Cardiac Defects in DiGeorge Syndrome (22q11.2 Deletion Syndrome)
The most common cardiac defects in DiGeorge syndrome are conotruncal defects, specifically tetralogy of Fallot, interrupted aortic arch type B, and truncus arteriosus. 1
Prevalence and Pattern
Congenital heart disease (CHD) occurs in approximately 60-80% of patients with 22q11.2 deletion syndrome. 1, 2 The cardiac manifestations follow a distinctive pattern that should raise clinical suspicion for this genetic condition.
Specific Cardiac Defects
Major Conotruncal Defects (Most Common)
The hallmark cardiac lesions include:
- Tetralogy of Fallot - the most frequently encountered major defect 1, 2
- Interrupted aortic arch type B - highly associated with 22q11.2 deletion 1, 2
- Truncus arteriosus - another classic conotruncal anomaly 1, 2
- Pulmonary atresia with ventricular septal defect - often with major aortopulmonary collaterals 1
Additional Cardiac Features
Beyond the primary conotruncal defects, several associated anomalies increase diagnostic suspicion:
- Ventricular septal defects - actually the most common overall cardiac finding, though considered "minor" CHD 1
- Aortic arch anomalies - including right aortic arch and aberrant subclavian artery 1, 3
- Crossed pulmonary arteries 1
- Vascular rings - can cause tracheal/esophageal compression presenting as stridor or feeding difficulties 1
Clinical Significance for Diagnosis
The presence of an aortic arch anomaly concurrent with any conotruncal defect strongly predicts 22q11.2 deletion status (odds ratio 5.07). 4 This combination should prompt immediate genetic testing.
Current screening guidelines recommend testing for 22q11.2 deletion in patients with:
- Tetralogy of Fallot 2
- Truncus arteriosus 2
- Interrupted aortic arch type B 2
- Conoventricular septal defects 2
- Isolated aortic arch anomalies 2
Surgical Considerations
Patients with 22q11.2 deletion and cardiac defects face increased perioperative complications despite similar mortality rates compared to non-syndromic patients. 1, 5 These complications include:
- Prolonged mechanical ventilation 1
- Extended hospital stays 1
- Higher risk with pulmonary atresia/VSD and interrupted aortic arch 5
The complex anatomy typically requires intracardiac repair in infancy or early childhood, with frequent need for reintervention during childhood and adolescence. 1
Long-Term Cardiac Surveillance
All patients with 22q11.2 deletion require periodic cardiac surveillance regardless of whether CHD was initially present. 1 This includes monitoring for:
- Dilated aortic root 1
- Arrhythmias 1
- Progressive valvular dysfunction in those with prior surgical repair 1
Genetic Mechanism
The cardiac phenotype results from haploinsufficiency of genes in the 22q11.2 region, particularly TBX1, which causes dysfunction of neural crest cells and the anterior heart field during embryonic development. 1, 3