanded polytetrafluoroethylene (ePTFE), the bilayer graft shows better hemocompatibility (platelet adhesion, hemolysis rate, various clotting times, and plasma recalcification time (PRT)) and in vitro and in vivo biocompatibility, which thus is a promising material for the vascular graft.

Determination of Significant Three-Dimensional Hemodynamic Features for Postembolization Recanalization in Cerebral Aneurysms Through Explainable Artificial Intelligence

BACKGROUND

Recanalization poses challenges after coil embolization in cerebral aneurysms. Establishing predictive models for postembolization recanalization is important for clinical decision making. However, conventional statistical and machine learning (ML) models may overlook critical parameters during the initial selection process.

METHODS

In this study, we automated the identification of significant hemodynamic parameters using a PointNet-based deep neural network (DNN), leveraging their three-dimensional spatial features. Further feature analysis was conducted using saliency mapping, an explainable artificial intelligence (XAI) technique. The study encompassed the analysis of velocity, pressure, and wall shear stress in both precoiling and postcoiling models derived from computational fluid dynamics simulations for 58 aneurysms.

RESULTS

Velocity was identified as the most pivotal parameter, supported by the lowest P value from statistical analysis and the highest area under the receiver operating characteristic curves/precision-recall curves values from the DNN model. Moreover, visual XAI analysis showed that robust injection flow zones, with notable impingement points in precoiling models, as well as pronounced interplay between flow dynamics and the coiling plane, were important three-dimensional features in identifying the recanalized aneurysms.

CONCLUSIONS

The combination of DNN and XAI was found to be an accurate and explainable approach not only at predicting postembolization recanalization but also at discovering unknown features in the future.

Early Institutional Experience with One-Piece Bifurcated-Fenestrated Stentgraft in the Treatment of Abdominal Aortic Aneurysms

PURPOSE

To review the early experience of the use of a bifurcated-fenestrated endograft (Bif-FEVAR) to treat abdominal aortic aneurysms (AAA) in a high-volume aortic center.

METHODS

A retrospective single-center analysis was conducted between March 2019 and April 2021 including consecutive patients that underwent Bif-FEVAR. Only patients without a proper infrarenal neck and a distance <70 mm between the lowest target artery and the native or prosthetic aortic bifurcation were considered. All Bif-FEVAR custom-made devices were manufactured by Cook Medical (Inc., Bloomington, Indiana). Demographics, anatomical features, technical success, major adverse events, 30-day mortality, and survival according to Kaplan-Meier were analyzed according to Society for Vascular Surgery standards.

RESULTS

Overall, 10 patients (100% male with median age 78) were included. The median preoperative maximal aneurysm diameter was 68 mm [51-84]. Eight patients were treated for a proximal type I endoleak after endovascular aneurysm repair. A total of 36 fenestrations were planned. The median operative time was 144 min [127-168], with a median fluoro time of 40.5 min [34-54] and a median dose area product of 73 Gy cm2 [61-89]. Technical success rate was 100%. No patients experienced a major postoperative adverse event. Median follow-up time was 8 months [6-13].

CONCLUSION

Bif-FEVAR is technically feasible when there is a short distance below the lowest target artery and the aortic bifurcation, with favorable short-term results.

CLINICAL IMPACT

This study assessed the use of an innovative one-piece bifurcated fenestrated stent-graft as a primary procedure or in the treatment of proximal endoleak after standard infrarenal EVAR. We demonstrated these custom-made devices can be used safely with favorable short-term results. One-piece bifurcated fenestrated stent-grafts extend the indications of FEVAR for patients with an unusually short distance between the lowest renal artery and the aorto-iliac bifurcation or the diverter flow of a preexisting bifurcated infrarenal stent-graft.

Endovascular Coil Embolization of an Enlarging Gastroduodenal Artery Aneurysm

Gastroduodenal artery aneurysms are a rare type of visceral aneurysm that can lead to rupture and death. We present a 75-year-old male with history of hypertension, diabetes, and hyperlipidemia with an incidental finding of a 3.2 × 3.7 cm gastroduodenal aneurysm found on abdominal computed tomography angiography (CTA). After refusing surgical intervention, he was seen two years later and presented with an enlarged gastroduodenal aneurysm, now 5.0 × 5.1 cm, visible on a repeat abdominal CTA. Upon his continued refusal for an open surgery, we elected for endovascular repair of this GDA aneurysm via coil embolization.

Polyglycerol sebacate-based elastomeric materials for arterial regeneration

Synthetic vascular grafts are commonly used in patients with severe occlusive arterial disease when autologous grafts are not an option. Commercially available synthetic grafts are confronted with challenging outcomes: they have a lower patency rate than autologous grafts and are currently unable to promote arterial regeneration. Polyglycerol sebacate (PGS), a non-toxic polymer with a tunable degradation profile, has shown promising results as a small-diameter vascular graft component that can support the formation of neoarteries. In this review, we first present an overview of the synthesis and modification of PGS followed by an examination of its mechanical properties. We then report on the performance, degradation, regeneration, and remodeling of PGS-based small-diameter vascular grafts, with a focus on efforts to reduce thrombosis, prevent dilation, and promote cellular residency and extracellular matrix regeneration that resembles the native artery in spatial distribution and organization. We also highlight recent advances in the incorporation of novel in situ cell sources for arterial regeneration and their potential application in PGS-based vascular grafts. Finally, we compare vascular grafts fabricated using PGS-based materials with other elastomeric alternatives.

