March 1997

Endoluminal Stent Grafts for Infrarenal Abdominal Aortic Aneurysms

Blum U, Voshage G, Lammer J, Beyersdorf F, Tollner D, Kretschmer G, Spillner G, Polterauer P, Nagel G, Holzenbein T, Thurnher S, and Langer M.

N Engl J Med 1997;336:13-20

[ see abstract below ]

It was only a matter of time before stenting followed the course of blood flow out from the heart to the periphery. Exciting new applications of stents are beginning to transform the field of vascular surgery. Experimental applications are beginning for carotid stenoses, and a significant number of patients have now been stented for aortic aneurysm repair.

This report in the NEJM details the most extensive series to date. 154 patients underwent aneurysmal repair by stenting. 21 were straight stents, and 133 were bifurcated. General anesthesia was performed, but given that the stents were placed via a peripheral arteriotomy it seems plausible that anesthesiologists might consider regional anesthesia for these procedures. The 86% success rate, defined as complete exclusion of the aneurysm from the circulation, was similar to other trials.

Minor and major complications were noted in 10% of patients, with 3 major complications - 1 death from acute hepatic failure, 1 patient requiring emergency surgery due to rupture of the iliac artery, and 1 patient suffering an embolus that required amputation of a leg. Interestingly, 15% suffered mild renal failure, and 3% suffered severe decrements in renal function. This level probably surpasses the renal effect seen with aortic clamping. All patients had a postimplantation syndrome consis ting of leukocytosis and elevated C-reactive protein levels.

The time to perform these procedures was comparable for that of an open procedure, lasting 50-220 minutes for straight grafts and 45 -270 minutes for bifurcated grafts. Length of hospital stay was similar, averaging almost 7 days, although the reason for these extended stays were not clearly explained in the text of the paper. # and 6 month follow-up revealed that secondary failure - defined as minor spontaneous reperfusion of the grafts, occurred in seven patients. These were successfully treated in return visits. A much longer term follow-up is required to judge the true success rate of this new intervention.

Although the results reported here are far from an outstanding improvement on an open procedure, the potential benefits from performing closed procedures are obvious, assuming that the technical details are perfected. Patients with severe cardiac and/or pulmonary co-morbidities, a common occurrence in the aortic aneurysm population, could undergo limited interventions. Effects on pulmonary mechanics would be minimized. Hemodynamic consequences of open aneurysmal repair, the associated fluid shifts, and postoperative oozing leading to anemia will be eliminated or lessened. Hemodynamic responses to pain should be curtailed. That theoretically should result in a lowering of postoperative cardiac complications, unless, as many of us suspect, the cardiac complications more often are the result of a pro-thrombotic state than hemodynamic perturbation. This is important as the effect of the stent on coagulation status is not necessarily any better than open placement of a graft. W hile there is great promise in these stent procedures, much more time and experience are necessary before we know whether this approach is truly in our patients' best interests.

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ABSTRACT