actas urol esp. 2009;33(10):1141-1144
ACTAS UROLÓGICAS ESPAÑOLAS
www.elsevier.es/actasuro
Clinical note
New case of an infrarenal abdominal aortic aneurysm
associated with horseshoe kidney
Nerea Senarriaga Ruiz de la Illaa, Reyes Vega Manriqueb, Isabel Lacasa Viscasillasa, Iñaki
Iriarte Soldevillaa, and Miguel Unda Urzaiza,*
aDepartment
bDepartment
of Urology, Hospital of Basurto, Bilbao, Vizcaya, Spain.
of Vascular Surgery, Hospital of Basurto, Bilbao, Vizcaya, Spain.
ARTICLE INFORMATION
A B S T R A C T
Article history:
We review the association between surgically resolvable aortic disease and horseshoe
Received on 5 February 2008
kidney with a discussion of diagnostic problems and therapeutic options.
Accepted on 18 February 2008
Male patient 81 years of age with horseshoe kidney and an abdominal aortic aneurysm
that was discovered by chance in an abdominal ultrasound during a check-up for his
Keywords:
prostate condition.
Aortic aneurysm
A retroperitoneal approach was used in order to resect the aneurysm and perform an
Horseshoe kidney
aorto-aortic bypass with no complications occurring. Two years after the diagnosis, the
Retroperitoneal approach
patient is still asymptomatic from a vascular point of view.
The co-presence of horseshoe kidney and aortic disease needing surgical correction is
infrequent, but it significantly increases the technical complexity of aortic reconstruction.
A literature review is included.
© 2009 AEU. Published by Elsevier España, S.L. All rights reserved.
Aneurisma de aorta abdominal infrarrenal en asociación con riñón
en herradura: aportación de un caso
R E S U M E N
Palabras clave:
Se analiza la relación entre enfermedad aórtica quirúrgica y riñón en herradura, y se
Aneurisma aórtico
comentan los problemas diagnósticos y las diferentes posibilidades terapéuticas.
Riñón en herradura
Paciente de 81 años con riñones en herradura que, durante el seguimiento de su
Abordaje retroperitoneal
enfermedad prostática, se descubre de forma casual por ecografía un aneurisma de aorta
abdominal. Se realizó mediante abordaje retroperitoneal una resección del aneurisma y
bypass aortoaórtico, sin complicaciones. A los 2 años del diagnóstico, el paciente continúa
asintomático en cuanto a la alteración vascular.
La coexistencia de riñón en herradura y afección aórtica que precise corrección quirúrgica
ocurre con poca frecuencia, pero incrementa de forma significativa la complejidad técnica
de la reconstrucción aórtica. Se realiza una revisión de la literatura.
© 2009 AEU. Publicado por Elsevier España, S.L. Todos los derechos reservados.
*Author for correspondence.
E-mail: [email protected] (N. Senarriaga Ruiz de la Illa).
0210-4806/$ - see front matter © 2009 AEU. Published by Elsevier España, S.L. All rights reserved.
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actas urol esp. 2009;33(10):1141-1144
Introduction
Horseshoe kidney is one of the most common renal
malformations and is usually associated with normal renal
function. It is associated with abdominal aortic aneurysms
that require surgical correction at a rate of 1-5/1,000. Today,
the vast majority of cases are diagnosed prior to surgery, and
computerized tomography (CT) is the main diagnostic test.
If open surgery is chosen, two approaches can be used
for the most part: transperitoneal and retroperitoneal.
Endovascular treatment is another therapeutic option if the
anatomy permits.
Case report
A male patient, 81 years old, was sent from the clinic to
our urology consultation offices for lower urinary tract
symptoms. He presented with a past medical history of
hypertension treated with angiotensin converting enzyme
inhibitors, surgical intervention for a duodenal ulcer in 1961,
and cholecystectomy in 2002.
An infrarenal abdominal aortic aneurysm was diagnosed
informally on abdominopelvic ultrasound. Using CT, it was
found not to involve the bifurcation of the iliacs. Furthermore,
the kidneys were seen in that examination to have morphology
consistent with horseshoe kidney, with an isthmus located at
the level of infrarenal abdominal aorta. Our case reveals a
situation that in principle was more favourable at the time
of surgical intervention, since the aneurysm began distally,
4cm from the origin of the main renal arteries, of which there
were two, one for each half of the kidney.
There was no additional artery at the level of the
isthmus.
In successive follow-ups, a progressive increase was seen
in aortic diameter, reaching a maximum diameter of 8cm on
one CT scan (fig. 1).
Given these findings, the department of vascular surgery
decided to go forward with surgical treatment of the
aneurysm.
