Aortic clamping during elective operations for infrarenal disease: The influence of clamping time on renal function

AbstractObjective: Aortic clamping proximal to the renal arteries is sometimes necessitated during infrarenal and juxtarenal aortic surgery and may be associated with an increased risk of renal ischemia and its consequences. The aim of the study was to estimate this risk and possibly identify a “safe” duration of renal ischemia. Methods: Medical records were retrospectively reviewed for 60 consecutive patients (from 1987 to 1994) with abdominal aortic aneurysm (n = 43) and occlusive disease (n = 17) confined to the infrarenal or juxtarenal aorta who underwent infrarenal aortic reconstruction with temporary suprarenal clamping. The data obtained included risk factors, preoperative and postoperative serum creatinine level, blood urea nitrogen (BUN) value, proteinuria before surgery, and suprarenal clamping times. Results: The mean age of the patients was 64.4 years (± 11.4 years), and 74% were men. Concomitant cardiac disease was present in 41% of the patients, and 9% had diabetes. The preoperative creatinine level was 1.21 mg/dL (± 0.54 mg/dL), and the BUN value was 16.6 mg/dL (± 7.8 mg/dL). During surgery, blood flow to the renal arteries was interrupted for 32.0 minutes (± 17 minutes). None of the surviving patients needed dialysis or had signs of acute renal failure after the operations, but transient azotemia (rise in creatinine level) occurred in 23% of the patients. Risk factors for this condition were high preoperative creatinine values and hypotension during surgery, but the main determinant was total renal ischemia time. Odds ratios for such transient renal dysfunction showed as much as a 10-fold risk when suprarenal aortic clamping was greater than 50 minutes as compared with 30 minutes or less. Conclusion: Postoperative renal function impairment is rare in this group of patients. If suprarenal clamp duration (renal ischemia time) is brief, patients with normal preoperative creatinine levels exhibit no increase or a marginal increase in BUN or creatinine levels after surgery. Accordingly, suprarenal aortic clamping less than 50 minutes in this patient group appears safe and well tolerated. (J Vasc Surg 2002;36:13-8.

Sphingosine-1-phosphate promotes the differentiation of adipose-derived stem cells into endothelial nitric oxide synthase (eNOS) expressing endothelial-like cells.

BACKGROUND: Adipose tissue provides a readily available source of autologous stem cells. Adipose-derived stem cells (ASCs) have been proposed as a source for endothelial cell substitutes for lining the luminal surface of tissue engineered bypass grafts. Endothelial nitric oxide synthase (eNOS) is a key protein in endothelial cell function. Currently, endothelial differentiation from ASCs is limited by poor eNOS expression. The goal of this study was to investigate the role of three molecules, sphingosine-1-phosphate (S1P), bradykinin, and prostaglandin-E1 (PGE1) in ASC endothelial differentiation. Endothelial differentiation markers (CD31, vWF and eNOS) were used to evaluate the level of ASCs differentiation capability. RESULTS: ASCs demonstrated differentiation capability toward to adipose, osteocyte and endothelial like cell phenotypes. Bradykinin, S1P and PGE were used to promote differentiation of ASCs to an endothelial phenotype. Real-time PCR showed that all three molecules induced significantly greater expression of endothelial differentiation markers CD31, vWF and eNOS than untreated cells. Among the three molecules, S1P showed the highest up-regulation on endothelial differentiation markers. Immunostaining confirmed presence of more eNOS in cells treated with S1P than the other groups. Cell growth measurements by MTT assay, cell counting and EdU DNA incorporation suggest that S1P promotes cell growth during ASCs endothelial differentiation. The S1P1 receptor was expressed in ASC-differentiated endothelial cells and S1P induced up-regulation of PI3K. CONCLUSIONS: S1P up-regulates endothelial cell markers including eNOS in ASCs differentiated to endothelial like cells. This up-regulation appears to be mediated by the up-regulation of PI3K via S1P1 receptor. ASCs treated with S1P offer promising use as endothelial cell substitutes for tissue engineered vascular grafts and vascular networks

eNOS transfection of adipose-derived stem cells yields bioactive nitric oxide production and improved results in vascular tissue engineering.