On the necessity to include arterial pre-stress in patient-specific simulations of minimally invasive procedures

Transcatheter aortic valve implantation (TAVI) and thoracic endovascular aortic repair (TEVAR) are minimally invasive procedures for treating aortic valves and diseases. Finite element simulations have proven to be valuable tools in predicting device-related complications. In the literature, the inclusion of aortic pre-stress has not been widely investigated. It plays a crucial role in determining the biomechanical response of the vessel and the device-tissue interaction. This study aims at demonstrating how and when to include the aortic pre-stress in patient-specific TAVI and TEVAR simulations. A percutaneous aortic valve and a stent-graft were implanted in aortic models reconstructed from patient-specific CT scans. Two scenarios for each patient were compared, i.e., including and neglecting the wall pre-stress. The neglection of pre-stress underestimates the contact pressure of 48% and 55%, the aorta stresses of 162% and 157%, the aorta strains of 77% and 21% for TAVI and TEVAR models, respectively. The stent stresses are higher than 48% with the pre-stressed aorta in TAVI simulations; while, similar results are obtained in TEVAR cases. The distance between the device and the aorta is similar with and without pre-stress. The inclusion of the aortic wall pre-stress has the capability to give a better representation of the biomechanical behavior of the arterial tissues and the implanted device. It is suggested to include this effect in patient-specific simulations replicating the procedures.

Small-diameter vascular graft composing of core-shell structured micro-nanofibers loaded with heparin and VEGF for endothelialization and prevention of neointimal hyperplasia

Despite the significant progress made in recent years, clinical issues with small-diameter vascular grafts related to low mechanical strength, thrombosis, intimal hyperplasia, and insufficient endothelialization remain unresolved. This study aims to design and fabricate a core-shell fibrous small-diameter vascular graft by co-axial electrospinning process, which will mechanically and biologically meet the benchmarks for blood vessel replacement. The presented graft (PGHV) comprised polycaprolactone/gelatin (shell) loaded with heparin-VEGF and polycaprolactone (core). This study hypothesized that the shell structure of the fibers would allow rapid degradation to release heparin-VEGF, and the core would provide mechanical strength for long-term application. Physico-mechanical evaluation, in vitro biocompatibility, and hemocompatibility assays were performed to ensure safe in vivo applications. After 25 days, the PGHV group released 79.47 ± 1.54% of heparin and 86.25 ± 1.19% of VEGF, and degradation of the shell was observed but the core remained pristine. Both the control (PG) and PGHV groups demonstrated robust mechanical properties. The PGHV group showed excellent biocompatibility and hemocompatibility compared to the PG group. After four months of rat aorta implantation, PGHV exhibited smooth muscle cell regeneration and complete endothelialization with a patency rate of 100%. The novel core-shell structured graft could be pivotal in vascular tissue regeneration application.

Outcome Analysis From a Multicenter Registry on Unibody Stent-Graft System for the Treatment of Spontaneous Infrarenal Acute Aortic Syndrome (MURUSSIAS Registry)

PURPOSE

This study reports the outcomes from a Multicenter Registry on unibody stent-graft system for the treatment of spontaneous infrarenal acute aortic syndrome (MURUSSIAS registry).

MATERIALS AND METHODS

The retrospective MURUSSIAS registry included spontaneous infrarenal acute aortic dissection (IAAS) managed with the unibody stent-graft system (AFX endovascular AAA system; Endologix Inc., Irvine, California) outside the current instruction for use. IAAS considered aortic dissection (AD), intramural hematoma (IMH), and penetrating aortic ulcer (PAU). Indications to IAAS treatment were symptoms, associated dilated abdominal aorta (>3 cm), rapidly-growing (>0.5 cm/6 months) aorta, IAAS disease progression. Measured results were technical success, early (within 30 days) and midterm outcomes (after 30 days), including mortality, complications, symptoms recurrence, type I/III endoleak occurrence, stent-graft patency, survival, and freedom from reintervention. The mean follow-up was 22.12 ± 17 months.

RESULTS

The MURUSSIAS registry included 83 patients from 7 participating centers. IAAS indication to treatment were symptoms in 42 (51%). In 14 (17%) patients, the infrarenal aortic length was <80 mm, and in 28 (34%), the aortic bifurcation diameter was <16 mm. Technical success was 100%. Mortality occurred early in 1 (1%) and at the midterm in 3 (4%) patients. Complications occurred early in 10 (12%) patients (1 severe, 3 moderates, and 6 mild) and at midterm in 2 (2%) (2 moderate). No symptoms' recurrence or type I/III endoleaks were registered. The 36-month estimated survival and freedom from reinterventions were 89% and 92%, respectively.

CONCLUSIONS

The MURUSSIAS registry is the largest collection of spontaneous IAAS managed endovascularly using the AFX endovascular AAA system. The IAAS peculiar anatomic features were fitted with the used technique with excellent results. This treatment strategy might be considered in IAAS unless specifically-designed endovascular solutions will be available also in the emergent setting. Further studies are required to assess the longer-term performances and the stability of the reported technique.

CLINICAL IMPACT

The lack of specifically designed devices for infrarenal acute aortic syndrome (IAAS) disease remains an issue principally for its specific anatomic features. The MURUSSIAS registry retrospectively examined the outcomes of spontaneous IAAS treated using the unibody stent-graft system in a spontaneous national study; and reports the largest available data on this topic. The use of the unibody stent-graft system showed to fit the anatomic peculiarities of IAAS with excellent outcomes. This IAAS treatment strategy should be considered unless specifically designed endovascular solutions will be available.

