Recovery from kidney failure associated with chronic thromboembolic pulmonary hypertension following pulmonary thomboendarterectomy.

The occurrence of renal failure in pulmonary hypertension (PH) is an ominous sign and implies excessive adverse hemodynamic factors. Pharmacologic agents to treat the PH are the mainstay of management, whereas diuretics assist in management of fluid overload. However, when such measures fail, dialysis and ultrafiltration (UF) become necessary to manage progressive azotemia and hypervolemia. Reversal of PH is essential to interrupt this vicious cycle of multisystem failure; otherwise, the need for renal replacement therapy would be permanent.

The effect of angioplasty of single arteriovenous fistula-associated stenosis on arteriovenous fistula blood flow rate.

INTRODUCTION: Percutaneous balloon angioplasty of arteriovenous fistula-associated stenosis is performed for a variety of indications. Successful percutaneous transluminal angioplasty (PTA) is expected to increase in arteriovenous fistula blood flow rate (Qa). A validated approach to predicting changes in Qa based upon stenosis characteristics is not available. METHODS: Three baseline parameters were determined in a group of patients with a single arteriovenous fistula-associated stenosis undergoing PTA. These were percent estimated stenosis, stenosis minimum luminal diameter, and baseline Qa. The relationship between these parameters and changes in Qa following PTA was analyzed using Spearman's rank correlation and linear regression. RESULTS: 113 patients (total group) were studied. Of these,106 had peripheral stenosis (total peripheral subgroup) and 7 had central stenosis. For the total group and total peripheral subgroup, a highly significant inverse correlation was seen between changes in Qa and baseline Qa. A weaker correlation was seen between changes in Qa and minimum luminal diameter, but no correlation was seen with percent estimated stenosis. A minimum luminal diameter ⩽2.0 mm was predictive of ⩾300-mL/min increases in Qa, whereas a minimum luminal diameter >4.5 mm was associated with <300-mL/min increases in Qa. PTA of Central vein stenosis was not associated with significant changes in Qa. CONCLUSION: Baseline Qa is the best predictor for change in Qa following PTA. Stenosis minimum luminal diameter cutoffs of ⩽2.0 and >4.5 mm are useful in predicting the magnitude of changes in Qa. Percent estimated stenosis is not predictive of change in Qa. PTA of central veins does not seem to change Qa.

Exploring correlations between anatomic characteristics of dialysis arteriovenous fistula stenosis and arteriovenous fistula blood flow rate (Qa).

BACKGROUND: Radiologic justification for endovascular treatment of a dialysis arteriovenous fistula circuit stenosis is currently based on ⩾50% severity. However, the clinical significance of any given stenosis is not always clear. The minimum luminal diameter of any stenotic lesion in the arteriovenous fistula circuit might exert a more predictive effect on the arteriovenous fistula blood flow rate (Qa). METHODS: To investigate relationships between anatomic parameters of stenosis and Qa, this study was conducted in a cohort of patients with a variety of arteriovenous fistula stenotic lesions. The goals were to determine (1) the degree of correlation between arteriovenous fistula stenosis estimated during the procedure, and that which is measured, and (2) the correlations between two anatomic stenosis parameters (percent stenosis and stenosis minimum luminal diameter) and Qa. RESULTS: The cohort comprised 113 patients. Only a moderate correlation between estimated and measured stenosis was seen. A correlation between measured stenosis and Qa for the whole cohort was not seen, but a weak correlation between estimated stenosis and Qa was seen. Correlations between stenosis minimum luminal diameter and Qa were superior. The superiority of stenosis minimum luminal diameter to percent stenosis in correlating with a Qa of <500 mL/h was also demonstrated by receiver operating characteristics curve analysis. Stenosis minimum luminal diameter cutoffs of ⩽2.5 mm or >4 mm seemed to have a good predictive value of Qa. CONCLUSIONS: Percent stenosis determination is fraught with uncertainty and exhibits a weak correlation with Qa. Compared with percent stenosis, the minimum luminal diameter of the stenosis demonstrates a superior correlation with Qa.

