Tricuspid Atresia (TA)

Know what feeds the lungs - Before anything else, find out from the echo report and the cardiology notes what supplies pulmonary blood flow: a duct held open with prostaglandin, a modified Blalock-Taussig shunt, flow across a VSD, or a Glenn. That single fact drives the whole plan.

Keep the prostaglandin running - In the cyanotic neonate with critical pulmonary stenosis, pulmonary atresia, or a very small VSD, pulmonary flow is ductal-dependent and prostaglandin is what is keeping the child alive. Do not let the infusion lapse during transport or a line change.

Saturation reflects flow balance - All the mixing happens in the left atrium, so systemic saturation tracks the ratio of pulmonary to systemic venous return. A falling number usually means the flow balance has shifted, not that you have an airway problem.

Debubble everything - The right-to-left atrial shunt is obligate, so air in a line has a direct path to the coronary and cerebral circulation. Clear every line and stopcock before it goes near the patient.

Confirm the anatomy yourself - Echocardiography is diagnostic: absent flow across the tricuspid valve on color Doppler, with a dominant left ventricle beside a small right. The ECG carries a characteristic left superior axis (QRS -30 to -90) with diminished right ventricular forces, and the chest film shows decreased pulmonary vascular markings when flow is limited.

Restrictive atrial septum - If the atrial communication is too small it chokes the obligate right-to-left flow and the child stays profoundly hypoxemic. The fix is a balloon atrial septostomy in the cath lab, not more oxygen.

The pink patient - With a large VSD and no pulmonary stenosis these children are not blue. They arrive tachypneic, tachycardic and hepatomegalic, feeding poorly and failing to grow, usually on diuretics. That is pulmonary overcirculation and heart failure.

Chronic cyanosis leaves a mark - Long-standing hypoxemia drives erythrocytosis and hyperviscosity, with thromboembolism and headaches, plus reduced lung compliance, pulmonary hypertension, renal insufficiency, heart failure and arrhythmias. Keep them hydrated and do not let a long fast concentrate them further.

Mind the shunted arm - A modified Blalock-Taussig shunt is a PTFE graft from the right subclavian artery to the right pulmonary artery, so site the arterial line and the cuff away from it.

Interstage infants are fragile - The window between the first-stage shunt and the Glenn carries the highest mortality of the whole pathway. Shunt thrombosis or stenosis occurs in around 20%, in-hospital mortality after a modified Blalock-Taussig shunt sits near 12%, and necrotizing enterocolitis and stroke are not rare. A shunted infant booked for a minor non-cardiac case is not a routine patient.

Know the palliation stage - Stage one is a systemic-to-pulmonary shunt or a pulmonary artery band. Stage two is the bidirectional Glenn or hemi-Fontan at about six months, after which upper body venous pressure drives pulmonary flow. Stage three is the Fontan at two to three years, with the entire systemic venous return flowing passively to the lungs. See the Fontan Circulation and Single Ventricle entries for the physiology after each.

Look for associated syndromes - Tricuspid atresia has been reported with trisomies, VACTERL and 22q11 deletion, so check whether genetic testing was done before you assume a normal airway and normal kidneys.

Tricuspid atresia (TA) is complete agenesis of the tricuspid valve, so there is no communication between the right atrium and right ventricle and the RV is hypoplastic. All systemic venous return has to cross the atrial septum right-to-left and mix with pulmonary venous blood in the left atrium, leaving the left ventricle as the only functional pumping chamber. Systemic saturation therefore reflects the ratio of pulmonary to systemic venous return.

How much blood reaches the lungs depends on three things: the degree of pulmonary outflow obstruction, whether a VSD is present, and the relationship of the great arteries. With pulmonary atresia or critical stenosis, pulmonary flow is ductal-dependent and the neonate turns blue as the duct closes. Without obstruction, pulmonary overcirculation and heart failure appear as PVR falls. It is the third most common cyanotic congenital heart defect, around 1.2 per 10,000 live births.