We report a case of baby who had an unusual cause for absent femoral
pulses. A term, male infant presented after normal pregnancy and delivery
with absent femoral pulses on routine newborn examination. Four-limb blood
pressure measurement showed a difference of 30 mmHg in systolic pressures
between upper and lower limbs. The initial echocardiogram suggested a diagnosis
of aortic coarctation, but further assessment by a cardiologist showed
a thrombus at the aortic isthmus with small collaterals and a persistent
ductus arteriosus supplying the descending aorta. Cerebral ultrasonography
showed gross abnormality of left middle cerebral artery (LMCA) territory
raising the possibility of cerebral infarction. There was no improvement
with prostaglandin E2 or streptokinase. Magnetic resonance imaging showed
cystic encephalomalacia of LMCA territory, suggesting prenatal insult,
and confirmed complete obstruction of the aortic lumen. He underwent thrombectomy
with subclavian flap augmentation of the aorta on day 7 of life and had
an uneventful postoperative recovery, but unfortunately still suffers from
a dense right hemiparesis and seizures and now has evolving cerebral palsy.
A thrombophilia screen was negative.
Fig 1: MRI scan of the brain showing extensive encephalomalacia
in the left cerebral hemisphere
Fig 2: Echocardiogram – Supra-sternal view showing an organised
thrombus in the Distal Transverse Aortic Arch (DTA: Distal transverse arch;
Dao: Descending aorta; LSCA: Left subclavian artery)
Fig 3: MRI scan of the aorta showing thrombus in the arch. The
appearance of the arch mimics coarctation of the aorta.
Discussion
Causes of absent or reduced femoral pulses in neonatal period amongst
others include coarctation of the aorta and bilateral dislocation of the
hips. Aortic thrombosis can simulate aortic coarctation and can be potentially
life threatening with significant morbidity1, 2. Aortic thrombus
is not uncommonly associated with umbilical arterial cannulation in the
neonatal intensive care setting3. De novo neonatal aortic
obstruction due to thrombus is rare. In this case we hypothesise that a
thrombus embolised into the systemic circulation at around 22-24 weeks
of gestation (based on the MRI findings). The aortic isthmus, lying between
the left subclavian artery and ductus arteriosus, is the narrowest part
of the aorta and obstruction at this point mimics aortic coarctation or
interruption. The fact that the thrombus was well-organised and collateral
vessels had developed confirmed its chronic nature.
Acknowledgement
Dr Andrew Wood, Consultant Radiologist, University Hospital of Wales,
Cardiff, UK
References
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de Godoy JM, De Marchi CH, Silva MG, Carvalho MC, Moscardini A, Medeiros
JC. Thrombosis of the abdominal aorta in a newborn: case report and review
of literature. J Pediatr Surg 2003;38(4):E11
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Rodriguez M, Sosenko I. Catheter-induced aortic thrombus masquerading as
coarctation of the aorta. Clin Pediatr 1989;28:581-584.
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Das BB, Sahoo S, Ivy DD. Neonatal aortic arch thrombosis masquerading as
coarctation of the aorta. Pediatr Cardiol 2004;25:80-83
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