Nicholas Chalmers

High-risk clinical presentations in atherosclerotic renovascular disease: prognosis and response to renal artery revascularization

BACKGROUND Current trial data may not be directly applicable to patients with the highest risk presentations of atherosclerotic renovascular disease, including flash pulmonary edema, rapidly declining kidney function, and refractory hypertension. We consider the prognostic implications of these presentations and response to percutaneous revascularization. STUDY DESIGN Single-center prospective cohort study; retrospectively analyzed. SETTING & PARTICIPANTS 467 patients with renal artery stenosis ≥50%, managed according to clinical presentation and physician/patient preference. PREDICTORS Presentation with flash pulmonary edema (n = 37 [7.8%]), refractory hypertension (n = 116 [24.3%]), or rapidly declining kidney function (n = 46 [9.7%]) compared to low-risk presentation with none of these phenotypes (n = 230 [49%]). Percutaneous revascularization (performed in 32% of flash pulmonary edema, 28% of rapidly declining kidney function, and 28% of refractory hypertension patients) compared to medical management. OUTCOMES Death, cardiovascular (CV) event, end-stage kidney disease. RESULTS During a median follow-up of 3.8 (IQR, 1.8-5.8) years, 55% died, 33% had a CV event, and 18% reached end-stage kidney disease. In medically treated patients, flash pulmonary edema was associated with increased risk of death (HR, 2.2; 95% CI, 1.4-3.5; P < 0.001) and CV event (HR, 3.1; 95% CI, 1.7-5.5; P < 0.001), but not end-stage kidney disease, compared to the low-risk phenotype. No increased risk for any end point was observed in patients presenting with rapidly declining kidney function or refractory hypertension. Compared to medical treatment, revascularization was associated with reduced risk for death (HR, 0.4; 95% CI, 0.2-0.9; P = 0.01), but not CV event or end-stage kidney disease, in patients presenting with flash pulmonary edema. Revascularization was not associated significantly with reduced risk for any end point in rapidly declining kidney function or refractory hypertension. When these presentations were present in combination (n = 31), revascularization was associated with reduced risk for death (HR, 0.15; 95% CI, 0.02-0.9; P = 0.04) and CV event (HR, 0.23; 95% CI, 0.1-0.6; P = 0.02). LIMITATIONS Observational study; retrospective analysis; potential treatment bias. CONCLUSIONS This analysis supports guidelines citing flash pulmonary edema as an indication for renal artery revascularization in atherosclerotic renovascular disease. Patients presenting with a combination of rapidly declining kidney function and refractory hypertension also may benefit from revascularization and may represent a subgroup worthy of further investigation in more robust trials.

High-risk clinical presentations in atherosclerotic renovascular disease

BACKGROUND Current trial data may not be directly applicable to patients with the highest risk presentations of atherosclerotic renovascular disease, including flash pulmonary edema, rapidly declining kidney function, and refractory hypertension. We consider the prognostic implications of these presentations and response to percutaneous revascularization. STUDY DESIGN Single-center prospective cohort study; retrospectively analyzed. SETTING & PARTICIPANTS 467 patients with renal artery stenosis ≥50%, managed according to clinical presentation and physician/patient preference. PREDICTORS Presentation with flash pulmonary edema (n = 37 [7.8%]), refractory hypertension (n = 116 [24.3%]), or rapidly declining kidney function (n = 46 [9.7%]) compared to low-risk presentation with none of these phenotypes (n = 230 [49%]). Percutaneous revascularization (performed in 32% of flash pulmonary edema, 28% of rapidly declining kidney function, and 28% of refractory hypertension patients) compared to medical management. OUTCOMES Death, cardiovascular (CV) event, end-stage kidney disease. RESULTS During a median follow-up of 3.8 (IQR, 1.8-5.8) years, 55% died, 33% had a CV event, and 18% reached end-stage kidney disease. In medically treated patients, flash pulmonary edema was associated with increased risk of death (HR, 2.2; 95% CI, 1.4-3.5; P < 0.001) and CV event (HR, 3.1; 95% CI, 1.7-5.5; P < 0.001), but not end-stage kidney disease, compared to the low-risk phenotype. No increased risk for any end point was observed in patients presenting with rapidly declining kidney function or refractory hypertension. Compared to medical treatment, revascularization was associated with reduced risk for death (HR, 0.4; 95% CI, 0.2-0.9; P = 0.01), but not CV event or end-stage kidney disease, in patients presenting with flash pulmonary edema. Revascularization was not associated significantly with reduced risk for any end point in rapidly declining kidney function or refractory hypertension. When these presentations were present in combination (n = 31), revascularization was associated with reduced risk for death (HR, 0.15; 95% CI, 0.02-0.9; P = 0.04) and CV event (HR, 0.23; 95% CI, 0.1-0.6; P = 0.02). LIMITATIONS Observational study; retrospective analysis; potential treatment bias. CONCLUSIONS This analysis supports guidelines citing flash pulmonary edema as an indication for renal artery revascularization in atherosclerotic renovascular disease. Patients presenting with a combination of rapidly declining kidney function and refractory hypertension also may benefit from revascularization and may represent a subgroup worthy of further investigation in more robust trials.

