Patients referred for arteriovenous fistula construction: a retrospective outcome analysis.

OBJECTIVES: With lower rates of sepsis and re-interventions, arteriovenous fistula (AVF) is the preferred vascular access modality. The aim of this study is to evaluate the outcomes of patients referred for AVF construction at a single center in Cork, Ireland. METHODS: The current study is a single-center retrospective review of all patients who underwent AVF creation between 2015 and 2017. Additionally, the kidney disease clinical patient management system was used to provide statistics on AVF use in Ireland. RESULTS: 39.3% of hemodialysis patients in Ireland use an AVF for vascular access. Regional use ranged from 50 to 20% across Irish hemodialysis centers. At Cork University Hospital, 192 AVFs were created. The population was 69.3% male (n = 133), 30.7% female (n = 59) with a mean (±SEM) age of 58.8 ± 1.03 years. 69.5% of females received a brachiocephalic AVF (BCAVF) while 13.6% had a radiocephalic AVF (RCAVF) constructed. Significance was seen when comparing gender and AVF type (p < 0.001). Fifty-four percent of the fistulae were brachiocephalic (n = 103), 33% were radiocephalic (n = 63), and 4% were brachiobasilic (n = 8). BCAVF patients (62.7 ± 1.2 years) were significantly older than patients receiving a RCAVF (54.5 ± 1.9 years, p < 0.001). A post-operative thrill or continuous flow on Doppler was present in 99% of patients (n = 190) with maturation and complication rates of 82.7% (n = 153) and 5.7% (n = 11) respectively. 69.9% of AVFs were needled for hemodialysis (n = 114). CONCLUSIONS: AVF outcomes at this center are consistent with reported statistics in the literature. Patient age, sex, and diabetic status may influence the use of proximal AVF. AVF creation rates in Ireland are below international reported recommendations.

A Systematic Review and Meta-analysis of Thrombotic Events Following Endovenous Thermal Ablation of the Great Saphenous Vein.

OBJECTIVES: A systematic review and meta-analysis was performed to determine the incidence of thrombotic events following great saphenous vein (GSV) endovenous thermal ablation (EVTA). METHODS: MEDLINE, Embase and conference abstracts were searched. Eligible studies were randomised controlled trials and case series that included at least 100 patients who underwent GSV EVTA (laser ablation or radiofrequency ablation [RFA]) with duplex ultrasound (DUS) within 30 days. The systematic review focused on the complications of endovenous heat induced thrombosis (EHIT), deep venous thrombosis (DVT), and pulmonary embolism (PE). The primary outcome for the meta-analysis was deep venous thrombotic events which were defined as DVT or EHIT Type 2, 3, or 4. Secondary outcomes for the meta-analysis were EHIT Type 2, 3, or 4, DVT and PE. Subgroup analyses were performed for both the RFA and EVLA groups. Pooled proportions were calculated using random effects modelling. RESULTS: Fifty-two studies (16,398 patients) were included. Thrombotic complications occurred infrequently. Deep venous thrombotic events occurred in 1.7% of cases (95% CI 0.9-2.7%) (25 studies; 10,012 patients; 274 events). EHIT Type 2, 3, or 4 occurred in 1.4% of cases (95% CI 0.8-2.3%) (26 studies; 10,225 patients; 249 events). DVT occurred in 0.3% of cases (95% CI = 0.2%-0.5%) (49 studies; 15,676 patients; 48 events). PE occurred in 0.1% of cases (95% CI = 0.1-0.2%) (29 studies; 8223 patients; 3 events). Similar results were found when the RFA and EVLA groups were analysed separately. CONCLUSION: Thrombotic events occur infrequently following GSV EVTA. Given the large numbers of procedures worldwide and the potential for serious consequences, further research is needed on the burden of these complications and their management.

Preconditioning Shields Against Vascular Events in Surgery (SAVES), a multicentre feasibility trial of preconditioning against adverse events in major vascular surgery: study protocol for a randomised control trial.

