Stenosis at the graft-vein junction caused by intimal hyperplasia (IH) is the major cause of failure of vascular access grafts used for hemodialysis. There is a strong relationship between hemodynamic factors and formation of IH. The hemodynamic pattern and the location of IH are different in arterial bypass grafts (ABGs) compared with arteriovenous grafts (AVGs). In an ABG, end-to-side anastomosis of the expanded polytetrafluoroethylene graft and artery produces hemodynamic changes around the junction. IH develops at the arterial floor and the toe and heel of the distal anastomosis. Low shear stress and oscillating shear forces at the arterial floor and the heel plus a high wall sheer stress (WSS) gradient at the toe probably promote IH development. Compliance mismatch between the graft and artery causes turbulence that may contribute to IH formation. The blood flow rate in AVGs is 5-10 times greater than that in ABGs. High flow causes turbulence that injures endothelial cells and eventually results in IH. The peak WSS in AVGs is about 6 N/m(2), much higher than that in ABGs. Excessively high WSS may effect IH formation in AVGs. Several venous cuff or patch anastomotic designs have been used in attempts to regulate hemodynamic factors in grafts. In ABGs, these designs appear to help decrease IH formation. In AVGs, however, they generally have not improved patency rates. In a high-flow system such as an AVG, more drastic changes in anastomotic design may be required.

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The guideline committee of Japanese Society for Dialysis Therapy (JSDT), chaired by Dr Ohira, has published an original Japanese guideline, 'Guidelines for Vascular Access Construction and Repair for Chronic Hemodialysis'. The guideline was created mainly because of the existence of numerous factors characteristic of Japanese hemodialysis therapy, which are described in this report, and because we recognized the necessity for standardization in vascular access-related surgeries. This guideline consists of 10 chapters, each of which includes guidelines, explanations or comments and references. The first chapter discusses informed consent of vascular access (VA)-related surgeries, which often resulted in trouble between dialysis staff and patients. The second chapter describes the fundamentals of VA construction and timing of the introduction of hemodialysis with emphasis on the avoidance of catheter indwelling if at all possible. In the third chapter, arteriovenous fistula (AVF) construction and management are discussed from the viewpoint of the most preferable type of VA. The fourth chapter deals with arteriovenous grafts (AVG) which has recently increased in clinical applications. The factors which improve the AVG patency rate are discussed and postoperative management methods are emphasized to avoid possible complications. The fifth chapter deals with short and long-term vascular catheters. It is emphasized that these methods are definitely effective but, at the same time, are apt to be associated with several serious complications and might result in vascular damage. In the sixth chapter, superficialization of an artery is explained. This was originally for emergency use or backup but has been used permanently in 2-3% of Japanese hemodialysis patients. In the seventh chapter, methods for the use of VA are described and the buttonhole method is referred to as one of the options for patients who complain of intense pain at every cannulation. In the eighth chapter, the importance of continuous monitoring is stressed for maintaining appropriate function of VA. As a rule, the internal shunt type VA (AVF, AVG) places a burden on cardiac function. Thus, in the ninth chapter, it is stressed that VA construction, maintenance and repair should always be carried out with consideration of cardiac function which is not constant but variable. The 10th chapter forms one of the cores of this guideline and deals with repair and timing of VA. It is shown how to select a surgical or interventional repair method. In the final 11th chapter, VA types and resultant morbidity and mortality of hemodialysis patients are reviewed.

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