Does central venous stenosis affects the brachial artery flow volume and peripheral vascular resistive index in patients on maintenance hemodialysis? A retrospective study.

BACKGROUND: A well-functioning vascular access (VA) is crucial for the patients on maintenance hemodialysis (HD). Central venous stenosis (CVS) is a common, yet, overlooked complication of VA as its diagnosis is challenging. Moreover, its effect on the flow volume (FV) and the peripheral resistive index (RI) was not well discussed before. Despite the availability of doppler ultrasound (DUS) in most centers, direct visualization of central veins using DUS is quite difficult. METHODS: This is a retrospective single-center self-controlled cohort study that was conducted in a specialized vascular access management tertiary center in Japan and included all patients with CVS who underwent percutaneous transluminal angiography (PTA) with or without vascular stenting in the period from January 2014 to September 2022. The patients were divided according to their VA type into arteriovenous fistula (AVF), and arteriovenous graft (AVG) groups, then subdivided, according to the type of stenosis, into two subgroups: CVS, and mixed central and peripheral venous stenosis (MVS) groups. The FV and RI of the feeding artery were compared in the same procedure before and after PTA to assess the impact of the procedure itself. RESULTS: Data of 485 percutaneous transluminal angiography procedures (PTA), performed in 95 patients during the period from January 2014 to September 2022, were collected. FV and RI were significantly affected in the patients with MVS than patients with CVS. After PTA, both FV and RI were significantly improved. The improvement rate of FV and RI after PTA were significantly higher in patients with MVS than patients with CVS. However, it was difficult to determine the cut-off value to diagnose or to assess the improvement of CVS. CONCLUSION: Our findings suggest that FV and RI measurement by DUS are good tools, along with the clinical findings for assessment of CVS in certain situations.

Current state of dialysis treatment and vascular access management in Japan.

According to the data from the Japanese Society for Dialysis Therapy, the number of dialysis patients was about 330,000 at the end of 2016. The mean age of newly initiated patients was 69.4 years and that of maintenance was 68.2 years. And, diabetic nephropathy is the most common primary disease, with an incidence rate of 43.2%. These results mean that the systemic vascular condition is getting worse. In spite of these backgrounds, the patients of 97.3% were treated by hemodialysis; therefore, careful management of vascular access is essential to better maintain the condition of patients. The Dialysis Outcomes and Practice Patterns Study shows that vascular access modalities are an important factor in determining prognoses of patients and that prognosis in Japan is one of the best worldwide. In Japan, the use of arteriovenous fistulae accounts for 95% of vascular access modalities. However, a statistic by Japanese Society for Dialysis Therapy suggests that the use of arteriovenous graft has been increasing. In 2005, Japanese Society for Dialysis Therapy Guidelines recommended percutaneous transluminal angioplasty be the first choice for the treatment of vascular access stenosis. Since then, percutaneous transluminal angioplasty has become an important procedure for long-term maintenance of the morphology and function of vascular access. In Japan, approximately 60% of percutaneous transluminal angioplasty are conducted by nephrologists and urologists; in addition, arteriovenous fistulae creation procedures are also performed by them. According to my private opinion, such conditions above show that even in the absence of standardized training on vascular access management, doctors on site perform their duties in an appropriate manner. However, the problems of how we evaluate the specificity in Japan and pass it down the generations still remain.

Standard procedures of endovascular treatment for vascular access stenosis in our facility - clinical usefulness of ultrasonography.

In Japan, the number of patients receiving dialysis is 314,180 at the end of 2013 and 97% are treated with hemodialysis. And the mean age of patients and the percentage of diabetes have been increasing. For this reason, preparations of a new vascular access (VA) and its long-term maintenance have become difficult. In the guidelines by the Japanese Society for Dialysis Therapy (JSDT), endovascular treatment (ET) is positioned as the first line for VA stenosis. The procedure of ET itself is very simple. The revision of Japanese health insurance set an expensive technical fee for ET in 2012. It also added a restriction by which the claims for both technical and material fees would be denied, if the treatment was performed within 3 months after a previous treatment. This makes determination of best treatment timing more important. The functional evaluation using ultrasonography (US) is a useful monitoring index for determination of the ET timing for patients with stenosis. We investigated the cumulative relative frequency of flow volume (FV) and resistant index (RI) of brachial artery in arteriovenous graft (AVG) and arteriovenous fistula (AVF) cases with access failures. As a result, the cut-off values of FV and RI in AVG were 480 mL/min and 0.57, and in AVF were 354 mL/min and 0.61, respectively. Therefore we determine the treatment timing based on these results. Since 2012, active monitoring using US could have decreased the number of treatment patients by 100 per year. This meant that objective evaluation by US enabled treatments at a more suitable time to promote the proper use of medical expenses for EV treatment.