Aneurysmal expansion of the visceral patch after thoracoabdominal aortic replacement: An argument for limiting patch size?

AbstractIntroduction: Thoracoabdominal aortic replacement requires visceral vessel revascularization and is usually performed with Crawford's inclusion technique or a large Carrel patch. This segment of retained native aorta may be prone to recurrent aneurysmal disease. We reviewed our experience with patients in whom aneurysmal expansion of the visceral patch was detected. Methods: The records of 107 patients undergoing thoracoabdominal aortic replacement operations performed or followed up at the Johns Hopkins Hospital between 1992 and 2000 were reviewed. All patients had visceral patches created for type II, III, or IV aneurysms. Visceral patches were considered aneurysmal if the maximal diameter of the aortic prosthesis and patch was 4.0 cm or more. Results: Patch aneurysmal expansion (mean, 5.4 cm) was detected in eight patients (7.5%). All three women had connective tissue disorders (mean age, 36 years), and all five men had atherosclerotic disease (mean age, 73 years). Five patients were symptom free with their aneurysms detected by surveillance computed tomography scans; two patients had back pain prompting computed tomography scans; and one patient presented with an emergency patch rupture. Aneurysmal patches were successfully revised in three patients. Two patients died in the operating room, and three patch aneurysms (< 5 cm) are still being observed. The mean time to the detection of aneurysmal expansion was 6.5 years after the original operation. Therapy consisted of replacement of a segment of the thoracoabdominal aortic graft and refashioning a smaller patch, including only the visceral artery orifices with separate attachment of the left and possibly right renal artery. Conclusions: Although Crawford's inclusion method of visceral patch construction is generally durable, patients undergoing thoracoabdominal aortic replacement require yearly surveillance for the detection of aneurysmal expansion of the visceral patch. We recommend limiting visceral patch size at the original operation by routinely excluding the orifice of the left renal artery. Patients at high risk for recurrent aneurysmal expansion, such as those with connective tissue disorders, will benefit from creating small visceral patches and possibly implanting both renal arteries separately during the original operation. (J Vasc Surg 2001;34:405-10.

Current Advancements and Strategies in Tissue Engineering for Wound Healing: A Comprehensive Review

SIGNIFICANCE: With an aging population leading to an increase in diabetes and associated cutaneous wounds, there is a pressing clinical need to improve wound-healing therapies. RECENT ADVANCES: Tissue engineering approaches for wound healing and skin regeneration have been developed over the past few decades. A review of current literature has identified common themes and strategies that are proving successful within the field: The delivery of cells, mainly mesenchymal stem cells, within scaffolds of the native matrix is one such strategy. We overview these approaches and give insights into mechanisms that aid wound healing in different clinical scenarios. CRITICAL ISSUES: We discuss the importance of the biomimetic niche, and how recapitulating elements of the native microenvironment of cells can help direct cell behavior and fate. FUTURE DIRECTIONS: It is crucial that during the continued development of tissue engineering in wound repair, there is close collaboration between tissue engineers and clinicians to maintain the translational efficacy of this approach

Durability of thoracoabdominal aortic aneurysm repair in patients with connective tissue disorders

