A 5-day-old girl is being evaluated for fussiness, poor feeding, and decreased urine output that began this morning. She was born to a 31-year-old woman via an uncomplicated vaginal delivery at home. During the first 2 days of life, the infant had latched and fed well and made an adequate number of wet diapers. Temperature is 36.4 C (97.5 F), pulse is 170/min, and respirations are 80/min. Blood pressure is 60/40 mm Hg in the right upper extremity and 40/26 mm Hg in the right lower extremity. Femoral pulses are markedly decreased compared to brachial pulses. There is no heart murmur. Bilateral fine rales are present. Laboratory results are as follows:
| Sodium | 137 mEq/L |
| Potassium | 4.1 mEq/L |
| Chloride | 100 mEq/L |
| Bicarbonate | 16 mEq/L |
| Lactic acid | 18 mg/dL (normal: 9-16) |
An x-ray of the chest reveals cardiomegaly with pulmonary edema. Immediate therapy is aimed at increasing which of the following?
Coarctation of the aorta | |
Pathology |
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Clinical features |
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Complications |
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Treatment |
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*After closure of ductus arteriosus. BP = blood pressure. | |
This neonate has pulmonary edema and cardiomegaly in addition to decreased urine output and lactic acidosis, which are findings concerning for acute heart failure complicated by cardiogenic shock (eg, hypoperfusion). Given this patient's lower extremity hypotension and poor femoral pulses relative to upper extremity blood pressure and brachial pulses, the most likely cause is severe aortic coarctation manifesting after closure of the ductus arteriosus (DA).
In utero, deoxygenated blood flows from the right side of the heart to the placenta for oxygenation via the DA and descending aorta. After birth, the DA begins to close as blood flows to the lungs for oxygenation due to decreased pulmonary vascular resistance and increased systemic vascular resistance (SVR).
In aortic coarctation, the DA initially provides a route for blood to supply the descending aorta. However, upon DA closure (usually within days after delivery), blood delivered to distal tissues through a severely narrowed aorta alone is inadequate, causing poor distal perfusion. In addition, increased left ventricular afterload due to aortic coarctation can lead to congestive heart failure (eg, poor feeding, pulmonary edema, cardiomegaly) from pressure overload.
Patients with suspected severe aortic coarctation should immediately receive prostaglandin E1 to maintain patency of the DA. This allows blood from the pulmonary artery to supply the descending aorta (right-to-left shunting), restoring distal perfusion.
(Choice A) Tetralogy of Fallot would cause cyanosis immediately after birth when the associated pulmonary stenosis is severe. Patency of the DA is required to provide blood flow to the pulmonary circulation from the aorta (ie, left-to-right shunt).
(Choices B and C) Transposition of the great arteries results in parallel circuits of systemic and pulmonary blood flow, typically causing cyanosis immediately after birth. This condition requires the presence of a shunt (eg, DA) for both left-to-right and right-to-left mixing of blood to provide pulmonary perfusion and systemic oxygenation.
(Choice E) Increasing SVR (eg, norepinephrine) in aortic coarctation would further increase left ventricular afterload, worsening cardiac output and tissue perfusion.
Educational objective:
Aortic coarctation can present with acute heart failure and cardiogenic shock upon closure of the ductus arteriosus. Administration of prostaglandin E1 maintains ductal patency, which restores systemic blood flow by shunting blood from the pulmonary artery to the aorta (right-to-left).