Tetralogy of Fallot

Tetralogy of Fallot has four key features that all result from an anterior deviation of the inter-ventricular septum: a large non-restrictive VSD, overriding of the aorta (where the aorta is positioned directly over the VSD), RVOT obstruction (can be infundibular, valvar PS, supra-valvar PS and PA stenosis) and right ventricular hypertrophy.

Surgical repair consists of VSD patch, relief of RVOT obstruction, +/- pulmonary valve replacement.

Associated anomalies are PFO/ASD, additional muscular VSDs, R sided aortic arch, aortic root dilatation, AR, and various aorto-pulmonary connection abnormalities.

Both Repaired and Unrepaired Tetralogy of Fallot patients should be referred to a tertiary centre specialising in congenital heart disease. The following is a guide as to the echocardiographic follow up of these patients.

2D Echo / Colour Doppler – Unrepaired
Assessment of the overall function of the ventricular mass
Non-restrictive VSD
Aortic override – best seen from PSLAX
RVOT obstruction, assess degree and site(s) of turbulence on colour flow
Pulmonary regurgitation
Degree of RVH, best seen from sub-costal views
2D Echo / Colour Doppler – Repaired
Assessment of the RV size, systolic function (visual, TAPSE, MPI)
LVfunction – ? paradoxical IV septal motion, suggesting RV volume overload
Residual VSD, size, turbulence
Aortic root size, AR
Residual RVOT obstruction, turbulence on colour flow
Degree of pulmonary regurgitation
Degree of RVH, best seen from sub-costal views

Doppler Measurements – Unrepaired
Low velocity flow across unrestrictive VSD
RVOT obstruction, degree by Peak PG (Bernoulli , 4V sq) and site
Utilise stand-alone CW Doppler to search for high velocity signals suggestive of peripheral pulmonary stenosis
Doppler Measurements – Repaired
Residual VSD V max, ? restrictive / unrestrictive jet
RVOT obstruction, sites, degree (using peak PG derived from Bernoulli : 4V sq) : including branch pulmonary arteries
Degree of PR – CW jet intensity, PR PHT, early diastolic jet termination
RV diastolic dysfunction (restrictive physiology) – antegrade late diastolic flow in MPA on PW Doppler, coinciding with atrial systole
Utilise stand-alone CW Doppler to search for high velocity signals suggestive of peripheral pulmonary stenosis

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