Patient-Specific Haemodynamic Analysis of Virtual Grafting Strategies in Type-B Aortic Dissection: Impact of Compliance Mismatch.

INTRODUCTION: Compliance mismatch between the aortic wall and Dacron Grafts is a clinical problem concerning aortic haemodynamics and morphological degeneration. The aortic stiffness introduced by grafts can lead to an increased left ventricular (LV) afterload. This study quantifies the impact of compliance mismatch by virtually testing different Type-B aortic dissection (TBAD) surgical grafting strategies in patient-specific, compliant computational fluid dynamics (CFD) simulations. MATERIALS AND METHODS: A post-operative case of TBAD was segmented from computed tomography angiography data. Three virtual surgeries were generated using different grafts; two additional cases with compliant grafts were assessed. Compliant CFD simulations were performed using a patient-specific inlet flow rate and three-element Windkessel outlet boundary conditions informed by 2D-Flow MRI data. The wall compliance was calibrated using Cine-MRI images. Pressure, wall shear stress (WSS) indices and energy loss (EL) were computed. RESULTS: Increased aortic stiffness and longer grafts increased aortic pressure and EL. Implementing a compliant graft matching the aortic compliance of the patient reduced the pulse pressure by 11% and EL by 4%. The endothelial cell activation potential (ECAP) differed the most within the aneurysm, where the maximum percentage difference between the reference case and the mid (MDA) and complete (CDA) descending aorta replacements increased by 16% and 20%, respectively. CONCLUSION: This study suggests that by minimising graft length and matching its compliance to the native aorta whilst aligning with surgical requirements, the risk of LV hypertrophy may be reduced. This provides evidence that compliance-matching grafts may enhance patient outcomes.

Bail-Out TEVAR through a Branch of Four-Arm Dacron Graft for Misdeployment of a Frozen Elephant Trunk Prosthesis.

The frozen elephant trunk (FET) is an effective method for making the distal anastomosis more proximal and facilitating aortic remodeling in acute aortic dissection. However, misdeployment of FET to the false lumen has been reported in several cases. Such cases are usually treated with bail-out thoracic endovascular aortic repair (TEVAR) through the femoral artery or additional FET under direct vision to redirect the blood flow to the true lumen. We encountered a case of misdeployment of FET into the false lumen during open aortic surgery for the treatment of Stanford type A acute aortic dissection. After reconstruction of the aorta and all arch vessels, we performed antegrade bail-out TEVAR through a side branch of the four-arm Dacron graft as main access using a pull-through technique through the right femoral artery, which was perfused from the true lumen. This technique, which uses a Dacron graft branch for stent graft access, enabled us to confirm the true lumen because the distal anastomotic site was definitely the true lumen, and we were also able to avoid access difficulties at the iliac artery.

Tratamiento quirúrgico del leiomiosarcoma de vena cava inferior

Introducción: La baja incidencia del leiomiosarcoma de la vena cava inferior dificulta tanto la estandarización del diagnóstico como el tratamiento. Objetivo: Presentar el manejo realizado en nuestro centro de un paciente que desarrolló un leiomiosarcoma de vena cava inferior, una patología de baja incidencia y que las posibilidades de realizar un rescate quirúrgico son muy bajas. Resultados: Se presenta el caso de un paciente de 54 años con una tumoración sólida en porción infrarrenal y yuxtarrenal de vena cava inferior de 71 × 76 × 117 mm compatible con leiomiosarcoma de vena cava, con infiltración de uréter derecho que ocasiona uropatía obstructiva derecha grado I-II sin alteración de la función renal, que fue resecada y reconstruida mediante prótesis sin complicaciones. Discusión: Se discute la fisiopatología, el diagnóstico y manejo en relación con el caso presentado. Conclusión: la baja incidencia de estos tumores dificulta tanto la estandarización del diagnóstico como del tratamiento, aunque la cirugía sigue siendo el tratamiento de elección.

Introduction: The low incidence of leiomyosarcoma of the inferior vena cava hinders both the standardization of diagnosis and treatment. Objective: To present the management carried out in our center of a patient who developed an inferior vena cava leiomyosarcoma, a low incidence pathology with uncertain surgical rescue. Results: 54-year-old patient with a solid tumor in the infrarenal and juxtarenal portions of the inferior vena cava of 71 × 76 × 117 mm compatible with leiomyosarcoma of the vena cava, with infiltration of the right ureter that causes right obstructive uropathy grade I-II without kidney function changes; tumour was resected and continuity reconstructed with a prosthesis without complications. Discussion: The pathophysiology, diagnosis and management are commented. Conclusion: the low incidence of these lesions makes it difficult to standardize both diagnosis and treatment, although surgery remains the treatment of choice.

