To the Editor.—The article by Adar et al1 advocated more frequent division of the left renal vein during repair of aortic aneurysms. Though I concur that this maneuver may afford a few important centimeters of aortic exposure, several notes of caution should be raised. In the authors' retrospective review, there was no significant effect of left renal vein division on overall renal function. Since these patients presumably had functioning right kidneys, it is not possible to assess the effect of this technique on the left kidney because no differential renal function data were provided. Furthermore, these authors failed to emphasize the importance of preserving venous collateral pathways to the safety of this method.
Using an animal model, it has been demonstrated that the venous hypertension, which follows division of the left renal vein, reduces renal perfusion to 68.9% of control levels within 15 minutes.2 This impairment of