av Fistula Patency Loss as a Cause of Fistula Failure and Its Relation to Hyperphosphatemia in Chronic Hemodialysis Patients

End-stage renal disease is a chronic disease requiring treatment with dialysis or renal transplantation. Patients require an adequate vascular access for hemodialysis (HD). Autologous arteriovenous fistula (AVF) is gold standard to maintain vascular access for HD . Vascular access-related complications can lead to patient morbidity and reduction of patient quality of life.The complication rate related to permanent HD vascular access remains relatively high and access related problems are responsible for 50% of the hospitalization of dialysis patients. Secondary failures are not rare and in need of adequate attention and care. Once the AVF has been placed. It is recommended that serial monitoring of the AVF should be done for long term effective function. Delays in preventing complications may lead to AVF dysfunction. However, little is known about the factors determining long term prognosis of an AVF.

Primary patency (intervention-free access survival) was defined as the interval from time of access placement to any intervention designed to maintain or reestablish patency or to access thrombosis or the time of measurement of patency. Assisted primary patency (thrombosis-free access survival) was defined as the interval from time of access placement to access thrombosis or time of measurement of patency, including intervening manipulations (surgical or endovascular interventions) designed to maintain the functionality of a patent access. Secondary patency (access survival until abandonment) was defined as the interval from time of access placement to access abandonment or time of measurement of patency, including intervening manipulations (surgical or endovascular interventions) designed to reestablish the functionality of thrombosed access .

In patients having chronic renal failure (CRF), several changes occur in bone metabolism due to the development of secondary hyperparathyroidism. There are increased calcium and phosphate release from bones to the blood, causing the deposition of calcium and phosphate in the intima-media layer of arterial wall and eventuating vascular calcification in these patients. The deposition of these electrolytes increases the risk of cerebrovascular and coronary complications as well. Thus, a decrease in the quality of fistula occurs in these tracts utilized frequently at the arteriovenous fistula (AVF) operations.