This study evaluates the durability of a novel tissue engineered blood vessel (TEBV) created by seeding a natural vascular tissue scaffold (decellularized human saphenous vein allograft) with autologous adipose-derived stem cells (ASC) differentiated into endothelial-like cells. Previous work with this model revealed the graft to be thrombogenic, likely due to inadequate endothelial differentiation as evidenced by minimal production of nitric oxide (NO). To evaluate the importance of NO expression by the seeded cells, we created TEBV using autologous ASC transfected with the endothelial nitric oxide synthase (eNOS) gene to produce NO. We found that transfected ASC produced NO at levels similar to endothelial cell (EC) controls in vitro which was capable of causing vasorelaxation of aortic specimens ex vivo. TEBV (n = 5) created with NO-producing ASC and implanted as interposition grafts within the aorta of rabbits remained patent for two months and demonstrated a non-thrombogenic surface compared to unseeded controls (n = 5). Despite the xenograft nature of the scaffold, the TEBV structure remained well preserved in seeded grafts. In sum, this study demonstrates that upregulation of NO expression within adult stem cells differentiated towards an endothelial-like lineage imparts a non-thrombogenic phenotype and highlights the importance of NO production by cells to be used as endothelial cell substitutes in vascular tissue engineering applications

Assessing the Operative Log Data of Traditional (5+2) vs. Integrated (0+5) Vascular Training Programs

Introduction: In 2006, the Accreditation Council for Graduate Medical Education (ACGME) approved an integrated 5 year vascular surgery residency program. Operative experience can be used as a surrogate marker for success in the evolving field of vascular surgery training. Objective: The purpose of this study is to compare the operative experience of those graduating from the traditional (5+2) vascular training program with the integrated (0+5) program. Methods: National operative case log data supplied by the ACGME was gathered and organized for vascular surgery residents graduating between 2013 and 2018. Mean case numbers were compared between integrated vascular residents and traditional vascular fellows (mean case numbers for vascular fellows included cases from their general surgery residencies). Results: The 5+2 trainees performed 36% more overall procedures than the 0+5 trainees (mean, 1650 vs 1050). The greater number of overall procedures performed by the 5+2 trainees was primarily realized by an increased number of abdomen (e.g. biliary, small/large intestine) cases. However, the 5+2 trainees performed 8% less vascular procedures (mean, 786 vs 854). The greater number of vascular procedures performed by the 0+5 trainees was primarily realized by increased numbers of endovascular (e.g. endovascular peripheral obstruction) and venous (e.g. caval filter) cases. Discussion: The integrated 0+5 graduates performed more total vascular procedures than their 5+2 counterparts. The overall total operative experience remains greater for the traditional 5+2 graduates, given their additional two years of training. Further longitudinal studies will be needed to fully assess the effect of the new integrated 0+5 training paradigm

Fate of the lower extremity in patients with VA-ECMO via femoral cannulation

Background: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a salvage therapy in patients with severe cardiopulmonary failure. Femoral cannulation is associated with limb complications including ischemia, limb loss, arterial infections and wound infections. This study aims to evaluate these complications and management related to successful outcomes. Methods: A retrospective review was conducted in 17 patients requiring VA- ECMO support via femoral cannulation from 1/ 2010 till 4/2012. After cannulation, all patients had near infared spectroscopy (NIRS) monitoring after cannula placement and most had placement of distal arterial perfusion catheters (DPC). At decannulation, all patients had femoral cutdown with closure of arteriotomies by primary repair or patch angioplasty with bovine pericardium. Primary study endpoints included ischemia, limb loss, arterial infection; secondary endpoints were wound infection and post-discharge symptoms. Results: Seventeen patients were supported with VA-ECMO during the study period with arterial cannula size of 16-20 French. All patients had NIRS monitoring after cannula placement and 13/17 patients had DPC placement, with no subsequent ischemia. Two of 4 patients without DPC developed ischemia; one was decannulated and the other resolved spontaneously. At decannulation, open arterial repair was performed as described. In this study population, simple wound infection occurred in 3/17with Vacuum Assisted Closure (VAC) devices were placed at the timed if appropriate. There were no arterial infections and no instances of limb ischemia requiring amputation. There were no complaints of rest pain during outpatient follow-up. Conclusions: Limb complications related to femoral cannulation for VA-ECMO can lead to prolonged morbidity and limb loss. NIRS and placement of DPC, primary repair of arteriotomy or patch angioplasty, along with aggressive wound care, can dramatically decrease rates of limb ischemia, limb loss and infection