Meta-Analysis of Outcomes of Endovascular Treatment of Infrapopliteal Occlusive Disease With Drug-Eluting Stents

Purpose To review emerging evidence regarding the use of bare metal (BMS) vs. drug-eluting stents (DES) in the treatment of infrapopliteal occlusive disease. Methods A systematic review of the literature was undertaken to identify all studies comparing stent treatments of infragenicular vessels in patients with chronic lower limb ischemia. Validated methods to assess the methodological quality of the included studies were applied. Outcome data were pooled, and combined overall effect sizes were calculated using fixed or random effects models. The search identified 4 randomized clinical trials and 2 observational studies reporting on 544 patients (287 treated with DES and 257 treated with BMS). Data are presented as the odds ratio (OR) with 95% confidence interval (CI) and the number-needed-to-treat (NNT). Results Primary patency, freedom from target lesion revascularization, and clinical improvement at 1 year were significantly higher in the DES recipients compared to patients treated with BMS (OR 4.511, 95% CI 2.897 to 7.024, p<0.001, NNT 3.5; OR 3.238, 95% CI 2.019 to 5.192, p<0.001, NNT 6.0; and OR 1.792, 95% CI 1.039 to 3.090, p=0.036, NNT 7.3, respectively). No significant differences in limb salvage and overall survival at 1 year were identified between the groups (OR 2.008, 95% CI 0.722 to 5.585, p=0.181; OR 1.262, 95% CI 0.605 to 2.634, p=0.535, respectively). Sensitivity analyses investigating the potential effects of study design and type of DES on the combined outcome estimates validated the results. Conclusion Our analysis has demonstrated superior short-term results with DES compared with BMS, expressed by increased patency and freedom from target lesion revascularization. The influence of this finding on clinical surrogate endpoints, such as limb salvage, remains unknown.

Management of transplant renal artery stenosis and its impact on long term allograft survival: a single centre experience

BACKGROUND Transplant renal artery stenosis (TRAS) is a recognized complication resulting in post-transplant hypertension associated with allograft dysfunction. It is a commonly missed but potentially treatable complication that may present from months to years after transplant surgery. In this retrospective study, we compared management strategies and outcomes of TRAS from 1990 to 2005. METHODS Case notes of transplant recipients with TRAS demonstrated by angiography were reviewed. Angiography and was carried out when there was a clinical or Doppler ultrasound suspicion of TRAS. The clinical diagnosis of TRAS was based on uncontrolled refractory/new-onset hypertension and/or unexplained graft dysfunction in the absence of another diagnosis, such as rejection, obstruction or infection. The two-tailed Student t-test was used to analyse the differences between mean arterial pressure, serum creatinine, and estimated glomerular filtration rate before and after the intervention. RESULTS Sixty-seven patients with angiogram-confirmed TRAS were included. Forty-four, 9 and 14 patients were managed with primary percutaneous transluminal renal angioplasty (PTRA), surgical intervention and conservative treatment, respectively. Uncontrolled hypertension was the most common presentation noted in 74.62%. Post-anastamotic single stenosis was the commonest occurrence (n = 53). Angioplasty had the highest 1- and 5-year graft survival rate of 91% and 86%, respectively. The worst prognosis was noted in patients treated with secondary PTRA after failed surgery or secondary surgery after failed primary PTRA. CONCLUSIONS TRAS is a recognized complication resulting in loss of renal allografts. Early Doppler ultrasound is a good primary diagnostic tool. Early intervention is associated with a good long-term graft function.

New treatments for infrapopliteal disease: devices, techniques, and outcomes so far.

The use of endovascular treatment of infrapopliteal disease has increased in popularity in recent years. An improvement in technical success rates due to the availability of newer devices has fuelled an increased interest in the subject. The pathogenesis, indications for treatment, and outcome measures of infrapopliteal disease differ from larger vessel intervention. Diabetes and renal failure are prevalent. Neuropathy and venous disease contribute to the etiology of ulceration. Most interventions are undertaken for critical limb ischemia rather than claudication. Therefore, a range of conservative, pharmacological, and invasive therapies are provided. Conventional percutaneous transluminal angioplasty (PTA) using modern low-profile systems is associated with high technical success rates. However, initial data from recent randomized, controlled trials suggest that drug-eluting stents are consistently achieving improved patency over PTA alone or over bare metal stents. This review summarizes recent advances in the treatment of infrapopliteal disease.