BACKGROUND: Patients undergoing vascular surgery procedures constitute a 'high-risk' group. Fatal and disabling perioperative complications are common. Complications arise via multiple aetiological pathways. This mechanistic redundancy limits techniques to reduce complications that target individual mechanisms, for example, anti-platelet agents. Remote ischaemic preconditioning (RIPC) induces a protective phenotype in at-risk tissue, conferring protection against ischaemia-reperfusion injury regardless of the trigger. RIPC is induced by repeated periods of upper limb ischaemia-reperfusion produced using a blood pressure cuff. RIPC confers some protection against cardiac and renal injury during major vascular surgery in proof-of-concept trials. Similar trials suggest benefit during cardiac surgery. Several uncertainties remain in advance of a full-scale trial to evaluate clinical efficacy. We propose a feasibility trial to fully evaluate arm-induced RIPC's ability to confer protection in major vascular surgery, assess the incidence of a proposed composite primary efficacy endpoint and evaluate the intervention's acceptability to patients and staff. METHODS/DESIGN: Four hundred major vascular surgery patients in five Irish vascular centres will be randomised (stratified for centre and procedure) to undergo RIPC or not immediately before surgery. RIPC will be induced using a blood pressure cuff with four cycles of 5 minutes of ischaemia followed by 5 minutes of reperfusion immediately before the start of operations. There is no sham intervention. Participants will undergo serum troponin measurements pre-operatively and 1, 2, and 3 days post-operatively. Participants will undergo 12-lead electrocardiograms pre-operatively and on the second post-operative day. Predefined complications within one year of surgery will be recorded. Patient and staff experiences will be explored using qualitative techniques. The primary outcome measure is the proportion of patients who develop elevated serum troponin levels in the first 3 days post-operatively. Secondary outcome measures include length of hospital and critical care stay, unplanned critical care admissions, death, myocardial infarction, stroke, mesenteric ischaemia and need for renal replacement therapy (within 30 days of surgery). DISCUSSION: RIPC is novel intervention with the potential to significantly improve perioperative outcomes. This trial will provide the first evaluation of RIPC's ability to reduce adverse clinical events following major vascular surgery. TRIAL REGISTRATION: www.clinicaltrials.gov NCT02097186 Date Registered: 24 March 2014.

Early outcome following endovascular repair of pararenal aortic aneurysms: triple- versus double- or single-fenestrated stent-grafts.

PURPOSE: To review the early outcome following endovascular repair of pararenal aortic aneurysm using fenestrated stent-grafts and to determine if the number of fenestrations required is predicative of outcome. METHODS: A retrospective analysis was conducted of 20 consecutive patients (18 men; mean age of 75 ± 7 years) treated with stent-grafts containing either ≤ 2 fenestrations (n = 10, group 1) or 3 fenestrations (n = 10, group 2). Target vessels also included those accommodated by a scallop (renal artery or superior mesenteric artery in group 1 and the celiac artery in group 2). RESULTS: Comorbidities were similar in both groups. Aneurysm size [median 6.9 (IQR 6.7-8.3) versus 6.0 cm (IQR 5.8-6.6), p = 0.03], procedure time (mean 6.6 ± 2.1 versus 4.6 ± 1.7 hours, p = 0.04), and intensive care stay [median 4.5 (IQR 2-14) versus 2 (IQR 1-3) days, p = 0.07] were greater in group 2. There were 2 postoperative deaths, both in group 2. Morbidity was significant and similar in both groups (4 patients in group 1 and 3 patients in group 2), including 1 patient requiring long-term hemodialysis. Target vessel preservation was similar in both groups (96% overall). There were 2 type II endoleaks (one in each group) and no type I or III endoleak. CONCLUSION: Triple-fenestrated stent-grafts allow patients with extensive pararenal aneurysms and significant comorbidity to be treated by endovascular means. Although the number of patients treated was small, which limited the validity of the comparison, longer procedures and greater early morbidity and mortality were seen in the triple-fenestrated group. At present, the procedures are technically more demanding and associated with increased risk compared with double or single fenestrations, but the technology continues to evolve.

Temporary axillobifemoral bypass as an adjunct to endovascular aneurysm repair using fenestrated stent grafts.

Prolonged endovascular procedures requiring a large diameter sheath in each groin can be associated with significant intraoperative lower limb ischemia, particularly in those with pre-existing peripheral vascular disease. We report the case of a patient who suffered severe ischemia-reperfusion injury following endovascular repair of a pararenal aortic aneurysm using a fenestrated stent graft and describe the use of temporary axillobifemoral bypass in a patient with similar comorbidities undergoing the same procedure. We propose this adjunctive technique as a means of maintaining antegrade limb perfusion and avoiding the peripheral and central metabolic consequences of ischemia-reperfusion injury.

Preloaded fenestrated stent-grafts for the treatment of juxtarenal aortic aneurysms.

