Supervised exercise training improves cardiorespiratory fitness and reduces perioperative risk in peripheral artery disease patients with intermittent claudication.

INTRODUCTION: This study examined to what extent supervised aerobic and resistance exercise combined with continued unsupervised exercise training improves cardiorespiratory fitness and corresponding perioperative risk in peripheral artery disease (PAD) patients with intermittent claudication. METHODS: A total of 106 patients (77% male) were enrolled into the study, alongside 155 healthy non-PAD control participants. Patients completed supervised exercise therapy (aerobic and resistance exercises of the upper and lower limbs) twice a week for 10 weeks. Thereafter, 52 patients completed 12 weeks of an unsupervised tailored home-based exercise. Pain-free walking distance (PWD), maximum walking distance (MWD), peak oxygen uptake ([Formula: see text]) and perioperative risk were assessed before and after both exercise interventions. RESULTS: Patients were highly unconditioned relative to healthy controls ([Formula: see text]=11.9 vs 24.2ml/kg/min, p=<0.001) with 91% classified as high perioperative risk (peak oxygen uptake <15ml/kg/min). Supervised exercise increased PWD (+44±81m, p=<0.001), MWD (+44±71m, p=<0.001) and [Formula: see text] (+1.01±1.63ml/kg/min, p=<0.001) and lowered perioperative risk (91% to 85%, p=<0.001). When compared with supervised exercise, the improvements in PWD were maintained following unsupervised exercise (+11±91m vs supervised exercise, p=0.572); however, MWD and [Formula: see text] decreased (-15±48m, p=0.030 and -0.34±1.11ml/kg/min, p=0.030, respectively) and perioperative risk increased (+3%, p=<0.001) although still below baseline (p=<0.001). CONCLUSIONS: Supervised aerobic and resistance exercise training and, to a lesser extent, unsupervised tailored exercise improves walking capacity and cardiorespiratory fitness and reduces perioperative risk in PAD patients with intermittent claudication.

Takayasu's arteritis and acute type B aortic dissection treated with a stent graft.

OBJECTIVES: Takayasu's arteritis is a large vessel vasculitis which usually involves the aorta and its first generation branches. Aortic dissection, however, is a rare manifestation of Takayasu's arteritis and for this reason optimum management in both short and long term is unknown. METHODS: This is a case of a 31-year-old female presenting with acute type B AD in association with underlying TA which failed to respond to conservative management and underwent thoracic stent grafting (TEVAR). RESULTS: Despite successful coverage of the intimal breach in the thoracic aorta by TEVAR there were complications with delivery of the stent which required a conduit sutured to the right common iliac artery. Also post-TEVAR computed tomography showed a localised dissection of the origin of the left common carotid artery which may have been iatrogenic possibly due to the stiff guidewire used during delivery of the stent graft to the thoracic aorta. CONCLUSIONS: The use of TEVAR for an acute type B AD in those with TA may be problematic. The fragility of the major arteries increases the likelihood of iatrogenic periprocedural complications and long-term surveillance is essential due to significant chance of further arterial complications in type B AD occurring in TA.

Cardiorespiratory fitness fails to predict short-term postoperative mortality in patients undergoing elective open surgery for abdominal aortic aneurysm.