Management of transposed arteriovenous fistula swing point stenosis at the basilic vein angle of transposition by stent grafts.

INTRODUCTION: Transposed basilic vein arteriovenous fistulas suffer from stenosis at their basilic angle of transposition (BAT). This lesion exhibits frequent recurrence after angioplasty. The primary goal of this study was to determine the effect of stent-graft placement on BAT lesion- and access-patency. The secondary goals were to determine the frequency of intervention pre- and post-stent placement and stent-associated stenosis. METHODS: Thirty-seven cases had stent-grafts placed at their BAT to manage stenosis. Cases served as their own controls by analyzing their lesion- and access-patency pre- and post-stent placement. Student's t-test was used for analysis of continuous variables. Categorical variables were evaluated by Fisher's exact test. Tests were considered significant when p was ≤0.05. RESULTS: At 6 and 12 months, pre-stent lesion primary patency rates were 29% and 3%, and post-stent were 57% and 40%, respectively. Lesion primary assisted patency rates were 39% and 13%, and post-stent were 91% and 80%, respectively. At 6 and 12 months, pre-stent access primary patency rates were 29% and 3%, and post-stent were 26% and 19%, respectively. Pre-stent primary access assisted patency rates were 36% and 10%, and post-stent were 82% and 75%, respectively. Lesion intervention rates averaged 0.47/month pre-stent and 0.13/month post-stent. Access intervention rate averaged 0.50/month pre-stent, and 0.15/month post-stent. Stent-associated stenosis was seen in 23 cases. CONCLUSIONS: Treatment of BAT stenosis with stent-grafts had positive impact on the target lesion and the dialysis access circuit.

Open repair and venous inflow plication of the arteriovenous fistula is effective in treating vascular steal syndrome.

BACKGROUND: Vascular steal syndrome related to a dialysis arteriovenous fistula (AVF) can lead to symptoms of distal ischemia, limb loss, digit ulceration, and gangrene. Several complex procedures have been used to augment and restore distal limb perfusion while maintaining a functional AVF. We reviewed our experience in treating AVF-related vascular steal syndrome by simple plication of the initial AVF inflow segment. METHODS: Clinical data of 26 patients (15 men; mean age, 58 years; range, 26-80) with vascular steal syndrome related to their AVF underwent plication during a 36-month period. There were 18 brachial-cephalic AVFs and 8 brachial-basilic AVFs with vein transposition. Relevant clinical variables, imaging studies, and treatment variables were analyzed. RESULTS: Eighty-four percent of patients had hypertension, 62% were diabetics, and 15% had a previous limb or digit amputated. Hand pain, skin ulceration, or gangrene was present in 96%, 15%, and 12% of patients, respectively; 19% of patients had more than one symptom. Twelve (46%) patients had an aortic arch and upper extremity arteriogram, of which 67% showed evidence of arterial disease. One patient required percutaneous balloon-expandable stent treatment of a proximal left subclavian artery stenosis to improve flow. Duplex-derived volume flow measurements of the AVF were obtained with an average flow of 1.95 ± 0.83 L/min. Open repair and venous inflow plication was performed in all 26 patients. Average flow reduction in patients with preoperative and postoperative flow measurements was 0.6 ± 0.5 L/min (P < 0.05). There was a 12% revision rate within 3 months. Symptom resolution was achieved in 92% of patients while maintaining a functioning access out to 1 year. Two remaining patients who did not improve and proceeded to ligation of the AVF. CONCLUSIONS: Surgical plication of the initial AVF inflow segment offers a simple solution to preserve the dialysis access and resolve symptoms related to vascular steal associated with high volume flow through the AVF.

Percutaneous thrombectomy of AVF: immediate success and long-term patency rates.

