Editor's Choice - Nationwide Analysis of Patients Undergoing Iliac Artery Aneurysm Repair in the Netherlands.

OBJECTIVE: The new 2019 guideline of the European Society for Vascular Surgery (ESVS) recommends consideration for elective iliac artery aneurysm (eIAA) repair when the iliac diameter exceeds 3.5 cm, as opposed to 3.0 cm previously. The current study assessed diameters at time of eIAA repair and ruptured IAA (rIAA) repair and compared clinical outcomes after open surgical repair (OSR) and endovascular aneurysm repair (EVAR). METHODS: This retrospective observational study used the nationwide Dutch Surgical Aneurysm Audit (DSAA) registry that includes all patients who undergo aorto-iliac aneurysm repair in the Netherlands. All patients who underwent primary IAA repair between 1 January 2014 and 1 January 2018 were included. Diameters at time of eIAA and rIAA repair were compared in a descriptive fashion. The anatomical location of the IAA was not registered in the registry. Patient characteristics and outcomes of OSR and EVAR were compared with appropriate statistical tests. RESULTS: The DSAA registry comprised 974 patients who underwent IAA repair. A total of 851 patients were included after exclusion of patients undergoing revision surgery and patients with missing essential variables. eIAA repair was carried out in 713 patients, rIAA repair in 102, and symptomatic IAA repair in 36. OSR was performed in 205, EVAR in 618, and hybrid repairs and conversions in 28. The median maximum IAA diameter at the time of eIAA and rIAA repair was 43 (IQR 38-50) mm and 68 (IQR 58-85) mm, respectively. Mortality was 1.3% (95% CI 0.7-2.4) after eIAA repair and 25.5% (95% CI 18.0-34.7) after rIAA repair. Mortality was not significantly different between the OSR and EVAR subgroups. Elective OSR was associated with significantly more complications than EVAR (intra-operative: 9.8% vs. 3.6%, post-operative: 34.0% vs. 13.8%, respectively). CONCLUSION: In the Netherlands, most eIAA repairs are performed at diameters larger than recommended by the ESVS guideline. These findings appear to support the recent increase in the threshold diameter for eIAA repair.

Deletrious effect of prolonged cold ischemia on renal function.

The detrimental effect of prolonged cold ischemia (CI) on posttransplant renal function has long been recognized. However, the cellular consequences of CI have not been clearly defined. This study describes a model for the identification of CI-induced injury by evaluating ex-vivo renal metabolism and function prior to reperfusion. Small bovine kidneys were cold stored in Viaspan for 24-, 48-, 72-, and 96 h. Kidneys were then warm perfused (32 degrees C) using Exsangiunous Metabolic Support (EMS) technology and evaluated for oxidative metabolism, vascular dynamics and function. Oxygen consumption, vascular resistance, and diuresis were stable in kidneys with CI up to 48 h. After 72- and 96 h of CI, vascular resistance was increased while oxygen consumption and diuresis were reduced (P < 0.05). Glomerular filtration rate was diminished at CI greater than 24 h (P < 0.05). Results show that function was compromised with CI greater than 24 h and preceded the loss of cell viability following 48 h of CI.

Pretransplantation prognostic testing on damaged kidneys during ex vivo warm perfusion.

BACKGROUND: Further expansion of the donor pool with ischemically damaged kidneys will be predicated on the ability to develop prognostic testing. Using a well-established canine autotransplantation injury model, we assessed whether actual restoration of renal metabolism by ex vivo warm perfusion could be used to predict the status of an organ before transplantation. METHODS: Kidneys were subjected to 30 min of warm ischemia followed by 24 hr of static storage in ViaSpan at 4 degrees C. After warm ischemia and static storage the kidneys were transitioned to 3 hr of warm perfusion using Exsanguinous Metabolic Support technology. During this period, parameters indicative of renal metabolism and vascular function were used to predict outcomes prospectively. Parameters included measures of oxidative metabolism, perfusion characteristics, and vascular condition. A Viability Score (VS) was calculated as the sum of the three parameters mentioned above. Results were grouped by a VS>2 and a VS<2. RESULTS: A clear association between the severity and duration of graft dysfunction and the VS was observed. Organs with a VS>2 had a significantly milder period of acute tubular necrosis, with both a less severe rise in serum creatinine (mean of 4.4 vs. 11 mg/dl) and a shorter recovery period (mean of 8 vs. 18 days) than those with a VS<2. CONCLUSIONS: Results indicate the possibility of utilizing warm perfusion to evaluate kidneys before transplantation. The VS developed demonstrated efficacy in classifying the severity of the acute tubular necrosis and the occurrence of primary nonfunction, offering a sensitive assay for prospective organ testing.