AbstractObjective: Thoracoabdominal aortic aneurysm (TAAA) repair is a durable procedure performed with reasonable perioperative mortality and morbidity in patients with atherosclerotic aortic disease. However, the long-term outcome and durability of TAAA repair performed in patients with a connective tissue disorder (CTD) is not well known. Methods: The records of 257 patients who underwent TAAA repair at the Johns Hopkins Hospital between January 1992 and December 2001 were reviewed. Survival analysis was performed with Kaplan-Meier analysis, and subgroups were compared with the log-rank test. Multivariable analysis was performed with the Cox proportional hazards model and logistic regression. Results: Patients with CTD (n = 31) were seen earlier (mean age, 48.6 ± 2.9 years) than patients without CTD (mean age, 69.1 ± 0.6 years; P < .0001, Mann-Whitney U test) and had a greater incidence rate of aortic dissection (52% versus 19%; P < .0001, χ2 test) and extent I or II aneurysm (77% versus 64%; P = .04). The perioperative (30-day) mortality rate was 6.5% in patients with CTD, which was similar to the rest of the cohort (P = .39, Fisher exact test). The incidence rate of paraparesis/paraplegia was 12.9%/6.5% in patients with CTD, and CTD was the only factor predictive of paraparesis (P = .03; odds ratio, 9.3; logistic regression). The cumulative survival rate among the entire cohort was 53.4% ± 4.4% at 5 years (Kaplan-Meier), and no difference was seen among patients with or without CTD (P = .16, log-rank test) or among different Crawford extents (P = .29). Of the two late (>6 months) deaths in patients with CTD, none were from aortic rupture or dissection, compared with two of 31 late deaths in patients without CTD. Multivariable analysis confirmed that postoperative renal failure (P = .03) predicted mortality but neither CTD (P = .93), nor Crawford extent (P = .21, Cox regression) predicted mortality. Among survivors, no mean difference was found in largest aortic diameter on follow-up imaging in patients with or without CTD (4.7 ± 0.3 cm versus 4.4 ± 0.3 cm; P = .47, Mann-Whitney U test). The cumulative graft patency rate, representing long-term graft stability and with death, rupture, dissection, or recurrent aneurysm as endpoints, was 47.5% ± 4.6% at 5 years (Kaplan-Meier) and was similar in patients with or without CTD (P = .10, log-rank test). Conclusion: TAAA repair appears to be a durable operation, with a reasonable 5-year patient survival rate and a low risk of postoperative paraplegia or additional aortic events. Patients with CTD can expect their outcome, including long-term survival and aortic stability, to be similar to patients without CTD. (J Vasc Surg 2002;36:696-703.

Multiscale, patient-specific computational fluid dynamics models predict formation of neointimal hyperplasia in saphenous vein grafts

Stenosis due to neointimal hyperplasia (NIH) is among the major causes of peripheral graft failure. Its link to abnormal hemodynamics in the graft is complex, and isolated use of hemodynamic markers is insufficient to fully capture its progression. Here, a computational model of NIH growth is presented, establishing a link between computational fluid dynamics simulations of flow in the lumen and a biochemical model representing NIH growth mechanisms inside the vessel wall. For all three patients analyzed, NIH at proximal and distal anastomoses was simulated by the model, with values of stenosis comparable to the computed tomography scans

An in silico study of the influence of vessel wall deformation on neointimal hyperplasia progression in peripheral bypass grafts

Neointimal hyperplasia (NIH) is a major obstacle to graft patency in the peripheral arteries. A complex interaction of biomechanical factors contribute to NIH development and progression, and although haemodynamic markers such as wall shear stress have been linked to the disease, these have so far been insufficient to fully capture its behaviour. Using a computational model linking computational fluid dynamics (CFD) simulations of blood flow with a biochemical model representing NIH growth mechanisms, we analyse the effect of compliance mismatch, due to the presence of surgical stitches and/or to the change in distensibility between artery and vein graft, on the haemodynamics in the lumen and, subsequently, on NIH progression. The model enabled to simulate NIH at proximal and distal anastomoses of three patient-specific end-to-side saphenous vein grafts under two compliance-mismatch configurations, and a rigid wall case for comparison, obtaining values of stenosis similar to those observed in the computed tomography (CT) scans. The maximum difference in time-averaged wall shear stress between the rigid and compliant models was 3.4 Pa, and differences in estimation of NIH progression were only observed in one patient. The impact of compliance on the haemodynamic-driven development of NIH was small in the patient-specific cases considered

Future research directions to improve fistula maturation and reduce access failure

With the increasing prevalence of end stage renal disease there is a growing need for hemodialysis. Arteriovenous fistulae (AVF) are the preferred type of vascular access for hemodialysis but maturation and failure continue to present significant barriers to successful fistula use. AVF maturation integrates outward remodeling with vessel wall thickening in response to drastic hemodynamic changes, in the setting of uremia, systemic inflammation, oxidative stress and preexistent vascular pathology. AVF can fail due to both failure to mature adequately to support hemodialysis, as well as development of neointimal hyperplasia (NIH) that narrows the AVF lumen, typically near the fistula anastomosis. Failure due to NIH involves vascular cell activation and migration and extracellular matrix remodeling with complex interactions of growth factors, adhesion molecules, inflammatory mediators, and chemokines, all of which result in maladaptive remodeling. Different strategies have been proposed to prevent and treat AVF failure, based on current understanding of the modes and pathology of access failure; these approaches range from appropriate patient selection and use of alternative surgical strategies for fistula creation, to the use of novel interventional techniques or drugs to treat failing fistulae. Effective treatments to prevent or treat AVF failure requires a multidisciplinary approach involving nephrologists, vascular surgeons and interventional radiologists, allowing careful patient selection and the use of tailored systemic or localized interventions to improve patient-specific outcomes. This review provides contemporary information on the underlying mechanisms of AVF maturation and failure and discusses the broad spectrum of options that can be tailored for specific therapy