In-hospital thromboembolic complications after frozen elephant trunk aortic arch repair

OBJECTIVE

This study evaluated the frequency and clinical impact of thromboembolic complications after frozen elephant trunk aortic arch repair using the Thoraflex device (Terumo Aortic).

METHODS

A total of 128 consecutive patients (mean age 67.9 ± 13.7 years, 31.0% female) underwent frozen elephant trunk aortic arch repair using the Thoraflex device between September 2014 and May 2021 in 4 Canadian centers. Patient baseline characteristics, intraoperative details, and frozen elephant trunk thromboembolic complications were collected retrospectively and analyzed.

RESULTS

Fifteen patients (11.7%) had thrombus visualized within the frozen elephant trunk stent graft on imaging (n = 8; 53.3%) or had a thromboembolic event (n = 9; 60.0%) before hospital discharge. Sites of embolism were mesenteric (n = 8; 88.9%), renal (n = 4; 44.4%), and iliofemoral (n = 1; 11.1%). Patients who experienced thromboembolic complications were more likely to have a history of autoimmune disease (n = 3; 20.0% vs n = 2; 1.8%; P = .01) and implantation of a longer frozen elephant trunk stent graft (150 mm vs 100 mm) (n = 13; 86.7% vs n = 45; 39.8%; P < .001). All patients with thromboembolic complications received therapeutic anticoagulation, and a smaller proportion required an open surgical (n = 5; 33.3%) or an endovascular (n = 2; 13.3%) intervention. Radiographic resolution of thromboembolic complications was observed in 86.7% of patients (n = 13). In-hospital mortality occurred in 1 patient, stroke occurred in 1 patient, and transient spinal cord injury occurred in 1 patient.

CONCLUSIONS

Thromboembolic complications occur more often than previously recognized after frozen elephant trunk aortic arch repair using the Thoraflex device and are associated with increased rates of surgical and endovascular reintervention. Prevention and management of these complications require further study.

Outcomes of "Anterior Versus Posterior Divisional Branches of the Hypogastric Artery as Distal Landing Zone for Iliac Branch Devices": The International Multicentric R3OYAL Registry

OBJECTIVE

The aim of this multicentric registry was to assess the outcomes of "anteRior versus posteRior divisional bRanches Of the hYpogastric artery as distAl landing zone for iLiac branch devices (R3OYAL)."

METHODS

The main exposure of interest for the purpose of this study was the internal iliac artery (IIA) divisional branch (anterior vs posterior) that was used as distal landing zone. Early endpoints included technical success and adverse events. Late endpoints included survival, primary/secondary IIA patency, and IIA branch instability.

RESULTS

A total of 171 patients were included in the study, of which 50 received bilateral implantation of iliac branch devices (IBDs). This resulted in a total of 221 incorporated IIAs included in the final analysis, of which 40 were anterior divisional branches and 181 were posterior divisional branches. Technical success was high in both groups (anterior division: 98% vs posterior division: 100%, P = .18). Occurrence of any adverse event was noted in 14% of patients in both groups (P = 1.0). The overall rate of freedom from the composite IBD branch instability did not show significant differences between patients receiving distal landing in the anterior or posterior division of the IIA at 3 years (79% vs 87%, log-rank test = .215). The 3-year estimates of IBD patency were significantly lower in patients who received distal landing in the anterior divisional branch than those who received distal landing in the posterior divisional branch (primary patency: 81% vs 96%, log-rank test = .009; secondary patency: 81% vs 97%, log-rank test < .001).

CONCLUSIONS

The use of the anterior or posterior divisional branches of the IIA as distal landing zone for IBD implantation shows comparable profiles in terms of immediate technical success, perioperative safety, and side-branch instability up to 3 years. However, IBD patency at 3 years was higher when the distal landing zone was achieved within the posterior divisional branch of the IIA.

CLINICAL IMPACT

The results from this large multicentric registry confirm that use of the anterior or posterior divisional branches of the internal iliac artery (IIA) as distal landing zone for implantation of iliac branch devices (IBD) shows comparable profiles of safety and feasibility, thereby allowing to extend the indications for endovascular repair of aorto-iliac aneurysms to cases with unsuitable anatomy within the IIA main trunk. Although mid-term rates of device durability and branch instability seem to be similar, the rates of primary and secondary IBD patency at three years was favored when the distal landing zone was achieved in the posterior divisional branch of the IIA.

Complex Endovascular Repair of Paravisceral Infective Native Aortic Aneurysms

OBJECTIVE

To report the early and mid-term outcome of complex endovascular repair (EVAR) for paravisceral infective native aortic aneurysms (INAA).

METHODS

Interrogation of a prospectively maintained database identified consecutive patients who underwent non-elective complex EVAR for paravisceral INAAs in a single institution between December 2013 and June 2020. All patients were considered to have definite INAAs based on diagnostic criteria. Patients who had prior aortic repair were excluded.

RESULTS

A total of 26 patients (19 men; mean age 67 years [SD = 11.4]; median diameter 60 mm [IQR: 55-73]) with acute symptomatic (n = 24) or contained ruptured (n = 2) aneurysms underwent surgeon-modified fenestrated EVAR (SM-FEVAR; n = 24) or chimney-periscope EVAR (CHIMPS; n = 2). Median observed follow-up was 36.2 months (18.3-53.5). Nine patients had positive venous blood cultures and a further seven had recent or concomitant infection. All patients received pre- and post-operative antibiotic therapy and rifampicin-soaked endografts. A total of 95 vessels were targeted for preservation and 86 were stent-grafted. One vessel occluded intra-operatively and a further 3 occluded within 30 days. The 30-day/in-hospital mortality was 11.5% (n = 3), and the estimated 1- and 3-year survival (±SD) was 85% ± 7%. Infection-related complications (IRCs) occurred in two patients: both developed new INAA within 30 days of index repair and were treated by EVAR with no mortality. Estimated 3-year freedom from late re-intervention was 100%. One patient required infrarenal EVAR for a non-infective aneurysm at 43 months.

