Sodium Thiosulfate Treatment of Vascular Calcification in ESRD

Cardiovascular disease is the major cause of death in the hemodialysis population and calcification of the major arteries (coronary, aorta, and carotid) are a play a central role in this process. The major causes of the calcification are many, including high levels of phosphorus, low levels of inhibitors of calcification, positive calcium balance, and oxidative stress. Once vascular calcification is present, it is usually progressive. There is no known treatment to reverse established vascular calcification. Sodium thiosulfate has been used extensively and safely to treat calcific uremic arteriopathy (a disease, in part due to calcification of small arteries) in dialysis patients. It increases the solubility of calcium by up to 100,000 fold and is also a potent anti-oxidant. It therefore has to potential to also decrease the amount of calcium in large arteries in dialysis patients and, hence improve survival. We will study hemodialysis (HD) patients at high risk for cardiovascular disease and death by obtaining a multidetector computerized tomography (MDCT) Scan of the coronary arteries, carotid arteries and aorta and an assessment of coronary artery stenoses by a simultaneous intravenous infusion of contrast. At the same setting, we will perform tests of pulse wave velocity (PWV) and carotid ultrasound carotid intima-media thickness(CIMT)studies. In those patients at high risk for cardiovascular death, defined as a coronary artery calcification score (CACS)of greater than 50, sodium thiosulfate at a dose of 12.5-25 gm/1.73 M2 will be infused over 15-30 minutes after each dialysis treatment for 5 months. The above studies will then be repeated.