Chapter 5: Cardiology

CONGENITAL HEART DISEASE: NEWBORN SCREENING FOR CONGENITAL HEART DISEASE (CHD)

Goal is to identify critical congenital heart defects after birth but before hospital discharge and before signs of illness develop.

Epidemiology

• Critical congenital heart defects occur in 1 of 4 infants born with any CHD.

• Screening is most likely to detect the following critical congenital heart defects: hypoplastic left heart syndrome, pulmonary atresia, tetralogy of Fallot, total anomalous pulmonary venous return, transposition of the great arteries, tricuspid atresia, and truncus arteriosus.

Diagnostics

• Perform pulse oximetry screening (also see https://www.cdc.gov/ncbddd/heartdefects/hcp.html).

  • ✓ Pulse oximetry complements but does not replace thorough history and physical exam.

  • ✓ Perform at 24–48 hours of age (to minimize false positive results) or just before discharge if age <24 hours at discharge.

  • ✓ Apply pulse oximeter to right hand and one foot.

• Failed screening definition

  • ✓ O₂ saturation <90%; OR

  • ✓ O₂ saturation <95% in right hand and foot on 3 measurements, each separated by 1 hour; OR

  • ✓ >3% absolute difference in O₂ saturation between right and foot on three measurements, each separated by 1 hour

Management

• Any infant who fails screening requires evaluation to identify cause of hypoxemia.

  • ✓ Consider echocardiography unless a reversible cause is identified and treated appropriately.

  • ✓ Consider cardiology consultation.

CONGENITAL HEART DISEASE—CYANOTIC LESIONS WITH LIMITED PULMONARY CIRCULATION: TRICUSPID ATRESIA

A form of cyanotic CHD in which there is no outlet from the right atrium (RA) to the right ventricle (RV) and the RV is hypoplastic. The entire systemic blood flow enters the left atrium (LA) via a patent foramen ovale (PFO) or an atrial septal defect (ASD).

Epidemiology

• 1% of congenital heart defects

Pathophysiology

• A ventricular septal defect (VSD) is usually present. The pathophysiology in tricuspid atresia depends on whether the great arteries are normally-aligned or transposed and on whether there is any obstruction to pulmonary or systemic blood flow.

Clinical Manifestations

• With pulmonary atresia or severe pulmonary stenosis, presentation is within 24–48 hours; most patients present by 2 months of age with cyanosis and tachypnea.

• Occasionally, patients with transposition of the great arteries (TGA) develop pulmonary overcirculation and present with CHF.

• Rarely, older patients present with cyanosis, dyspnea on exertion, polycythemia, and easy fatigability.

• On exam: May have holosystolic murmur at left sternal border or ejection systolic murmur at left upper sternal border; single S2; increased left ventricle (LV) impulse

Diagnostics

• Chest x-ray: May show pulmonary undercirculation or overcirculation

• ECG: Left-axis deviation, RA enlargement, LV hypertrophy

• Echocardiography: Usually sufficient to delineate anatomic features

Management

Medical