Original Report: Patient-Oriented, Translational Research American

Journal of

Nephrology

Received: October 14, 2014 Accepted: May 26, 2015 Published online: July 10, 2015

Am J Nephrol 2015;41:420–425 DOI: 10.1159/000433607

Arteriovenous Grafts: Early Ultrasonography Tells Their Fortune Jaroslav Kudlicka a, d Jan Malik a Vladimir Tuka a Eva Chytilova a Zdislava Krupickova a Barbora Grauova a Jaroslava Vorcakova a David Janak d Jan Kavan c Otomar Kittnar d Marcela Slavikova b   

 

 

 

a

 

 

 

 

 

 

 

Third Department of Internal Medicine, b Second Department of Surgery, and c Department of Radiology, First Faculty of Medicine, Charles University in Prague and General University Hospital, d Institute of Physiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic  

 

 

 

Abstract Background: The patency of arteriovenous grafts (AVG) for hemodialysis is mostly limited by growing stenoses that lead to decreasing of blood flow, thromboses and finally to access failure. The aim of this study was to find out if detection of any pathology by duplex Doppler ultrasonography (DDU) early after creation of AVG could identify those with lower survival. Methods: We retrospectively enrolled AVG examined by DDU in our center within 40 days after their creation during the last 10 years. The findings were divided into 4 subgroups: (1a) normal finding, (1b) DDU risk factor (low flow volume, medial calcinosis of the feeding artery, presence of intimal hyperplasia in the venous anastomosis), (2a) non-significant or (2b) significant stenosis. The primary outcome measure was the cumulative survival of people with AVGs, and the secondary was the primary (unassisted) survival. All patients underwent DDU surveillance every 3 months with pre-emptive treatment of significant stenoses. Results: Overall, 340 cases were found; the median follow-up was 565 days. Normal DDU finding had 60% cases, DDU risk factor 18% cases, non-significant stenosis 13% cases and significant stenosis 9% cases. Occurrence of early sig-

© 2015 S. Karger AG, Basel 0250–8095/15/0415–0420$39.50/0 E-Mail [email protected] www.karger.com/ajn

nificant stenosis was associated with high risk of access loss (hazards ratio (HR) 14.73; 95% CI 5.10–42.58; p < 0.0001). Similarly, the presence of a DDU risk factor and of a non-significant stenosis were related to significantly shorter access lifespan (HR 2.86; 95% CI 1.10–7.40; p = 0.03 and HR 2.83; 95% CI 1.12–7.17; p = 0.03, respectively). Conclusion: DDU examination of AVG early after their creation can identify those at higher risk and may contribute to individualize the surveillance strategy. © 2015 S. Karger AG, Basel

Introduction

The functionality of a vascular access is necessary for successful long-term conventional hemodialysis treatment [1]. According to clinical data and guidelines, the choice of arteriovenous graft (AVG) using expanded polytetrafluoroethylene (PTFE) takes place after preferred native arteriovenous fistula (AVF), but before the insertion of permanent venous catheter, which brings a higher mortality risk [2–4]. The patency of the mature AVG is mostly limited by developing stenoses on the basis of neointimal hyperplasia, which occurs especially in the venous anastomosis or in adjacent outflow vein [5]. The reduction of the blood flow due to progression of a Jaroslav Kudlicka, MD Third Department of Internal Medicine General University Hospital, U Nemocnice 1 CZ–12808 Prague 2 (Czech Republic) E-Mail jaroslav.kudlicka @ vfn.cz

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Key Words Hemodialysis · Survival · Ultrasonography · Vascular access

Patients and Methods For the purpose of this study, we retrospectively analyzed data of hemodialyzed patients from the registry in the Vascular Access Centre, General University Hospital in Prague, Czech Republic, which provides care with the use of at least 50 dialysis units. Patients with AVGs (1 AVG per patient) were selected if they had been newly created in the years 2003–2013 and met the following inclusion criteria: (1) DDU examination within 40 days after the AVG creation and (2) follow-up period of at least 3 months. The loss of follow-up was defined as loosing contact with a patient after the first 90 since 1,460 days after creation of the access, excluding those who reached the primary outcome and/or were created less than 1,460 days before the end of the study period. All the patients with AVG were treated with antiplatelet agents. Aspirin was routinely provided and those who did not tolerate aspirin were switched to clopidogrel. A pre-operative phlebography was provided when a hemodialysis catheter was previously placed in the central vein in order to exclude the stenosis in the vein. When the stenosis was detected (including non-significant), a new vascular access tried to be placed on the other extremity despite the possible angioplasty. A pre-operative ultrasonographical mapping was not routinely performed except when needed by a surgeon. The primary outcome measure of the study was established as the clear record of the definitive failure of the vascular access (access thrombosis not re-

Early Ultrasonography of AVGs

sponding to therapy or graft infection leading to graft explantation). We also analyzed the time of the first intervention (unassisted primary survival), both endovascular and surgical. Basic history and medication data were collected. According to the first DDU examination we divided the cases into 2 groups: (1) no stenosis and (2) stenosis group. The no-stenosis group was further subdivided into 2 subgroups: (1a) completely normal finding and (1b) the presence of any DDU risk factor (defined below). Similarly, the stenosis group was further divided into the following subgroups: (2a) non-significant stenosis and (2b) significant stenosis. The standardized DDU examinations were performed by 5 skilled ultrasonographers (each doing >300 DDU vascular examinations per year). The DDU examination consisted of visualizing all parts of the vascular access by B-mode and color Doppler mapping as described in detail earlier [9]. When stenosis was suspected (narrowing in B-mode and/or aliasing in color Doppler mapping), the residual diameter was measured in the longitudinal view, and the peak systolic velocity ratio was calculated as the ratio of the peak systolic blood flow velocity in the stenotic and prestenotic site. Moreover, the DDU examination included the estimation of the vascular access flow volume calculated as the crosssectional area of the lumen multiplied by time-averaged mean velocity. The access flow volume was measured 3 times in the venous part of the graft at least 2 cm distal to the venous anastomosis, and the mean flow volume was reported. According to the previously described definition of stenosis used in our center [9–11], the stenosis was described as significant if there was a combination of >50% lumen reduction in B-mode and peak systolic velocity ratio >2, together with at least one of the following additional criteria: (1) low blood flow (25%) and/or (3) residual diameter

Arteriovenous grafts: early ultrasonography tells their fortune.

The patency of arteriovenous grafts (AVG) for hemodialysis is mostly limited by growing stenoses that lead to decreasing of blood flow, thromboses and...
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