One of the complications of arteriovenous fistulas in chronic hemodialyzed patients is the onset of an aneurysm which can be at risk of rupture. Traditional surgical repair is not always feasible and may not be successful in these cases, leading therefore to the loss of a functioning vascular access and requiring in any case the temporary use of a central venous catheter to allow regular hemodialysis sessions. We applied to this kind of aneurysm the same experience developed in the management of major arterial aneurysms and we considered endografting repair a good alternative in this case. In this paper we present the successful treatment of an arteriovenous fistula aneurysm using that technique. A distal radio-cephalic arteriovenous fistula in one of our patients presented an aneurysm with high risk of rupture. The endografting repair with percutaneous insertion of a WallgraftTM endoprosthesis was well tolerated and the vascular access could be used the day after, without the need for a central venous catheter insertion.

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A sigmoidal relationship, fitting a four-parameter model, has been demonstrated in in vivo and in vitro studies to link the parathyroid hormone (PTH) secretion rate and calcium concentration changes. In uraemic patients different patterns of calcium-mediated PTH secretion were reported in different types of renal bone diseases and a shift to the right and a steeper slope has been observed in secondary hyperparathyroidism. To gain more information that could predict indexes for successful medical therapy we investigated the calcium-PTH sigmoidal relationship in 42 hyperparathyroid patients with different degrees of secondary hyperparathyroidism; we classified as moderate those patients presenting basal PTH (PTHbas) < 600 pg/ml and bone alkaline phosphatase (AP) < 500 U/l, and severe those with a PTHbas > or = 600 pg/ml and bone AP > or = 500 U/l. Changes in ionized calcium (iCa) were induced by calcium-free dialysis on the first day, to induce hypocalcaemia up to serum iCa 3.5 mEq/l, and calcium 8 mEq/l dialysis on the third day, to induce hypercalcaemia. The moderate hyperparathyroidism patients had PTHmax, PTHmin and slope, calculated in absolute values and relative values, lower than severe hyperparathyroidism patients but they did not differ in the minimal to maximal PTH ratio. In the moderate group the PTHbas correlated with all the curve parameters except PTHmin, calculated both in absolute and percentage values, while in the severe group PTHmin was the only parameter correlating to the PTHbas. In conclusion, by performing the dynamic test, we found that some glands were not suppressible among moderate hyperparathyroidism patients.