Congenital Heart Disease: Newborn Stabilization & Murmurs

Screening and the cyanotic newborn

Why screen. Critical congenital heart disease can look normal while the ductus arteriosus is open; pulse oximetry finds hypoxemia before the duct closes.

The screen misses many left-sided obstructive lesions, above all coarctation of the aorta. A passed screen never replaces feeling the femoral pulses.

Hyperoxia test. Give 100% oxygen for about 10 minutes and measure PaO2 from the right radial artery (preductal). In lung disease, oxygen crosses ventilated alveoli and PaO2 climbs above 150 mm Hg. With a fixed right-to-left intracardiac shunt, PaO2 stays below 150 (often below 100) because the shunted blood never reaches the lungs.

Reading cyanosis. Acrocyanosis of the hands and feet is normal in the first days; blue lips and tongue are not. Cyanosis with little respiratory distress favors the heart; marked distress favors the lungs. Methemoglobinemia gives a low saturation with a normal PaO2, and severe persistent pulmonary hypertension of the newborn can also fail the hyperoxia test, so echocardiography settles the question.

Ductal-dependent lesions and prostaglandin E1

Timing. These infants often look well at birth and decompensate as the duct constricts, typically on days 2–7, occasionally later in the first weeks, often after discharge.

Left-sided obstruction. Hypoplastic left heart syndrome (HLHS) and critical coarctation or aortic stenosis present as a previously well neonate who becomes gray and mottled, with tachypnea, weak or absent femoral pulses, hepatomegaly, and lactic acidosis. In coarctation, arm blood pressure exceeds leg pressure, and foot SpO2 may be lower than right-hand SpO2 because deoxygenated blood reaches the descending aorta through the duct. Coarctation is associated with Turner syndrome and bicuspid aortic valve.

A gray, mottled neonate in the first 2 weeks may have sepsis, a ductal-dependent lesion, salt-wasting congenital adrenal hyperplasia, or an inborn error of metabolism. Draw cultures and give antibiotics, and start PGE1 when pulses are weak or cyanosis persists; never wait for the echocardiogram.

Prostaglandin E1 (alprostadil). A continuous infusion relaxes ductal smooth muscle and reopens or maintains the duct. It is started on clinical suspicion. Apnea is the key adverse effect, so be ready to intubate, especially in small infants; fever, flushing, and hypotension also occur, and prolonged use causes cortical hyperostosis and gastric outlet obstruction. Indomethacin and ibuprofen have the opposite effect and are used to close a symptomatic PDA in preterm infants.

Oxygen caution in HLHS. When the duct supplies the body, high inspired oxygen lowers pulmonary vascular resistance and diverts flow to the lungs at the expense of the systemic circulation; saturations around 75–85% are acceptable. HLHS then requires staged palliation (Norwood, Glenn, Fontan) or transplant.

Transposition of the great arteries (TGA). The aorta arises from the right ventricle and the pulmonary artery from the left, creating two parallel circulations. Profound cyanosis appears within hours of birth with little distress, a single loud S2, and an egg-on-a-string heart on X-ray; maternal diabetes is a risk factor. Survival depends on mixing through a patent foramen ovale, PDA, or VSD. Start PGE1; if the atrial septum is restrictive, perform balloon atrial septostomy (Rashkind). The definitive arterial switch follows in the first weeks of life.

Tetralogy of Fallot and hypercyanotic spells

Anatomy and findings. VSD, overriding aorta, right ventricular outflow tract (RVOT) obstruction, and right ventricular hypertrophy. The degree of RVOT obstruction sets the degree of cyanosis. The harsh systolic ejection murmur at the left upper sternal border comes from the RVOT obstruction, not the VSD. X-ray shows a boot-shaped heart with reduced pulmonary markings. Tetralogy is associated with 22q11.2 deletion. Complete surgical repair is performed in infancy.

Spell physiology. Crying, feeding, dehydration, or agitation tightens the infundibulum and lowers systemic vascular resistance (SVR), so more blood crosses the VSD right to left. The infant becomes hyperpneic and deeply cyanotic, and the murmur softens or vanishes because less blood crosses the obstructed outflow tract. Unrepaired older children instinctively squat, which raises SVR.

Avoid inotropes, which worsen infundibular spasm, and vasodilators, which lower SVR and increase the shunt. A spell is an indication for timely surgical repair.

Left-to-right shunts and Eisenmenger syndrome

VSD. The most common congenital heart defect; its murmur may be inaudible in the first days while pulmonary resistance is high. Small restrictive defects are loud but benign (the smaller the defect, the louder the murmur), whereas a large defect with pulmonary hypertension may be quiet with a loud P2.

Large VSD and heart failure. As pulmonary vascular resistance falls over the first 4–8 weeks, a large VSD floods the lungs: tachypnea, sweating and tiring during feeds, poor weight gain, and hepatomegaly, sometimes with an apical diastolic rumble from increased mitral inflow. Treat with furosemide and calorie-dense feeds (with or without an ACE inhibitor), then close the defect surgically in infancy before pulmonary vascular disease becomes irreversible.

ASD. The fixed split S2 reflects a constant right-sided volume load; the systolic ejection murmur comes from extra flow across the pulmonary valve, not from blood crossing the low-pressure atrial defect. Larger defects are closed, usually by transcatheter device, to prevent right ventricular dilation, atrial arrhythmias, and pulmonary hypertension in adulthood.

PDA. Risk factors are prematurity, congenital rubella, and high altitude. The rubella triad is PDA (or pulmonary artery stenosis), cataracts, and sensorineural deafness.

Endocarditis prophylaxis is not indicated for an unrepaired simple VSD, ASD, or PDA; it is reserved for groups such as unrepaired cyanotic disease, prosthetic valves or material, and prior endocarditis.

Eisenmenger syndrome. A large shunt left unrepaired remodels the pulmonary arterioles until pulmonary pressure exceeds systemic pressure and flow reverses. Late cyanosis, clubbing, polycythemia, and a loud P2 follow. With a PDA, deoxygenated blood enters the aorta beyond the left subclavian artery, producing differential cyanosis: blue, clubbed toes with pink fingers. Closing the defect is then contraindicated; care relies on pulmonary vasodilators and, ultimately, transplant. Pregnancy carries a high maternal mortality.

Innocent versus pathologic murmurs

Innocent profile. Soft (grade ≤2/6), systolic (the venous hum is the only innocent murmur with a diastolic component), short, with a normal S2, no click or thrill, and variation with position, in an asymptomatic child who is growing well. These murmurs need no testing, only reassurance.

Venous hum versus PDA. Both are continuous, but a PDA persists when the child lies down and comes with bounding pulses.

Red flags that call for an echocardiogram and pediatric cardiology referral:

• Any diastolic murmur (venous hum excepted) or a holosystolic murmur
• Grade ≥3/6, a palpable thrill, or a harsh quality
• Abnormal S2 (fixed split, single, or loud P2) or an ejection click
• Weak, delayed, or bounding pulses
• Symptoms: poor feeding, failure to thrive, syncope, exertional chest pain

Hypertrophic cardiomyopathy is the systolic murmur that gets louder on standing or with Valsalva, the opposite of a Still's murmur.