Coarctation
Coarctation is a stenosis of the proximal descending aorta varying in anatomy,
physiology and clinical presentation. Coarctation of the aorta is a relatively common
defect that accounts for approx 5% of all congenital heart defects. Coarctation of the
aorta may occur as an isolated defect or in association with various other lesions,
most commonly bicuspid aortic valve and ventricular septal defect (VSD). It may be a
feature of a congenital abnormality syndrome, particularly Turner’s syndrome. The
coarctation may be discrete, or a long, tubular narrowing; the former is more
common. The classic coarctation is located in the thoracic aorta distal to the origin of
the left subclavian artery at about the level of the ductal structure (juxtaductal).
The suprasternal notch echo window allows evaluation of the aortic arch to assess
the transverse aortic arch, isthmus, and severity of coarctation. Doppler is used to
measure the gradient at the site of coarctation and to identify the pattern of diastolic
decay typically seen in patients with severe obstruction.
Coarctations may be repaired surgically or they may be stented. The echo
assessment of these patients is very similar to that of a newly diagnosed coarctation.
If stented, it is often possible to visualise the proximal end of the stent. There may be
2D artefacts associated with the stent, therefore, stand alone CW Doppler is
essential to assess the descending aortic velocity. Other imaging modalities may be
useful in this patient population.
2D Echo / Colour Doppler
Location of constriction, diameter in mm
Aortic root, ascending aorta, transverse aorta and descending aortic dimensions
Turbulence / acceleration on colour Doppler
Left ventricular dimensions particularly wall thickness
Presence of bicuspid aortic valve
Presence/degree of aortic regurgitation
Doppler Measurements
Peak velocity across bicuspid aortic valve / ascending aorta.
Peak velocity across the coarctation, noting the step-up at the site of the narrowing
Presence of diastolic decay of coarctation jet envelope
N.B. Stand alone Doppler is essential in obtaining the descending aortic signal
Common Pitfalls/Limitations
If the velocity in the ascending aorta is increased, it is important to apply the full
Bernoulli equation to assess the severity of the coarctation.
Full Bernoulli: 4(V22 – V12)
The Doppler severity of the coarctation may be underestimated in patients with
significant collateral vessels supplying the descending aorta.
Repaired coarctations may be associated with aneurysm formation, this is difficult
to exclude on echo, therefore, further imaging investigations may be indicated (e.g.
MRI).