To the Editor.–We read with interest the recent article by Mohr and Smith, "Polytetrafluoroethylene Graft Aneurysms" (Archives 1980;115:1467-1470). We previously noted the development of expanded polytetrafluoroethylene (PTFE) aneurysms in grafts with a wall thickness of 0.5 mm, placed for hemodialysis.1 Our observations may shed some light on some of the difficulties the graft manufacturers faced.
Although we have placed equal numbers of PTFE grafts in the arm and the leg, the five that became aneurysmal were all in the leg. Four of the five had an initial diameter of 8 mm, and one, 6 mm. All became aneurysmal in less than six months except the 6-mm graft, which took 14 months. All of the patients were mildly hypertensive although only one was receiving medication. Electron microscopic examination of the graft material showed that dilation was not the result of fibrillar breaks but resulted from a gradual stretching of