Rapid Review·Cardiovascular
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Congenital Heart Disease
T1Must knowPersistent Pulmonary Hypertension of the Newborn
Focus on
The lungs never let go of fetal life: pulmonary resistance stays high after birth, so blood keeps shunting right to left through the ductus and foramen ovale and the baby is hypoxemic with a structurally normal heart. Post-term, meconium, low Apgars, a preductal saturation higher than postductal. Oxygen, gentle ventilation, correct the acidosis, inhaled nitric oxide, ECMO when that fails.
Key takeaways
What it is and who gets it
Persistent pulmonary hypertension of the newborn
pulmonary vascular resistance stays abnormally high after birth, so blood keeps shunting right-to-left through the ductus and foramen ovale, bypassing the lungs, in a heart with no structural defect.The ductal gradient
the ductal shunt produces a pre- and postductal oxygenation gradient; the preductal (right hand) saturation is higher than the postductal.Risk factors
meconium aspiration syndrome (the classic), neonatal pneumonia and sepsis, perinatal asphyxia, lung hypoplasia from congenital diaphragmatic hernia, post-term delivery.- Maternal non-steroidal anti-inflammatory or serotonin-reuptake-inhibitor use in late pregnancy.
Clinical features and diagnosis
Within 24 hours of birth
low Apgar scores, cyanosis and respiratory distress (tachypnea, grunting) out of proportion to the film, labile oxygenation with handling or crying.Heart findings
a prominent (loud, single) S2 from the pulmonary hypertension, a right-ventricular heave, a tricuspid regurgitation murmur; poor perfusion in severe cases.Differential cyanosis
preductal saturation higher than postductal by over 5 to 10 percent.Initial tests
pre- and postductal pulse oximetry, a blood gas (hypoxemia, acidosis), a chest film (the underlying lung disease, or clear fields in the idiopathic form), a sepsis workup, glucose and calcium.Echocardiography is essential
it excludes structural cyanotic heart disease (which the hyperoxia test cannot separate from severe pulmonary hypertension).- It shows the high pulmonary pressure, right-to-left shunting across the ductus and foramen, a bowed septum, and a normal heart (Approach to Neonatal Cyanosis).
| Persistent pulmonary hypertension | Cyanotic congenital heart disease | Lung disease (respiratory distress syndrome, pneumonia) | |
|---|---|---|---|
| Heart structure | Normal | Abnormal | Normal |
| Pre- and postductal gradient | Preductal higher (ductal right-to-left shunt) | Usually equal (reversed in transposition) | Equal |
| Response to 100 percent oxygen | Poor and labile | Poor and fixed | Good |
| Chest film | The underlying cause, or clear | Lesion-specific silhouette | Parenchymal disease |
| Echocardiography | Pulmonary hypertension, shunting through the duct and foramen, normal anatomy | A structural defect | Normal |
| Key therapy | Oxygen, ventilation, inhaled nitric oxide, extracorporeal support | Prostaglandin E1, surgery | Surfactant, positive pressure, antibiotics |
Management
Supportive care
treat the cause (antibiotics, surfactant, surgery for the hernia after stabilization), minimal handling and sedation, normothermia, normal glucose and calcium.Correct acidosis and hold the systemic pressure
acidosis constricts pulmonary vessels; volume and inotropes keep the systemic pressure up, because a higher systemic pressure reduces the right-to-left shunt.Oxygen
the most potent pulmonary vasodilator, with gentle mechanical ventilation.Inhaled nitric oxide for severe cases
lowers pulmonary artery pressure; sildenafil or milrinone as adjuncts.Extracorporeal membrane oxygenation (ECMO) as the last resort
for infants failing maximal therapy.Complications
Long-term neurodevelopmental problems
developmental delay, motor deficits and hearing impairment after severe disease; schedule hearing screening and developmental follow-up.Acute
right-ventricular failure and air leak.A post-term newborn with meconium aspiration is cyanotic and labile within hours; the right-hand saturation is 95 percent and the foot 82 percent, and echo shows a structurally normal heart with high pulmonary pressure. What is the diagnosis, and what is the key therapy for severe cases?
Persistent pulmonary hypertension of the newborn (right-to-left ductal shunt: preductal higher than postductal). Treat the cause, give oxygen with gentle ventilation, correct acidosis and support systemic pressure; inhaled nitric oxide for severe cases, ECMO as the last resort. Do not close the ductus.
How it's tested
A 42-week infant born through thick meconium has Apgars of 4 and 6 and is cyanotic at 6 hours with a saturation of 85% in the right hand and 72% in the foot; echo shows a normal heart with right-to-left flow through the ductus and foramen: PPHN — oxygen, gentle ventilation, correct acidosis, sedation, then inhaled nitric oxide; ECMO if refractory.
Why must an echocardiogram be done before labeling it PPHN: the hyperoxia test fails in both PPHN and cyanotic congenital heart disease — only echo excludes a structural lesion.
Same infant with an oxygenation index of 45 despite nitric oxide and maximal ventilation: ECMO.
A newborn with PPHN and a scaphoid abdomen with bowel sounds in the chest: congenital diaphragmatic hernia — pulmonary hypoplasia; stabilize (iNO often fails), then surgical repair.
What explains the preductal–postductal saturation gradient: deoxygenated blood crossing the ductus into the descending aorta below the right subclavian.
Go deeper
Related Step 2 pages: Approach to Neonatal Cyanosis, Fetal Circulation & Transition at Birth, Patent Ductus Arteriosus, Transposition of the Great Arteries, Approach to Congenital Heart Disease, Cor Pulmonale
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