Bao-Ngoc Nguyen

Comparison of outcomes for open abdominal aortic aneurysm repair and endovascular repair in patients with chronic renal insufficiency.

Objective:This study investigates whether this practice is supported by multicenter prospectively collected data. Background:Currently, open abdominal aortic aneurysm (AAA) repair (OPEN) is preferred over endovascular repair (EVAR) in patients with chronic renal insufficiency because of the concern that the contrast load used for EVAR may result in postoperative dialysis. Methods:Patients who underwent EVAR and OPEN for infrarenal AAA were identified in the NSQIP database from 2005 to 2010. Preoperative renal function was assessed by estimated glomerular filtration rate (eGFR) calculated by the Chronic Kidney Disease Epidemiology Collaboration equation. Patients with chronic renal insufficiency were further stratified into 2 different groups: moderate (eGFR = 30–60 mL/min) and severe (eGFR <30 mL/min) renal dysfunction. Multivariate regression model was used for data analysis. Results:We identified 13,191 patients who underwent AAA repair: 9877 patients underwent EVAR and 3314 underwent OPEN. Forty percent of patients had eGFR of less than 60 mL/min. OPEN in patients with moderate renal dysfunction resulted in significantly higher mortality, cardiovascular events, and combined outcomes. However, in patients with severe renal dysfunction, these outcomes were similarly high in both OPEN and EVAR. Most importantly, OPEN in patients with moderate renal dysfunction resulted in 5.2 times higher risk of dialysis. Conclusions:Contrary to current practice, and despite the use of contrast, EVAR should be the first choice in patients with moderate renal dysfunction if they have the appropriate anatomy. Higher threshold for AAA repair with either OPEN or EVAR should be applied in patients with severe renal dysfunction because postoperative complications were significantly high with either approach.

The effect of graft configuration on 30-day failure of infrapopliteal bypasses

BACKGROUND Despite advances in endovascular techniques, infrapopliteal bypasses are still required for limb salvage. Short-term graft patency is an important outcome parameter reflecting technical considerations and acute graft thrombosis. Both are important prerequisites for long-term patency. In this analysis, we compared the 30-day patency of all conduit configurations for infrapopliteal bypasses. METHODS All primary infrapopliteal bypasses from the American College of Surgeons-National Surgical Quality Improvement Program database between 2005 and 2010 were divided into six groups: (1) great saphenous vein (GSV); (2) prosthetic conduit (prosthetic); (3) prosthetic conduit with a distal anastomotic venous adjunct (ADJ), such as a cuff or patch (prosthetic + ADJ); (4) composite graft of prosthetic and a vein segment (composite); (5) spliced autogenous vein (spliced vein); and (6) arm vein. Thirty-day graft failure, patient demographics, and operative details were compared among groups. A multivariate model was used for statistical analysis. RESULTS A total of 5375 infrapopliteal bypasses were analyzed by conduit: GSV, 3983 (75%); prosthetic, 898 (17%); spliced vein, 160 (3%); prosthetic + ADJ, 112 (2%); arm vein, 93 (2%); and composite, 91 (2%). The difference among groups in demographics and comorbidities was not statistically significant. Perioperative mortality rates were similar among different conduits. After adjusting for sex, age, weight, race, and previous cardiac surgery, the bypass conduit had a significant independent association with 30-day graft patency (P = .006). The GSV failure rate was 7.5%. Composite had a significantly higher 30-day failure rate (15.4%, P = .006). There was no significant difference in 30-day failure rate of spliced vein (5.6%, P = .37) or arm vein (4.3%, P = .24) conduits compared with GSV. Prosthetic had significantly higher 30-day failure rate than GSV (10.5%, P = .004). The addition of adjuvant venous tissue at the distal anastomosis of prosthetic bypasses did not significantly improve their 30-day patency (failure rate of 9.8% for prosthetic + ADJ and 10.5% for prosthetic). There was no significant difference in graft patency between alternative venous conduits (arm vein/spliced vein) and prosthetic + ADJ. CONCLUSIONS Venous conduits (GSV, spliced vein, arm vein) deliver the best 30-day patency for infrapopliteal bypasses, and GSV remains the most commonly used graft. Prosthetic grafts had a higher 30-day failure rate. Composite grafts should be abandoned because their early patency is not better than pure prosthetic conduits. The addition of a distal venous adjunct did not seem to improve acute prosthetic graft patency, which may reflect lack of effect on thrombogenicity rather than the myointimal hyperplastic response that effects long-term failure of infrapopliteal bypass.