Adjunctive proximal aortic and aortodistal prosthetic wrapping of vascular anastomoses for Adamantiadis-Behçet's aortic/aortoiliac aneurysms: A revisit.

BACKGROUND: We described our local experiences with a single-layer wrapping technique for the vascular anastomoses in patients with Adamantiadis-Behçet's aortic/aortoiliac aneurysms using InterGard Silver-impregnated Dacron® patch prosthesis. METHODS: Between January 2013 to December 2019, we retrospectively reviewed 20 patients presented with Adamantiadis-Behçet's aortic/aortoiliac aneurysms. All patients presented with Adamantiadis-Behçet's aortic/aortoiliac aneurysms. Two groups were analyzed, Group I, considered as a control group (n = 20). While group II (n = 20), of which prosthetic wrapping was performed. Follow up took place for a maximum of 24 months. RESULTS: during a six-year retrospective study period, 20 patients were recruited. They included 15 males and five females (ratio 3:1). The median age was 30.5 ± 4.2 years. Anastomotic pseudoaneurysms were reported in group I (control, [non-wrapping group]). While group II doesn't (wrapping group). Paired samples t test revealed a significant difference between those underwent wrapping and those with non-wrapping (p = .019 and .038). False aneurysms were reported in 80% of the non-wrapping group as estimated by the Kaplan-Meier curves. While Log-rank test results revealed a significant difference between both the studied groups (p < .008). Primary graft patency was 90% at 24 months as reported by the Kaplan-Meier survival method. CONCLUSIONS: adjunctive wrapping for vascular anastomoses using Intergard Silver-impregnated Dacron® patch in patients with Adamantiadis-Behçet's aortic/aortoiliac aneurysms is an applicable, simple, and reliable technique. It was associated with low morbidity and mortality rates. Moreover, we discussed a relatively old technique aiming to explore its success and safety in treating arterial aneurysms in Adamantiadis-Behçet's disease patients.

Expanding perigraft seroma after ascending aorta replacement.

BACKGROUND: Perigraft seroma is a persistent and sterile fluid confined within a fibrous pseudomembrane surrounding a graft that develops after graft replacement. Development of perigraft seroma is an uncommon complication that occurs after the surgical repair of the thoracic aorta using woven polyester grafts. mechanism underlying perigraft seroma formation remains unclear. CASE PRESENTATION: Herein, we describe the case of 77-year-old man who underwent repeat sternotomy for the treatment of large perigraft seroma 1 year after ascending aorta replacement for acute type A dissection. After removing a cloudy yellow fluid, we covered the prosthetic graft with fibrin glue and wrapped it with a new graft. Bacterial culture and laboratory examination of the fluid confirmed the final diagnosis of perigraft seroma, and there was no evidence of recurrence. The area in which fluid accumulated around the graft shrunk 1 year after surgery. CONCLUSIONS: The cause of a expanding perigraft after repair of the thoracic aorta remains unknown. Physicians should be aware that chronic expanding mediastinal seroma with Dacron grafts is one of the rare postoperative complications of thoracic aortic surgery. Applying fibrin glue to the graft surface might effectively prevent the recurrence of perigraft seroma.

Successful open surgical repair of large ilio-caval fistula presenting with congestive heart failure.

Ilio-caval arteriovenous fistula is a rare sequel of lumbar disc surgery or penetrating injury. We report a case of 40-year gentleman presenting with symptoms of congestive heart failure and continuous murmur heard over right iliac fossa. His past history was significant for lumbar disc surgery done twice 1 year back. Computed tomography angiogram confirmed a large fistulous communication between right common iliac artery and inferior vena cava. Open surgical repair was performed as the fistula was not well suited for endovascular repair. We successfully managed this case by open surgical ligation of right common iliac artery proximal and distal to fistula and continuity restored with interposition Dacron graft. He was relieved of symptoms and performing well on follow-up.

Infrarenal Vena Cava Leiomyosarcoma Treated With Surgical Resection and Vascular Reconstruction.

Leiomyosarcoma of the inferior vena cava is a rare malignant tumor with a poor prognosis. We report a case of a 39-year-old woman admitted for a surgical resection of a retroperitoneal mass revealed by pain localised in the right lumbar fossa. Computed tomography of the abdomen revealed a heterogeneous retroperitoneal mass compressing the inferior vena cava. Surgical resection was performed with the reconstruction of the inferior vena cava using a Dacron prosthesis, the diagnosis of vessel wall leiomyosarcoma was revealed by histopathology. Surgical resection with clear margins remains the only treatment offering the best survival rate. The complex nature of the surgery of those tumors is a major therapeutic challenge for surgeons.

