Hemodialysis graft mechanical thrombolysis with use of the Amplatz Thrombectomy Device: histopathologic evaluation of extracted myointimal tissue.

Overview

PURPOSE: To histopathologically evaluate material extracted from thrombosed hemodialysis access grafts by the Amplatz Thrombectomy Device (ATD). MATERIALS AND METHODS: Thrombosed hemodialysis access grafts were recanalized with use of crossed catheter technique with introduction of the ATD through 8-F sheaths. After removal of the ATD from the introducer sheath, the tip of the device was visually inspected. Discernible tissue in the impeller/housing mechanism was gently extracted with a hemostat and preserved in formalin. Specimens were evaluated histologically with hematoxylin-eosin and smooth muscle immunoperoxidase stains. RESULTS: The ATD was utilized in 18 patients with acutely thrombosed grafts. Sufficient tissue for pathologic evaluation was extracted from 10 devices. Histopathologic analysis yielded findings of fibrotic myointima in all 10 cases with positive smooth muscle stains. CONCLUSIONS: The unexpected, although consistent, finding of intimal and myointimal tissue fragments in the impeller/housing mechanism of the ATD raises questions with respect to the mechanism of tissue extraction and concerns regarding the use of the device in native vessels. Further studies are indicated to determine whether this apparent intimal injury will have a deleterious effect on vessel patency.