Poly-ADP-ribose polymerase inhibition enhances ischemic and diabetic wound healing by promoting angiogenesis

Objective: Chronic nonhealing wounds are a major health problem for patients in the United States and worldwide. Diabetes and ischemia are two major risk factors behind impaired healing of chronic lower extremity wounds. Poly‐ADP‐ribose polymerase (PARP) is found to be overactivated with both ischemic and diabetic conditions. This study seeks a better understanding of the role of PARP in ischemic and diabetic wound healing, with a specific focus on angiogenesis and vasculogenesis. Methods: Ischemic and diabetic wounds were created in FVB/NJ mice and an in vitro scratch wound model. PARP inhibitor PJ34 was delivered to the animals at 10 mg/kg/d through implanted osmotic pumps or added to the culture medium, respectively. Animal wound healing was assessed by daily digital photographs. Animal wound tissues, peripheral blood, and bone marrow cells were collected at different time points for further analysis with Western blot and flow cytometry. Scratch wound migration and invasion angiogenesis assays were performed using human umbilical vein endothelial cells (HUVECs). Measurements were reported as mean ± standard deviation. Continuous measurements were compared by t‐test. P < .05 was considered statistically significant. Results: A significant increase in PARP activity was observed under ischemic and diabetic conditions that correlated with delayed wound healing and slower HUVEC migration. The beneficial effect of PARP inhibition with PJ34 on ischemic and diabetic wound healing was observed in both animal and in vitro models. In the animal model, the percentage of wound healing was significantly enhanced from 43% ± 6% to 71% ± 9% (P < .05) by day 7 with the addition of PJ34. PARP inhibition promoted angiogenesis at the ischemic and diabetic wound beds as evidenced by significantly higher levels of endothelial cell markers (vascular endothelial growth factor receptor 2 [VEGFR2] and endothelial nitric oxide synthase) in mice treated with PJ34 compared with controls. Flow cytometry analysis of peripheral blood mononuclear cells showed that PARP inhibition increased mobilization of endothelial progenitor cells (VEGFR2+/CD133+ and VEGFR2+/CD34+) into the systemic circulation. Furthermore, under in vitro hyperglycemia and hypoxia conditions, PARP inhibition enhanced HUVEC migration and invasion in Boyden chamber assays by 80% and 180% (P < .05), respectively. Conclusions: Delayed healing in ischemic and diabetic wounds is caused by PARP hyperactivity, and PARP inhibition significantly enhanced ischemic and diabetic wound healing by promoting angiogenesis. Clinical Relevance: Chronic nonhealing wounds, a major health problem in the United States, affect 6.5 million people and cost

Hemodialysis vascular access construction in the upper extremity: a review.

25 billion annually. The two major risk factors of poor wound healing are arterial occlusive disease and diabetes. Because 40% of diabetics also have arterial occlusive disease, the people with combined ischemic and diabetic wounds have the highest risk for limb loss. Biologic treatment to enhance angiogenesis through gene and cellular therapy has been studied extensively to promote limb salvage. A better understanding of the mechanisms behind poor healing in diabetic and ischemic wounds is needed for the identification of new treatment targets.

