L.L. Lau

Endovenous laser treatment for long saphenous vein incompetence.

Endovenous laser treatment is a percutaneous technique used for the treatment of long saphenous vein (LSV) incompetence. This paper presents the results of an uncontrolled case series undertaken to assess the feasibility, safety and efficacy of this technique.

Cytokine Activation and Intestinal Mucosal and Renal Dysfunction are Reduced in Endovascular AAA Repair Compared to Surgery

Purpose: To compare endovascular (EVR) to open repair (OR) of abdominal aortic aneurysm (AAA) for cytokine activation, changes in the intestinal mucosal barrier, and renal dysfunction. Methods: In a prospective nonrandomized study, 15 patients admitted to a university hospital for elective infrarenal AAA repair (8 OR and 7 EVR) were recruited. Intestinal permeability was assessed preoperatively (PO), at day 1 (D1), and at day 3 (D3) after surgery using the lactulose/mannitol differential excretion (LMR) test. Renal damage was assessed from measurements of the urinary albumin:creatinine ratio (ACR); cytokine activation was based on the urinary concentration of tumor necrosis factor receptor p55 (TNF-Rp55) at the same time points. Serum creatinine and urea concentrations were measured preoperatively and daily for 5 days postoperatively. Results: A significant increase in LMR was found in the OR group at D1 and D3 compared to PO (p<0.05). The LMR increase at D3 was significantly greater in the OR group (p<0.01). A significant difference was observed in the percentage rise in ACR on D1 in the OR group compared to the EVR group (p<0.005). The urinary TNF-Rp55 concentration was significantly elevated in the OR group at D1 (p<0.05) and D3 (p<0.05) compared to baseline; in the EVR group, it was elevated at D1 (p<0.05) compared to PO. The difference was also significant for this marker between the 2 groups at D1 (p<0.01). No significant change was observed in the serum creatinine or urea concentrations in either group perioperatively Conclusions: Endovascular AAA repair is associated with less cytokine production and less intestinal and renal dysfunction compared to the open approach.

Implications of Attendance Patterns in Northern Ireland for Abdominal Aortic Aneurysm Screening

INTRODUCTION Evidence supports the introduction of an abdominal aortic aneurysm (AAA) screening programme. The aims of this study were to estimate future disease patterns and to determine the effect of the proportion attending on the programmes cost-effectiveness. PATIENTS AND METHODS The results of the local AAA screening programme were reviewed. Ultrasonic infrarenal aortic diameter of 30 mm was considered aneurysmal. Projected population numbers from the Department of Health and current disease prevalence were used to estimate future number of potential patients. The Multi-centre Aneurysm Screening Study (MASS) Markov model was used to calculate an incremental cost-effectiveness ratio (ICER) and 95% uncertainty intervals (UI), using a 30-year time horizon and 3.5% per annum discount, to determine the effect of attendance. RESULTS Men were recruited from August 2004 to May 2010. 13316 were invited for a scan and 5931 (44.5%) attended. 321 AAA were diagnosed, giving a prevalence of 5.4%, while 27 large AAA (0.46%) were repaired. The annual incidence of AAA until 2021 will range from 441 to 526, with an incidence of 40-48 large AAA, with both showing a gradual increase with time. Using this attendance rate, the ICER was calculated at £2350 per life-year gained (95% UI: £1620-£4290), or £3020 per quality-adjusted life-year gained (95% UI: £2080-£5500). CONCLUSIONS The prevalence of disease in this local AAA screening was similar to other studies. The low attendance will result in many AAA being missed, but will not impact greatly on the long-term cost-effectiveness.

Retroperitoneal Repair of Abdominal Aortic Aneurysm Reduces Bowel Dysfunction

Objective: To assess the effect of intestinal manipulation and mesenteric traction on gastro-intestinal function and postoperative recovery in patients undergoing abdominal aortic aneurysm (AAA) repair. Methods: Thirty-five patients undergoing AAA repair were randomised into 3 groups. Group I (n = 11) had repair via retroperitoneal approach while Group II (n = 12) and Group III (n = 12) were repaired via transperitoneal approach with bowel packed within the peritoneal cavity or exteriorised in a bowel bag respectively. Gastric emptying was measured pre-operatively (day 0), day 1 and day 3 using paracetamol absorption test (PAT) and area under curve (PAUC) was calculated. Intestinal permeability was measured using the Lactulose-Mannitol test. Results: Aneurysm size, operation time and PAT (on day 0 and day 3) were similar in the three groups. On day 1, the PAUC was significantly higher in Group I, when compared with Group II and Group III (P = .02). Resumption of diet was also significantly earlier in Group I as compared to Group II and Group III. The intestinal permeability was significantly increased in Group II and Group III at day 1 when compared with day 0, with no significant increase in Group I. Retroperitoneal repair was also associated with significantly shorter intensive care unit (P = .04) and hospital stay (P = .047), when compared with the combined transperitoneal repair group (Group II and III). Conclusion: Retroperitoneal AAA repair minimises intestinal dysfunction and may lead to quicker patient recovery when compared to transperitoneal repair.

