Impact of pre-operative venography on the planning and outcome of vascular access for hemodialysis patients

Demography and Outcomes of Arteriovenous Fistula: Challenges and Future Directions

The incidence and prevalence rates of treated end-stage kidney disease (ESKD) patients are on the rise worldwide. Hemodialysis remains the main modality of providing renal replacement therapy for the ESKD patients, and the preferred vascular access is an arteriovenous fistula (AVF). The objective is to assess the patency rates and primary failures of the AVF. All patients who attended the Royal Hospital in Muscat, Oman, from January 2010 to December 2014 for AVF creation were included in this study. Data were extracted from the hospital's electronic medical record system where data are entered prospectively. During the period of study from 2010 to 2014, 465 primary fistulae were created in 427 patients. The mean age of the patient was 58 years. Only 6% needed general anesthesia, while the rest were done under regional or local anesthesia. Fifty-one percent of the patients were diabetic. Preemptive AVF was constructed in only 12% of patients. Most cases (47%) had left brachiocephalic (BC) fistulae. The left radiocephalic (RC) fistulae constituted 25.7% and the left brachiobasilic fistulae 9.9%. The remaining were constructed in the right upper limb. The total patency was achieved in 80% of fistulae and the failure rate was 20% at 6 months. Whereas, at 12 months, the total patency rate was 71% and the failure rate was 29%. Thus, we can conclude that more than 50% of patients, half of them being females, were diabetics. This resulted in more fistulae being constructed in the arm, namely left BC fistulae and left RC fistulae. Furthermore, it is important to note that only a very small percentage of patients had an established preemptive AVF. These factors may be responsible for a failure rate of 20% and 29% of the AVFs at 6 months and 12 months, respectively.

Prevalence of Central Vein Stenosis in Patients Referred for Vein Mapping

BACKGROUND AND OBJECTIVES

Central vein stenosis is considered to be common in patients on hemodialysis but its exact prevalence is not known. In this study, we report the prevalence of central vein stenosis in patients with CKD referred for vein mapping.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective study of adult patients who had bilateral upper extremity venographic vein mapping from September 1, 2011 to December 31, 2015. Patients with and without stenosis were compared for differences in clinical or demographic characteristics. Multiple logistic regression was used to identify independent associations between patient characteristics and central vein stenosis.

RESULTS

There were 525 patients who underwent venographic vein mapping during the study period, 27% of whom were referred before initiation of hemodialysis. The mean age (±SD) and body mass index were 59 (±15) years and 28 (±7), respectively. Women accounted for 45% of patients; 82% were black. The prevalence of central vein stenosis was 10% (95% confidence interval [95% CI], 8% to 13%) for the whole group, and 13% (95% CI, 10% to 17%) among patients with tunneled central venous dialysis catheters. Current use of tunneled hemodialysis catheters (odds ratio [OR], 14.5; 95% CI, 3.25 to 65.1), presence of cardiac rhythm devices (OR, 5.07; 95% CI, 1.82 to 14.11), previous history of fistula or graft (OR, 3.28; 95% CI, 1.58 to 6.7), and history of previous kidney transplant (OR, 18; 95% CI, 4.7 to 68.8) were independently associated with central vein stenosis.

CONCLUSIONS

In this population, the prevalence of central vein stenosis was 10% and was clustered among those with tunneled hemodialysis catheters, cardiac rhythm device, and previous history of dialysis access or transplant.

Predicting Arteriovenous Fistula Maturation with Intraoperative Blood Flow Measurements

Objective

To establish the criteria for intraoperative blood flow measurements taken at the time of autologous arteriovenous fistula (AVF) construction to predict future access maturation and thereby avoid waiting periods for futile fistulas to declare themselves.

Methods

From April 2006 through to March 2007 consecutive patients undergoing native AVF construction at one institution underwent intraoperative measurements of blood flow using transit-time ultrasound technology. No action was taken based upon the flow measurement at the time of surgery. Patients were followed and data collected comprising demographics and AVF maturation. A fistula was considered mature when it was successfully accessed for hemodialysis (HD) at least three times. Statistical analysis was performed including receiver operating characteristics (ROC), ANOVA, and Chi square using the JMP software package.