Management of a common and proper hepatic artery aneurysm.

First-line management of hepatic artery aneurysms is via an endovascular approach. However, unfavorable anatomy may preclude this. We present a patient with an aneurysm involving most of the common hepatic artery and the entire proper hepatic artery including the emergence of the right and left hepatic artery and the gastroduodenal artery. The endovascular approach was not feasible due to unfavorable anatomy. The patient was successfully treated with an open bifurcated Dacron graft.

An experimental evaluation of a concept to improve conventional aortic prostheses.

Conventionally used textile prosthesis for traditional open surgical repair (OSR) of aortic aneurysms have a lower compliance than the native aortic tissue. Graft placements lead to an acute drop in compliance which effects cardiovascular risk and the development of graft related complications. A custom-made spring casing was applied to a Dacron graft segment under physiological pressure conditions within a five-element biventricular mock circulation loop, to investigate experimentally a concept to improve the compliance of a conventional aortic prosthesis by changing the transverse graft cross-section. Two different prosthesis locations, proximal and distal of compliant silicone tubing were used to study uniaxial graft compression with an elastic device. To characterise the devices' performance by means of pulse pressure (PP), diastolic pressure (Pdia) and pulse wave velocity(PWV), fluid pressures and flow were recorded. In a proximal graft setting (ascending aorta repair) elastic uniaxial compression with a custom-made spring casing (2 cm width) could significantly reduce PP by 10-14% (p < .001) and slowed PWV from 6.7 to 5.2 m/s (22%, p = .002). Applied to a graft in a distal position, the spring casing demonstrated less impact on PP (2-10%), but significantly reduced PWV in this mock aorta segment from 13.7 to 5.5 m/s (60%, p = .004). In conclusion, a newly conceptualised spring casing applied to the external wall of synthetic aortic grafts can reduce PP and slow PWV. By restoring elastic aortic recoil in stiff textile aortic prostheses, the presented concept is a potential solution to improve long-term aortic prosthesis related complications.

Identification of viscoelastic properties of Dacron aortic grafts subjected to physiological pulsatile flow.

In vascular surgery, most synthetic vascular grafts currently used for large vessels replacements are made of Dacron (polyethylene terephthalate; PET). In this study, the dynamic response of these synthetic arterial substitutes to physiological pulsatile conditions is investigated in depth. Experiments were performed on a mock circulatory loop developed to replicate physiological pulsatile pressure and flow. Two different models of Dacron grafts (branched and straight) were tested at various heart rate conditions. Results are presented in terms of cyclic axisymmetric diameter changes, hysteretic loops of the pressure-diameter change, and viscoelastic parameters, such as loss factor and storage modulus that are identified from the hysteresis loop. The amplitude of cyclic diameter change of the Dacron graft was found to be always below 0.2% for all the heart rates considered (from 57 to 187 bpm). The loss factor of the Dacron graft slightly increased with the heart rate; almost no effect of the pulse rate was observed on the storage modulus, which was identified to be around 100 MPa. Both glycerol-water mixture (i.e. the blood analogue fluid) and saline solution were used in the circulatory loop and results did not present significant differences between the two cases. This shows that the effect of the shear load on the dynamic response of Dacron grafts is negligible. A comparison between Dacron vascular implants and human thoracic aortas shows a large mismatch in their viscoelastic mechanical properties.

Successful Treatment of Staphylococcus schleiferi Infection after Aortic Arch Repair: In Situ Aortic Arch Replacement and Domino Reconstruction of the Debranching Graft using Autologous Iliac Artery.

A 62-year-old Japanese male presented with graft infection by Staphylococcus schleiferi 50 days after debranching of the left subclavian artery and frozen elephant trunk repair for the entry closure of a Stanford type B aortic dissection. The graft was removed, and the patient was successfully treated using in situ reconstruction of the arch with omental flap coverage, removal of the debranching graft, autologous iliac artery grafting, and longterm antibiotics. Domino reconstruction of the infected debranching graft using autologous external iliac artery and a Dacron graft can thus be a good option in similar cases.

Intimal sarcoma in an ascending aortic Dacron graft mimicking a thrombus.

Although aortic sarcomas are extremely rare, they may arise in association with a Dacron graft. Here, we report a case of an intimal sarcoma in an ascending aortic Dacron graft implanted 17 years earlier. The patient presented with multiple cerebral infarctions; clinically, a thrombus was found to cause the embolic stroke. He successfully underwent re-replacement of the ascending aorta. Although the initial postoperative histopathological diagnosis was a thrombus, he died of multiple metastases of the malignant tumour after 5 months of the surgery. A histopathological re-evaluation of the explant using immunohistochemistry revealed that the mass was an intimal sarcoma.