The purpose of this study was to report the results obtained in a cohort of 520 cases of thrombosed arteriovenous fistulas (AVF) treated by percutaneous intervention over a period of 8 years. The methods used varied according to the individual characteristics of the case. A clinical success rate of 91.1% was obtained with no significant difference being noted among radial-cephalic, brachial-cephalic, and brachial-basilic AVFs. The mean primary patency for this group was 227.3 ± 14.6 days, and the mean assisted primary patency was 677.2 ± 44.6 days. The lower arm AVFs had both a primary patency and an assisted primary patency that were significantly better than the upper arm cases (p = 0.006 and 0.002, respectively). The primary patency for radial-cephalic AVFs was significantly better than that for brachial-cephalic AVFs (p = 0.021), but not for brachial-basilic cases (p = 0.122). Assisted primary patency for radial-cephalic cases was significantly superior to the values for either patients with a brachial cephalic (p = 0.046) or a brachial-basilic (p = 0.004). Complications occurred in seven cases (1.3%), all of which were venous ruptures. Blood flow was affected in four cases. Only one of these was salvaged with angioplasty balloon tamponade. In the remaining three cases, the AVF was lost.

Outcomes of arteriovenous grafts following simultaneous thrombectomy and stent graft placement across the venous anastomosis.

Arteriovenous grafts (AVGs) suffer from high thrombosis rates. It is not known whether placement of stent grafts at the venous anastomosis (VA) of thrombosed AVGs would impact future thrombosis. This is a retrospective study evaluating a group of AVGs that underwent endovascular thrombectomy with placement of a stent graft at their VA. The study period was a minimum of 1 year or until kidney transplantation or death. Primary and secondary AVG patency rates were obtained using Kaplan-Meier survival estimates. Demographic parameters were analyzed using Cox multivariate analysis. The effect of early vs. late first thrombosis was also studied. Sixty-six patients were included in the study. Of these, 53 (80%) experienced ≥1 thrombotic event during the study period. Thrombosis led to AVG loss in 26 (39%). The primary patency was 47%, 35%, and 21% at 3, 6, and 12 months, respectively. The assisted primary patency was 50%, 38%, and 25% at 3, 6, and 12 months, respectively. The secondary patency rate was 85%, 76%, and 72% at 3, 6, and 12 months, respectively. Thus, poor primary patency rates were observed despite stent graft placement at the VA. In addition, early thrombosis following stent graft placement was associated with worse AVG outcomes.

A comparison between the HeRO graft and conventional arteriovenous grafts in hemodialysis patients.

Venous stenosis and occlusion are a major cause of vascular access dysfunction and failure. The HeRO Graft bypasses occlusion and traverses stenosis with outflow directly into the central venous circulation. A randomized, multicenter study was conducted to evaluate the efficacy and safety of the HeRO Graft relative to conventional AV grafts. The design was to enroll 143 patients in a 2:1 randomization ratio between HeRO and conventional AV control groups. Data on 72 subjects (52 HeRO Graft and 20 AV graft controls) were obtained. The HeRO Graft and control cohorts were comparable in baseline characteristics. Adequacy of dialysis, bacteremia rates, and adverse events were consistent between groups. Twelve month Kaplan-Meier estimates for primary and secondary patency rates were 34.8% and 67.6% in the HeRO Graft cohort, and 30.6% and 58.4% in the control cohort. There was no statistical difference in terms of patency between groups. The rates of intervention were 2.2/year for HeRO Graft and 1.6/year for the control (p = 0.100). Median days to loss of secondary patency was 238 for HeRO Graft versus 102 for the control (p = 0.032). The HeRO Graft appears to provide similar patency, adequacy of dialysis, and bacteremia rates to those of conventional AV grafts.

Long-term performance of the hemodialysis reliable outflow (HeRO) device: the 56-month follow-up of the first clinical trial patient.

The Hemodialysis Reliable Outflow (HeRO) Vascular Access Device is a novel long-term subcutaneous dialysis graft, ideally suited for catheter-dependent patients and patients dialyzing with failing fistulas or grafts due to venous outflow stenosis. This case presentation depicts the clinical course of the first patient to enter a Food and Drug Administration approved clinical trial and receive the HeRO device. The course of this patient over 56 months of follow-up provides the longest experience with the HeRO device to-date. In this patient, the HeRO device provided long-term dialysis access patency in conjunction with adequate dialysis and a low intervention rate.

