Heterotaxy syndrome with polysplenia
There was no evidence of acute infiltrate on front (PA) or lateral chest
films, which showed mild cardiomegaly; bilateral morphologically left
main stem bronchii (Figure 1). Abdominal and pelvic CT revealed
polysplenia, midline liver, situs ambiguous, and interrupted inferior
vena cava with azygous continuation (Figures 2 and 3).
Heterotaxy syndrome is a general term that describes disruption in
normal positioning of the visceral organs in the chest and abdomen. This
generality encompasses the wide spectrum of findings found with this
disorder. The arrangement of visceral organs and vessels, which
otherwise follow a standard developmental pattern, is abnormal. In situs
solitus, the heart apex, spleen, stomach, aorta, and bi-lobed lung lay
to the left of midline; the tri-lobed lung, gallbladder, liver, and
inferior vena cava lay to the right. In situs inversus, these organs are
located the exact opposite of the normal asymmetry. Both situs inversus
and situs solitus are orderly arrangements of the viscerovascular
structures of the body that are delineated during embryogenesis. In
situs ambiguous, otherwise known as heterotaxy syndrome, the arrangement
of organs within the body is disorderly. The prevalence is estimated to
be 1.4 in 10,000 infants. This is likely an underestimation, as it is
based on patients with clinical manifestations of heart disease.1
with situs ambiguous traditionally have been categorized based on the
number of spleens. Those with polysplenia typically are associated with
hyparterial pulmonary bronchi, while asplenic patients usually have
eparterial bronchi. Several overlapping anatomical abnormalities are
found in both of these entities. Certain cases do not fit into this
classification.2 Nonetheless, the traditional system will be utilized to characterize the findings in this case.
Asplenic patients have a higher incidence of congenital heart disease with serious cardiac manifestations.2,3
This typically leads to earlier presentation and detection. In
contrast, there have been reports, as in this case, of asymptomatic
patients with polysplenia diagnosed later in life.4 While cardiac defects are comparatively fewer in this group, the diagnosis carries a mortality rate of 75% at 5 years
Cardiac anomalies in the heterotaxy syndrome
occur during embryogenesis. Common morphologic abnormalities include
atrial septal defects, ventricular septal defects, and bilateral
superior vena cava. In polysplenia patients, the inferior vena cava is
commonly discontinuous with the atrium. Venous return is via the
left-sided azygous or occasionally hemi-azygous vessels, as seen in this
case. In comparison, the asplenic grouping usually has normal venous
drainage via the IVC. However, abnormal venous drainage above the
diaphragm in the form of TAPVR is a frequent finding in asplenia. Other
vessel abnormalities include transposition of the great arteries.2,3,5 Visceral positioning and heart morphology are not always congruent.3
manifestations associated with the polysplenic group include bilateral
bi-lobed lungs, a midline liver, variable stomach location, and
hyparterial bronchi.2,5 Intestinal malrotation is common in this syndrome, but complications such as obstruction or volvulus are infrequent.6 Other less common anatomic variations are biliary atresia, pancreatic malformations, and urogenital anomalies.2,5
asplenia, findings typically include bilateral tri-lobed lungs,
eparterial bronchii and, occasionally, ipsilateral location of the aorta
and inferior vena cava. Gastrointestinal abnormalities are also
frequently found in this subset.2,3
syndrome’s etiology is not yet known. However, altered embryogenesis via
a combination of several internal and external influences is thought to
contribute to the abnormal asymmetrical anatomic patterning. Animal
models have delineated certain chromosomal and genetic foci also thought
to be involved with this sequencing.7 A familial
distribution, specifically X-linked recessive and autosomal recessive
modes of inheritance, have been reported, but most cases are sporadic in
Treatment depends on the associated
abnormalities. Prognosis is generally poor in those affected with
cardiac abnormalities. Improvements in antenatal diagnosis, and
corrective measures such as the Fontan procedure, have significantly
decreased the morbidity and mortality in patients that are candidates
for this type of treatment.9 Functionality of the spleen
should be assessed if splenic abnormalities are present. Patients with
nonfunctional spleens or asplenia are at an increased risk for
infections from encapsulated organisms, which can lead to septicemia and
death. Typically, treatment consists of prophylactic antibiotics and
immunizations.10 Malrotation of the intestinal tract can be
surgically treated. One recent report recommends surgery only if
symptoms or imaging dictate an obstruction and ischemia is rare.6
The surgeon must be aware of the individual’s specific anatomy as there
can be significant variability in each case. This information could
have serious implications in management and treatment for the patient.
Heterotaxy syndrome is a rare disorder that commonly presents early in
life secondary to associated cardiac manifestations. However, it has
many possible presentations due to the variability of organ involvement.
Occasionally, it can go undetected for many years, as in this case.
Identification of the subtle anatomic manifestations can greatly impact
the treatment of primary and secondary sequelae of this syndrome.
- Hernanz-Schulman M. Asplenia/Polysplenia. Available at: http://www.emedicine.com/Radio/topic58.htm. Accessed 2005.
- Ticho BS, Goldstein AM, Van Praagh R. Extracardiac anomalies in
the heterotaxy syndromes with focus on anomalies of midline-associated
structures. Am J Cardiol. 2000;85:729-734.
- Applegate KE, Goske MJ, Pierce G, Murphy, D. Situs revisited: Imaging of the heterotaxy syndrome. Radiographics. 1999;19:837-852.
- Marx MV, Van Allan R. SIR 2005 film panel case: Heterotaxia with polysplenia. J Vasc Interv Radiol. 2005;16:1055-1059.
- Peoples WM, Moller JH, Edwards JE. Polysplenia: A review of 146 cases. Pediatr Cardiol. 1983;4:129-137.
- Choi M, Borenstein SH, Hornberger L, Langer JC. Heterotaxia
syndrome: The role of screening for intestinal rotation abnormalities. Arch Dis Child. 2005;90:813-815.
- Belmont JW, Mohapatra B, Towbin JA, Ware SM. Molecular genetics of heterotaxy syndromes. Curr Opin Cardiol. 2004;19(3):216-220.
- Lin AE, Ticho BS, Houde K, et al. Heterotaxy: Associated conditions and hospital-based prevalence in newborns. Genet Med. 2000;2:157-172.
- Kaulitz R, Hofbeck M. Current treatment and prognosis in children with functionally univentricular hearts. Arch Dis Child. 2005;90:757-762.
- Long S, Pickering L, Prober C. Principles and Practice of Pediatric Infectious Diseases, 2nd Edition. Churchill Livingstone. 2003:651-652; An imprint of Elsevier.