Coarctation of the Aorta

Published on 07/06/2015 by admin

Filed under Neonatal - Perinatal Medicine

Last modified 07/06/2015

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14 Coarctation of the Aorta

I. CASE

A 28-year-old white woman, gravida 2, para 1+0, was referred at 22 weeks’ gestation by the obstetrician for ventricular disproportion (right ventricle [RV] larger than left ventricle [LV] for gestation).

D. Fetal management and counseling

1. Ultrasound plus amniocentesis with karyotyping for chromosomal anomalies.

a. Trisomies.

b. Turner’s syndrome (XO).

c. Fluorescent in situ hybridization (FISH) screen for chromosome 22q11 microdeletion.

2. Follow-up includes serial antenatal fetal echocardiography studies at 4-week intervals.

a. Size and function of the LV (apex forming).

b. Diameters of the mitral and aortic valves and the presence of subaortic stenosis. Assessment of valve morphology might become easier later in gestation.

c. Size of the transverse aortic arch compared to the ductus.

d. Size and direction of flow across the foramen ovale. Right-to-left flow is normal in the fetus.

e. Size and direction of flow through the distal aortic arch.

f. The patency of the ductus arteriosus. Any constriction of the ductus in late gestation could lead to heart failure and fetal death.

g. The flow pattern in the pulmonary veins, especially diastolic a wave reversal as an indirect measure of increased pressure in the LA.

h. Missed ventricular septal defect (VSD), which is common in the context of aortic CoA.

i. Development of heart failure (rare).

F. Neonatal management

1. Medical.

a. Following delivery of a baby with a prenatal diagnosis of probable CoA, prostaglandin E1 (PGE1) may be initiated if the coarctation is clearly more severe, with significant arch hypoplasia, or if there is a concern that the left heart size may be borderline, particularly if there is retrograde distal arch flow.

b. Otherwise, many cases of prenatally diagnosed CoA might not be ductus arteriosus dependent and may not require surgical correction in the neonatal period.

c. Lack of blood pressure differences while the ductus arteriosus is still patent is the norm because the ductus arteriosus may be providing critical blood flow to the lower body beyond the level of the coarctation.

d. The hyperoxia test should be performed in either case because it can provide useful physiologic data that can help in appropriately managing the infant.

e. In critical neonatal CoA, the ductus arteriosus often supplies blood flow to the distal arch. The hyperoxia test would in such a state reveal a normal Pao2 (>250 mm Hg) in the preductal area, whereas the postductal area will fail the hyperoxia test as a result of right-to-left shunting through the ductus arteriosus. Occasionally, where there is a discrete coarctation, the baby passes preductal and postductal hyperoxia tests.

f. The two-dimensional echocardiogram shows the site and extent of coarctation. The Doppler examination reveals a disturbed flow distal to the coarctation and signs of delayed emptying in the proximal descending aorta, with continuous flow through the distal arch beginning at the most proximal point of significant arch hypoplasia or obstruction. In the presence of a patent ductus, there is usually no gradient across the coarctation.

g. In borderline situations, or when the infant passes the hyperoxia test and there is still suspicion of coarctation, the ductus could be allowed to close while the vital signs and blood pressures are monitored in the intensive care unit, with follow-up echocardiography to confirm the diagnosis. Ductal constriction can result in a discrete shelf’s evolving at the site of the distal arch where the ductus joins the aorta. This type of coarctation can continue to evolve even weeks to months beyond the neonatal period.

2. Surgical.

a. The surgical procedure of choice varies from institution to institution.

b. The appropriate surgical procedure also is determined by the type of coarctation, whether there is significant proximal arch hypoplasia or only a discrete contraductal shelf.

c. Transcatheter intervention.

d. Balloon angioplasty or stenting is the treatment of choice for recurrent coarctation, and in some institutions it is used more routinely for discrete native coarctation identified in older infants and children.