Tetralogy of Fallot

Tetralogy of Fallot
Patients with this condition are common in the Clinical Examination as it is a relatively common condition and the patients are usually stable. They may pre or post repair.



Pulmonary stenosis

Overriding Aorta

Right Ventricular Hypertrophy
1/2500 births
commonest cyanotic congenital heart disease

Tetralogy patients present because of either their PS or VSD.
The degree of cyanosis and its age of onset depends on the degree of PS, as the stenotic pulmonary area does not grow normally, exacerbating the problem as the child grows.
Severe cyanosis is rare at birth, but a loud murmur from D1 of life is heard in the pulmonary area. There is a single second heart sound. A small percentage with severe pulmonary stenosis may require a shunt shortly after birth (approx 10%).
Typical ToF patients do not develop heart failure because the PS prevents overcirculation and preserves systemic output.
Rarely the PS is mild and the VSD big. Such patient behave as if they have a VSD. The pulmonary stenosis protects against pulmonary hypertension.

Most children are managed conservatively at birth with the plan to perform corrective surgery at approx 9-18 months.
Prior to repair patients suffer hypercyanotic spells which is thought to be the result of infundibular spasms. It can be precipitated by physical activity and is often relieved by squatting, which obstructs the femoral arteries and thus obstructs LV output, and so encourages blood flow into the lungs.
Severe episodes of “spelling’ may influence the timing of surgery.

(Pre corrective surgery)
Pulmonary murmur
Possible thoracotomy scar for B T shunt (examine for radial pulses)
Possible dysmorphic features

(Post corrective surgery)
Mid line sternotomy scar +/- thoracotomy scar if previously shunted.
Pulmonary stenosis murmur persists despite intervention/repair

ECG – right atrial hypertrophy, right ventricular hypertrophy, right axis deviation
CXR –  boot shaped heart, decreased pulmonary vasculature, a small percentage have a right sided aortic arch

Exam vignette
I examined this 5 year old boy who looks pink and well perfused in room air.
He looks an appropriate height and weight for his age but I would like to confirm this by plotting his height and weight on a centile chart.
On inspection he has a mid line sternotomy scar but no other scars. There are no dysmorphic features or clubbing.
On examination he has a 4/6 ejection systolic murmur loudest in the pulmonary region. The apex was in the 5th intercostal space in the midclavicular line and his chest was clear.
These findings are consistent with an operative repair of a congenital heart defect. The location of the murmur could be consistent with pulmonary stenosis which could be found in the context of Tetralogy of Fallot.

Filed in Cardiovascular
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