Surgical and Endovascular Intervention for Dialysis Access Maturation Failure During and After Arteriovenous Fistula Surgery: Review of the Evidence.

BACKGROUND: Maturation failure is the major obstacle to establishing functional arteriovenous fistulae (AVF) for haemodialysis treatment. Various endovascular and surgical techniques have been advocated to enhance fistula maturation and to increase the number of functional AVFs. This narrative review considers the available evidence of interventional techniques for treatment of AVF non-maturation. RESULTS: Intra-operative vein dilation and anastomosis modification results in a clinical maturation rate of 74-92% and a 6 month cumulative AVF patency of 79-93%. Percutaneous transluminal angioplasty (PTA) with or without accessory vein obliteration is successful in 43-97% of patients. The long-term primary patency of PTA is rather low and multiple re-interventions are needed to achieve an acceptable cumulative fistula patency. The results of surgical revision exceed the results of endovascular intervention, with a mean primary one year patency of 73% (range 68-78%) compared with 49% (range 28-72%), respectively. The role of accessory vein obliteration remains unclear. CONCLUSION: Intervention for autologous arteriovenous fistula non-maturation is worthwhile and results in an increased number of functional fistulae. The outcome of surgical revision is better than endovascular and might be preferable in certain patient populations.

Indicators of acute and persistent renal damage in adult thrombotic microangiopathy.

BACKGROUND: Thrombotic microangiopathies (TMA) in adults such as thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS) are life-threatening disorders if untreated. Clinical presentation is highly variable and prognostic factors for clinical course and outcome are not well established. METHODS: We performed a retrospective observational study of 62 patients with TMA, 22 males and 40 females aged 16 to 76 years, treated with plasma exchange at one center to identify clinical risk factors for the development of renal insufficiency. RESULTS: On admission, 39 of 62 patients (63%) had acute renal failure (ARF) with 32 patients (52%) requiring dialysis treatment. High systolic arterial pressure (SAP, p = 0.009) or mean arterial pressure (MAP, p = 0.027) on admission was associated with acute renal failure. Patients with SAP>140 mmHg on admission had a sevenfold increased risk of severe kidney disease (OR 7.464, CI 2.097-26.565). MAP>100 mmHg indicated a fourfold increased risk for acute renal failure (OR 4.261, CI 1.400-12.972). High SAP, diastolic arterial pressure (DAP), and MAP on admission were also independent risk factors for persistent renal insufficiency with the strongest correlation for high MAP. Moreover, a high C-reactive protein (CRP) level on admission correlated with renal failure in the course of the disease (p = 0.003). At discharge, renal function in 11 of 39 patients (28%) had fully recovered, 14 patients (23%) remained on dialysis, and 14 patients (23%) had non-dialysis-dependent chronic kidney disease. Seven patients (11%) died. We identified an older age as risk factor for death. CONCLUSIONS: High blood pressure as well as high CRP serum levels on admission are associated with renal insufficiency in TMA. High blood pressure on admission is also a strong predictor of sustained renal insufficiency. Thus, adult TMA patients with high blood pressure may require special attention to prevent persistent renal failure.

Bismuth coating of non-tunneled haemodialysis catheters reduces bacterial colonization: a randomized controlled trial.

BACKGROUND: Haemodialysis (HD) catheter-related blood stream infections are a major cause of morbidity and mortality in patients with acute and chronic renal failure. METHODS: We conducted a randomized, prospective, double-blinded trial investigating the clinical value of bismuth-coated non-tunneled HD catheters in patients in need of temporary short-term vascular access. A standard catheter (SC) was compared to a surface-modified, bismuth-film-coated catheter (FCC). After removal of the catheter for any reason, both arterial and venous lumina were rinsed and the fluid cultured for detection of bacterial colony-forming units (CFU). The catheter tip was placed in a tube containing sterile saline, sonicated and shortly centrifuged to remove debris (3 min at 1000 g). The supernatant was cultured and assayed for DNA content. RESULTS: Seventy-seven patients in three HD units were randomized. Thirteen patients suffered from acute renal failure, 60 patients from chronic renal failure, and four patients without renal insufficiency were treated with plasma exchange. The time to catheter removal was not significantly different between groups, with a mean of 18.5 +/- 2 days for SC and 15.1 +/- 2 days for FCC. In most cases, the reasons for catheter removal were related to no further need for extracorporeal therapy or establishment of a permanent vascular access. Six catheters for SC and four catheters for FCC were removed because of presumed infection. Bacterial colonization was significantly lower for coated catheters compared to standard catheters, both for cultured catheter tips as well as for CFU in rinse fluids (P < 0.05). CONCLUSIONS: Surface modification with bismuth film reduces bacterial colonization of temporary non-tunneled HD catheters in a clinical trial. Larger trials with these modified catheters are justified to further investigate the effect on catheter-related infections, complications and costs.

