Tricuspid Valve Dysplasia

Tricuspid valve dysplasia is a congenital malformation of the tricuspid valve apparatus. The leaflets are thickened, nodular and redundant with restricted motion, the chordae are short or absent, the papillary muscles are abnormal and the annulus is dilated.

The leaflet attachments are at the normal annular level, which distinguishes it from Ebstein anomaly. It occurs in isolation or with pulmonary stenosis or atresia with intact ventricular septum, other right heart lesions, chromosomal abnormalities (trisomies 13, 18 and 21), and maternal lithium exposure. It is rare.

Severe disease is recognised in the foetus or neonate with massive tricuspid regurgitation, right atrial enlargement, cardiomegaly and pulmonary hypoplasia from lung compression.

Pathophysiology. Severe regurgitation increases right atrial and right ventricular volume.

In the neonate, high pulmonary vascular resistance prevents right ventricular ejection through the pulmonary valve (functional pulmonary atresia), so pulmonary blood flow is ductus dependent and there is right-to-left shunting through the foramen ovale. As pulmonary resistance falls over days, forward flow improves.

Later, chronic volume overload causes right atrial and right ventricular dilatation, atrial tachyarrhythmia, systemic venous congestion (hepatomegaly, ascites, oedema) and low output. Mild forms are tolerated for decades.

• Foetus and neonate: cardiomegaly on foetal echocardiography, hydrops, cyanosis, heart failure, respiratory distress from pulmonary hypoplasia, and a holosystolic murmur at the lower left sternal edge that increases with inspiration.
• Child and adult: fatigue, exertional dyspnoea, ankle swelling, ascites, palpitations from atrial flutter or fibrillation, prominent jugular venous pulsation with large v waves, pulsatile liver, and right ventricular heave.

Red flags.

• Neonatal cyanosis with massive regurgitation or functional pulmonary atresia
• Foetal hydrops or severe cardiomegaly
• Refractory right heart failure
• New atrial flutter or fibrillation
• Falling right ventricular function
• Paradoxical embolism or cyanosis in an adult

• Echocardiography: thickened, nodular leaflets with restricted motion, short or absent chordae, dilated annulus, leaflet attachments at the normal annular level (without apical displacement of the septal leaflet), severe regurgitant jet, right atrial and right ventricular size, pulmonary valve forward flow, and right-to-left atrial shunt. Severe regurgitation is a vena contracta of 7 mm or more, an effective regurgitant orifice area of 40 mm2 or more, a regurgitant volume of 45 mL or more, systolic hepatic vein flow reversal, and a dense triangular continuous wave signal with early peak.
• Foetal echocardiography: severity of regurgitation, cardiothoracic ratio, ductal flow direction, pulmonary valve function and associated lesions.
• Chest X-ray: wall-to-wall cardiomegaly in severe neonatal disease.
• ECG: right atrial enlargement with tall P waves, and right bundle branch block.
• Cardiac MRI: right ventricular volumes, ejection fraction and regurgitant volume in older patients.
• Ambulatory ECG: atrial arrhythmia.
• Blood tests: liver function, renal function, NT-proBNP in right heart failure.

Differential diagnosis.

• Ebstein anomaly (apical displacement of the septal leaflet by 8 mm/m2 body surface area or more, sail like anterior leaflet)
• Uhl anomaly
• Pulmonary atresia with intact ventricular septum
• Secondary functional regurgitation from pulmonary hypertension or right ventricular dilatation
• Endocarditis
• Carcinoid heart disease
• Rheumatic or myxomatous valve disease
• Pacing or defibrillator lead induced regurgitation
• Traumatic flail leaflet
• Arrhythmogenic right ventricular cardiomyopathy

Neonate with severe disease and functional pulmonary atresia.

• Prostaglandin E1 (alprostadil) 0.05 to 0.1 microgram/kg/min intravenously to keep the ductus open, reduced to the lowest effective rate (usually 0.01 to 0.05 microgram/kg/min), maximum 0.4 microgram/kg/min. Be ready to ventilate because of apnoea. Monitor temperature, blood pressure and heart rate. Prolonged use causes gastric outlet obstruction and cortical hyperostosis.
• Inhaled nitric oxide 20 ppm (maximum 40 ppm) to lower pulmonary vascular resistance and encourage forward flow, with methaemoglobin monitoring. Ventilate with careful pressures, because lung hypoplasia limits tolerance of hyperinflation.
• When forward flow does not establish, surgical options are a systemic-to-pulmonary shunt with tricuspid orifice closure (Starnes procedure) leading to staged single ventricle palliation, valve repair or replacement, or heart transplantation.

Older children and adults.

• Diuretics for congestion: furosemide in adults 40 mg orally once daily in the morning, increased to 80 to 120 mg daily as needed; monitor sodium, potassium and creatinine. Furosemide in infants and children: 0.5 to 1 mg/kg intravenously every 6 to 12 hours, or 1 to 2 mg/kg orally every 6 to 12 hours, maximum 6 mg/kg daily; monitor sodium, potassium, creatinine and weight.
• Spironolactone 25 mg orally once daily, increased to 50 mg once daily; check potassium and creatinine at 1 week and 4 weeks. Withhold at potassium over 5.5 mmol/L and avoid at creatinine clearance under 30 mL/min.
• Atrial flutter or fibrillation: apixaban 5 mg orally twice daily, reduced to 2.5 mg twice daily when at least two of age 80 years or over, weight 60 kg or under and serum creatinine 133 micromol/L or over are present. Also 2.5 mg twice daily at creatinine clearance 15 to 29 mL/min, and avoided under 15 mL/min. Maximum 10 mg daily. Long term. Catheter ablation for flutter in a specialist centre.
• Surgery is indicated for symptoms attributable to regurgitation, progressive right ventricular dilatation or falling right ventricular function, atrial arrhythmia not controlled, cyanosis, or paradoxical embolism. Valve repair (annuloplasty, leaflet augmentation, chordal reconstruction) is preferred when possible. Replacement uses a bioprosthesis, because mechanical valves in the tricuspid position have a high thrombosis rate.
• After a bioprosthesis: warfarin 5 mg orally once daily at the start (2 to 3 mg in older adults, liver impairment or interacting drugs), adjusted to an INR of 2.0 to 3.0, no fixed maximum, for 3 months; INR every 2 to 3 days at the start, weekly until stable, then every 4 to 12 weeks. Then aspirin 75 to 100 mg orally once daily long term.
• Endocarditis prophylaxis only for prosthetic material, previous endocarditis or unrepaired cyanotic disease.

Special groups. Pregnancy is tolerated with mild regurgitation and preserved right ventricular function. Risk rises with severe regurgitation, right ventricular dysfunction or arrhythmia; counsel before conception. Warfarin is avoided in the first trimester and enoxaparin 1 mg/kg subcutaneously every 12 hours with anti-Xa monitoring is used (1 mg/kg once daily at creatinine clearance under 30 mL/min).

Monitoring. Echocardiography every 6 to 12 months in moderate or severe regurgitation, and every 1 to 2 years in mild disease. Cardiac MRI every 2 to 3 years for right ventricular size and function. ECG and ambulatory ECG yearly. Liver function, renal function and NT-proBNP when symptomatic. After surgery, echocardiography at 3 months and then yearly.

Referral and escalation. Refer foetal cases to foetal cardiology and plan delivery at a paediatric cardiac centre. Refer all symptomatic neonates the day of diagnosis. Adults go to a congenital heart disease centre. Escalate urgently for cyanosis, refractory right heart failure or new arrhythmia.