Pericardial Patch Angioplasty Heals via an Ephrin-B2 and CD34 Positive Cell Mediated Mechanism

Pericardial patches are commonly used in vascular surgery to close arteriotomies. The mechanism of early healing after patch implantation is still not well defined. We used a rat aortic patch model to assess pericardial patch healing and examined Ephrin-B2, a marker of arterial identity, expression within the post-implantation patch. We also determined whether endothelial progenitor cells (EPC) are associated with early patch healing in the arterial environment.Wistar rats (200-250 grams) underwent infrarenal aortic arteriotomy and then closure via bovine or porcine pericardial patch angioplasty. Control groups included subcutaneously implanted patches. Patches were harvested at 0-30 days and analyzed by histology, immunohistochemistry, immunofluorescence and Western blot as well as quantitative PCR.Prior to implantation, pericardial patches are largely composed of collagen and are acellular. Following arterial implantation, increasing numbers of CD68-positive cells as well as Ephrin-B2 and CD34 dual-positive cells are found within both bovine and porcine pericardial patches, whereas the infiltrating cells are negative for vWF and α-actin. Porcine patches have a luminal monolayer of cells at day 7, compared to bovine patches that have fewer luminal cells. Subcutaneously implanted patches do not attract Ephrin-B2/CD34-positive cells. By day 30, both bovine and porcine pericardial patches develop a neointima that contains Ephrin-B2, CD34, and VEGFR2-positive cells.Both CD68-positive and Ephrin-B2 and CD34 dual-positive cells infiltrate the pericardial patch early after implantation. Arteriotomy closure via pericardial patch angioplasty shows patch adaptation to the arterial environment that may involve a foreign body response as well as localization of EPC. Arterial remodeling of pericardial patches support endothelialization and may represent a paradigm of healing of scaffolds used for tissue engineering

A rare case of a retroperitoneal enterogenous cyst with in-situ adenocarcinoma

<p>Abstract</p> <p>Background</p> <p>Retroperitoneal enterogenous cysts are uncommon and adenocarcinoma within such cysts is a rare complication.</p> <p>Case presentation</p> <p>We present the third described case of a retroperitoneal enterogenous cyst with adenocarcinomatous changes and only the second reported case whereby the cyst was not arising from any anatomical structure.</p> <p>Conclusion</p> <p>This case demonstrates the difficulties in making a diagnosis as well as the importance of a multi-disciplinary approach, and raises further questions regarding post-operative treatment with chemotherapy.</p

Genetic analysis of haemophilia A in Bulgaria

BACKGROUND: Haemophilias are the most common hereditary severe disorders of blood clotting. In families afflicted with heamophilia, genetic analysis provides opportunities to prevent recurrence of the disease. This study establishes a diagnostical strategy for carriership determination and prenatal diagnostics of haemophilia A in Bulgarian haemophilic population. METHODS: A diagnostical strategy consisting of screening for most common mutations in the factor VIII gene and analysis of a panel of eight linked to the factor VIII gene locus polymorphisms was established. RESULTS: Polymorphic analysis for carrier status determination of haemophilia A was successful in 30 families out of 32 (94%). Carrier status was determined in 25 of a total of 28 women at risk (89%). Fourteen prenatal diagnoses in women at high risk of having a haemophilia A – affected child were performed, resulting in 6 healthy boys and 5 girls. CONCLUSION: The compound approach proves to be a highly informative and cost-effective strategy for prevention of recurrence of haemophilia A in Bulgaria. DNA analysis facilitates carriership determination and subsequent prenatal diagnosis in the majority of Bulgarian families affected by haemophilia A