INTRODUCTION: Preoperative cardiopulmonary exercise testing aids surgical risk stratification and is an established predictor of mid- to long-term survival in patients undergoing elective open abdominal aortic aneurysm repair. Whether cardiopulmonary exercise testing also predicts 30-day mortality in this population remains to be established. MATERIALS AND METHODS: Data for 109 patients (mean age 72 years) who underwent cardiopulmonary exercise testing to assess risk for surgical abdominal aortic aneurysm repair was analysed. Patients were classified according to cardiopulmonary fitness as fit (peak oxygen uptake ≥ 15ml O2.kg-1.min-1) or unfit (peak oxygen uptake less than 15ml O2.kg-1.min-1) and further stratified according to clamp position (infrarenal or suprarenal). Between-group postoperative outcomes were compared for in-hospital 30-day mortality, postoperative morbidity scale scores (day 5) and hospital length of stay. RESULTS: Seventy-nine patients underwent open surgery and 30 patients were treated conservatively. No deaths were recorded at 30 days post-surgery. Unfit patients with infrarenal clamping exhibited higher postoperative morbidity scale scores (64% vs 26%) and longer length of stay (four days) than fit patients (p < 0.05). Conversely, with suprarenal clamping, postoperative morbidity scale scores were similar and length of stay longer (three days) in fit compared with unfit patients (p < 0.05). DISCUSSION AND CONCLUSION: Preoperative fitness level defined by peak oxygen uptake failed to identify patients at risk of 30-day mortality when undergoing elective abdominal aortic aneurysm repair. Postoperative morbidity and length of stay in patients with suprarenal clamping was high independent of cardiopulmonary fitness. These findings suggest that cardiopulmonary exercise testing may be a useful predictor of complications following infrarenal rather than suprarenal clamping but may not be a good predictor of 30-day mortality.

Cardiorespiratory fitness is impaired and predicts mid-term postoperative survival in patients with abdominal aortic aneurysm disease.

NEW FINDINGS: What is the central question of this study? To what extent cardiorespiratory fitness is impaired in patients with abdominal aortic aneurysmal (AAA) disease and corresponding implications for postoperative survival requires further investigation. What is the main finding and its importance? Cardiorespiratory fitness is impaired in patients with AAA disease. Patients with peak oxygen uptake of <13.1 ml O2  kg-1  min-1 and ventilatory equivalent for carbon dioxide at anaerobic threshold ≥34 are associated with increased risk of postoperative mortality at 2 years. These findings demonstrate that cardiorespiratory fitness can predict mid-term postoperative survival in AAA patients, which may help to direct care provision. ABSTRACT: Preoperative cardiopulmonary exercise testing is a standard assessment of cardiorespiratory fitness (CRF) and risk stratification. However, to what extent CRF is impaired in patients undergoing surgical repair of abdominal aortic aneurysm (AAA) disease and the corresponding implications for postoperative outcome requires further investigation. We measured CRF during an incremental exercise test to exhaustion using online respiratory gas analysis in patients with AAA disease (n = 124, aged 72 ± 7 years) and healthy sedentary control subjects (n = 104, aged 70 ± 7 years). Postoperative survival was examined for association with CRF, and threshold values were calculated for independent predictors of mortality. Patients who underwent preoperative cardiopulmonary exercise testing before surgical repair had lower CRF [age-adjusted mean difference of 12.5 ml O2  kg-1  min-1 for peak oxygen uptake ( V ̇ O 2 peak ), P < 0.001 versus control subjects]. After multivariable analysis, both V ̇ O 2 peak and the ventilatory equivalent for carbon dioxide at anaerobic threshold ( V ̇ E / V ̇ C O 2 - AT ) were independent predictors of mid-term postoperative survival (2 years). Hazard ratios of 5.27 (95% confidence interval 1.62-17.14, P = 0.006) and 3.26 (95% confidence interval 1.00-10.59, P = 0.049) were observed for V ̇ O 2 peak  < 13.1 ml O2  kg-1  min-1 and V ̇ E / V ̇ C O 2 - AT ≥ 34, respectively. Thus, CRF is lower in patients with AAA, and those with a V ̇ O 2 peak  < 13.1 ml O2  kg-1  min-1 and V ̇ E / V ̇ C O 2 - AT ≥ 34 are associated with a markedly increased risk of postoperative mortality. Collectively, our findings demonstrate that CRF can predict mid-term postoperative survival in AAA patients, which may help to direct care provision.

The cardiopulmonary exercise test grey zone; optimising fitness stratification by application of critical difference.