PURPOSE: To describe a novel technique for target vessel catheterization in patients with juxtarenal abdominal aortic aneurysms requiring treatment with fenestrated stent-grafts (FSG). METHODS: The standard FSG design was modified, substituting a thin-wall tube for the solid central obturator that serves as both an attachment point for the distal end of the graft as well as a top cap retriever. Through this tube, two 0.020-inch wires are run from the hub of the delivery system through the stent-graft, out through each fenestration, and up to the proximal edge of the graft, where they are attached by sutures. The sutures are connected to a trigger wire on the control hub. The preloaded wires facilitate passage of a sheath to the fenestration, providing stability while target vessel catheterization takes place and avoiding the use of a large sheath in the contralateral groin. A third wire attached to the inside of the top cap facilitates its safe retrieval via a 6-mm balloon. The preloaded FSG was used in 5 male patients (mean age 75.6 years) with either juxtarenal aneurysms (n = 2) or aneurysms previously treated with infrarenal stent-grafts that had developed type I endoleak (n = 3). In 3 cases, a double fenestrated stent-graft was required, and in 2 cases a triple fenestrated device was deployed, with scallops for the superior mesenteric or celiac arteries. RESULTS: Sixteen of 17 target vessels were preserved, and all aneurysms were successfully excluded with no endoleak at completion. In 2 patients, tortuosity encountered during device delivery caused twisting of the wires within the preloaded FSG, preventing successful advancement of a sheath over a preloaded wire. An approach from the contralateral groin was necessary to complete the procedure in 1 case, but the target vessel was lost in the other. CONCLUSION: The use of a preloaded FSG is feasible and facilitates the catheterization of fenestrations and of target arteries. This method has the potential to reduce procedure times and lower the risk of intraoperative lower limb ischemia.

In situ fenestration in the aortic arch.

In situ fenestration of aortic stent grafts has the potential to allow for continued perfusion of supra-aortic trunks, without the need for extra-anatomic bypass, and without the need for custom-made devices. Angulation of the target vessel relative to the arch is an obstacle to success with this technique. In this report, we describe a case of successful in situ fenestration of the left subclavian artery (LSA) in a patient with an aortic arch aneurysm, treated with an endovascular stent graft. We outline a novel technique using through and through wire access and a pre-curved semi-rigid sheath, which allows successful access to the lumen of the aortic stent graft, despite an acute angle at the take-off of the LSA.

Endovascular treatment for chronic type B dissection: limitations of short stent-grafts revealed at midterm follow-up.

PURPOSE: To examine the incidence of and the indications for re-intervention, as well as the changes in aortic morphology, in patients with chronic type B aortic dissection who underwent endovascular intervention for false lumen aneurysms. METHODS: A retrospective analysis was conducted of 10 patients (8 men; mean age 63 years, range 45-79) who underwent stent-graft repair of aneurysmal false lumen expansion related to chronic type B aortic dissection at a median 16 months (range 2-71) from the initial diagnosis. All grafts had been oversized by 10% relative to the normal non-dissected aorta and were implanted to cover the primary entry tear. Follow-up computed tomography scans were analyzed to define changes in aortic morphology. RESULTS: Mean radiological follow-up was 56 months (median 64.5; range 19-86.5). There was no perioperative mortality or stroke; no cases of aortic rupture were recorded during follow-up. One patient suffered a procedure-related stroke with postoperative hemiparesis following re-intervention for proximal erosion 15 months after the initial treatment. In 6 of the 7 re-interventions performed in 6 patients at a median 42 months after the index procedure, stent-graft extension was required to treat erosion of the dissection membrane that had resulted in endoleak with false lumen reperfusion. The extent of dissection, duration of follow-up, or length of aortic coverage was not predictive of the need for re-intervention during follow-up. At last follow-up, the mean false lumen diameter at the level of the stented aorta was significantly smaller than at baseline (11+/-15 versus 24+/-15 mm, p<0.01). This was associated with false lumen thrombosis at the level of the stent-graft in 9 of 10 cases, although 7 patients had persistent false lumen perfusion distal to the stent-graft. CONCLUSION: Endovascular stent-graft treatment is effective therapy for chronic type B dissection patients with false lumen aneurysms. Erosion of the dissection membrane, causing proximal or distal endoleak, is the most common reason for re-intervention during midterm follow-up.

Endovascular treatment of acute complicated type B dissection: morphological changes at midterm follow-up.