Transforming growth factor-β in liver cancer stem cells and regeneration

Purpose This article reviews the conventional vascular access types in the upper extremities for hemodialysis. Methods We performed a literature search for autogenous arteriovenous fistula in the upper extremities. Results The upper extremities have four potential sites: radio-cephalic or radio-basilic transposition in the forearm, and brachio-cephalic or brachio-basilic transposition in the upper arm. A pre-operative Duplex ultrasound provides valuable information regarding arterial inflow and venous outflow. The surgical approach to fistula formation and final product depends on vein diameter and length as well as proximal vein patency. The discussion focuses on access outcomes and management of common complications. Conclusions The upper extremity arteriovenous fistula is the preferred access for hemodialysis. A number of arteriovenous fistulas can be created in the upper extremities. The Duplex ultrasound identifies suitable arteries and veins for successful arteriovenous hemodialysis fistula creation. Arteriovenous hemodialysis fistula has the best long-term patency outcomes and the lowest associated morbidity and mortality. Early detection and intervention can save the fistula when complications occur.

Which Is Best for Abdominal Aortic Aneurysms Treatment with Chronic Renal Insufficiency: Endovascular Aneurysm Repair or Open Repair?

Cancer stem cells have established mechanisms that contribute to tumor heterogeneity as well as resistance to therapy. Over 40% of hepatocellular carcinomas (HCCs) are considered to be clonal and arise from a stem‐like/cancer stem cell. Moreover, HCC is the second leading cause of cancer death worldwide, and an improved understanding of cancer stem cells and targeting these in this cancer are urgently needed. Multiple studies have revealed etiological patterns and multiple genes/pathways signifying initiation and progression of HCC; however, unlike the transforming growth factor β (TGF‐β) pathway, loss of p53 and/or activation of β‐catenin do not spontaneously drive HCC in animal models. Despite many advances in cancer genetics that include identifying the dominant role of TGF‐β signaling in gastrointestinal cancers, we have not reached an integrated view of genetic mutations, copy number changes, driver pathways, and animal models that support effective targeted therapies for these common and lethal cancers. Moreover, pathways involved in stem cell transformation into gastrointestinal cancers remain largely undefined. Identifying the key mechanisms and developing models that reflect the human disease can lead to effective new treatment strategies. In this review, we dissect the evidence obtained from mouse and human liver regeneration, and mouse genetics, to provide insight into the role of TGF‐β in regulating the cancer stem cell niche. (Hepatology Communications 2017;1:477–493)

A NOVEL FRAILTY BASED VASCULAR RISK SCORE FOR PREDICTION OF POOR OUTCOMES IN PERIPHERAL VASCULAR INTERVENTION

� Endovascular aneurysm repair (EVAR) should be the first-line therapy for abdominal aortic aneurysm (AAA) in patients with moderate renal dysfunction (30 mL/min < estimated glomerular filtration rate [eGFR] <60 mL/min) because of better outcomes compared with open repair. � ElectiverepairofAAAinpatientswithsevererenaldysfunction(eGFR<30mL/min) should be avoided because of significant risk of postoperative renal failure/dialysis with either EVAR or open repair. � Intravascular ultrasound (IVUS) and CO2 arteriograms should be used for the initial EVAR procedure to minimize contrast nephrotoxicity. � Follow-up protocols after EVAR should include color duplex ultrasound and abdominal radiograph to prevent further decline of renal function due to multiple CT angiograms (CTAs).

Unusual sites for hemodialysis vascular access construction and catheter placement: A review.

Frailty has been proposed as a predictor of postoperative morbidity and mortality in aging vascular surgery population. We developed a frailty-based vascular risk score (VRS) applicable to range of postoperative outcomes and tested it in patients who have undergone peripheral vascular interventions

Postoperative complications after common femoral endarterectomy.

As more end-stage renal disease patients require hemodialysis and live longer, many will fail to develop or maintain a functioning upper extremity vascular access. When a patient exhausts vascular access sites in the upper extremities, new fistulas and grafts can be constructed in the lower extremities, thorax, and abdomen as long as a pair of proximate artery and vein provide adequate blood inflow and outflow, respectively. When only a moderate size vein with adequate blood flow provides a conduit to either a patent superior or inferior vena cava, inserting a double-lumen venous hemodialysis catheter can provide temporary or permanent access. We review the literature and report the unusual sites for hemodialysis vascular access and catheter placement.