Total resection of an infected aortic arch aneurysm caused by Mycobacterium avium: a case report.

BACKGROUND: Infected aortic arch aneurysms caused by Mycobacterium avium are rare in immunocompetent individuals. Promptly recognizing these aneurysms is important because delays in treatment result in aneurysm rupture and a high fatality rate. Although Salmonella species, Streptococcus species, Staphylococcus aureus, and S. epidermis are commonly found in immunocompetent individuals, to our knowledge, infected aortic arch aneurysms caused by M. avium have not yet been reported. CASE PRESENTATION: We report the case of a 63-year old immunocompetent man who underwent total arch replacement following infection by the nontuberculous mycobacteria M. avium. The procedure involved total aneurysmal resection and arch replacement with a rifampicin-bonded gelatin-sealed woven Dacron graft. He was discharged without complications and remained asymptomatic after 30 months. CONCLUSION: In this brief report, we outline and discuss the rare successful case of total arch replacement using total aneurysmal resection and rifampicin-bonded gelatin-sealed woven Dacron graft for an infected aortic arch aneurysm resulting from M. avium in an immunocompetent patient.

Vascular suture line wrapping for Aortoiliac anastomoses following open surgical repair of Infrarenal Behçet's Aortoiliac aneurysms.

BACKGROUND: This study was conducted to evaluate our local experiences of adjunctive mechanical prosthetic wrapping for aortoiliac vascular anastomoses as a prophylactic measure following surgical repair of Behçet's aortoiliac aneurysms. The goal of prosthetic wrapping to reinforce the vascular anastomoses by mechanical protection to reduce the bleeding complications, and consequently pseudoaneurysm formation. This was aided by the administration of pre- and postoperative immunosuppressive therapy as an adjuvant treatment. METHODS: A seven-year retrospective study was conducted between January 2006 and December 2012, retrieving data of patients with Behçet's aortoiliac aneurysms. All patients underwent open surgical repair using a heparin-bonded synthetic Dacron® graft. Data for all patients were retrieved and analyzed for diagnostic procedures, graft selection, as well as, different methods of surgical repair. Graft-related complications such as anastomotic pseudoaneurysms, occlusion, and thrombosis were also reported. RESULTS: Sixteen patients were recruited in this study. There were  11 (69%) males and 5 (31%) females with the male to female ratio 2:1. The patients' age ranged between 25 and 47 years with the mean of 36.4 ± 7.3. All Behçet's aortic/aortoiliac aneurysms were repaired by the application of heparin-bonded Dacron® tube and bifurcated grafts. The anastomotic wrapping technique was performed for both the proximal and the distal vascular anastomoses. The technical success of aortoiliac aneurysm and wrapping techniques was achieved in 100% of patients. All patients were given pre- and postoperative systemic immunosuppressive therapy. No graft-related complications were reported except for only one anastomotic pseudoaneurysm that developed at one of the right iliac anastomoses, that developed within 24 months after follow up. CONCLUSIONS: Mechanical prosthetic wrapping for vascular anastomoses in patients with Behçet's aortic/aortoiliac aneurysms is a feasible, simple, and reliable technique with low morbidity and mortality. It was performed as a prophylactic measure to avoid the development of postoperative anastomotic pseudoaneurysms. It must be performed for all patients with Behçet's arterial aneurysms whenever possible. Furthermore, the supplemental administration of pre- and postoperative systemic immunosuppressive therapy should be considered as an important factor for the prophylaxis and prevention of anastomotic pseudoaneurysms and other graft-related complications.

Experiments on dynamic behaviour of a Dacron aortic graft in a mock circulatory loop.

Woven Dacron grafts are currently used for the surgical treatment of aortic aneurysm and acute dissection, two otherwise fatal pathologies when aortic wall rupture occurs. While Dacron is chosen for aortic grafts because of characteristics such as biocompatibility and durability, few data are available about the dynamic response of Dacron prosthetic devices and about their side effects on the cardiovascular system. In this study, a Dacron graft was subjected to physiological flow conditions in a specifically-developed mock circulatory loop. Experiments were conducted at different physiological pulsation-per-minute rates. Results show that, in comparison to an aortic segment of the same length, the prosthesis is extremely stiffer circumferentially, thus limiting the dynamical radial expansion responsible for the Windkessel effect in human arteries. The prosthesis is instead excessively compliant in the axial direction and develops preferentially bending oscillations. This very different dynamic behaviour with respect to the human aorta can alter cardiovascular pressure and flow dynamics resulting in long-term implant complications.