PURPOSE: To review midterm results and morphological changes following endovascular treatment of acute complicated type B dissection and to study the relation between extent of dissection and treatment outcome. METHODS: Between February 2001 and March 2008, 52 patients (38 men; median age 67 years, range 40-82) received thoracic stent-grafts for acute complicated type B dissections. Outcome for those patients treated for intramural hematoma (IMH; group 1, n = 7) or type IIIa dissection (group 2, n = 17) were compared to those with type IIIb dissection (group 3, n = 28). True lumen index (TLi), false lumen index (FLi; ratio of true or false lumen diameter, respectively, to the sum of both), and FL perfusion were calculated prior to treatment and at the last follow-up from computed tomographic angiography (CTA) scans. RESULTS: Perioperative morbidity and mortality rates were 28.5% and 28.5% in group 1, 18% and 12%, respectively, for group 2, and 18% and 11% for group 3. No adjunctive treatment or re-intervention was required in groups 1 or 2, while the rates were 37% and 22%, respectively, for these events in group 3 (p = 0.009 and p = 0.034, respectively, versus groups 1 + 2). Mean imaging surveillance was 31 months, and no patients were lost to follow-up. In group 2, there was 1 case of persistent FL perfusion at last CTA, whereas in group 3, 68% had persistent FL perfusion detected; the mean FLi ranged from 0.12 at the level of the carina to 0.33 at the level of the inferior mesenteric artery. Half of the patients in this group had an increase in FL diameter correlating significantly with FL perfusion, mostly distal to the stented aorta. CONCLUSION: Despite similar morbidity and perioperative mortality rates, outcomes following endovascular treatment of acute complicated type B dissection varied with the extent of the dissection. Persistent FL perfusion below the stent-graft, associated with aneurysm expansion and the need for re-intervention, was seen most often in type IIIb dissection. Patients with the more limited type IIIa dissection or IMH were likely to be cured by endovascular therapy.

Abdominal aortic aneurysm diameter: a comparison of ultrasound measurements with those from standard and three-dimensional computed tomography reconstruction.

OBJECTIVE: Aortic aneurysm size is a critical determinant of the need for intervention, yet the maximal diameter will often vary depending on the modality and method of measurement. We aimed to define the relationship between commonly used computed tomography (CT) measurement techniques and those based on current reporting standards and to compare the values obtained with diameter measured using ultrasound (US). METHODS: CT scans from patients with US-detected aneurysms were analyzed using three-dimensional reconstruction software. Maximal aortic diameter was recorded in the anteroposterior (CT-AP) plane, along the maximal ellipse (CT-ME), perpendicular to the maximal ellipse (CT-PME), or perpendicular to the centerline of flow (CT-PCLF). Diameter measurements were compared with each other and with maximal AP diameter according to US (US-AP). Analysis was performed according to the principles of Bland and Altman. Results are expressed as mean +/- standard deviation. RESULTS: CT and US scans from 109 patients (92 men, 17 women), with a mean age of 72 +/- 8 years, were included. The mean of each series of readings on CT was significantly larger than the mean US-AP measurement (P < .001), and they also differed significantly from each other (P < .001). The CT-PCLF diameter was larger than CT-AP and CT-PME by mean values of 3.0 +/- 6.6 and 5.9 +/- 6.0 mm, respectively. The CT-ME diameter was larger than CT-PCLF by a mean of 2.4 +/- 5 mm. The US-AP diameter was smaller than CT-AP diameter by 4.2 +/- 4.9 mm, CT-ME by 9.6 +/- 8.0 mm, CT-PME by 1.3 +/- 5 mm, and smaller than CT-PCLF by 7.3 +/- 7.0 mm. Aneurysm size did not significantly affect these differences. Seventy-eight percent of 120 pairs of intraobserver CT measurements and 65% of interobserver CT measurements differed by <2 mm. CONCLUSIONS: CT-based measurements of aneurysm size tend to be larger than the US-AP measurement. CT-PCLF diameters are consistently larger than CT-PME as well as CT-AP measurements. These differences should be considered when applying evidence from previous trials to clinical decisions.

Duplex ultrasound in aneurysm surveillance following endovascular aneurysm repair: a comparison with computed tomography aortography.