Endovascular management of the "failing to mature" arteriovenous fistula.

The "failing to mature" arteriovenous fistula (AVF) is frequently encountered among patients in need of hemodialysis (HD). It is essential that its prompt recognition and management are conducted in a timely manner to allow its use in HD. The physical examination is essential in early identification of the "failing to mature" AVF and helps guide initial endovascular management. In most instances, endovascular evaluation successfully identifies all the lesions that have contributed to AVF derangement and retarded its proper maturation. It is common to find juxta-arterial stenosis as well as venous stenosis in the body of the AVF, or its venous outflow tract. However, a wide spectrum of lesions can be seen, and in many instances, multiple lesions coexist in the same deranged AVF. Identifying and understanding the impact of all the lesions is a prerequisite for any intervention. Balloon angioplasty is the mainstay of management of stenotic lesions. Accessory vein obliteration or ligation is necessary in some cases. Procedure-related complications are low and are reduced by caution and experience. Overall, endovascular management is successful in converting the "failing to mature" AVF to usable HD access in the majority of cases, but multiple interventions may be needed in some before the AVF can be used for HD. Once usable, these AVFs have good long-term assisted patency rates. When endovascular management is unsuccessful or not possible, surgical revision of the AVF, or creation of a new AV vascular access is necessary.

Intravenous methoxy polyethylene glycol-epoetin beta for haemoglobin control in patients with chronic kidney disease who are on dialysis: a randomised non-inferiority trial (MAXIMA).

BACKGROUND: Conventional treatment with epoetin to manage anaemia in chronic kidney disease needs frequent administrations, changes of dose, and close monitoring of haemoglobin concentrations. We aimed to compare the effectiveness of methoxy polyethylene glycol-epoetin beta, given intravenously at 2-week or 4-week intervals, with epoetin treatment one to three times per week for haemoglobin control in haemodialysis patients. METHODS: We screened 1115 adult patients from 96 centres who had stable chronic renal anaemia and were on dialysis treatment and intravenous maintenance epoetin. We did an open-label, parallel-group, non-inferiority trial to compare two dosing intervals of methoxy polyethylene glycol-epoetin beta with standard epoetin treatment. We established baseline haemoglobin concentration and eligibility over a 4-week run-in period. 223 patients were randomly assigned to receive methoxy polyethylene glycol-epoetin beta every 2 weeks, and 224 to receive it every 4 weeks. The initial dose was based on the average epoetin dose given during the week before the switch. The primary endpoint was change in haemoglobin concentration between baseline and the assessment period. We analysed patients both by intention to treat and per protocol. This study is registered with ClinicalTrials.gov, number NCT00077610. FINDINGS: We excluded 133 of the 673 randomised patients from the per-protocol analysis because they had inadequate iron status or fewer than five haemoglobin measurements during the assessment period or needed red blood cell transfusions. The mean change from baseline haemoglobin for patients who had switched to intravenous methoxy polyethylene glycol-epoetin beta every 2 weeks (-0.71 g/L, 95% CI -2.20 to 0.77) or every 4 weeks (-0.25 g/L, -1.79 to 1.29) was non-inferior to the mean change for patients who continued treatment with epoetin (-0.75 g/L, -2.26 to 0.75) (p<0.0001 for both comparisons). Of the 666 patients who received at least one dose of study drug, the incidence of adverse events or serious adverse events did not differ between groups (p=0.30 and p=0.40, respectively). INTERPRETATION: This long-acting erythropoiesis-stimulating agent is as safe as conventional epoetin treatment, and can maintain anaemia management in haemodialysis patients when given intravenously at 4-week dosing intervals.

Endovascular treatment of the "failing to mature" arteriovenous fistula.