Value of diabetes as an independent predictor of death in subjects with end-stage renal disease.

BACKGROUND AND PURPOSE: Diabetic subjects on hemodialysis have a poor survival. The authors performed a Kaplan-Meier survival analysis of diabetic versus nondiabetic subjects and investigated the value of diabetes as an independent predictor of death in these end-stage renal disease (ESRD) subjects. PATIENTS AND METHODS: From 1997 to 2003, 135 ESRD subjects (41 diabetics) were enrolled in a survival study beginning at the start of dialysis. Inclusion criterion was onset of dialysis at least 6 months before study entry. Exclusion criteria comprised age < 45 years, coronary artery disease (CAD), critical limb ischemia (CLI), or malignancies at ESRD onset up to 6 months after study entry. Subjects with clinical signs of vascular disease were followed up by coronary or peripheral angiographies. RESULTS: Baseline risk factors were similar between diabetic and nondiabetic subjects. The 5-year survival rate in nondiabetic subjects was 76.9% (95% confidence interval [CI] = 62-86%) versus 76.4% (95% CI = 53-89%) in diabetic patients (p = 0.402). Consistent with this finding, the Cox proportional hazards model revealed that diabetes does not significantly change the risk of death in ESRD subjects. De novo CAD developed in 35 and CLI in ten subjects, but both diseases were present more frequently in nonsurvivors (42% vs. 23%; p = 0.052) versus survivors (21% vs. 5%; p = 0.005). CONCLUSION: Diabetes is not an independent predictor of death in the ESRD study group presented here. Prevention of CAD and CLI in diabetic subjects is most important to improve survival.

Duplex ultrasound and renin ratio predict treatment failure after revascularization for renal artery stenosis.

BACKGROUND: The aim of this study was to find predictors to identify patients with hypertension who will not improve after removal of renal artery stenosis (RAS). METHODS: Prospective study of patients with unilateral stenosis (>60% diameter reduction) and hypertension in 24-h measurements despite antihypertensive drugs, who underwent revascularization (surgery/angioplasty). Examinations were performed before treatment and after 3 and 6 months after exclusion of restenosis. Studies included 24-h blood pressure, creatinine clearance, 99Tc MAG3 scintigraphy, and measurements of renal vein plasma renin activity (PRA). Intrarenal resistance indices (RI) were determined with duplex ultrasound before and 30 min after administration of intravenous enalaprilat. Improvement of hypertension was defined by a score consisting of 24-h mean arterial pressure and the number of antihypertensive drugs. RESULTS: From December 2000 to December 2003, 50 patients completed the study. Improvement of hypertension was observed in 18 patients (36%). Comparison between responders (n = 18) and nonresponders (n = 32) revealed significant differences only for RI and PRA measurements. The largest area under the curve in receiver-operating characteristic (ROC) analysis for prediction of no improvement of hypertension was found for RI (stenosis side), which was nearly identical for measurements before and after administration of angiotensin-converting enzyme (ACE) inhibitor. The highest sensitivities and specificities predicting which patients will not improve were found for RIs > or = 0.55. The highest univariate odds ratio (OR 44, confidence interval [CI] 4.8-404) was found for the parameters of RI > or = 0.55 and a renin ratio of <1:1.5. CONCLUSIONS: Resistance indices of the poststenotic kidney above 0.55 and a negative renin ratio can predict a poor outcome concerning arterial blood pressure response after restoration of renal blood flow for unilateral renal artery stenosis.

Management of arterial stenosis affecting kidney graft perfusion: a single-centre study in 53 patients.

