What is the management of outflow tract abnormalities in individuals with Down syndrome?

Management of Outflow Tract Abnormalities in Individuals with Down Syndrome

Individuals with Down syndrome who have outflow tract abnormalities should receive specialized cardiac care with regular monitoring, with surgical intervention indicated for significant right ventricular outflow tract obstruction (RVOTO) when Doppler peak gradient exceeds 64 mmHg (peak velocity >4m/s). 1

Common Cardiac Abnormalities in Down Syndrome

• Atrioventricular septal defect (AVSD) is the most common cardiac anomaly in Down syndrome 1
• Many patients with Down syndrome have outflow tract abnormalities including right ventricular outflow tract obstruction (RVOTO) and left ventricular outflow tract obstruction 1
• Ventricular septal defects (VSDs) are also common in Down syndrome patients 1, 2
• Tetralogy of Fallot and other conotruncal anomalies can occur in association with AVSD in Down syndrome 1

Diagnostic Evaluation

• Echocardiography is the first-line diagnostic technique for identifying outflow tract abnormalities, providing visualization of RVOTO, pulmonary valve anatomy, and right ventricular hypertrophy 1
• Doppler echocardiography provides gradient measurements across obstructions, presence and severity of pulmonary regurgitation, and right ventricular systolic pressure 1
• Cardiac MRI and CT provide additional important information about levels of obstruction, particularly at subinfundibular, conduit, or branch pulmonary artery levels 1
• Electrocardiogram typically shows superior left-axis deviation with a counterclockwise loop in the frontal plane in patients with AVSD 1
• Chest X-ray may reveal cardiomegaly and increased pulmonary vascular markings 1

Indications for Intervention in Right Ventricular Outflow Tract Obstruction

• RVOTO at any level should be repaired regardless of symptoms when Doppler peak gradient exceeds 64 mmHg (peak velocity >4m/s) 1
• In valvular pulmonary stenosis, balloon valvotomy should be the intervention of choice 1
• In asymptomatic patients where balloon valvotomy is ineffective and surgical valve replacement is the only option, surgery should be performed when systolic right ventricular pressure exceeds 80 mmHg 1
• Intervention should be considered with gradient <64 mmHg in the presence of symptoms, decreased right ventricular function, double-chambered right ventricle, important arrhythmias, or right-to-left shunting via an ASD or VSD 1

Surgical Considerations in Down Syndrome

• Patients with Down syndrome have better surgical prognosis for complete AVSD repair compared to non-Down patients 3
• Down syndrome patients show decreased risk for biventricular repair and lower mortality and morbidity in cases of complex cardiac malformations requiring palliative operations 3
• The need for Norwood type surgery is less frequent among Down syndrome patients (1.5% vs 12.0% in non-Down patients) 3
• Freedom from reoperation is higher in Down syndrome patients (94.6% vs 81.4% in non-Down patients) due to lower prevalence of mitral valve anomalies and left ventricular outflow tract obstructions 3

Follow-up Recommendations

• Lifelong regular follow-up of all patients with cardiac abnormalities is recommended, including evaluation in specialized grown-up congenital heart disease (GUCH) centers 1
• Particular attention should be paid to residual shunt, AV valve malfunction, ventricular enlargement and dysfunction, pulmonary artery pressure elevation, subaortic stenosis, and arrhythmias 1
• Surgically repaired AVSD without significant residual abnormalities should be seen at least every 2-3 years 1
• In case of residual abnormalities, follow-up intervals should be shorter 1
• For patients with repaired VSD without residual abnormalities, 5-year intervals may be reasonable 1

Special Considerations in Down Syndrome

• Respiratory issues are common in Down syndrome patients and may complicate management of cardiac conditions 1
• Both upper and lower airways may be affected, with common issues including macroglossia, adenotonsillar hypertrophy, laryngomalacia, smaller and narrow trachea, and tracheo- and bronchomalacia 1
• Patients with Down syndrome have a high incidence of obstructive sleep apnea which can exacerbate pulmonary hypertension 1
• Renal abnormalities are also common in Down syndrome and should be screened for with renal ultrasound to preserve good renal functional prognosis 4

Exercise and Pregnancy Recommendations

• No restrictions are required in patients after VSD closure or with small VSD without pulmonary hypertension, significant arrhythmias, or left ventricular dysfunction 1
• Patients with pulmonary arterial hypertension must limit themselves to low-intensity recreational activity/sports 1
• Pregnancy is contraindicated in Eisenmenger syndrome but has low risk in asymptomatic patients with normal left ventricular function and no pulmonary arterial hypertension 1
• The recurrence rate of congenital heart disease has been reported at 6-10% 1

Endocarditis Prophylaxis

• Endocarditis prophylaxis is recommended only for high-risk patients 1
• Prophylaxis is indicated if residual VSD is present 1
• Prophylaxis is questionable in closed VSD 1