ENDOLEAKAGE AFTER STENT-GRAFT TREATMENT OF ABDOMINAL ANEURYSM - IMPLICATIONS ON PRESSURE AND IMAGING - AN IN-VITRO STUDY

Background: Endoleakage is a fairly common problem after endovascular repair of abdominal aortic aneurysm and may prevent successful exclusi on of the aneurysm. The consequences of endoleakage in terms of pressu re in the aneurysmal sac are not exactly known. Moreover, the diagnosi s of endoleakage is a problem because visualization of endoleaks can b e difficult. Method: With an ex vivo model of circulation with an arti ficial aneurysm managed by means of a tube graft, studies were perform ed to evaluate precisely known diameters of endoleaks with both imagin g techniques (computed tomography and digital subtraction angiography) and pressure measurements of the aneurysmal sac. The experiments were performed without endoleak (controls) and with 1.231-French (0.410 nu n), a-French (1 mm), and 7-french (2.33 nun) endoleaks. Pressure and i maging were evaluated in the absence and presence of a simulated open lumbar artery. The pressure in the prosthesis and in the aneurysmal sa c were recorded simultaneously. Digital subtraction angiography with a nd without a Lucite acrylic plate, computed tomographic angiography, a nd delayed computed tomographic angiography were performed. For the fi rst experiments, the aneurysmal sac was filled with starch solution. A ll tests were repeated with fresh thrombus in the aneurysmal sac. Resu lts: Each endoleak was associated with a diastolic pressure in the ane urysmal sec that was identical to diastolic systemic pressure, althoug h the pressure curve was damped. At digital subtraction angiography wi thout a Lucite acrylic plate, the 1.231-French (0.410 mm) endoleak was visualized without an open lumbar artery. When a Lucite acrylic plate was added, the endoleak was not visible until a lumbar artery was ope ned. In the presence of thrombus within the aneurysmal sac, all endole aks mere not visualized at digital subtraction angiography. At compute d tomographic angiography, all endoleaks were not visualized in the ab sence of a thrombus mass in the aneurysmal sac, In the presence of thr ombus within the aneurysmal sac, the 1.231-French (0.410 nun) endoleak became visible after opening of a simulated lumbar artery. At delayed computed tomographic angiography; all endoleaks were visualized witho ut and with thrombus. Conclusion: Every endoleak, even a very small on e, caused pressure greater than systemic diastolic pressure within the aneurysmal sac. However, small endoleaks were not visualized with dig ital subtraction angiography and computed tomographic angiography, whe reas all endoleaks were visualized with a delayed computed tomographic angiography protocol. We believe that follow-up examinations after st ent graft placement for aortic aneurysms should focus on pressure meas urements, but until this is clinically feasible, delayed computed tomo graphic angiography should be performed.