Rapid Review·Cardiovascular
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Congenital Heart Disease
T1Must knowTricuspid Atresia
Focus on
No tricuspid valve, so the right atrium can only empty through an ASD and the lungs are fed only through a VSD or the duct. A cyanotic newborn with a holosystolic murmur, a single S2 and — the giveaway — left axis deviation on an ECG that should show right dominance. Prostaglandin E1, then the single-ventricle pathway ending in the Fontan.
Key takeaways
What it is
Absent tricuspid valve
no flow from the right atrium to the right ventricle, so the right atrium enlarges and the right ventricle is hypoplastic, with underdevelopment of the pulmonary valve or artery.How blood gets through
venous blood can only reach the left atrium through an atrial septal defect (mixing with arterial blood: cyanosis), the right ventricle through a ventricular septal defect, and the lungs through that defect or a ductus, as on the Tricuspid atresia anatomy.Survival needs both an interatrial and an interventricular (or ductal) communication
all have an atrial defect, most a ventricular defect, many a ductus.Association
maternal diabetes.Clinical features
Central cyanosis and respiratory distress within days of birth
worse as the duct closes; diminished peripheral pulses.Jugular venous distension with a prominent a wave
atrial contraction against the atretic valve.The murmur
a holosystolic murmur at the lower left sternal border (flow through the ventricular defect) with a single S2.Diagnosis
Transthoracic echocardiography is confirmatory
absent valve, hypoplastic ventricle, size of the defects, ductal dependence.Electrocardiogram, the classic clue
left axis deviation (the left ventricle is the only working pump, so it hypertrophies) with tall peaked P waves of right atrial enlargement, as on the Tricuspid atresia ECG.Chest film
minimal pulmonary vascular markings without a ventricular defect; increased markings with a large defect (too much flow from the strong left ventricle).| Lesion | Pulmonary markings | Axis | Murmur |
|---|---|---|---|
| Tricuspid atresia | Decreased (unless a large ventricular defect) | Left | Holosystolic, single S2 |
| Tetralogy of Fallot | Decreased | Right | Harsh ejection at the left upper sternal border, single S2 |
| Transposition of the Great Arteries | Increased | Right | None; single loud S2 |
| Total Anomalous Pulmonary Venous Return | Increased (or edema if obstructed) | Right | Soft flow murmur, right ventricular heave |
| Truncus Arteriosus | Increased | Biventricular | Harsh systolic, click, single S2 |
| Ebstein Anomaly | Decreased | Right, tall P waves, pre-excitation | Tricuspid regurgitation, gallop |
Management and complications
Alprostadil (prostaglandin E1)
maintains the ductus for survival; balloon atrial septostomy if the atrial defect is restrictive.Staged single-ventricle surgery
in order.- Blalock-Taussig-Thomas shunt: subclavian to pulmonary artery, in the neonate.
- Bidirectional Glenn: superior vena cava to pulmonary artery, at 4 to 6 months.
- Fontan: inferior vena cava to the pulmonary arteries at 2 to 4 years, so venous blood reaches the lungs without a pump.
Complications
untreated, hypoxemia and death in infancy.- After the Fontan: arrhythmias, thromboembolism, protein-losing enteropathy, Fontan-associated liver disease, exercise limitation.
A 2-day-old is cyanotic with a holosystolic murmur and a single S2; the electrocardiogram shows left axis deviation and tall peaked P waves, and the lungs look under-perfused. What is the lesion, and what is the first drug?
Tricuspid atresia (left axis in a cyanotic newborn, decreased pulmonary markings). Start alprostadil (prostaglandin E1) to keep the ductus open, then staged surgery (shunt, Glenn, Fontan).
How it's tested
A 3-day-old with worsening cyanosis, a holosystolic murmur at the left lower sternal border, a single S2, a chest film with dark lungs, and an ECG showing left axis deviation with tall P waves: tricuspid atresia — prostaglandin E1, echocardiogram, then a Blalock-Taussig-Thomas shunt.
Why does left axis deviation point to this diagnosis: the RV is hypoplastic and the LV dominant, so the electrical axis swings left — a newborn should have a right axis.
How does systemic venous blood reach the lungs when there is no tricuspid valve: RA → ASD → LA → LV → VSD → RV outflow/pulmonary artery, or via the ductus.
A 12-year-old with a Fontan circulation develops edema, low albumin and diarrhea: protein-losing enteropathy — a classic Fontan complication.
A cyanotic newborn with tricuspid atresia and transposition presents with heart failure rather than deep cyanosis: unobstructed pulmonary flow — diuretics and a pulmonary artery band rather than a shunt.
Go deeper
Guidelines: 2018 AHA/ACC Adult Congenital Heart Disease Guideline
Related Step 2 pages: Approach to Neonatal Cyanosis, Hypoplastic Left Heart Syndrome, Approach to Congenital Heart Disease, Fetal Circulation & Transition at Birth, Tetralogy of Fallot, Ebstein Anomaly
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