Results

During the 12-month period, 70 autologous AVFs were created including 41 antecubital brachiocephalic, 21 radiocephalic, and 8 basilic vein transpositions in 35 females and 33 males with a mean age of 58 ± 1.7 (mean ± SEM). The group included 37 Hispanic, 17 Native American, 10 Caucasian, 3 African American and 1 Asian patient. The etiology of renal failure comprised 53 diabetics, 13 hypertensives, 1 polycystic kidney disease and 1 congenital abnormality. Complete follow-up was available in 69/70 AVFs in 67 patients. Patients were excluded from analysis if they had not yet started dialysis (n=12), stopped or died (n=4) before their fistula was accessed. Patients whose AVFs were patent, but required a secondary procedure to achieve a functional access were considered non-functional. There was a significant difference between the maximal intraoperative flow rates between functional and non-functional AVFs (573.6 ± 103 mL/min vs. 216.8 ± 35.8 mL/min; p<0.05). There was no difference between groups in regard to age, gender, race or etiology of renal failure. ROC analysis suggested a threshold value of 140 mL/min for radiocephalic and 308 mL/min for brachiocephalic AVFs to predict maturation to a functional access.

Conclusion

Intraoperative blood flow measurements obtained at the time of autologous AVF construction can identify fistulas that are unlikely to mature; and therefore, that require immediate revision or abandonment which will ultimately expedite the establishment of a useful access in the HD patient. This is the first study to establish the minimal flow values uniquely needed for both radial artery and brachial artery AVFs to expect primary maturation to a functional access.

A Prospective, Randomized Trial of Routine Duplex Ultrasound Surveillance on Arteriovenous Fistula Maturation

BACKGROUND AND OBJECTIVES

Use of arteriovenous fistulas, the most preferred type of access for hemodialysis, is limited by their high maturation failure rate. The aim of this study was to assess whether aggressive surveillance with routine duplex ultrasound and intervention can decrease the maturation failure rate of arteriovenous fistulas.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a single-center, parallel-group, randomized, controlled trial of patients undergoing autogenous arteriovenous fistula. Patients were randomly assigned (1:1) to either the routine duplex or selective duplex group. In the routine duplex group, duplex ultrasound and physical examination were performed 2, 4, and 8 weeks postoperatively. In the selective duplex group, duplex examination was performed only when physical examination detected an abnormality. The primary end point was the maturation failure rate 8 weeks after fistula creation. Maturation failure was defined as the inability to achieve clinical maturation (i.e., a successful first use) and failure to achieve sonographic maturation (fistula flow >500 ml/min and diameter >6 mm) within 8 weeks.

RESULTS

Between June 14, 2012, and June 25, 2014, 150 patients were enrolled (75 patients in each group), and 118 of those were included in the final analysis. The maturation failure rate was lower in the routine duplex group (8 of 59; 13.6%) than in the selective duplex group (15 of 59; 25.4%), but the difference was not statistically significant (odds ratio, 0.46; 95% confidence interval, 0.18 to 1.19; P=0.10). Factors associated with maturation failure were women (odds ratio, 3.84; 95% confidence interval, 1.05 to 14.06; P=0.04), coronary artery disease (odds ratio, 6.36; 95% confidence interval, 1.62 to 24.95; P<0.01), diabetes (odds ratio, 6.10; 95% confidence interval, 1.76 to 21.19; P<0.01), and the preoperative cephalic vein diameter (odds ratio, 0.30; 95% confidence interval, 0.13 to 0.71; P<0.01).

CONCLUSIONS

Postoperative routine duplex surveillance failed to prove superiority compared with selective duplex after physical examination for reducing arteriovenous fistula maturation failure. However, the wide 95% confidence interval for the effect of intervention precludes a firm conclusion that routine duplex surveillance was not beneficial.

Arteriovenous Vascular Access Selection and Evaluation

When making decisions regarding vascular access creation, the clinician and vascular access team must evaluate each patient individually with consideration of life expectancy, timelines for dialysis start, risks and benefits of access creation, referral wait times, as well as the risk for access complications. The role of the multidisciplinary team in facilitating access choice is reviewed, as well as the clinical evaluation of the patient.

The association of endothelial progenitor cell markers with arteriovenous fistula maturation in hemodialysis patients

AIMS

Arteriovenous fistula (AVF) failure is one of the most important clinical problems in end-stage renal disease. Endothelial progenitor cells (EPCs) have a role on vascular angiogenesis and endothelialization. We aimed to investigate the association markers of EPCs on AVF maturation by measuring the surface expressions of CD34, CD309 and CD133 on the monocytes.

METHODS

This prospective observational study was conducted in 54 voluntary patients with end-stage renal disease who were admitted for their first renal replacement therapy and were available for AVF creation. Venography was performed in all patients before AVF creation. Six patients were excluded due to inadequate veins after venographic imaging, and also seven patients were excluded due to postoperative thrombosis. The blood samples were analyzed a day before the fistula operation, and the expressions of CD34, CD133 and CD309 on the surface of monocytes were measured.