CONCLUSION

Complex EVAR for paravisceral INAAs is associated with acceptable early and mid-term outcomes and is an acceptable alternative to open surgery. We propose that these patients are managed with long-term antimicrobials, impregnation of graft material with rifampicin, and rigorous post-operative surveillance.

CLINICAL IMPACT

A multi-disciplinary approach is required to deliver the best possible outcome for patients with this challenging aortic pathology.

Six-year clinical and computed tomography angiography follow-up after Nexus implantation

Endovascular aortic arch repair (Ar-TEVAR) with single-branch, off-the-shelf Nexus aortic arch system has shown promising early and 3-year outcomes. There is lack of data regarding long-term results of this specific device, particularly regarding patency of supra-aortic bypasses and stability of the connection between the 2 modules. This case report describes 6-year clinical and imaging follow-up of a 74-year-old patient who underwent Ar-TEVAR with Nexus. Over 6 years, the patient experienced minor complications unrelated to the device. The patency of supra-aortic bypasses and integrity of the device's connection were confirmed. Computed tomography angiography constantly showed exclusion of the aneurysm and reduction of the aneurysmal sac. In conclusion, although extended research and broader data are needed, this case provides encouraging evidence of long-term results of Ar-TEVAR with Nexus.

Hybrid noncovered open stents in repair of DeBakey type 1 acute aortic dissections

OBJECTIVES

The indications for use, evidence base and experience with the novel noncovered open hybrid surgical stents for acute type A aortic dissection repair for concurrent stabilization of the 'downstream' aorta remains limited. We review the evidence base and the development of these stents.

METHODS

Data were collected from Pubmed/Medline literature search to develop and review the evidence base for safety and efficacy of non-covered surgical stents. Existing guidelines for use and developments were reviewed.

RESULTS

A single randomized control trial and 4 single-centre studies were included in the review with a total worldwide experience of 241 patients. The deployment was easy and did not add significantly to the primary operation. The mortality and new stroke ranged from 6.3-18.7%. Safe and complete deployment was accomplished in 92-100%. There was no device-related reintervention. There was a significant improvement in malperfusion in over 90% of the cases with varying degrees of remodelling (60-90%) of the downstream aorta.

CONCLUSIONS

Open noncovered stent grafts represent a major technical advancement as an adjunct procedure for acute dissection repairs, e.g. hemiarch repair. It has potential for wider use by non-aortic surgeons due to simplicity of technique. Limited safety and efficacy data confirm the device to be safe, feasible and reproducible with potential for wider adoption. However, long-term trial and registry data are required before recommendations for standard use outside of high-volume experienced aortic centres.

Long-term observation of polycaprolactone small-diameter vascular grafts with thickened outer layer and heparinized inner layer in rabbit carotid arteries

In our previous study, the pristine bilayer small-diameterin situtissue engineered vascular grafts (pTEVGs) were electrospun from a heparinized polycaprolactone (PCL45k) as an inner layer and a non-heparinized PCL80k as an outer layer in the thickness of about 131 μm and 202 μm, respectively. However, the hydrophilic enhancement of inner layer stemmed from the heparinization accelerated the degradation of grafts leading to the early formation of arterial aneurysms in a period of 3 months, severely hindering the perennial observation of the neo-tissue regeneration, host cell infiltration and graft remodeling in those implanted pTEVGs. Herein to address this drawback, the thickness of the outer layers was increased with PCL80k to around 268 μm, while the inner layer remained unchangeable. The thickened TEVGs named as tTEVGs were evaluated in six rabbits via a carotid artery interpositional model for a period of 9 months. All the animals kept alive and the grafts remained patent until explantation except for one whose one side of arterial blood vessels was occluded after an aneurysm occurred at 6 months. Although a significant degradation was observed in the implanted grafts at 9 month, the occurrence of aneurysms was obviously delayed compared to pTEVGs. The tissue stainings indicated that the endothelial cell remodeling was substantially completed by 3 months, while the regeneration of elastin and collagen remained smaller and unevenly distributed in comparison to autologous vessels. Additionally, the proliferation of macrophages and smooth muscle cells reached the maximum by 3 months. These tTEVGs possessing a heparinized inner layer and a thickened outer layer exhibited good patency and significantly delayed onset time of aneurysms.

Complex aortic-arch pseudoaneurysm with aorto-innominate vein fistula in a case of traumatic chest injury

A patient in his late 30s presented with issues of retrosternal chest pain and palpitations. He had sustained a splinter injury to the left hemithorax a year ago for which he had been managed with a tube thoracostomy. During subsequent evaluations, he was found to have atrial fibrillations and a CT angiography revealed an arch of the aorta pseudoaneurysm with a fistulous communication with the innominate vein, which being a rare condition has no established treatment protocols. Endovascular salvage of the condition required an aortic Ishimaru zone 2 deployment of the thoracic endovascular aortic repair stent graft to provide an adequate landing zone. The elective left subclavian artery revascularisation was obtained by a left carotid artery to left subclavian artery bypass. Post procedure there was complete exclusion of the pseudoaneurysm sac, and the fistulous aorto-venous communication inflow tract. The patient recuperated well and has returned to full active duties.