BACKGROUND: Cardiorespiratory fitness can inform patient care, although to what extent natural variation in CRF influences clinical practice remains to be established. We calculated natural variation for cardiopulmonary exercise test (CPET) metrics, which may have implications for fitness stratification. METHODS: In a two-armed experiment, critical difference comprising analytical imprecision and biological variation was calculated for cardiorespiratory fitness and thus defined the magnitude of change required to claim a clinically meaningful change. This metric was retrospectively applied to 213 patients scheduled for colorectal surgery. These patients underwent CPET and the potential for misclassification of fitness was calculated. We created a model with boundaries inclusive of natural variation [critical difference applied to oxygen uptake at anaerobic threshold (V˙O2-AT): 11 ml O2 kg-1 min-1, peak oxygen uptake (V˙O2 peak): 16 ml O2 kg-1 min-1, and ventilatory equivalent for carbon dioxide at AT (V̇E/V̇CO2-AT): 36]. RESULTS: The critical difference for V˙O2-AT, V˙O2 peak, and V˙E/V˙CO2-AT was 19%, 13%, and 10%, respectively, resulting in false negative and false positive rates of up to 28% and 32% for unfit patients. Our model identified boundaries for unfit and fit patients: AT <9.2 and ≥13.6 ml O2 kg-1 min-1, V˙O2 peak <14.2 and ≥18.3 ml kg-1 min-1, V˙E/V˙CO2-AT ≥40.1 and <32.7, between which an area of indeterminate-fitness was established. With natural variation considered, up to 60% of patients presented with indeterminate-fitness. CONCLUSIONS: These findings support a reappraisal of current clinical interpretation of cardiorespiratory fitness highlighting the potential for incorrect fitness stratification when natural variation is not accounted for.

The infraclavicular approach for Paget-Schroetter syndrome.

Introduction Paget-Schroetter syndrome is a rare effort thrombosis of the axillary-subclavian vein, mainly occurring in young male patients. Current management involves immediate catheter directed thrombolysis, followed by surgical decompression of the subclavian vein. This has been invariably performed using a transaxillary or supraclavicular approach. However, the subclavian vein crosses the first rib anteriorly just behind the manubrium and can also be accessed via an infraclavicular incision. Methods MEDLINE® and Embase™ were searched for all studies on outcomes in patients undergoing infraclavicular first rib resection for treatment of Paget-Schroetter syndrome. Measured outcomes included freedom from reintervention, secondary patency and symptom resolution. Studies on neurogenic, arterial and iatrogenic venous thoracic outlet syndrome were not included. Findings Six studies (involving 268 patients) were eligible. The overall secondary venous patency rate was 98.5%. There was freedom from reintervention in 89.9% of cases and among those patients with reocclusion, 84.0% had chronic thrombosis (symptom duration >14 days), with 76.2% having a venous segment stenosis of >2cm. Only 3 of the 27 patients remained occluded despite reintervention. The infraclavicular approach provides excellent exposure to the subclavian vein and allows reconstruction when required. Moreover, this approach enables complete resection of the extrinsic compression that precipitated the initial thrombotic event, with excellent long-term patency rates. In conclusion, the infraclavicular route may have significant advantages compared with the transaxillary or supraclavicular approaches for successful and durable treatment of Paget-Schroetter syndrome.

Changes in microvascular density differentiate metabolic health outcomes in monkeys with prior radiation exposure and subsequent skeletal muscle ECM remodeling.

Radiation exposure accelerates the onset of age-related diseases such as diabetes, cardiovascular disease, and neoplasia and, thus, lends insight into in vivo mechanisms common to these disorders. Fibrosis and extracellular matrix (ECM) remodeling, which occur with aging and overnutrition and following irradiation, are risk factors for development of type 2 diabetes mellitus. We previously demonstrated an increased incidence of skeletal muscle insulin resistance and type 2 diabetes mellitus in monkeys that had been exposed to whole body irradiation 5-9 yr prior. We hypothesized that irradiation-induced fibrosis alters muscle architecture, predisposing irradiated animals to insulin resistance and overt diabetes. Rhesus macaques (Macaca mulatta, n = 7-8/group) grouped as nonirradiated age-matched controls (Non-Rad-CTL), irradiated nondiabetic monkeys (Rad-CTL), and irradiated monkeys that subsequently developed diabetes (Rad-DM) were compared. Prior radiation exposure resulted in persistent skeletal muscle ECM changes, including a relative overabundance of collagen IV and a trend toward increased transforming growth factor-ß1. Preservation of microvascular markers differentiated the irradiated diabetic and nondiabetic groups. Microvascular density and plasma nitrate and heat shock protein 90 levels were lower in Rad-DM than Rad-CTL. These results are consistent with a protective effect of abundant microvasculature in maintaining glycemic control within radiation-induced fibrotic muscle.

