Hypoplastic Right Heart Syndrome (HRHS)
HRHS is characterized by a small right ventricle, with pulmonary valve atresia with intact ventricular septum.
Fig 1
Incidence: Rare, accounting for 1.7% of structural heart defects.
Sonographic findings:
Fig 2, Fig 3, Fig 4
- Small right ventricle on the FCV.
- Atresia of the pulmonic valve.
- Intact ventricular septum.
- The tricuspid valve may be small but patent thus distinguishing HRHS from triscuspid atresia.
- Doppler imaging usually shows minimal or no flow across the tricuspid valve or sometimes tricuspid valve regurgitation, with reversal of flow in the ductus arteriosus/pulmonary artery.
- An atrial septal defect is usually present.
Associations: Other defects of the heart, not related to extracardiac anomaly or chromosome abnormalities.
Management: Careful prenatal and postnatal search for associated anomalies is required. Termination of pregnancy should be considered before viability.
Prognosis: Overall poor, but better than that of HLHS. However, the mortality rate is still high. Surgical correction is appropriate in some selected cases.
Fig 1: Schematic drawing of tricuspid atresia; Note small right atrium (RA) and right ventricle (RV) and VSD (LA = left atrium, LV = left ventricle)
Fig 2: Hypoplastic right heart syndrome Very small right ventricle (*)
Fig 3: Hypoplastic right heart syndrome Left : Four-chamber view: small right ventricle (*) with common atrium
Fig 4: Hypoplastic right heart syndrome Short-axis view: small pulmonary trunk (arrow) compared to aorta (*) with large atrium
Video clips of Hypoplastic right heart syndrome
Hypoplastic right heart: Long-axis view: small right ventricle and small pulmonary trunk (*) compared with ascending aorta (arrow) (arrowhead = spine)
Triscuspid atresia: Four-chamber view: extremely small right ventricle (*) with VSD, thickened and echogenic tricuspid valve (arrowhead = spine)
Tricuspid atresia: Four-chamber view: small right ventricle (*), with thickened and echogenic tricuspid valve (IVS=interventricular septum)
Tricuspid atresia: Four-chamber view: small right ventricle (arrow) with interventricular septum defect (*),arrowhead = spine
Tricuspid atresia: Four-chamber view: small right ventricle (*), with thickened and echogenic tricuspid valve (IVS=interventricular septum arrowhead = spine)