Tetralogy of Fallot

Published on 07/06/2015 by admin

Filed under Neonatal - Perinatal Medicine

Last modified 07/06/2015

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7 Tetralogy of Fallot

I. CASE

A 43-year-old white woman, gravida 2, para 1+0, was referred at 18 weeks’ gestation to an obstetrician for an abnormal cardiac axis on four-chamber view assessment and echogenic focus in the heart.

D. Fetal management and counseling

1. Management: Diagnosis of tetralogy of Fallot (TOF) should prompt referral for the following:

a. Thorough anatomic examination by ultrasound.

b. Amniocentesis.

2. Follow-up.

a. Serial antenatal studies were made at 6-week intervals.

    (1) Growth of pulmonary arteries (Fig. 7-2), branch pulmonary artery hypoplasia, or discontinuity of the branch pulmonary arteries are assessed.

b. If a significant gradient develops through either the VSD or the RVOT with high blood velocities, restriction of the VSD should be excluded.

c. Development of hydrops fetalis is uncommon in fetal TOF unless there is a chromosomal abnormality (not related to structural heart defect) or restriction of the VSD.

d. Congestive heart failure (CHF) can develop with:

F. Neonatal management

1. Overview.

a. Cyanotic TOF.

b. Classic TOF with pulmonary stenosis.

2. Medical.

a. Hypoxic spells should be recognized and treated appropriately.

b. Oral propranolol 2 to 4 mg/kg per day may be used to prevent hypoxic spells and delay corrective surgery.

3. Surgical.

a. Palliation: In infants with severe RV outflow obstruction and cyanosis or uncontrollable hypoxic spells in whom corrective surgery cannot be performed, palliation in the form of a modified Blalock–Taussig shunt may be created using a Gortex tube to anastomose the subclavian artery or brachiocephalic artery and the ipsilateral pulmonary artery.

b. Correction.

II. YOUR HANDY REFERENCE

A. Tetralogy of Fallot (Figs. 7-4 and 7-5)

1. Prevalence.

a. TOF accounts for 10% of all congenital heart disease. It is the most common form of cyanotic heart disease beyond infancy.

b. TOF is one of the more commonly encountered forms of heart disease in the fetus, and in one series it is the third most commonly identified form of structural heart disease. This could be due to the very common occurrence of aneuploidy and extracardiac structural pathology rather than recognition of the pathology at routine obstetrics assessment.

c. Classic TOF can be missed if echocardiographic examination of the fetal heart is confined to the four-chamber view, because an abnormal four-chamber view is rarely observed in this condition. One might see an abnormal four-chamber view in tetralogy with absent pulmonary valve, with mitral valve obstruction, or with restrictive VSD, all of which are less common than the classic form of TOF.

d. Allan and Sharland (1992) studied a total of 125 cases of TOF diagnosed prenatally. They found:

2. Outcome.

a. Two studies (Berning and colleagues [1996] and Hornberger and colleagues [1999]) have shown that perinatal mortality may be as high as 35% to 75%.

b. The perinatal outcome of fetal TOF is worse than that observed for postnatally identified TOF. The possible explanation is the relatively high incidence of aneuploidy and extracardiac anomalies.

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