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Dr Hasan Dosluoglu (Buffalo, NY): Was the finding of 7% in-stent restenosis related to the preoperative presence of renal artery disease? And if so, was there a difference between the bare stents and the covered stents in those people who had preoperative disease in their renal arteries?

Dr Walid Mohabbat. The difference in the two groups pertains to the level of the aortic aneurysmal disease. We looked back on all the patients that developed a stenosis and an occlusion, and we looked at the operative records for evidence of renal artery stenosis, and this was seen in about 20% of all cases. This was a poor marker, however, so only in cases where there was a severe stenosis was this mentioned on the operative report.

We feel that if we actually go back and look at the procedural angiograms and the procedural videos from each case, we would see a much higher incidence of renal artery stenosis preoperatively in both groups. However, we didn't look at all cases for that particular finding, so we don't know, but we suspect that they are comparable in both groups.

Dr Richard Cambria (Boston, Mass). If I understand your information correctly, about 20% of your patients had a decrement in renal function. So my first question to you is: What was the percentage of patients who had either major deterioration in renal function or who went on to dialysis?

And if Dr Greenberg would take the question, have you done any retrospective look at the CT [computed tomography] scan information? Are there specifics of anatomy that you correlated with the embolization where—the other way of asking the question—are there factors that you identified where you might want to avoid extensive juxtarenal endograft manipulation?

Dr Mohabbat. Well, firstly, to address the issue of embolization and endograft manipulation. In each case that we detected embolization on the postoperative CT scan, we went back and looked at the preoperative CT scan and looked at the neck and also the visceral segment of the aorta for thrombus formation and the like. We did find that in each case with embolization, there was aortic disease in the visceral segment with extensive thrombus burden. However, when looking at a population with juxtarenal and thoracoabdominal aortic aneurysms, whether this differed between those who embolized and those who didn't embolize we don't know.

Dr Roy Greenberg. In answer to the first part of the question, there were only about three or four patients in the entire series that progressed to dialysis. For the purposes of this analysis, we took a very aggressive stance with respect to identification of changes in the baseline GFR [glomerular filtration rate]. Any drop in GFR >30%, irrespective of the absolute GFR level, was considered significant. Therefore, even if a patient's creatinine was 0.8 at the beginning of the procedure and it changed to during follow-up to 1.3, that was included in the group with deterioration of renal function. So in the manuscript you will see there are a lot of details in terms of how severe that dysfunction was. The relevance of a 30% change in the context of an otherwise normal GFR is subject to speculation.

With respect to analysis of patients suffering embolization, we could not determine any predictive. Thoracoabdominal aneurysms frequently have a lot of debris above the renal arteries. This is inherent with the disease, but thoracoabdominal aneurysms did not fare worse in terms of long-term renal function in contrast to juxtarenal aneurysms. Thus, the extent of aneurysmal disease was not associated with worse renal function. When we specifically looked at the patients suffering embolization, the numbers were too small to develop any statistical relevance.