Identification and implications of transgraft microleaks after endovascular repair of aortic aneurysms

Purpose: The purpose of this report is to describe an interesting cause of endoleak and detail-specific techniques for identifying small transgraft de fects, which we have termed microleaks. Methods. Four patients underwent endovascular repair of abdominal aortic an eurysms with modular nitinol/polyester endoprostheses and were studied afte r 6 to 30 months. All patients were enrolled in standard follow-up radiogra phic surveillance protocols. Results: Three of the four abdominal aortic aneurysms continued to expand a fter endograft repair. Standard computed tomography imaging with precontras t, dynamic contrast, and delayed imaging frequently identifies endoleak, al though it fails to precisely identify microleaks as the source. Color flow duplex ultrasound scan was performed on three patients and perigraft "jets, " small areas of color flow adjacent to the endograft, were identified in a ll. Microleaks were identified in one patient who underwent digital subtrac tion axteriography with directed efforts to completely opacify the prosthes is lumen and multiple oblique projections. In another patient, contrast art eriography with balloon occlusion of the distal endograft clearly depicted midgraft microleaks that might otherwise be mistaken for graft porosity or cuff junction endoleaks. No microleaks were diagnosed on angiograms when th ese directed efforts were not performed. Aneurysm exploration before aortic clamping provided conclusive determination of the presence of blood flow t hrough the wall of the endoprosthesis in two patients. Conclusions: Microleaks occur up to 2.5 years after endovascular repair of aortic aneurysms. Although computed tomography demonstrates the presence of an endoleak in these patients, the exact site of origin usually remains ob scure. Doppler ultrasound scan and directed arteriography appear to be of g reater utility for identifying the presence and location of microleaks. Bal loon occlusion arteriography and aneurysm exploration without arterial clam ping provide definitive evidence of microleaks. Although the clinical signi ficance of microleaks remains unclear, long-term monitoring of patients is imperative to diagnose and treat these and other modes of endograft failure before they progress to aneurysm rupture.