Late Non-Anastomotic Rupture of a Bifurcated Dacron Aortic Graft Treated Using a Gore Excluder Limb Endoprosthesis.

Dacron vascular prostheses have been widely used in vascular surgery since the mid-1970s. They have been proven to be the most durable and reliable conduits for arterial replacement in aortic and peripheral surgeries for decades. However, an extremely rare complication, namely late non-anastomotic graft rupture, due to intrinsic structural prosthetic disruption can occur, resulting in acute hemorrhage or false aneurysm formation. We report a case of this rare complication due to non-anastomotic rupture of a bifurcated knitted Dacron aortic vascular graft in a patient who had undergone an aorto-bi-iliac bypass 6 years ago. The patient was successfully treated in an emergency setting with endovascular therapy using an iliac limb of an abdominal aortic endoprosthesis.

Late Non-Anastomotic Rupture of a Bifurcated Dacron Aortic Graft Treated Using a Gore Excluder Limb Endoprosthesis

Dacron vascular prostheses have been widely used in vascular surgery since the mid-1970s. They have been proven to be the most durable and reliable conduits for arterial replacement in aortic and peripheral surgeries for decades. However, an extremely rare complication, namely late non-anastomotic graft rupture, due to intrinsic structural prosthetic disruption can occur, resulting in acute hemorrhage or false aneurysm formation. We report a case of this rare complication due to non-anastomotic rupture of a bifurcated knitted Dacron aortic vascular graft in a patient who had undergone an aorto-bi-iliac bypass 6 years ago. The patient was successfully treated in an emergency setting with endovascular therapy using an iliac limb of an abdominal aortic endoprosthesis.

Dacron graft as replacement to dissected aorta: A three-dimensional fluid-structure-interaction analysis.

Aortic dissection (AD) is a serious medical condition characterized by a tear in the intima, the inner layer of the aortic walls. In such occurrence, blood is being diverted to the media (middle) layer and may result in patient death if not quickly attended. In the case where the diseased portion of the aorta needs to be replaced, one common surgical technique is to use a graft made of Dacron, a synthetic fabric. We investigate the response of a composite human aortic segment-Dacron graft structure subjected to blood flow using the three-dimensional fluid-structure-interaction (FSI) capability in Abaqus. We obtain stress and strain profiles in each of the three layers of the aortic walls as well as in the Dacron graft. Results are compared when elastic and hyperelastic models are used and when isotropy vs. anisotropy is assumed. The more complex case (hyperelastic-anisotropy) is represented by the Holzapfel-Gasser-Ogden (HGO) model which also accounts for the orientation of the fibers present in the tissues. The fluid flow is taken as Newtonian, incompressible, pulsatile and turbulent. The simulation show that for all the cases, the von Mises stress distribution at aorta-Dacron interface is well below the ultimate strength of the aorta. No significant change in radial displacement at the interface of the two materials due to blood flow is observed. Computation cost is also addressed and results show that the hyperelastic-anisotropic model takes about three times longer to run than the elastic isotropic case. Trade-off between accuracy and computational cost has to be weighted.

True aneurysm of Dacron graft 33 years after surgery.

Dacron grafts have been used as a conduit for large calibre arteries for many years successfully. However, these grafts can undergo complications such as aneurysm formation, rupture, and failure [1]. We report an unusual complication of a Dacron graft in a 45-year-old woman who had undergone extra-anatomical bypass for Takayasu aorto-arteritis aged 12 years. She presented with pain and pulsatile swelling in the left hypochondrium. Imaging confirmed huge fusiform aneurysm of Dacron graft involving all of its length. She underwent median sternotomy with laparotomy to replace aneurysmal graft with new Dacron graft.

Double aneurysm of the superior mesenteric artery: case report.

Superior mesenteric artery aneurysms are rare, accounting for less than 0.5% of all intra-abdominal aneurysms. They are mainly caused by atherosclerosis and septic emboli resulting from bacterial endocarditis. Although uncommon, these aneurysms are considered dangerous because of possible complications such as rupture with hemorrhage and intestinal ischemia. Since the consequences can be very serious, early diagnosis and treatment are essential to improve outcomes. Although there is no well-defined consensus, recommended treatments include open surgery, endovascular therapy, and watchful waiting with periodic examinations. In this article we report the case of an asymptomatic 58-year-old man with an incidental and unusual finding of two superior mesenteric artery aneurysms. Since anatomy was not favorable for an endovascular approach, open surgery was performed, using a dacron graft to successfully repair the artery.