In recent literature, surgically created hemodialysis (HD) arteriovenous fistulas (AVF) have high rates of primary failure. Endovascular treatment holds promise to salvage these fistulae. The outcomes of 119 patients who had a "failing to mature" AVF and presented for endovascular management were evaluated prospectively. All patients underwent a fistulogram. Stenotic lesions underwent balloon angioplasty, and accessory veins underwent obliteration. Technical success was determined immediately after the procedure. AVF salvage was determined by successful use during HD. Patients were followed up for 1 yr, during which primary and secondary AVF patency rates were measured. The distribution of stenoses was as follows: Artery, 6 (5.1%); arterial anastomosis, 56 (47.1%); juxta-arterial anastomosis, 76 (63.9%); peripheral vein, 70 (58.8%); and central vein, 10 (8.4%). Significant accessory veins were present in 35 (29.4%). Mixed lesions were found in 85 (71.4%). The technique was successful in 107 (89.9%), and the AVF was salvaged in 99 (83.2%). Follow-up of salvaged fistulae showed a total event rate of 0.38/access-year, thrombosis rate of 0.12/access-year, and loss rate of 0.04/access-year. Endovascular treatment of "failing to mature AVF" is safe and effective when performed in a dedicated center.

Salvage of a severely dysfunctional arteriovenous fistula with a strictured and occluded outflow tract.

Arteriovenous fistulas (AVFs) created for the purpose of hemodialysis are frequently lost due to various vascular lesions. Endovascular therapies with percutaneous transluminal balloon angioplasty have become very valuable in treating AVF dysfunction due to vascular stenosis. Experience with these therapies is relatively limited. In this case report, we present a patient with a severely dysfunctional AVF. The vascular lesions affecting his AVF were numerous and severe. We show how the application of aggressive endovascular treatment succeeded in restoring use of his AVF. Throughout the discussion we share observations and personal experiences that may be useful for interventionalists and health care practitioners involved with the maintenance, use, and treatment of dialysis vascular accesses.

Presence of a failed kidney transplant in patients who are on hemodialysis is associated with chronic inflammatory state and erythropoietin resistance.

Patients returning to hemodialysis (HD) after failure of their kidney transplant suffer from high morbidity and mortality rates. It is common practice to keep failed kidney transplants in place. It is not known if these failed kidney transplants induce an inflammatory state that contributes to morbidity and mortality. In a single facility, patients starting on HD with failed kidney transplant were identified (Group A) and screened for the presence of chronic inflammatory state. Those with clinical symptoms attributed to the failed allograft (Group A1) were not offered transplant nephrectomy unless deemed necessary during follow-up. Their clinical and laboratory data were followed up for 6 months. Similar data were obtained from a group of incident HD patients (Group B). Forty-three patients had a failed Kidney transplant (Group A). Of these, 29 comprised Group A1 and 14 Group A2. Group B comprised 121 patients. In comparison with Group B, Group A exhibited worse anemia and erythropoietin resistance index (ERI), had lower serum albumin and prealbumin, and higher CRP. Group A1 had lower Hb and higher ferritin, CRP, and ESR in comparison with Group A2. Following transplant nephrectomy, Group A1 had improvement in ERI, serum albumin, prealbumin, ferritin, fibrinogen, CRP, and ESR. At 6 months, Group A1 had higher Hb and serum albumin levels, and lower CRP and ERI in comparison with Group A2. Group B parameters showed no change during follow-up. Patients returning to HD following failure of their kidney transplant suffer from a chronic inflammatory state. Resection of failed transplants in symptomatic patients is associated with amelioration of markers of chronic inflammation. Transplant nephrectomy should be considered a treatment option for patients with failed kidney transplants, especially if they exhibit signs and symptoms of chronic inflammatory state.

Infectious complications of old nonfunctioning arteriovenous grafts in renal transplant recipients: a case series.