Systematic Review and Meta-analysis of the Effect of Internal Iliac Artery Exclusion for Patients Undergoing EVAR.

OBJECTIVE: Endovascular abdominal aortic aneurysm repair (EVAR) sometimes requires internal iliac artery (IIA) coverage to achieve a landing zone in the external iliac artery. The aim of this study was to determine complication rates following IIA exclusion. MATERIALS AND METHODS: A systematic review of key journals was undertaken from January 1980 to April 2016. Studies detailing occlusion (using coils or plugs) or coverage of the IIA with outcome data were included. Weighted means were calculated for continuous variables. Meta-analysis was performed when comparative data were available. Quality was assessed using the GRADE system. RESULTS: Sixty-one non-randomised studies (2671 patients; 2748 IIAs) were analysed. Fifteen per cent of EVARs require IIA sacrifice. Buttock claudication (BC) occurred in 27.9% of patients, although 48.0% resolved after 21.8 months. BC rates were 32.6% with coils, 23.8% with plugs, and 12.9% with coverage alone, and less with unilateral (vs. bilateral) IIA treatment (OR 0.57, 95% CI 0.36-0.91). More proximal coil placement resulted in lower rates of BC (OR 0.12, 95% CI 0.03-0.48). Erectile dysfunction occurred in 10.2% of males, with higher rates after coiling. Type II endoleaks were more frequent after covering alone; however re-interventions were rare. Significant ischaemic events (bowel/gluteal/spinal ischaemia) were very rare. Plugs were quicker to place and required less radiation (p < .001) than coils. GRADE scoring was very low for all outcomes. CONCLUSION: Overall the quality of reported data on IIA sacrifice is poor. Buttock claudication and erectile dysfunction occurred frequently after IIA sacrifice. Where both options are technically possible, plugs could be considered preferential to coils, and placed as proximally in the IIA as possible.

Comparison between the TRS-398 code of practice and the TG-51 dosimetry protocol for flattening filter free beams.

Dosimetry protocols for external beam radiotherapy currently in use, such as the IAEA TRS-398 and AAPM TG-51, were written for conventional linear accelerators. In these accelerators, a flattening filter is used to produce a beam which is uniform at water depths where the ionization chamber is used to measure the absorbed dose. Recently, clinical linacs have been implemented without the flattening filter, and published theoretical analysis suggested that with these beams a dosimetric error of order 0.6% could be expected for IAEA TRS-398, because the TPR20,10 beam quality index does not accurately predict the stopping power ratio (water to air) for the softer flattening-filter-free (FFF) beam spectra. We measured doses on eleven FFF linacs at 6 MV and 10 MV using both dosimetry protocols and found average differences of 0.2% or less. The expected shift due to stopping powers was not observed. We present Monte Carlo k Q calculations which show a much smaller difference between FFF and flattened beams than originally predicted. These results are explained by the inclusion of the added backscatter plates and build-up filters used in modern clinical FFF linacs, compared to a Monte Carlo model of an FFF linac in which the flattening filter is removed and no additional build-up or backscatter plate is added.

Essential steps in the performance of safe retroperitoneal aortic surgery.

Endovascular stent grafting has become the primary modality when assessing patients for treatment of abdominal aortic aneurysms (AAA). The traditional open approach is transperitoneal (TP) but many suggest the retroperitoneal method (RP) has significant benefits. Retroperitoneal aortic surgery may be unfamiliar to many surgeons as they have been trained in the TP approach. This paper provides specific tips for the critical steps of this approach enabling it to be performed with ease and minimal morbidity.

Systematic review and meta-analysis of the efficacy of perineural local anaesthetic catheters after major lower limb amputation.

