Invasive coronary angiography (ICA) has long been the established gold standard in assessing graft patency following coronary artery bypass graft (CABG). Over the past decade or so however, improvements in computed tomography angiography (CTA) technology have allowed its emergence as a useful clinical tool in graft assessment. The recent introduction of 64-slice and now 128-slice scanners into widespread distribution, and the development of 320-detector row technology allowing volumetric imaging of the entire heart at single points in time within one cardiac cycle, has increased the potential of CTA to supersede ICA in this capacity. This study sought to examine the evidence surrounding this potential. A best evidence topic was constructed according to a structured protocol. The enquiry: In [patients who have undergone coronary artery bypass graft surgery] is [computed tomography angiography or invasive coronary angiography] superior in terms of [graft patency assessment, stenosis detection, radiation exposure and complication rate]? Four hundred and twenty-four articles were identified from the search strategy. Four additional articles were identified from references of key articles. Seventeen articles selected as best evidence were tabulated. The reliability of CTA as a tool in the detection of graft patency and stenosis has continued to improve with each successive generation of multislice technology. The latest 64- and 128-slice CTA techniques are able to detect graft patency and stenosis with very high sensitivities and specificities comparable with ICA, while remaining non-invasive procedures associated with fewer complications (ICA carries a 0.08% risk of myocardial infarction and 0.7% risk of minor complications in clinically stable patients). Present limitations of the technology include the accurate visualization of distal anastomoses and clip artefacts. In addition, the capacity of diagnostic ICA to be combined simultaneously with percutaneous coronary interventions is an important advantage and a further limitation of CTA alone. Recent developments, however, including the derivation of fractional flow reserve and perfusion assessment from CTA as functional measures of stenosis severity have given CTA at present the capacity to become a first-line tool in the assessment of patients with suspected graft dysfunction. Novel computer-automated diagnostic software, though currently in infancy, has shown promise in facilitating and speeding image interpretation. With further improvements in scanning technologies, CTA is likely to supersede ICA for graft assessment in the near future.
Background This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. Methods This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score‐matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score‐matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery. Results A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score‐matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498). Conclusion There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast‐induced nephropathy should not be used as a reason to avoid contrast‐enhanced CT.
The peri-operative use of angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers is thought to be associated with an increased risk of postoperative acute kidney injury. To reduce this risk, these agents are commonly withheld during the peri-operative period. This study aimed to investigate if withholding angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers peri-operatively reduces the risk of acute kidney injury following major non-cardiac surgery. Patients undergoing elective major surgery on the gastrointestinal tract and/or the liver were eligible for inclusion in this prospective study. The primary outcome was the development of acute kidney injury within seven days of operation. Adjusted multi-level models were used to account for centre-level effects and propensity score matching was used to reduce the effects of selection bias between treatment groups. A total of 949 patients were included from 160 centres across the UK and Republic of Ireland. From this population, 573 (60.4%) patients had their angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers withheld during the peri-operative period. One hundred and seventy-five (18.4%) patients developed acute kidney injury; there was no difference in the incidence of acute kidney injury between patients who had their angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers continued or withheld (107 (18.7%) vs. 68 (18.1%), respectively; p = 0.914). Following propensity matching, withholding angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers did not demonstrate a protective effect against the development of postoperative acute kidney injury (OR (95%CI) 0.89 (0.58-1.34); p = 0.567).
A best evidence topic in vascular surgery was written according to a structured protocol. The question addressed whether endovascular treatment improved peri-operative outcomes when compared to an open approach to restore arterial perfusion in acute mesenteric occlusive disease. Four hundred and ninety seven papers were identified using the reported search; of which 4 represented the best evidence to answer the question and are discussed. The evidence on this subject is limited, comprising largely of non-randomised retrospective cohort studies. The evidence suggests that endovascular treatment is associated with reduced mortality and has better short-term peri-operative outcomes, as well as longer-term survival - however many endovascular cases require subsequent open surgery. There is also conflicting evidence to suggest endovascular therapy is associated with longer ICU stays. Aside from procedural complications, factors such as patient status, time delay to diagnosis and treatment may play a greater role in determining mortality rates. In summary, endovascular therapy appears to be a feasible treatment option with post-operative complications and inpatient mortality rates lower than those seen in open surgery.
A best evidence topic in transplant surgery was written according to a structured protocol. The question addressed was: In adults undergoing renal transplantation, does pyeloureterostomy, as compared to ureteroneocystostomy, improve clinical outcomes? A total of 235 articles were identified using the search protocol described, of which six represented the best evidence available to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. These included one prospective cohort study, three retrospective cohort studies and two case series. The largest of the five cohort studies demonstrated significantly reduced levels of complications with pyeloureterostomy as compared to ureteroneocystostomy. The consensus from the remaining trials was that pyeloureterostomy is a safe but underused technique. However, the majority of the evidence pertaining to pyeloureterostomy and ureteroneocystostomy was archaic, with four of the six dating from pre-1990. Furthermore, the most recent articles (reported in 2010 and 2013) provide only level three and four evidence respectively, and contain important flaws with regard to patient-cohort allocation inherent to the study design. For these reasons we are cautious in recommending pyeloureterostomy over ureteroneocystostomy with the current evidence base, but would like to emphasise that pyeloureterostomy remains a safe surgical option which should form part of the modern transplant surgeon's reconstructive repertoire, particularly when managing patients in which multiple complications are anticipated, or when there is fear of ureteral vascular compromise, such as with cadaveric kidneys. We call for larger scale prospective trials to aid clarification of the roles of pyeloureterostomy and ureteroneocystostomy in renal transplant surgery and to enrich this prescient field with much needed 21st century evidence.
Adherence to BET guidelines has been variable. Authors are encouraged to adhere to journal guidelines and reviewers and editors to enforce them. BETs have received similar citation levels to other IJS articles. Means of increasing the visibility of published BETs such as social media sharing, conference presentation and deposition of abstracts in public repositories should be explored. More work is required to encourage more submissions from other surgical subspecialties other than gastrointestinal specialties.
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