Occult infection of old nonfunctioning arteriovenous grafts (AVGs) is frequent among hemodialysis patients. It is a risk factor for bacteremia and serious AVG-related infection. Immunocompromised patients are at increased risk of dissemination of occult AVG infection. We present a series of five renal transplant recipients who developed acute life-threatening infections that originated in their old nonfunctioning AVGs. Their presenting symptoms were noticeably varied. In two patients, infection of the AVG was characterized by local physical signs of infection around the AVG. In three patients, no physical signs of AVG infection were detected by physical examination. Among these, two presented with bacteremia, and one presented with failure to thrive. Detection of AVG infection in the absence of local signs of infection requires a high index of suspicion. Surgical resection and antimicrobial treatment led to a complete cure in four of these patients. One patient developed recurrent bacterial endocarditis and died. Old nonfunctioning AVGs are potential sources of serious infection in renal transplant recipients. Renal transplant recipients with old nonfunctioning AVGs who present with unexplained bacteremia, fever of unknown origin, or failure to thrive should be investigated for occult AVG infection. Screening for occult infection of the old nonfunctioning AVG may be considered before kidney transplantation, especially if the candidate gives a history of previous bacteremia or fever of unknown origin.

Occult infection of old nonfunctioning arteriovenous grafts: a novel cause of erythropoietin resistance and chronic inflammation in hemodialysis patients.

BACKGROUND: Occult infection of old nonfunctioning arteriovenous grafts (AVGs) is frequent among hemodialysis patients. It is a recognized cause of bacteremia and other infectious complications. Additionally, old nonfunctioning AVGs may be harbingers of other noninfectious complications. The aim of this study was to investigate whether occult infection of old nonfunctioning AVGs is a cause of a chronic inflammatory state in hemodialysis patients. METHODS: This study was performed in two phases: In the first phase (study 1), 22 patients with clinically proven occult infection of old nonfunctioning AVG were identified, and data on hemoglobin, weekly erythropoietin dose, and albumin levels were collected retrospectively. Comparisons were made between values obtained pre- and post-AVG resection. In the second phase (study 2), we examined whether the presence of a chronic inflammatory state is associated with occult AVG infection in old nonfunctioning AVGs. Twenty hemodialysis patients were identified with chronic inflammatory state based on erythropoietin dose (units/wk)/hematocrit ratio>470, serum albumin <3.3 g/dL, and CRP>25 mg/L. Among these patients, we found eight with old nonfunctioning AVGs. We then performed indium-labeled white blood cell (WBC) scans on the eight patients to screen for occult infection of old nonfunctioning AVGs. The AVGs with positive indium scan were resected and cultured. Data on hematocrit, erythropoietin dosing, serum albumin, ferritin, and CRP were obtained at 2 months following AVG resection and compared to pre-resection values. RESULTS: In study 1, the 22 patients with occult infection of old nonfunctioning AVG exhibited profound anemia and hypoalbuminemia. Their mean hemoglobin was 9.2 +/- 1.2 g/dL which improved to 11.6 +/- 0.8 g/dL (P < 0.05) 3 months after AVG resection. Their mean serum albumin was 3.3 +/- 0.5 g/dL which improved to 3.8 +/- 0.2 g/dL (P < 0.05) 3 months after AVG resection. Their mean erythropoietin dosages (units/patient/wk) fell from 14,240 +/- 350 to 6,675 +/- 455 (P < 0.05). In study 2, among the 8 patients with chronic inflammatory state and old nonfunctioning AVG, 6 (75%) had positive indium scans and underwent surgical resection that proved bacterial infection. Upon follow-up, the 2-month data showed a remarkable improvement in the following parameters: weekly erythropoietin dose/hematocrit ratio from 622 +/- 137 to 254 +/- 28 (P < 0.05), plasma ferritin values from 690 +/- 126 ng/mL to 247 +/- 42 ng/mL (P < 0.01), and plasma CRP from 56.7 +/- 9.0 to 14.5 +/- 3.8 mg/L (P < 0.01). Serum albumin values also improved from 3.07 +/- 0.08 g/dL to 3.34 +/- 0.14 g/dL (P = 0.13). Percent plasma iron saturation did not appreciably differ from baseline (20.5% +/- 4.4% to 19.8 +/- 1.9%, P = 0.89). CONCLUSIONS: Occult infection of old nonfunctioning AVG is a common cause of erythropoietin resistance and chronic inflammatory state among hemodialysis patients. Resection of old nonfunctioning AVGs with occult infection is associated with resolution of markers of chronic inflammatory state.