On physical examination, the patient had preserved pulses
and an expansive abdominal beating was palpated. The rest
of the examination was unremarkable.
A baseline echocardiogram and pulmonary function tests
were performed as part of the pre-operative protocol for
aneurysms, all without significant abnormalities.
A retroperitoneal approach was utilized with resection of
the infrarenal aortic aneurysm and aorto-aortic bypass with
a 16mm Hemashield prosthesis, all without intraoperative
complications. No lumbar or polar arteries were visualized.
The post-operative course went smoothly, without major
complications resulting from the procedure, and the patient
maintained adequate renal function. All pulses were present
at the time of discharge.
The patient remains asymptomatic with regards to
vascular disruption. All pulses are preserved in the lower
extremities as are his renal function parameters. A follow-up
CT-angiogram performed 6 months after the intervention
Figure 1 – Maximum aortic diameter, 8cm
Figure 2 – Follow-up computed angiotomography
Figure 3 – Aorto-aortic bypass
actas urol esp. 2009;33(10):1141-1144
1143
showed aorto-aortic bypass without leakage or evidence of
areas of aneurysmal dilatation (figs. 2 and 3).
Intravenous pyelogram was performed (fig. 4), showing
the kidneys with horseshoe morphology, as well as the
ureteropelvic junction in the anterior plane and the collecting
systems, all without significant abnormalities.
Discussion
Horseshoe kidney has a low incidence, affecting 1/400 people.
Described first by De Carpi in 1552, it is the most common
form of a fusion defect. In 1820, Morgagni described the first
horseshoe kidney with abnormalities and since then it has
become the most written about renal anomaly.1 It is two
times more common in males. No clear genetic influence has
yet been demonstrated, although cases have been described
in identical twins and in several members of the same family,
but that could be the result of gene expression with a low
degree of penetrance.1,2
The abnormality occurs in the embryo between the fourth
and sixth weeks of gestation. Anomalous development of
the renal pelvis and a slight alteration in the position of
the umbilical, pelvic, and inferior mesenteric vessels could
change the orientation of the kidneys and cause them to
fuse.1,3
In the vast majority –around 95%– the connection occurs
at the inferior poles.4 That point of connection, called the
isthmus, may be made up of normal renal parenchymal
tissue 85% of the time or, on the contrary, of fibrous or
dysplastic tissue. It is usually located lower in the abdomen,
in 40% of cases just below the level of the origin of the inferior
mesenteric artery. In 20% of cases the isthmus is located at
the level of the pelvis and, in the remaining cases, at the level
of the inferior poles of normal kidneys.5
The isthmus is located in front of the great vessels,
although in some cases it is found behind the inferior vena
cava, between the cava and the aorta, or posterior to both.2
Generally a malrotation is present, with the pelvis anterior
and extrarenal, with calyces that are normal in number but
oriented backwards. The ureters are shorter than normal and
cross in front of the isthmus,4 anterior to the renal vessels,
although retrocaval ureters have also been described. Despite
this angulation that affects the superior segment of the
ureter, the inferior segment leads into the bladder normally
and is rarely ectopic.1
The kidneys are smaller than usual and their average
weight ranges between 250 and 350g.2
The rate of vascular anomalies in horseshoe kidney is
elevated at 70%.6 Different arteries may also supply the
isthmus and adjacent parenchyma, such as the renal, aorta,
common iliac, external iliac, inferior mesenteric, or median
sacral.4,5,7,8
Our case is an example that over time these patients can
develop aortic aneurysms5 that, when surgical treatment
becomes necessary, significantly increase the technical
difficulty of aortic reconstruction.9
Diagnosis of this disease is often made incidentally by
ultrasound during examination for other diseases. These
Figure 4 – Intravenous pyelogram without significant
abnormalities.
days, prenatal diagnosis remains difficult, but is facilitated
if there are concomitant anomalies.2 We initially suspect
the diagnosis on a plain abdominal x-ray where the renal
shadows are seen lower than normal and have altered
longitudinal axes. Intravenous pyelogram shows the V
orientation of the kidneys and allows visualization of the
medial orientation of the calyces in relation to the pelvis,
which is turned towards the front. However, the inferior
calyx is invariably within the ureter towards the midline.3
Serial voiding cystourethrography is extraordinarily useful
for ruling out vesicoureteral reflux, which is present in more
than 50% of cases. Currently, thanks to the high sensitivity
of ultrasound, this must be performed only in patients with
ultrasound visualization of the distal ureter and in cases
with concomitant urinary tract infection.2 CT and magnetic
resonance provide complementary information when surgical
treatment is needed for other reasons. Isotopic studies (DMSA
or MAG-3) may be used to evaluate isthmus function in order
to differentiate an obstructive picture from a pelvis that
appears dilated because of its anterior orientation.3
The surgical approach, transperitoneal or retroperitoneal,
depends on the type of isthmus (fibrous or parenchymal), the
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actas urol esp. 2009;33(10):1141-1144
type of renal vasculature, and the anatomy of the collecting
system.8,10 Thus, the transperitoneal approach allows for
reanastamosis of the polar artery if necessary, but often
requires dividing the renal isthmus, especially if it is large
and covers the anterior area of the aneurysm. This increases
the risk of complications such as the development of urinary
fistulas and prosthetic infection.