Retroperitoneal Approach to Abdominal Aortic Aneurysm Repair Preserves Splanchnic Perfusion as Measured by Gastric Tonometry

BACKGROUND We investigated if minimizing bowel manipulation and mesenteric traction using the retroperitoneal approach in open abdominal aortic aneurysm (AAA) repair preserves splanchnic perfusion, as measured by gastric tonometry, and reduces the systemic inflammatory response and dysfunction of the various organs. METHODS Patients undergoing elective AAA repair were randomized into three groups. Group I had repair via the retroperitoneal approach, while groups II and III were repaired via the transperitoneal approach with the bowel packed within the peritoneal cavity or exteriorized in a bowel bag, respectively. A tonometer was used to measure gastric intramucosal pH (pHi), as an indicator of splanchnic perfusion, just prior to aortic clamping, during clamping, and at 0.5, 1, 2, 4, 6, and 12 hr after clamp release. Multiorgan dysfunction syndrome (MODS) and systemic inflammatory response syndrome (SIRS) scores were calculated and systemic interleukins (IL-6 and IL-10) measured at predetermined intervals. RESULTS Thirty-four patients were successfully randomized. The gastric pHi was significantly lower in group II (n=12) and group III (n=11) compared to group I (n=11) during aortic clamping and immediately after clamp release (p<0.05). The aortic clamp time, blood loss, MODS and SIRS scores, and systemic cytokine response were similar in all three groups. When the three groups were combined, there were significant positive correlations between the operation time, aortic clamp time, and amount of blood lost and transfused with plasma IL-6 levels and MODS score on the first postoperative day. CONCLUSION The retroperitoneal approach for open AAA repair is associated with gastric tonometric evidence of better splanchnic perfusion compared to the transperitoneal approach.

Interleukin-6 production is reduced by the extraperitoneal approach in elective abdominal aortic aneurysm repair

Abdominal aortic aneurysm (AAA) repair through a transperitoneal approach induces a systemic interleukin-6 (IL-6) response which may be related to manipulation of the bowel and mesenteric traction. This study investigates the effect of avoiding intestinal manipulation on IL-6 production by comparing the use of extraperitoneal and transperitoneal approaches in elective infrarenal AAA repair. Patients undergoing elective AAA repair were randomized into either transperitoneal (n=10) or extraperitoneal (n=8) groups. Samples of systemic and portal blood were collected intraoperatively before, during and after aortic cross clamping. In addition, systemic blood samples were obtained pre-induction, post-induction, and 6, 12, 24, and 48 hours after abdominal incision. Plasma IL-6 concentration was measured using a bioassay based on the proliferation of IL-6 dependent B9 Hybridoma cells (sensitivity of assay is 30–40 pg/ml). In the extraperitoneal group, IL-6 was not detected in either the portal or systemic circulations intraoperatively. With the transperitoneal group, IL-6 was detected in 15 of 40 (38%) portal, and 8 of 40 (20%) systemic intraoperative samples (p<0.001,x2 test). Postoperatively, IL-6 was detected in only 14 of 32 (44%) samples taken during the 48 hours after extraperitoneal repair but in 35 of 40 (88%) samples after transperitoneal repair (p<0.001,x2 test). At 6 hours, the systemic IL-6 concentration was significantly higher in the transperitoneal group (p<0.01, Mann-WhitneyU test). No correlation was seen between the plasma IL-6 concentration and aortic clamp time, duration of operation, or amount of blood lost or transfused. These results supports the suggestion that intestinal manipulation plays an important role in driving the systemic inflammatory response that may be seen after transperitoneal AAA repair.

The effects of N‐acetylcysteine on host inflammatory response and renal function in patients undergoing infra‐inguinal bypass surgery

forms at 50kDa. Protein application to human vascular endothelial cells leads to a specific phosphorylation of the Tie2 receptor, maximal at 1 μg/ml for each. Conclusion: Using rational design we have engineered the first small molecular mass ligands for the Tie2 receptor. Two of these ligands have been shown to activate the receptor. Studies are currently underway to test the functional effects of these novel ligands on vascular endothelial apoptosis, leakage and inflammation.