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ESSENTIALS OF DIAGNOSIS

  • Five features are characteristic:

    • – VSD.

    • – Concentric RVH.

    • – RV outflow obstruction due to infundibular stenosis.

    • – Septal overriding of the aorta in half the patients.

    • – A right-sided aortic arch in 25%.

  • Most adult patients with tetralogy of Fallot have been operated on, usually with an RV outflow patch and VSD closure. If patch overrides the pulmonary valve, pulmonary regurgitation is common.

  • Physical examination may be deceptive after classic tetralogy repair, with severe pulmonary valve regurgitation difficult to detect.

  • Echocardiography/Doppler may underestimate significant pulmonary valve regurgitation. Be wary if the RV is enlarged or enlarging.

  • Arrhythmias are common; periodic ambulatory monitoring is recommended.

  • Serious arrhythmias and sudden death may occur if the QRS is wide or the RV becomes quite large, or both.

GENERAL CONSIDERATIONS

Patients with tetralogy of Fallot have a VSD, RV infundibular stenosis, RVH, and a dilated aorta (in about half of patients it overrides the septum). If there is an associated ASD, the complex is referred to as pentalogy of Fallot. The basic lesion is a large VSD with migration of the septum above the VSD and under the pulmonary valve. There may or may not be pulmonary valve stenosis as well, usually due to a bicuspid pulmonary valve or RV outflow hypoplasia. The aorta can be quite enlarged and aortic regurgitation may occur. If more than 50% of the aorta overrides the ventricular septum, it is called double outlet RV. Two vascular abnormalities are common: a right-sided aortic arch (in 25%) and an anomalous left anterior descending coronary artery from the right cusp (7–9%). The latter is important in that surgical correction must avoid injuring the coronary artery when repairing the RV outflow obstruction. Pulmonary branch stenosis may also be present.

Most adult patients have undergone prior surgery. If significant RV outflow obstruction is present in the neonatal period, a systemic arterial to pulmonary artery shunt may be the initial surgical procedure to improve pulmonary blood flow, though many infants undergo repair without this first step. Most adults will have had this initial palliative repair, however. The palliative procedure enables blood to reach the underperfused lung either by directly attaching one of the subclavian arteries to a main PA branch (classic Blalock shunt) or, more likely, by creating a conduit between the two (modified Blalock shunt). Other types of systemic to pulmonary shunts no longer in use include a window between the right PA and the aorta (Waterston-Cooley shunt) or a window between the left PA and the descending aorta (Potts shunt). In the adult, there may be a reduced upper extremity pulse on the side used for the classic Blalock procedure. Total repair of the tetralogy of Fallot generally includes a VSD patch and usually an enlarging RV outflow tract patch, as well as a take-down of any prior arterial-pulmonary artery shunt. If the RV outflow tract patch ...

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