Assessment of access blood flow after preemptive angioplasty

In an effort to prolong the life of synthetic grafts used for hemodialysis access, current recommendations suggest regular monitoring of vascular access by means of measurements of access blood flows (ABFs) and/or pressures and prompt referral for prophylactic angiography with angioplasty when appropriate. Previous data suggested that angioplasty transiently reduces venous pressure, but repeated angioplasty is often required. Few data exist on the effect of angioplasty on ABF, especially the durability of the response. In this study, we report our experience with 49 consecutive angioplasties of 32 synthetic polytetrafluoroethylene grafts in which ABF was measured serially preangiography and postangiography using the Transonic hemodialysis monitor (Transonic Inc, Ithaca, NY). The primary indication for angiography was a low graft ABF rate (<600 mL/min). Although the most common site for stenosis was the venous anastomosis, the majority of grafts had multiple lesions requiring angioplasty. Mean ABF rate increased from 596 ± 41 to 922 ± 48 mL/min postangiography, an increase of almost twofold. This level of blood flow was maintained for the first month, but thereafter ABF began to decrease, reaching 672 ± 70 mL/min at 3 months and 658 ± 93 mL/min at 6 months. Two patients were lost to follow-up (one patient died, one patient received a transplant) and 2 grafts were electively ligated. The remaining 28 grafts were followed up for at least 6 months. Four grafts clotted within 3 months of angioplasty and were lost. Nine additional grafts required a second intervention (surgical revision, 2 grafts; repeated angioplasty, 7 grafts) within 6 months, either for a poor initial response to angioplasty or recurrent stenosis. Two of these 9 grafts subsequently clotted and were lost. In all, 22 of the 28 grafts remained patent at 6 months postangioplasty, and 15 grafts were maintaining an ABF greater than 600 mL/min without reintervention at 6 months. In summary, this study indicates that preemptive angioplasty of graft stenoses results in an initial doubling of ABF, but the effect is temporary, with the average ABF decreasing to baseline values by 3 months. Approximately half the grafts required reintervention for either thrombosis or recurrent low flow. However, sustained responses with ABF maintained at greater than 600 mL/min were achieved in the other half.