OBJECTIVE: The aim of this systematic review and meta-analysis was to evaluate the effects of using an intraoperatively placed perineural catheter (PNC) with a postoperative local anaesthetic infusion on immediate and long-term outcomes after lower limb amputation. METHODS: A systematic review of key electronic journal databases was undertaken from inception to January 2015. Studies comparing PNC use with either a control, or no PNC, were included. Meta-analysis was performed for postoperative opioid use, pain scores, mortality, and long-term incidence of stump and phantom limb pain. Sensitivity analysis was performed for opioid use. Quality of evidence was assessed using the GRADE system. RESULTS: Seven studies reporting on 416 patients undergoing lower limb amputation with PNC usage (n = 199) or not (n = 217) were included. Approximately 60% were transtibial amputations PNC use reduced postoperative opioid consumption (standardised mean difference: -0.59, 95% CI -1.10 to -0.07, p = .03), maintained on sensitivity analysis for large (p = .03) and high-quality (p = .003) studies, but was marginally lost (p = .06) on studies enrolling patients with peripheral arterial disease only. PNC treatment did not affect postoperative pain scores (p = .48), in-hospital mortality (p = .77), phantom limb pain (p = .28) or stump pain (p = .37). GRADE quality of evidence for all outcomes was very low. CONCLUSION: There is poor-quality evidence that PNC usage significantly reduces opioid consumption following lower limb amputation, without affecting other short- or long-term outcomes. Well-performed randomised studies are required.

Treatment of symptomatic coral reef aorta with an uncovered stent graft.

Coral reef aorta is a rare condition characterised by extreme calcific growths affecting the juxta and suprarenal aorta. It can cause symptoms due to visceral ischaemia, lower limb hypoperfusion, and distal embolisation. We present a case of a 61-year-old man with unresponsive hypertension, who was found to have an occluded right renal artery, and an extensive coral reef aorta with a marked pressure gradient across the lesion. Renal hypoperfusion secondary to aortic coral reef aorta was thought to be the cause for his hypertension. Endovascular placement of a balloon expandable uncovered stent resolved his hypertension within one month, with no adverse effects noted at subsequent follow-up. Endovascular treatment of coral reef aorta is technically possible and avoids a major vascular procedure.

Systematic review and meta-analysis of direct versus indirect angiosomal revascularisation of infrapopliteal arteries.

OBJECTIVE: The aim of this systematic review was to evaluate outcomes of direct revascularisation (DR) versus indirect revascularisation (IR) of infrapopliteal arteries to the affected angiosome for critical limb ischaemia. Both open and endovascular techniques were included. METHODS: A systematic review of key electronic journal databases was undertaken from inception to 22 March 2014. Studies comparing DR versus IR in patients with localised tissue loss were included. Meta-analysis was performed for wound healing, limb salvage, mortality, and re-intervention rates, with numerous sensitivity analyses. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. RESULTS: Fifteen cohort studies reporting on 1,868 individual limbs were included (endovascular revascularisation, 1,284 limbs; surgical revascularisation, 508 limbs; both methods, 76 limbs). GRADE quality of evidence was low or very low for all outcomes. DR resulted in improved wound healing rates compared with IR (odds ratio [OR] 0.40, 95% confidence interval [CI] 0.29-0.54) and improved limb salvage rates (OR 0.24, 95% CI 0.13-0.45), although this latter effect was lost on high-quality study sensitivity analysis. Wound healing and limb salvage was improved for both open and endovascular intervention. There was no effect on mortality (OR 0.77, 95% CI 0.50-1.19) or reintervention rates (OR: 0.44, 95% CI 0.10-1.88). CONCLUSION: DR of the tibial vessels appears to result in improved wound healing and limb salvage rates compared with IR, with no effect on mortality or reintervention rates. However, the quality of evidence on which these conclusions are based on is low.

Systematic review and meta-analysis of the retroperitoneal versus the transperitoneal approach to the abdominal aorta.