Hypothermia--a limiting factor in using warm ischemically damaged kidneys.

A study was performed to determine the limiting factors to expanding the donor pool with warm ischemically (WI) damaged kidneys. Canine kidneys were damaged by 30 min of WI, and then either cold stored (CS) in ViaSpan (4 degrees C) for 18 h, or warm perfused with exsanguineous metabolic support (EMS) technology (32 degrees C) for 18h, or subjected to combinations of both techniques. The kidneys were autotransplanted with contralateral nephrectomy. In kidneys with WI and CS alone, the mean peak serum creatinine value was 6.3mg/dL and took 14 days to normalize. In contrast, kidneys where renal metabolism was resuscitated ex vivo during 18 h of warm perfusion demonstrated mild elevations in the serum chemistries (2.6mg/dL). The damage in kidneys CS for 18h was ameliorated with 3 h of subsequent warm perfusion and eliminated by 18 h of warm perfusion. In contrast, reversing the order with CS following WI and 18h of warm perfusion resulted in a time-dependent increase in damage. These results identify hypothermia as a major limiting factor to expanding indications for kidney donation. While hypothermia represents the foundation of preservation in the heart-beating donor, its use in WI damaged organs appears to represent a limiting factor.

Exsanguinous metabolic support perfusion--a new strategy to improve graft function after kidney transplantation.

BACKGROUND: The compounding damage of warm ischemia (WI) followed by cold preservation is a major barrier in renal transplantation. Although the relative effect of WI is not yet well understood, therapeutic strategies have mostly focused on minimizing the pathology seen upon reperfusion from the cold. Our study was designed to examine the effect of restoration of renal metabolism by warm perfusion on graft survival and to investigate the compounding damage of WI. METHODS: Using a known critical canine autotransplantation model (1), kidneys were exposed to 30 min WI followed by 24 hr cold storage in Viaspan. They were then either reimplanted directly or first transitioned to 3 hr of warm perfusion with an acellular perfusate before reimplantation. Contralateral kidneys were subjected to 0, 30, or 60 min WI; 24 hr cold storage, and 3 hr warm perfusion. RESULTS: Transplanted kidneys that were warm perfused before reimplantation had both lower 24 hr posttransplant serum creatinine (median of 3.2 vs. 4.1 mg/dl) and lower peak serum creatinine (median of 4.95 vs. 7.1 mg/dl). Survival rate for warm perfused kidneys was 90% (9/10) vs. 73% (8/11). In the contralateral kidneys, metabolism was affected by the compounding damage of WI. Renal oxygen and glucose consumption diminished significantly, whereas vascular resistance and lactate dehydrogenase-release rose significantly with increasing WI. CONCLUSIONS: The results demonstrate a reduction of reperfusion damage by an acellular ex vivo restoration of renal metabolism. Furthermore, data from the contralateral kidneys substantiates the relative role of WI on metabolism in renal transplantation.

I: Negative effect of cold ischemia on initial renal function.