The retroperitoneal approach avoids the isthmus, but
offers difficult access to the iliac arteries.
If endovascular treatment is chosen, the main problem is
the exclusion of accessory renal arteries, bearing in mind that
80% of horseshoe kidneys have anomalous vascularisation.
Several authors believe that, when renal function is normal,
the occlusion of arteries with diameters less than 3mm or
those that supply less than 32% of the renal parenchyma will
not cause worsening.11,12
Conclusions
It is important to diagnose the combination of a horseshoe
kidney and aneurysm prior to surgery, due to anomalies in
the existing vasculature.13
Given the association of surgical aortic disease and
horseshoe kidney, the goal of treatment is the technical
solution of the aortic disease, while preserving renal blood
flow and without damaging the urinary tract.
For proper diagnosis and surgical treatment of aortic
aneurysm associated with horseshoe kidney, CT and
arteriography are indispensable tools.
Given that the surgical approach, transperitoneal or
retroperitoneal, depends on the parenchyma of the isthmus,
the type of vascularisation, and the anatomy of the urinary
tract, we are forced to conduct a thorough preoperative
evaluation of this disease and thereby facilitate the work of
the cardiovascular surgeons.
R E F E R E N C E S
1. Walsh PC, Retik AB, Vaughan E, Wein AJ. Anomalías del
tracto urinario superior. Campbell. 8.a ed. Tomo 3. Buenos
Aires: Médica Panamericana; 2004. p. 2080-4.
2. Jiménez Cruz JF, Rioja Sanz LA. Anomalías congénitas renales
de fusión. Tratado de Urología. 2.a ed. Tomo II. Barcelona:
Prous Science; 2006. p. 587-93.
3. Avérous M, Veyrac C. Malformaciones congénitas del riñón.
Enciclopedia Médico-Quirúrgica. París: Elsevier; 2002. p. 15-7.
4. Lobe TE, Martin EW, Cooperman M, et al. Abdominal aortic
surgery in the presence of a horseshoe kidney. Ann Surg.
1978;188:71-8.
5. López M, Gómez A, Aransay A. Malformaciones renales. Libro
del Residente de Urología. Madrid; 2007. p. 220-1.
6. Canova G, Masini R, Santero E, et al. Surgical treatment of
abdominal aortic aneurysm in association with horseshoe
kidney. Tex Heart Inst J. 1998;25:206-10.
7. Puras-Mallagray E, Luján-Huertas S, Aracil-Sanus E, et al.
Cirugía aórtica asociada a riñón en herradura. Nuestra
experiencia. Angiología. 1995;47:281-6.
8. Cohn LH, Stoney RJ, Wylie EJ. Abdominal aortic aneurysm
and horseshoe kidney. Ann Surg. 1969;170:870-4.
9. Ramírez Fabián M, Vicente Aldea MT, Ucar Terren A, et al.
Cirugía del aneurisma de aorta abdominal en presencia de
riñón en herradura. Arch Esp Urol. 1999;52:1087-9.
10. Marin Peralta JO, Montero M, García Ossa H, et al. Aneurisma
de aorta abdominal asociado a riñones en herradura. Rev
Chill Cir. 1996;48:289-92.
11. Gómez Vivanco R, Salazar Agorria A, Izagirre Loroño M.
Aneurisma de aorta abdominal infrarrenal en asociación
con riñón en herradura. Concurso de casos clínicos para
residentes de Angiología y Cirugía Vascular; 2005. p. 82-4.
12. Del Barrio Fernández M, Ballesteros Pomar M, Domínguez
Bahamonde JM, et al. Aneurisma de aorta abdominal y riñón
en herradura. Concurso de casos clínicos para residentes de
Angiología y Cirugía Vascular; 2006. p. 195-7.
13. Bietz D, Merendino K. Abdominal aneurysm and horseshoe
kidney: A review. Ann Surg. 1975;181:333-41.