RESULTS

Patients were divided into two groups after the evaluation of AVF maturation, as the mature group and the failure group. The CD309 expression level on the monocytes was 338.00 (35.00-479.00) in the mature group; however, it was 36.00 (5.50-237.00) (p 0.031) in the failure group. Multiple logistic regression analyses showed that both BMI and the mean fluorescence intensity level of CD309 expression on monocytes independently predicted AVF maturation.

CONCLUSIONS

The presence of DM and increased BMI negatively correlated with AVF maturation. High intensity of CD309 expression on monocytes was observed in patients with successful AVF maturation.

Clinical significance of upper-arm cephalic vein patency in autogenous radial-cephalic wrist fistulas for hemodialysis

OBJECTIVES

To investigate the significance of upper-arm cephalic veins (UACVs) in radial-cephalic arteriovenous fistulas (RCAVFs), the medical records of 183 patients who had undergone RCAVF creation were reviewed retrospectively.

METHODS

The patients were divided into two groups according to the status of the UACV upon preoperative venography: group A of 153 cases (83.6%) with a patent UACV and group B of 30 cases (16.3%) with a stenosed or occluded UACV. The clinical outcomes were compared.

RESULT

RCAVFs in group B had a significantly higher maturation failure rate (26.7% vs. 9.8%, p = 0.009) and lower primary/secondary patency rates (log-rank test, p < 0.0001) than those in the group A. The patients in group B required more frequent endovascular intervention to maintain access function (p = 0.002). The most common stenosis site was a draining vein in group B, in comparison to juxta-anastomosis in group A. In the multivariate analyses, the status of the UACV was an independent predictor of the primary and secondary patency rates of RCAVFs (p < 0.005).

CONCLUSION

UACV patency has a significant impact on clinical outcome for RCAVFs. When planning an RCAVF placement, venous status including the UACV should be considered.

Small dose contrast venography as venous mapping in predialysis patients

PURPOSE

This study was designed to evaluate radiocontrast-induced nephrotoxicity (RIN), and the image quality and findings of venography using small doses of radiocontrast as a venous mapping method in pre-dialysis patients.

METHODS

Twenty-eight patients with stage 4 and 5 chronic kidney disease underwent arm venography with 10-15 ml of dilute contrast medium. Image quality, venographic findings and glomerular filtration rate (GFR) before and after the procedure were evaluated.

RESULTS

Mean GFR was 19.3+/-5.8 ml/min/1.73 m2 (7-30 ml/min/1.73 m2). Image quality of venography in the forearm and upper arm veins was good in all patients. Central veins were visualized well in 26 (92.8%) patients. Eight (28.5%) patients showed cephalic veins inadequate for creation of radiocephalic arteriovenous fistula (AVF) because of occlusion or small diameter veins. There was no significant difference in GFR between the pre- and post-study (19.3+/-5.8 vs. 19.2+/-6.2 ml/min/1.73 m2, p=0.693). RIN developed (GFR: 17 to 13 ml/min/1.73 m2) in only one patient but without sequelae, and the GFR completely recovered to baseline level 7 days after the study.

CONCLUSION

Small dose venography is safe and effective for venous mapping in pre-dialysis patients.

Preoperative mapping for haemodialysis access surgery with CO(2) venography of the upper limb

OBJECTIVE

This study aims to evaluate the impact of CO(2) venography on the planning and outcome of native arteriovenous fistula (AVF) creation.

METHODS

Records of patients who underwent CO(2) venography prior to access surgery between January 2000 and December 2008 were reviewed. CO(2) venography was performed selectively in chronic kidney disease (CKD) in stage IV-V patients without suitable veins on clinical examination. Findings at surgery were compared to CO(2) venography images. Patency of AVFs was analysed by the Kaplan-Meier method. Differences in outcome of maturation were compared using a chi(2) test.

RESULTS

A total of 209 CO(2) venograms were obtained in 116 patients. In 89 patients (77%), 101 AVFs (21 forearm AVF (21%) and 80 elbow AVF (79%) were created. Surgical findings corresponded with CO(2) venography findings in 90% of patients. In 10 cases (10%), access was created at the elbow despite a patent forearm cephalic vein on CO(2) venography (n = 2) or access was attempted with a vein which was thought to be unsuitable on CO(2) venography (n = 8). Maturation rate of the latter was 50% (4/8) vs. 88% (80/91) for AVFs created with veins considered usable (P = 0.004). The overall maturation rate was 84% with 1-year primary, assisted primary and secondary patency rates of 63%, 70% and 71%, respectively.

CONCLUSION

CO(2) venography is a useful tool for venous mapping prior to vascular access surgery, resulting in an overall maturation rate of 84% and good patency rates.