We assessed clinical and duplex sonographic (CDS) findings, and outcome in patients with stenosis of the transplant renal artery (TRAS) or the aorto-iliac segment proximal to the graft (Prox-TRAS) treated with dilatation (PTA), stenting (PTAS) and surgery. From 1988 to 2002, of 1189 patients with renal transplantations, 117 underwent angiography. Fifty-three patients with TRAS (n = 37)/Prox-TRAS (n = 16) were found (4.4%). Clinical presentation included deterioration of hypertension (144 +/- 15/84 +/- 9, 157 +/- 22/90 +/- 10 mmHg; p < 0.001), increase of creatinine (1.7 +/- 0.9, 2.5 +/- 1.3 mg/dL; p = 0.01) and renal failure (n = 12). CDS indicated insufficient perfusion and differentiated between TRAS and Prox-TRAS. From renal transplantation (RTX) until the detection of stenosis pulsatility indices (PI) decreased from 1.2 +/- 0.46 to 0.98 +/- 0.29; (p = 0.001). Fifty-two patients underwent invasive treatment (21 PTA, 10 PTAS and 21 surgery) after which hypertension and creatinine significantly improved. PI increased. Restenosis occurred in 16 (52%) cases of the interventional (PTA 62% and PTAS 30%) and in 3 (14%) of the surgical group (p = 0.011). Hypertension and graft dysfunction due to perfusion problems are rare. Clinical findings are nonspecific but CDS findings are helpful to select patients for angiography. Invasive treatment leads to clinical improvement. Surgery yields better results than PTA, but additional stenting will probably improve the outcome of angioplasty.

Iliac artery stenosis proximal to a kidney transplant: clinical findings, duplex-sonographic criteria, treatment, and outcome.

BACKGROUND: Stenosis of the iliac segment proximal to the transplant renal artery (Prox-TRAS) is an uncommon cause of graft dysfunction and hypertension. We assessed the role of duplex sonography (DS) in regard to clinical and angiographic findings and followed the patients after percutaneous transluminal angioplasty (PTA), PTA stenting (PTAS), or surgery. METHODS: From January 1988 to August 2001, 97 of 1,064 kidney recipients underwent angiography for clinical or Doppler-sonographic suspicion of vascular problems. Kidney function, blood pressure, medication, and DS findings after renal transplantation (RTx) at the time of diagnosis of Prox-TRAS and after treatment were evaluated. RESULTS: Prox-TRAS was diagnosed in 16 patients (1.5%) (49.6+/-6.9 years). Four patients demonstrated early presentation of Prox-TRAS 1 to 7 days after RTx (group A), leading to acute renal failure but without hypertension. In all patients, DS revealed pulsus parvus et tardus, low pulsatility index (PI) (<1.0), and a pathologic flow profile in the iliac artery proximal and distal to the graft. After treatment (surgery in two patients, PTA in one patient, PTAS in one patient), all patients developed good renal function (creatinine 1.7+/-0.9 mg/dL). PI increased from 0.9+/-0.1 to 1.2+/-0.1 (P=0.04), and flow profile within the iliac artery distal to the graft normalized. Late presentation (3-209 months after RTx) of Prox-TRAS was observed in 12 patients (group B), causing an increase of creatinine in 11 patients (two patients receiving dialysis treatments), impairment of blood pressure (141+/-15 and 80.7+/-7 to 160+/-18 and 85+/-7 mm Hg, P=0.009), and an increase in antihypertensive drugs (2.1+/-1.1 and 4.3+/-1, P=0.003) in all patients. The PI was decreased when compared with values early after RTx (1.6+/-0.4 to 1.2+/-0.3, P=0.007), and flow profile in the iliac artery was pathologic. All patients except one were managed by surgery (n=6), PTA (n=1), or PTAS (n=4). Creatinine (2.7+/-1.4 to 1.8+/-0.4 mg/dL, P=0.02) and blood pressure (160+/-18/85+/-7 mm Hg to 138+/-7/82+/-9, P=0.018) improved. Antihypertensive drugs were reduced to 2.8+/-0.8 (P=0.01). PI increased from 1.2+/-0.3 to 1.9+/-0.5 (P=0.01). Flow profile within the iliac artery distal to the graft anastomosis normalized. Kidney function, blood pressure, and PI remained unchanged during follow-up (82+/-69.9 months) in both groups. CONCLUSIONS: Prox-TRAS is rare. Because clinical symptoms are similar to those of transplant renal artery stenosis, DS is a valuable tool for diagnosis and follow-up for this type of vascular lesion. Selective treatment with PTA, PTAS, or surgery improves kidney function and hypertension.

Kidney transplantation from related and unrelated living donors in a single German centre.