Tissue engineered vascular grafts are resistant to the formation of dystrophic calcification

Advancements in congenital heart surgery have heightened the importance of durable biomaterials for adult survivors. Dystrophic calcification poses a significant risk to the long-term viability of prosthetic biomaterials in these procedures. Herein, we describe the natural history of calcification in the most frequently used vascular conduits, expanded polytetrafluoroethylene grafts. Through a retrospective clinical study and an ovine model, we compare the degree of calcification between tissue-engineered vascular grafts and polytetrafluoroethylene grafts. Results indicate superior durability in tissue-engineered vascular grafts, displaying reduced late-term calcification in both clinical studies (p < 0.001) and animal models (p < 0.0001). Further assessments of graft compliance reveal that tissue-engineered vascular grafts maintain greater compliance (p < 0.0001) and distensibility (p < 0.001) than polytetrafluoroethylene grafts. These properties improve graft hemodynamic performance, as validated through computational fluid dynamics simulations. We demonstrate the promise of tissue engineered vascular grafts, remaining compliant and distensible while resisting long-term calcification, to enhance the long-term success of congenital heart surgeries.

Antioxidant and Trilayered Electrospun Small-Diameter Vascular Grafts Maintain Patency and Promote Endothelialisation in Rat Femoral Artery

Vascular grafts with a small diameter encounter inadequate patency as a result of intimal hyperplasia development. In the current study, trilayered electrospun small-diameter vascular grafts (PU-PGACL + GA) were fabricated using a poly(glycolic acid) and poly(caprolactone) blend as the middle layer and antioxidant polyurethane with gallic acid as the innermost and outermost layers. The scaffolds exhibited good biocompatibility and mechanical properties, as evidenced by their 6 MPa elastic modulus, 4 N suture retention strength, and 2500 mmHg burst pressure. Additionally, these electrospun grafts attenuated cellular oxidative stress and demonstrated minimal hemolysis (less than 1%). As a proof-of-concept, the preclinical evaluation of the grafts was carried out in the femoral artery of rodents, where the conduits demonstrated satisfactory patency. After 35 days of implantation, ultrasound imaging depicted adequate blood flow through the grafts, and the computed vessel diameter and histological staining showed no significant stenosis issue. Immunohistochemical analysis confirmed matrix deposition (38% collagen I and 16% elastin) and cell infiltration (42% for endothelial cells and 55% for smooth muscle cells) in the explanted grafts. Therefore, PU-PGACL + GA showed characteristics of a clinically relevant small-diameter vascular graft, facilitating re-endothelialization while preserving the anticoagulant properties of the synthetic blood vessels.

Hybrid surgery of vertebral artery transposition combined with scallop and fenestration technique for the repair of type B aortic dissection patient with isolated left vertebral artery: A case report

RATIONALE

Acute type B aortic dissection (ABAD) is a fatal cardiovascular disease with high morbidity and mortality. Isolated left vertebral artery (ILVA) is a rare aortic arch mutation originating from the aortic arch. The simultaneous occurrence of both increases the complexity and difficulty of thoracic endovascular aortic repair. However, there have been few reports on the recommendation of thoracic endovascular aortic repair treatment strategies for aortic dissection patients concomitant ILVA with insufficient landing zone. Here, we report a case of ABAD combined with ILVA treated with hybrid surgery of left vertebral artery transposition alliance with Scallop and in vivo fenestration endograft.

PATIENT CONCERNS

A 38-year-old middle-aged man was transferred to our vascular department with persistent pain in his lower abdomen for 8 hours.

DIAGNOSES

Preoperative computed tomography angiogram of the thoracic and abdominal aorta diagnosed with ABAD accompanied with ILVA.

INTERVENTIONS

Hybrid surgery of left vertebral artery transposition alliance with Scallop and in situ fenestration endograft for revascularization of ILVA, left subclavian artery, and left common carotid artery.

OUTCOMES

The hybridization operation was successfully completed. There were no complications of cerebral and spinal cord ischemia after operation. Computed tomography angiogram examination indicated no internal leakage existed in the stent and patency of the arch vessels and the transposed left vertebral artery follow-up 3 months after surgery.

LESSONS

This study gave us experience in the treatment of aortic dissection with left vertebral artery variation and suggested that left vertebral artery transposition combined with scallop and in vivo fenestration stent is safe and effective.

Iliac tortuosity increases reinterventions but not adverse outcomes following repair of juxtarenal aneurysms using physician-modified endografts

OBJECTIVE

Increased angulation of the proximal aortic neck has been associated with complications following endovascular repair of infrarenal aortic aneurysms, including increased incidence of endoleaks, stent migration, secondary interventions, and conversions. However, knowledge on the impact of aortoiliac tortuosity on outcomes following fenestrated repair remains limited. This study aims to quantify the effect of aortoiliac tortuosity on outcomes following fenestrated repair.

METHODS

A single-center, retrospective review of all patients who underwent a physician-modified endovascular repair for the treatment of juxtarenal aortic aneurysms under a single physician-sponsored investigation device exemption study from 2011 to 2021 was performed. Center luminal lines and geometric distances were obtained using TeraRecon software (San Mateo, CA). A tortuosity index was calculated (tortuosity index = centerline distance/geometric line distance) for each iliac vessel as well as for the infrarenal aorta according to Society for Vascular Surgery reporting standards. Aortic and iliac tortuosity were assessed independently and stratified as low and high. Demographics, comorbidities, anatomic and operative details, and outcomes were compared using univariable and multivariable analysis.