Acute occlusion of aortic endovascular aneurysm repair stent graft with bilateral limb ischemia

Endovascular aneurysm repair has dramatically changed the management of abdominal aortic aneurysms as an alternative to open repair. However, complications can occur, including stent graft migration, kinking, and occlusion, leading to compromise of the excluded aneurysm walls and acute limb ischemia. In the present report, we have described a case of migration and kinking of an abdominal aortic stent graft in the main body that led to occlusion of the abdominal aorta and bilateral acute limb ischemia. The patient required emergent explantation of the stent graft and open repair of the abdominal aneurysm with a rifampin-soaked Dacron graft, which achieved a favorable outcome

False lumen embolization as a rescue technique in the setting of acute and chronic dissecting aneurysms as adjunct to thoracic endovascular aortic repair.

Complicated type B aortic dissection (TBAD) is a life-threatening condition requiring surgical intervention. One such complication in the acute or chronic setting is aneurysmal degeneration. The dissected aortic wall is weakened, and the pressures in the false lumen are often high. In the past decade, thoracic endovascular aortic repair (TEVAR) has become the treatment of choice for TBAD. TEVAR can be complicated by lack of false lumen thrombosis, increasing the risk of death. We present three cases of TBAD with patent false lumens after TEVAR that were treated by false lumen coil embolization

Supradiaphragmatic Origin of the Celiac Trunk Leading To Median Arcuate Ligament Syndrome With Superior Mesenteric Artery Involvement

Median arcuate ligament (MAL) syndrome (MALS) is a rare condition caused by compression of the celiac artery by the MAL. Symptoms include abdominal pain, nausea, and weight loss. Rarely, the MAL can compress both the celiac artery and the superior mesenteric artery (SMA). We describe the case of a young man with MALS involving the celiac artery and SMA. Laparoscopic release of the MAL was performed, and the patient had resolution of his symptoms at 6 months of follow-up. A review of the literature identified only six cases of MALS involving the SMA and celiac artery, making this a rare occurrence

The Role and Outcomes of Thoracodistal Bypass

Objectives Endovascular procedures for lower extremity revascularization are becoming more commonplace due to low morbidity, mortality, and shorter length of stay. The role of open bypass must be reconsidered. Aortobifemoral bypass is the gold standard for extensive aortoiliac occlusive disease (AIOD); however, thoracodistal bypass holds a niche position. We investigate indications and outcomes of thoracodistal bypass. Methods Medical records of five patients who underwent thoracodistal bypass at Thomas Jefferson University Hospital (TJUH) between 2012 and 2019 were reviewed. Contemporary and historical literature was reviewed. Results Indications included calcified paravisceral pathology, previous failed or infected bypass grafts, and prior abdominal operations. Thirty-day mortality at our institution was 0%. Four out of five patients had patent grafts at one year. Complications included pulmonary, renal, bleeding, and wound complications in addition to need for reintervention. Conclusions Despite high complication rates associated with thoracodistal bypass, longterm patency and longterm survival rates are also high. Thoracodistal bypass continues to be a useful tool in select patients

Penumbra Aspiration Thrombectomy of the Superior Mesenteric Artery for Mesenteric Ischemia

Acute mesenteric ischemia from thromboembolic occlusion is a life-threatening emergency associated with a high mortality rate. Prompt diagnosis and intervention are vital to preserve viable bowel and prevent mortality. In the past decade, a shift has occurred toward minimally invasive alternatives such as endovascular therapies. We present a case of acute mesenteric ischemia from superior mesenteric artery thrombosis treated promptly with the Penumbra suction thrombectomy device (Penumbra Inc)