Correlation between post-transplant function and exposure to cold ischemia (CI) during preservation has been reported. We attempted to identify the effect of CI on renal function using exsanguinous metabolic support (EMS) technology, to eliminate effects of reperfusion complications. Small bovine kidneys were used to evaluate 4 vs. 24 hours of CI, after warm ischemic (WI) exposure of <15, 30 or 60 minutes. After CI, kidneys were warm perfused (30 degrees C to 32 degrees C) ex vivo using EMS technology. Restored renal metabolism and function were quantified by oxygen consumption, urine production, glomerular filtration rate (GFR), and hemodynamic characteristics. The results demonstrate a CI-associated lag phase in the restoration of metabolism, in which the longer cold-preserved kidneys exhibit a lower initial rate of oxygen consumption. However, after 3 hours of EMS perfusion there was no significant difference in the O2 consumed, urine flow, GFR, perfusion flow, or pressure between the kidneys stored for 4 or 24 hours. An initial reduction in metabolism after longer CI may influence the severity of actual reperfusion injury during transplantation. Therefore, these results provide preliminary evidence suggesting that an acellular warm temperature reperfusion ex vivo may enhance restoration of cellular metabolism and minimize damage from the cold seen upon actual reperfusion.

Kidney preservation in the next millenium.

For the past decades, severe hypothermia has represented the foundation of organ preservation in clinical transplantation. Beneficial as hypothermia has proven to be in preserving grafts from heart-beating donors, hypothermia does not seem to provide the window necessary for the prospective evaluation of organ function. With the increasing use of non-heart-beating donors, it is logical to propose that if organs are to be evaluated prospectively, it will be necessary to preserve them at warmer temperatures. Since both glomerular and tubular functions are inhibited at temperatures below 18 degrees C, such a goal will necessitate organ preservation at a temperature above 20 degrees C. The principle of preservation at warmer temperatures is not new, but with future developments and approaches, successful realization appears within reach. In this overview, a brief history of previous attempts at warm preservation, in the context of the current status of kidney preservation, is presented. Future developments and approaches, with the potential for prospective testing of the function and enhanced resistance to ischemic damage, will be discussed.

[Pseudomyxoma peritonei]. / Pseudomyxoma peritonei.

Pseudomyxoma peritonei was diagnosed in 3 men aged 38, 66 and 54 years with weight loss and distension of the abdomen. Pseudomyxoma peritonei results from seeding of the peritoneal cavity with mucus-producing epithelium. The disease is traditionally characterized by accumulation of huge amounts of mucinous ascites, relatively long survival and absence of distant, extraperitoneal metastases. Mostly, the primary tumour is an appendicular adenoma or adenocarcinoma. Sometimes, the primary tumor is localized in the ovaries. Extensive surgical debulking with postoperative intraperitoneal chemotherapy appears to be the treatment of choice.

Ischemia-reperfusion injury of rat kidney relates more to tubular than to microcirculatory disturbances.

Several pathophysiological mechanisms have been purported to be involved in the development of acute ischemic renal failure, such as impairment of tubular function and/or of the renal microcirculation. However, it has not been elucidated as yet which of these mechanisms relates to the extent of kidney damage. Besides, little is known about the time course relationship between tubular and microcirculatory disturbances during the development of ischemia-reperfusion injury. We therefore performed intravital videomicroscopy of the proximal tubules as well as the peritubular microcirculation of the rat renal cortex during the first 24 hr of reperfusion after varying lengths of warm ischemia (30 min, 30 WI group; 60 min, 60 WI group; 90 min, 90 WI group). In a separate group of animals subjected to the same protocol, the survival rate (SR) was determined. The SR in these groups were 100%, 20% and 0%, respectively. Initially, the tubular and microcirculatory changes (i.e., increased tubular diameter and reduced capillary blood flow) relate well to the length of warm ischemia as well as the SR. At a later stage of reperfusion, however, we observed that peritubular capillary blood flow and tubular diameter recovered more quickly in the 90 WI group than in the 30 WI and 60 WI groups. As a result, these parameters as obtained at 24 hr of reperfusion did not relate anymore to the survival rate. Besides, at this stage a severe loss of integrity of the tubular wall was noted in the 60 WI and 90 WI groups. These findings suggest that kidney viability is not determined by the extent of recovery of microcirculatory blood flow and/or tubular diameter during early reperfusion, but by the integrity of the tubular wall.

Retrograde oxygen persufflation in combination with UW solution enhances adenine nucleotide contents in ischemically damaged rat kidney during cold storage.