RESULTS

A total of 135 patients were identified. Thirty-eight patients (28%) had high aortic tortuosity, and 55 patients (42%) had high iliac tortuosity. Patients with high tortuosity were older (aortic: 78 vs 76 years; P = .04; iliac: 78 vs 75 years; P = .01) and differed by sex. Twenty-two percent of men and 50% of women had high aortic tortuosity (P = .01). Forty-seven percent of men and 20% of women had high iliac tortuosity (P = .01). There were no differences in comorbidities based on aortic tortuosity, but coronary artery disease (high: 58% vs low: 36%; P = .01) and hypertension (high: 69% vs low: 86%; P = .02) differed based on iliac tortuosity. Aneurysm diameter was larger for patients with high iliac tortuosity (72 mm vs 64 mm; P < .01), and fluoroscopy time was longer for patients with high aortic tortuosity (41 vs 31 minutes; P = .02). When outcomes were assessed, high iliac tortuosity was associated with increased rate of reinterventions (hazard ratio, 2.6; 95% confidence interval, 1.2-6.0) and type 1 or 3 endoleak (hazard ratio, 5.2; 95% confidence interval, 1.7-16); however, all other outcomes were similar.

CONCLUSIONS

Among patients treated with physician-modified endovascular repair for juxtarenal aneurysms, iliac tortuosity but not aortic tortuosity, is associated with increased reinterventions and type 1 or type 3 endoleaks. Long-term follow-up is critical for patients with high iliac tortuosity to ensure that high-risk endoleaks are identified and treated early to avoid the risk of rupture.

Proximalization of Frozen Elephant Trunk Procedure: Zone 0 or 1 versus Zone 2 or 3 Arch Repair

BACKGROUND

 Total arch replacement with the frozen elephant trunk (FET) procedure has changed the landscape of therapy for aortic arch diseases. The optimal landing zone for a FET is controversial. We sought to share our early and midterm results of the FET procedure as well as compare the clinical outcomes of proximal and distal FET anastomosis.

METHODS

 A total of 100 patients who underwent total arch replacement using the FET technique were identified between November 2014 and August 2021. According to the FET anastomosis over the aortic arch, patients were classified into two groups (zone 0/1 vs. zone 2/3). In-hospital mortality, complications, and midterm outcomes were assessed based on patient characteristics.

RESULTS

 The overall in-hospital mortality was 8%. Major complications occurred in 32% of patients, including spinal cord injury (5%), stroke (7%), and acute kidney injury requiring dialysis (7%). Zone 2/3 FET (odds ratio: 6.491, 95% confidence interval: 1.930-21.835, p = 0.003) was an independent predictor of the composite endpoint of major complications. The rate of complete false lumen thrombosis was comparable (64.3% vs. 71.4%, p = 0.567). All patients, patients with zone 0/1 FET, and patients with zone 2/3 FET had 3-year freedom from aorta-related events of 73.0, 70.2, and 75.0%, respectively. There were no significant differences (log-rank test, p = 0.500).

CONCLUSION

 Compared with zone 2/3, proximalization of FET using zone 0/1 for anastomosis was associated with better early outcomes and comparable rates of midterm aorta-related events. To substantiate its use, more research on this approach is required.

Ex vivo evaluation of 3 different right ventricular outflow tract substitutes

OBJECTIVES

The Ross procedure represents an excellent treatment option in younger patients with aortic stenosis but is limited by poor availability of homografts. In this study, we investigated the hydrodynamic performance of 3 different types of right ventricular outflow tract replacement with pericardium or synthetic material.

METHODS

Three different types of valved conduits were constructed using pericardium and/or synthetic material (Group PEPE: pericardial cusps and pericardial conduit, Group PEPR: pericardial cusps and Dacron conduit, Group PRPR: expanded polytetrafluoroethylene cusps and Dacron conduit). The conduits were designed according to the Ozaki method. Their hydrodynamic performance (effective orifice area, mean pressure gradient and leakage volume) were evaluated in a mock circulation loop at different hydrodynamic conditions.

RESULTS

Hydrodynamic assessment showed significantly larger effective orifice area of PEPE and PEPR compared to PRPR under all conditions and there were no significant differences between PEPE and PEPR [for condition 2: PEPE 2.43 (2.35-2.54) cm2, PEPR: 2.42 (2.4-2.5) cm2, PRPR: 2.08 (1.97-2.21) cm2, adjusted pairwise comparisons: PEPE versus PEPR: P = 0.80, PEPE versus PRPR: P  < 0.001, PEPR versus PRPR: P  < 0.001]. Mean pressure gradient was significantly lower for PEPE and PEPR compared with PRPR, whereas no significant differences were seen between PEPE and PEPR. Leakage volume was significantly lower for PEPE and PEPR compared with PRPR under all conditions while leakage was similar between PEPE and PEPR.

CONCLUSIONS

Pulmonary graft reconstruction with pericardium cusps showed superior hydrodynamic performance compared with polytetrafluoroethylene cusps. Our results suggest that it could be considered as an alternative substitute for right ventricular outflow tract replacement during the Ross procedure.

One-year outcomes of total arch replacement and frozen elephant trunk using the E-vita Open NEO

OBJECTIVES

In this cohort study, we aimed to assess the 1-year clinical outcomes of using the E-vita Open NEO™ hybrid prosthesis for total arch replacement with frozen elephant trunk (FET) to repair extensive aortic pathologies.