Arteriovenous fistula failure: Is there a role for accessory draining vein embolization?

Purpose Arterio-venous fistulae (AVFs) are accepted as the best form of haemodialysis vascular access (VA) but are plagued by high primary failure. Accessory drainage veins (ADVs) may account for up to 40% of these failures. Furthermore, they may also lead to low flow in ‘mature’ AVFs. Methods We analysed the results of 42 patients who underwent endovascular coiling of ADVs at our centre over a 4-year period. Results Indications were failure to mature in 34%, low flow or cannulation difficulty in 56% and thrombosis in 10% of cases. 95% procedures involved a combination of angioplasty and coiling with only 5% patients having coiling of ADV alone. Forearm AVFs constituted the majority of the cases as opposed to upper arm AVFs (74% vs. 26% respectively). Primary patency at 3, 6, 12, 18 and 24 months was 90%, 87%, 76%, 70% and 55% respectively. Successful dialysis was achieved in 10 of the 14 fistulae that had hitherto failed to mature. Coil migration was observed in 1 patient, which led to fistula occlusion. Conclusion Coil embolisation of ADVs is an effective treatment option for dysfunctional fistulae that can be performed at the same time as angioplasty.

Acute arteriovenous access failure: long-term outcomes of endovascular salvage and assessment of co-variates affecting patency.

Aims: This study reports long-term outcomes after endovascular salvage (EVS) for acute dialysis fistula/graft dysfunction. Methods: All patients presenting with acute fistula or graft dysfunction, excluding primary failures, referred for endovascular salvage were included in this single-centre prospective study. Results: Altogether, 410 procedures were carried out in 232 patients. Overall, the incidence of thrombosis/occlusion (per patient-year) was 0.12 for fistulae and 0.9 for grafts. The anatomical success rate for EVS was 94% for fistulae and 92% for grafts. Primary patency rates for fistulae at 1, 6, 12, 24 and 36 months were 82, 64, 44, 34 and 26%, respectively, whereas secondary patency rates were 88, 84, 74, 69 and 61%, respectively. Primary patency rates for grafts at 1, 6 and 12 months were 50, 14 and 8%. The overall rate of complications was 6% with no incidence of symptomatic pulmonary embolism. In a Cox regression model, upper-arm location of fistula (HR 1.9, p = 0.04, n = 144) was associated with lower primary patency, whereas the presence of thrombosis was associated lower primary (HR 1.9, p = 0.004, n = 144) and secondary patency (HR 3.7, p < 0.001, n = 144). Aspirin therapy was associated with longer primary patency (HR 0.6, p = 0.02, n = 144) and secondary patency (HR 0.58, p = 0.08, n = 144). Conclusion: EVS is effective but longer-term outcomes are poor. Presence of thrombosis portends poor fistula survival and strategies for prevention need attention. Balloon maceration, our preferred declotting technique, is safe and the most cost-effective method. Aspirin therapy for patients presenting with failure of fistulae deserves further investigation.

Imaging in the Dialysis Patient: The Role of Vascular Radiology in Hemodialysis Access

The article summarizes the role of vascular radiology in the imaging and salvage of hemodialysis fistulas and in the placement and maintenance of tunneled dialysis access catheters.

Simulation: Moving from technology challenge to human factors success

Recognition of the many limitations of traditional apprenticeship training is driving new approaches to learning medical procedural skills. Among simulation technologies and methods available today, computer-based systems are topical and bring the benefits of automated, repeatable, and reliable performance assessments. Human factors research is central to simulator model development that is relevant to real-world imaging-guided interventional tasks and to the credentialing programs in which it would be used.

Sites of Arterial Access and the Role of Closure Devices in Percutaneous Arterial Intervention

Arterial access is the essential first step for all arterial vascular interventions. This chapter reviews the range of sites of arterial access and discusses the merits of each. Selecting the appropriate access route may be crucial to the success of the procedure. Operators need to be aware of the options available and the potential risks involved. The common femoral artery is the standard access site because it is a large vessel which is readily accessible and has the hard bony surface of the femoral head posteriorly to facilitate haemostasis by manual compression. Alternative access via various upper and lower limb sites are sometimes useful. The arterial puncture is the most common source of complications of arterial intervention. Indeed retroperitoneal haemorrhage particularly after antegrade femoral puncture is clinically difficult to detect and can be fatal. Management of the puncture site after the procedure is crucial to patient safety. The range of arterial closure devices is discussed along with the evidence for their effectiveness and complications. The use of closure devices is compared to haemostasis by manual compression in terms of the complications associated with each technique and the evidence for safe early mobilisation.