Retrograde oxygen persufflation (ROP) has been reported to be beneficial to kidney preservation. The purpose of this study was to investigate whether use of ROP during cold storage (CS) with Universita of Wisconsin (UW) solution could ameliorate energy metabolism and functional recovery of ischemically injured rat kidneys and, moreover, to study the particular role of adenosine (ADO) in CS with ROP. Kidneys subjected to 30 min of warm ischemia (WI) were preserved for 24 h in 4 degrees C UW solution with or without ROP and with or without ADO. Measurements of tissue high-energy phosphate levels showed that reduced total adenine nucleotides (TAN) after 30 min of WI further declined during the subsequent CS. In ROP kidneys, however, TAN were less reduced, suggesting that even during CS, TAN can still be regenerated in the injured kidneys when ROP is combined with UW solution. When UW did not contain ADO, regeneration of TAN by ROP was slightly less than in the case of UW with ADO. This indicates that the supply of molecular oxygen is a significant factor in TAN resynthesis during CS. There was no statistically significant difference in survival rate between the ROP and CS groups, indicating that an improved energy status is not the sole determinant of functional recovery. We conclude that the gaseous oxygen supply provided by ROP during CS in UW solution ameliorates the energy state of ischemically injured rat kidneys and that exogenous ADO from the UW solution contributes to the improvement of energy metabolism to a limited extent.

Outcome of transplantation of non-heart-beating donor kidneys.

To reduce the shortage of kidneys for transplantation, we started a non-heart-beating (NHB) donor programme, and compared the short-term and long-term outcomes of kidneys from NHB donors with those of a matched group of kidneys from heart-beating (HB) donors. 57 NHB kidneys were procured at the University Hospital in Maastricht and at three regional hospitals in the Netherlands, and were transplanted in 21 transplant centres within the Eurotransplant exchange organisation. 114 matched controls from HB donors were selected from Eurotransplant files. Mean follow-up was 85 months. At 5 years, graft survival was 54% for NHB kidneys and 55% for HB kidneys; patient survival was 75% and 77%. Kidneys from NHB donors had a significantly higher rate of delayed graft function (60% vs 35%), resulting in a longer hospital stay. Primary non-function of the graft was seen as frequently in the NHB donor-kidney group as in the HB group (14% vs 8%, p = 0.3). We conclude that NHB donors are a valuable source of kidneys for transplantation.

Protection of canine renal grafts by renin-angiotensin inhibition through nucleoside transport blockade.

The aims of this study were (1) to investigate the effect of R 75231, a nucleoside transport inhibitor, on renin-angiotensin release after renal ischemia-reperfusion and (2) to establish a possible protective effect of this drug on renal function. We used a canine model for auto- transplantation of kidneys that had been subjected to 30 min of warm ischemia and subsequently to 24h of cold storage in HTK preservation solution, with immediate contralateral nephrectomy. R 75231 was injected intravenously into six dogs in two equal portions of 0.05 mg/kg both 30 min and 10 min before reanastomosis was established. Another six dogs were used as a control group. At 2 weeks post-transplantation, five out of six dogs in the R 75231 group and one out of six in the control group were still alive. Starting on day 4, serum creatinine was lower in the R 75231 group than in the control group (p < 0.005). In contrast to the control group, an inversion of the median preischemia adenosine/inosine ratio was observed in the R 75231 group after reperfusion (0.4 preischemia vs 4.0 after 60 min of reperfusion). Reperfusion of the graft resulted in an immediate increase in renin, angiotensin I, and angiotensin II venous blood levels in the control group. In the R 75231 group, renin, angiotension I, and angiotensin II levels were significantly lower. We conclude that administration of R 75231 before reperfusion has a protective effect on post-transplant function of kidneys that have been subjected to prolonged warm ischemia. This effect may, at least in part, be ascribed to inhibition of the breakdown and disposal of endogenous adenosine which, in turn, inhibits the excessive stimulation of the renin-angiotensin system in the early phase of reperfusion.