METHODS

We reviewed individuals who underwent thoracic aortic surgery between April 2021 and March 2023 from the Gangnam Severance Aortic Registry. Exclusion criteria included ascending aortic replacement, 1 or 2 partial arch replacement, descending aortic replacement and total arch replacement without an FET. Finally, all consecutive patients who underwent total arch replacement and FET with E-vita Open NEO for aortic arch pathologies between April 2021 and March 2023 were included in this cohort study. The patients were divided into 3 groups based on their pathology: acute aortic dissection, chronic aortic dissection and thoracic aortic aneurysm. The primary end point was in-hospital mortality. The secondary end points during the postoperative period comprised stroke, spinal cord injury and redo sternotomy for bleeding. Additionally, the secondary end points during the follow-up period included the 1-year survival rate, 1-year freedom from all aortic procedures and 1-year freedom from unplanned aortic interventions.

RESULTS

The study included 167 patients in total: 92 patients (55.1%) with acute aortic dissection, 20 patients (12.0%) with chronic aortic dissection and 55 patients (32.9%) with thoracic aortic aneurysm. The in-hospital mortality was 1.8% (n = 3). Strokes occurred in 1.8% (n = 3) of the patients, spinal cord injury in 1.8% (n = 3) and redo sternotomy for bleeding was performed in 3.0% (n = 5). There were no significant differences between the pathological groups. The median follow-up period (quartile 1-quartile 3) was 198 (37-373) days, with 1-year survival rates of 95.9%. At 1 year, the freedom from all aortic procedures and unplanned aortic interventions were 90.3% and 92.0%, respectively.

CONCLUSIONS

The 1-year clinical outcomes of total arch replacement with FET using the E-vita Open NEO were favourable. Long-term follow-up is required to evaluate the durability of the FET.

Early and midterm outcomes of fenestrated and branched endovascular aortic repair in thoracoabdominal aneurysms types I through III

BACKGROUND

Fenestrated and branched endovascular aortic repair (F/BEVAR) of thoracoabdominal aortic aneurysms (TAAAs) has shown high technical success and low early mortality rates. Aneurysm extent has been reported as a factor affecting outcomes. This study aimed to assess the early and midterm follow-up outcomes of patients managed by F/BEVAR for types I through III TAAAs.

METHODS

A single-center retrospective analysis was conducted, including data from consecutive, elective and urgent (symptomatic and ruptured cases), patients treated for types I through III TAAAs, between October 1, 2011, and October 1, 2022, using F/BEVAR. Degenerative and postdissection TAAAs were included. Patients received prophylactic cerebrospinal fluid drainage (CSFD), except those under therapeutic anticoagulation, those who were hemodynamically unstable, or those with failed CSFD application. When an initial thoracic endovascular aortic repair was performed, as part of a staged procedure, no CSFD was used. Later stages and nonstaged procedures were performed under CSFD. Thirty-day mortality and major adverse events (MAEs) were analyzed. Kaplan-Meier estimates were used for follow-up outcomes.

RESULTS

F/BEVAR for types I through III TAAAs was performed in 209 patients (56.9% males; mean age, 69.6 ± 3.2 years; mean aneurysm diameter, 65.2 ± 6.2 mm); 29.2% type I, 57.9% type II, and 12.9% type III. Urgent repair was performed in 26.7% of patients (56 cases; 23 ruptured and 33 symptomatic cases) and 153 were treated electively. Thirty-two patients (15.3%) were classified as American Society of Anesthesiologists (ASA) class IV. CSFD was used in 91% and staged thoracic endovascular aortic repair was performed in 51.2% of patients. Technical success was 93.8% (96.7% in elective vs 94.6% in urgent cases; P = .92). Thirty-day mortality was 11.0% (4.6% in elective vs 28.5% in urgent cases; P < .001) and MAEs were recorded in 17.2% of cases (7.8% in elective vs 42.8% in urgent cases; P < .001). Spinal cord ischemia rate was 20.5% (17.6% in elective vs 28.7% in urgent cases; P = .08), whereas 2.9% of patients presented paraplegia (1.3% in elective and 7.1% in urgent cases; P = .03). The mean follow-up was 16 ± 5 months. Survival was 75.0% (standard error, 4.0%) and freedom from reintervention was 73.3% (standard error, 4.4%) at 36 months. ASA IV and urgent repair were detected as independent factors related to early mortality and MAE, whereas ruptured aneurysm status was related to spinal cord ischemia evolution.

CONCLUSIONS

Endovascular repair for types I through III TAAAs provides encouraging early outcomes in terms of mortality, MAE, and paraplegia, especially in an elective setting. Setting of repair and baseline ASA score should be taken into consideration during decision-making.

Hemodynamic study on the therapeutic effects of varying diameter embolic coils in the treatment of intracranial aneurysms