OBJECTIVES: Cumulative radiation dose, cost, and increased demand for computed tomography aortography (CTA) suggest that duplex ultrasonography (DU) may be an alternative to CTA-based surveillance. We compared CTA with DU during endovascular aneurysm repair (EVAR) follow-up. METHODS: Patients undergoing EVAR had clinical and radiological follow-up data entered in a prospectively maintained database. For the purpose of this study, the gold standard test for endoleak detection was CTA, and an endoleak detected on DU alone was assumed to be a false positive result. DU interpretation was performed independently of CTA and vice versa. RESULTS: One hundred thirty-two patients underwent EVAR, of whom 117 attended for follow-up ranging from six months to nine years (mean, 32 months). Adequate aneurysm sac visualisation on DU was not possible in 1.7% of patients, predominantly due to obesity. Twenty-eight endoleaks were detected in 28 patients during follow-up. Of these, 24 were initially identified on DU (four false negative DU examinations), and eight had at least one negative CTA with a positive DU prior to diagnosis. Twenty-three endoleaks were type II in nature and three of these patients had increased sac size. There was one type I and four type III endoleaks. Two of these (both type III) had an increased sac size. Of 12 patients with increased aneurysm size of 5 mm or more at follow-up, five had an endoleak visible on DU, yet negative CTA and a further five had endoleak visualisation on both DU and CTA. Of six endoleaks which underwent re-intervention, all were initially picked up on DU. One of these endoleaks was never demonstrated on CTA and a further two had at least one negative CTA prior to endoleak confirmation. Positive predictive value for DU was 45% and negative predictive value 94%. Specificity of DU for endoleak detection was 67% when compared with CTA, because of the large number of false positive DU results. Sensitivity for DU was 86%, with all clinically significant endoleaks demonstrated on CTA also detected on DU. CONCLUSION: Despite its low positive predictive value, we found DU to be a sensitive test for the detection of clinically significant endoleaks. Given concerns about cumulative radiation exposure and cost, and the surprisingly low sensitivity of CTA for endoleak detection in this series, selective CTA based on DU surveillance may be a more appropriate long-term strategy.

Duration of increased bleeding tendency after cessation of aspirin therapy.

BACKGROUND: Aspirin has a significant effect on hemostasis, so it is often recommended that patients taking aspirin discontinue treatment before elective surgery. While off aspirin, these patients may be at risk of thrombosis. The optimum period of time that aspirin should be withheld is controversial. The aim of this study was to establish the duration of the antihemostatic effect of prolonged aspirin therapy. STUDY DESIGN: In a prospective study, 51 healthy volunteers were randomly assigned into 3 groups, each receiving an identical tablet for 14 days. One group received a placebo tablet; individuals in the other two groups received either 75 mg or 300 mg of aspirin once a day. Template bleeding times and specific platelet function testing (using the PFA-100; Dade Behring) were carried out on subjects before therapy and again after its completion until they returned to baseline. RESULTS: Thirty-eight volunteers complied sufficiently with the protocol to provide useful results. All bleeding times normalized within 96 hours and all platelet function tests within 144 hours after stopping aspirin. There was no demonstrable hemostatic defect in any volunteer persisting by or beyond the sixth day after treatment cessation. There was no apparent difference in duration of effect between those taking either 75 mg or 300 mg of aspirin. CONCLUSIONS: This study uses sensitive measures of platelet function to demonstrate the duration of increased bleeding tendency after withdrawal of aspirin therapy. It supports discontinuation of aspirin therapy 5 days before elective surgery (with the operation being performed on the sixth day).

The effect of aspirin on blood loss and transfusion requirements in patients with femoral neck fractures.

Although it is widely accepted that aspirin will increase the risk of intra- and post-operative bleeding, clinical studies have not consistently supported this assumption. We aimed to assess the effect of pre-operative aspirin on blood loss and transfusion requirements in patients undergoing emergency fixation of femoral neck fractures. A prospective case-control study was undertaken in patients presenting with femoral neck fractures. Parameters recorded included intra-operative blood loss, post-operative blood loss, transfusion requirements and peri-operative reduction in haemoglobin concentration. Of 89 patients presenting with femoral neck fractures 32 were on long-term aspirin therapy. Pre-operative aspirin ingestion did not significantly affect peri-operative blood loss, or change in haemoglobin concentration or haematocrit. However those patients taking aspirin pre-operatively had a significantly lower haemoglobin concentration and haematocrit and were more likely to be anaemic at presentation than those who were not receiving aspirin. Patients taking aspirin were also more likely to receive blood transfusion post-operatively.