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Persistent Pulmonary Hypertension of the Newborn (PPHN) is a serious neonatal condition where pulmonary vascular resistance (PVR) remains abnormally high after birth, resulting in right-to-left shunting through fetal circulatory pathways (ductus arteriosus, foramen ovale) and hypoxemic respiratory failure, despite structurally normal lungs.
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https://www.youtube.com/watch?v=WkBsat8Qh1w
Normal Transition at Birth vs. PPHN:
| Physiology | Mechanism |
|---|---|
| Pulmonary vascular resistance (PVR) | • Normal: PVR falls after first breaths → ↑ pulmonary flow |
| • PPHN: PVR remains high → blood shunts away from lungs (R→L shunting) | |
| Fetal circulation | • Normal: Closure of ductus arteriosus and foramen ovale |
| • PPHN: Persistent fetal circulation with R→L shunt via PDA or PFO |
| Type | Cause |
|---|---|
| 1. Maladaptation | |
| (most common) | • Perinatal asphyxia |
| • Meconium aspiration syndrome (MAS) | |
| • Sepsis | |
| • RDS | |
| • Pneumonia | |
| 2. Maldevelopment | • Pulmonary hypoplasia (e.g., congenital diaphragmatic hernia, renal agenesis) |
| • Oligohydramnios | |
| 3. Underdevelopment | • Congenital heart disease with pulmonary outflow obstruction |
| • Alveolar capillary dysplasia (rare, lethal) |
| Modality | Findings |
|---|---|
| CXR | Often normal or reflects underlying condition (e.g., MAS, RDS, pneumonia) |
| Echo | *Diagnostic modality of choice: |
| *****• Elevated pulmonary pressures | |
| • Right-to-left shunting across PDA or PFO | |
| • Normal cardiac anatomy (to exclude CHD) | |
| • Tricuspid regurgitation jet velocity > 40 mmHg | |
| • Flattened or D-shaped interventricular septum | |
| • Right atrial and ventricular dilation |