Endovascular coiling is the predominant method for treating cerebral aneurysms. Extensive reports on selecting coil length, hardness, and material are available. However, the impact of coil diameter on postoperative outcomes remains unclear. This study enrolled six personalized geometric models of intracranial aneurysms: three bifurcation aneurysms and three sidewall aneurysms. Four coil models were constructed by changing the coil diameter. Coil embolization was simulated using the finite element method. Computational fluid dynamics was used to characterize hemodynamics in the aneurysms after embolization. Evaluation parameters included velocity reduction, wall shear stress (WSS), low WSS (LWSS), oscillatory shear index (OSI), relative residence time (RRT), and residual flow volume in the aneurysms. At the peak time (t = 0.17 s), the proportion of LWSS area in bifurcation aneurysms increase with the rise in coil diameter: 0.8D, 71.28 ± 12.62% versus 1D, 74.97 ± 19.17% versus 1.2D, 78.88 ± 18.56% versus 1.4D, 84.00 ± 11.53% (mean ± SD). The proportion of high OSI area decreases as the coil diameter increases: 0.8D, 4.41% ± 2.82% versus 1.0D, 3.78 ± 3.33% versus 1.2D, 2.28% ± 1.77% versus 1.4D, 1.58% ± 1.11% (mean ± SD). The proportion of high RRT area increases as the coil diameter rises: 0.8D, 3.40% ± 1.68% versus 1.0D, 7.67 ± 4.12% versus 1.2D, 9.84% ± 9.50% versus 1.4D, 22.29% ± 14.28% (mean ± SD). Side wall aneurysms do not exhibit the aforementioned trend. Bifurcation aneurysms plugged with a coil of 1.4 times the diameter have the largest RFVs (<10 mm/s) within the group. Aforementioned patterns are not found in sidewall aneurysms. In the treatment of aneurysms with coiling, varying coil diameters can result in different hemodynamic environments within the aneurysm. Larger coil diameters have improved hemodynamic performance for bifurcation aneurysms. However, coil diameter and embolization effectiveness have no significant relationship for sidewall aneurysms.

Photo-induced universal modification of small-diameter decellularized blood vessels with a hemocompatible peptide improves in vivo patency

Decellularized vessels (DVs) have the potential to serve as available grafts for small-diameter vascular (<6 mm) reconstruction. However, the absence of functional endothelia makes them likely to trigger platelet aggregation and thrombosis. Luminal surface modification is an efficient approach to prevent thrombosis and promote endothelialization. Previously, we identified a hemocompatible peptide, HGGVRLY, that showed endothelial affinity and antiplatelet ability. By conjugating HGGVRLY with a phenylazide group, we generated a photoreactive peptide that can be modified onto multiple materials, including non-denatured extracellular matrices. To preserve the natural collagen of DVs as much as possible, we used a lower ultrahydrostatic pressure than that previously reported to prepare decellularized grafts. The photoreactive HGGVRLY peptide could be modified onto DV grafts via UV exposure for only 2 min. Modified DVs showed improved endothelial affinity and antiplatelet ability in vitro. When rat abdominal aortas were replaced with DVs, modified DVs with more natural collagen demonstrated the highest patent rate after 10 weeks. Moreover, the photoreactive peptide remained on the lumen surface of DVs over two months after implantation. Therefore, the photoreactive peptide could be efficiently and sustainably modified onto DVs with more natural collagens, resulting in improved hemocompatibility. STATEMENT OF SIGNIFICANCE: We employed a relatively lower ultrahydrostatic pressure to prepare decellularized vessels (DVs) with less denatured collagens to provide a more favorable environment for cell migration and proliferation. The hemocompatibility of DV luminal surface can be enhanced by peptide modification, but undenatured collagens are difficult to modify. We innovatively introduce a phenylazide group into the hemocompatible peptide HGGVRLY, which we previously identified to possess endothelial affinity and antiplatelet ability, to generate a photoreactive peptide. The photoreactive peptide can be efficiently and stably modified onto DVs with more natural collagens. DV grafts modified with photoreactive peptide exhibit enhanced in vivo patency. Furthermore, the sustainability of photoreactive peptide modification on DV grafts within bloodstream is evident after two months of transplantation.

A polyurethane-based hydrophilic elastomer with multi-biological functions for small-diameter vascular grafts

Thrombosis and intimal hyperplasia (IH) are two major problems faced by the small-diameter vascular grafts. Mimicking the native endothelium and physiological elasticity of blood vessels is considered an ideal strategy. Polyurethane (PU) is suitable for vascular grafts in mechanics because of its molecular designability and elasticity; however, it generally lacks the endothelium-like biofunctions and hydrophilicity. To solve this contradiction, a hydrophilic PU elastomer is developed by crosslinking the hydrophobic hard-segment chains containing diselenide with diaminopyrimidine-capped polyethylene glycol (PEG). In this network, the hydrophobic aggregation occurs underwater due to the uninterrupted hard-segment chains, leading to a significant self-enhancement in mechanics, which can be tailored to the elasticity similar to natural vessels by adjusting the crosslinking density. A series of in vitro studies confirm that the hydrophilicity of PEG and biological activities of aminopyrimidine and diselenide give the PU multi-biological functions similar to the native endothelium, including stable catalytic release of nitric oxide (NO) in the physiological level; anti-adhesion and anti-activation of platelets; inhibition of migration, adhesion, and proliferation of smooth muscle cells (SMCs); and antibacterial effect. In vivo studies further prove the good histocompatibility with both significant reduction in immune response and calcium deposition. STATEMENT OF SIGNIFICANCE: Constructing small-diameter vascular grafts similar to the natural vessels is considered an ideal method to solve the restenosis caused by thrombosis and intimal hyperplasia (IH). Because of the long-term stability, bulk modification is more suitable for implanted materials, however, how to achieve the biofunctions, hydrophilicity, and elasticity simultaneously is still a big challenge. In this work, a kind of polyurethane-based elastomer has been designed and prepared by crosslinking the functional long hard-segment chains with PEG soft segments. The underwater elasticity based on hydration-induced stiffening and the multi-biological functions similar to the native endothelium are compatible with natural vessels. Both in vitro and in vivo experiments demonstrate the potential of this PU as small-diameter vascular grafts.