BACKGROUND: Organ transplantation began in 1954 with living related donation (LRD). Because of organ shortage from cadavers, unrelated kidney donation (LURD) has been proposed and shown to have good results despite complete HLA mismatching. This study aims to look at differences and similarities comparing LRD and LURD performed in our centre since the implementation of the German transplant law in 1997. METHODS: Between January 1997 and July 2001, 62 out of 112 potential living donors and their recipients were accepted. Immunosuppression consisted of triple therapy (steroids, cyclosporin, mycophenolate) in patients with three or fewer mismatches, or quadruple therapy including mono- or polyclonal antibody treatment in patients with four or more mismatches or cytotoxic antibodies. LRD and LURD groups were compared for number and type of rejections, complications and kidney function at the end of observation (median 15.5 months, range 1-50 months). RESULTS: Out of 112 pairs presenting, transplantation was performed in only 62 cases (55.4%). Reasons to deny transplantation were medical problems of the potential donors in 19, psychological problems in 13, recipient problems in seven and other reasons in 11 pairs. In 38 cases LRD transplantation and in 24 cases LURD transplantation was carried out. Recipient age was significantly lower in the LRD group (37.7+/-12.1 years) compared with the LURD group (53.6+/-7.8 years). Mean donor age was 49.7+/-9.2 years in the LRD group and 50.3+/-9.1 years in the LURD group (ns). The number of mismatches was lower in LRD (2.1+/-1) than in LURD (4.4+/-0.9) (P=0.001) transplantation. The acute rejection rate was similar in both groups (52.2 vs 54.2%). OKT3 and tacrolimus rescue therapy for more severe rejections was more often applied in the LRD group but the difference did not reach the level of significance. There were more infectious complications in LURD transplantation (66.7 vs 36.4%, P=0.036) and a trend towards more surgical complications in LRD transplantation (28.9 vs 8.3%, P=0.062). One graft was lost due to transplant artery thrombosis and one recipient died 4 months after transplantation subsequent to cerebral ischaemia. Both patients belonged to the LRD group. Creatinine values at the end of observation time were 1.76+/-0.6 mg/dl in the LRD group and 1.62+/-0.5 mg/dl in the LURD group (ns). CONCLUSION: Although kidney transplantation from unrelated donors was performed with a lower HLA match and although the recipients were older, the results are equivalent to living related transplantation. Therefore, kidney transplantation from emotionally related living donors represents a valuable option for patients with end-stage renal disease. Careful selection of donors and recipients is a prerequisite of success.

[Arteriosclerotic renal artery stenosis. Significance, diagnosis and therapy options]. / Arteriosklerotische Nierenarterienstenose. Bedeutung, Diagnostik und Therapieoptionen.

BACKGROUND: Renal artery stenosis (RAS) can cause arterial hypertension and can lead to renal insufficiency. In 1999 16% of patients starting dialysis in Germany suffered from ischemic nephropathy. SCREENING: Cost-effective screening for RAS should be done by Doppler sonography or captopril renography. Doppler sonographic findings can be predictive in respect to progression of stenosis, renal atrophy and postinterventional course of hypertension and kidney survival. TREATMENT: The results of recent studies are helpful to select patients for preferential drug treatment or for interventional treatment.

Kidney transplantation in the elderly: age-matching as compared to HLA-matching: a single center experience.

BACKGROUND: We report the short-term outcome of our patients participating within the Eurotransplant age-matching program, where kidneys from donors >65 years are transplanted to recipients >65 years regardless of human leukocyte antigen (HLA) compatibility but with short cold ischemia times, in comparison with patients >60 years transplanted with HLA-matching. METHODS: Twenty-five patients (66.7+/-2.6 years) (donors 69+/-4.3 years) participated in this program (group A). The control group consisted of 21 patients (63+/-2.6 years) (group B) (donors 47.6+/-17.3 years). RESULTS: Despite significant differences in donor age, cold ischemia time (12.3+/-4.6 hr in A, 22.8+/-4.8 hr in B, P<0.001) and a mean of 4.4+/-1.4 vs. 2.3+/-1.6 HLA-mismatches (P<0.001), there was no difference regarding the incidence of delayed graft function (64 vs. 57%), rejections (52 vs. 66.7%), infections (56 vs. 52.4%), and other complications (80 vs. 71.4%). Mean serum creatinine after 6 months was 1.94+/-0.49 and 1.83+/-0.67 mg/dl (NS). CONCLUSION: The short-term results of the age-matching program are promising and comparable with results from patients of similar age with HLA-matching.