Application of ultrasound in nephrology practice

Ultrasonography plays critical roles in many aspects of nephrology practice. Applications include the evaluation of the kidneys and urinary tract, guidance for the percutaneous kidney biopsy and temporary hemodialysis access placement, and vascular ultrasound of upper extremities related to the permanent hemodialysis access. The simplicity of technique and the limited spectrum of pathological changes coupled with portability, low cost, and safety make sonography the modality of choice for kidney and vascular imaging. This review summarizes the indications for kidney and vascular ultrasound and describes the most commonly encountered findings. Although many ultrasound findings are nonspecific, their diagnostic use is greatly enhanced by knowledge of the clinical presentation. Therefore, it is essential for nephrologists to possess skills in performing and interpreting ultrasound studies in order to improve the care of patients with kidney diseases.

Vascular mapping: does it help to maximize fistulae placement?

The population of patients with ESRD in the United States is progressively increasing, with hemodialysis (HD) as the major mode of renal replacement therapy. The National Kidney Foundation's Dialysis Outcomes and Quality Initiative and the Fistula First Initiative recommend increasing the use of arteriovenous fistulae (AVF) in both incident and prevalent hemodialysis patients. One measure proposed is the use of pre-operative vascular mapping to assess the upper extremities for the presence of suitable vessels prior to the surgical creation of an AVF among both pre-dialysis CKD and ESRD patients on HD. This article aims to review the literature on vascular mapping, including the various techniques; their advantages and disadvantages; and whether they help to maximize the AVF creation rate as well as increase the use of AVF in the HD population.

Fistula salvage by endovascular therapy

Fistulas are considered superior to synthetic grafts as a hemodialysis vascular access; however, fistulas are not without problems. To maximize the number of fistulas being used in prevalent patients, it is important to have a program designed to salvage early failures or fistulas that fail to mature and those that become dysfunctional during the course of usage. Endovascular techniques have proven to be very effective in the management of both of these problems. These fistulas should be aggressively evaluated and treated because treatment carries with it a high expectation of successful salvage of what would have otherwise been an abandoned access.

Preoperative Evaluation for Vascular Access Creation

In an effort to increase the prevalence of arteriovenous fistulae (AVF), ultrasound vessel mapping (USVM) and upper extremity venography (UEV) have been suggested; however, the effectiveness of their combined use remains unknown. We studied the effect of such a combined protocol on arteriovenous (AV) access type change compared with physical examination alone. Consecutive patients with chronic kidney disease ( n = 137) after an initial estimation of the AV access type, based on physical examination, had USVM and UEV to detect vascular pathology that could potentially alter the original plan. USVM changed the preoperative plan in 31 (22.6%) patients; this was 36.7% ( n = 18) in diabetics compared with 14.8% ( n = 13) in nondiabetics ( p < .001). Patients for whom USVM changed the type of planned AV access had been on hemodialysis significantly longer (2.7 years vs 0.9 years; p < .001). Venography identified 18 patients with central vein stenosis that led to a site change in 12 of them. Significant venous stenosis in patients with a history of two or more central catheters placed and patients without such a history was 93% and 1%, respectively. In eight patients, intraoperative findings dictated AV graft placement or creation of a central AVF. The original plan was revised in 31%, and this rate was similar for distal AVF, central AVF, and AV grafts (38%, 26%, and 43%, respectively; all p > .05). The 30-day patency rate was 92.2%. A significant proportion of patients have vascular pathology severe enough to alter the access type as suggested by physical examination alone. USVM should be routinely performed, whereas UEV should be selectively performed in patients with a history of surgery or instrumentation of their central veins.

Therapeutic use of arteriovenous fistula in children with haemophilia

Haemophilia is an X-linked inherited bleeding disorder, which only affects males. Contemporary treatment of children with haemophilia requires adequate venous access for the administration of prophylactic therapy which commences as a relatively early age. In the majority of children this treatment is administered at home, usually by the parents and then, once competent, by the boys themselves. As venous access in young children is fraught with difficulty, central venous access devices have become the mainstay of haemophilia care. However, these devices come with their own difficulties, with infection and thrombosis causing significant side-effects in some children. Small but substantial cohorts of boys with haemophilia develop antibodies (or inhibitors) to coagulation factors, rendering them both more likely to experience bleeding and more complex to treat. These boys are, for reasons not yet fully understood, more likely to experience central line infections, which also affect overall treatment outcomes. Arteriovenous fistulae were used in four such boys in an attempt to eliminate central line infection and to enable continued treatment administration. The experience and outcomes of these four boys is discussed along with considerations and implications for nurses caring for them.