Repair of Abdominal Aortic Aneurysms in the Presence of the Horseshoe Kidney

Aim: Horseshoe kidney is the most common congenital kidney anomaly, occurring in 0.15-0.25% of all newborns. A medial fusion of the kidneys, mostly anteriorly to the aorta, is the main characteristic of this anomaly. The co-existence of abdominal aortic aneurysm (AAA) and horseshoe kidney is rare, occurring only in 0.12% of patients. The aim of this paper is to define the optimal management of patients with AAA associated with the horseshoe kidney.

Methods: This paper presents the analysis of patients operated at the Clinic for Vascular and Endovascular Surgery of the Clinical Center of Serbia in Belgrade due to AAA associated with the horseshoe kidney as well as the analysis of the previously published literature data regarding this topic.

Results: Between 1985 and 2011, data were collected retrospectively on 25 patients with the horseshoe kidney who underwent aortic surgery. Out of them, 6 patients had aortoiliac occlusive disease and 19 patients had aortic aneurysm. More detailed analysis of the aneurysmatic group was performed. Among them there were 16 male and three female patients, with the average age of 63.8 (50-76) years. Two patients had type IV of thoracoabdomial aortic aneurysm (TAA) according to Crawford-Saffi classification, while 17 had infrarenal abdominal aortic aneurysms. There were 15 elective and four urgent procedures due to aneurismal rupture. The presence of the horseshoe kidney was detected in 16 patients before surgery (84.2%) by means of Duplex ultrasonography, angiography, computed tomography and intravenous urography. Multiple renal arteries were presented in 12 (63.2%) cases. A transperitoneal approach was used in 16 cases with abdominal aortic aneurysm, while left retroperitoneal approach with partial extrapleural removal of the 11th rib was performed in two cases of thoracoabdominal aneurysm and in one patient with AAA. In 18 cases, kidney tissue transection was successfully avoided with vascular graft placement beneath the horseshoe kidney. In one case only, the division of the renal isthmus was performed. In all 12 cases with detected anomalous renal arteries, their reattachment into vascular graft has been performed. Two patients (10.5%) died during perioperative period. One of them had ruptured type IV TAA. Seventeen patients who survived were followed from one to twenty years (mean 6.6 years). During the follow up period we lost track of 4 patients. In this period there were no signs of graft occlusion, or renal failure.

Conclusion: Repair of an abdominal aortic aneurysm in the presence of the horseshoe kidney is a truly particular surgical challenge. It is associated with three main problems: choice of the surgical approach; the procedure regarding kidney isthmus preservation as well as recognition and reattachment of all significant anomalous renal arteries.