OBJECTIVES: The aim was to systematically review and meta-analyse the differences between the retroperitoneal (RP) and the transperitoneal (TP) approach to the infrarenal abdominal aorta. DESIGN: Systematic review and meta-analysis. METHODS: PubMed, the Cochrane library, Embase and ClinicalTrials.gov were searched for all studies on differences in clinical outcomes between the RP and TP approach. Outcomes were selected based on inclusion in two or more studies: Operative (length of procedure, intraoperative blood loss); Post operative complications (paralytic ileus, pneumonia, myocardial infarction (MI), renal failure and wound hernia); Mortality (30 day, 1 year); Post-operative changes in respiratory function (forced expiratory volume in 1 second, forced vital capacity); Length of hospital and Intensive care unit (ICU) stay and Cost. The data were pooled by outcome. RESULTS: Eight randomised and 21 cohort studies involving 3035 patients were included. Meta-analysis showed significantly lower rates of postoperative ileus (Odds ratio (OR) 0.17[95% CI 0.10, 0.32] p < 0.00001), pneumonia (OR 0.42[95% CI 0.26, 0.68] p = 0.0004), ICU stay (standardised mean difference (SMD) 0.67[95% CI 1.28, 0.06] p = 0.03), total hospital stay (SMD 0.88[95% CI 1.32, 0.44] p < 0.0001) and cost (SMD 1.15[95% CI 2.11, 0.19] p = 0.02) for patients undergoing a RP approach. Study quality was generally low, with conflicting results and concerns over publication bias in some cohort studies. CONCLUSIONS: The RP approach for open aortic surgery is associated with lower rates of postoperative ileus and pneumonia when compared to the TP approach.

Systematic review and meta-analysis of vein cuffs for below-knee synthetic bypass.

BACKGROUND: The aim was to investigate the possible benefit of vein cuffs for femoral to below-knee popliteal and femorodistal vessel synthetic bypass grafts. METHODS: PubMed, the Cochrane library, Embase and ClinicalTrials.gov were searched for all studies on any clinical effect of vein cuffs on synthetic grafts. Outcomes were selected based on inclusion in two or more studies: primary patency and limb survival. The data were subjected to meta-analysis by outcome. RESULTS: Three cohort and two randomized studies were selected for inclusion, involving 885 patients. Meta-analysis of five studies examining below-knee popliteal bypass showed a significant improvement for primary patency in cuffed grafts at 2 years, but not at 1 or 3 years (odds ratio at 2 years 0·46, 95 per cent confidence interval 0·22 to 0·97; P = 0·04). Limb salvage was significantly improved in cuffed grafts up to 2 years. Limb survival was also improved for cuffed distal grafts at 2 years (odds ratio 0·29, 0·11 to 0·75; P = 0·01) but showed no difference at any other time interval. Study quality was generally poor, with conflicting results. CONCLUSION: There was a small but significant benefit for vein cuffs on synthetic grafts used for femoral to below-knee popliteal anastomoses, but little benefit for femorodistal anastomoses.

Systematic review and meta-analysis of the effects of statin therapy on abdominal aortic aneurysms.

BACKGROUND: The aim was to investigate the effects of statin therapy on abdominal aortic aneurysm (AAA) disease. METHODS: PubMed, the Cochrane Library, Embase and ClinicalTrials.gov were searched for all studies on any clinical effect of statin therapy on AAA. Outcomes were selected based on their inclusion in two or more studies: AAA expansion rate, 30-day mortality, and short- and long-term postoperative mortality. The data were subjected to meta-analysis by outcome. RESULTS: Twelve cohort studies were selected for inclusion involving 11 933 individuals. Meta-analysis of four studies examining all-cause postoperative mortality showed a significant improvement with statin therapy at 1, 2 and 5 years (odds ratio (OR) at 5 years 0·57, 95 per cent confidence interval (c.i.) 0·42 to 0·79; P < 0·001) with minimal heterogeneity between the four included studies. There was no significant difference in 30-day mortality after AAA treatment in patients on statin therapy (OR 0·22, 0·02 to 2·90; P = 0·25). Sensitivity analysis including four high-quality studies examining AAA expansion rates showed no significant difference with statin therapy: standardized mean difference -0·14 (95 per cent c.i. -0·33 to -0·05) mm/year (P = 0·16). CONCLUSION: The claim of a reduction in AAA expansion rate with statin therapy is based on low-quality evidence and was not significant on meta-analysis. However, statin therapy did appear to improve all-cause survival after AAA repair.