From the Guidelines
The most common cardiac defects in Down syndrome are atrioventricular septal defects (AVSDs), which account for approximately 40-60% of congenital heart defects in these individuals, as supported by the most recent evidence from 1.
Cardiac Defects in Down Syndrome
The high prevalence of heart defects in Down syndrome is related to abnormal endocardial cushion development during embryogenesis, which is influenced by the genetic alterations associated with trisomy 21. Other frequent cardiac abnormalities include:
- Ventricular septal defects (VSDs)
- Atrial septal defects (ASDs)
- Tetralogy of Fallot
- Patent ductus arteriosus (PDA) These cardiac defects occur in about 40-60% of all children with Down syndrome, making cardiac evaluation essential for all newborns with this condition, as emphasized in 1 and 1.
Importance of Early Detection
Early detection through echocardiography is recommended for all infants with Down syndrome, ideally within the first month of life, even in the absence of symptoms or murmurs, as stated in 1. Many of these defects require surgical correction, with timing dependent on the specific defect and its severity. Without appropriate intervention, these cardiac defects can lead to pulmonary hypertension, heart failure, and increased mortality, which explains why cardiac disease remains a significant contributor to morbidity and reduced life expectancy in Down syndrome.
Clinical Implications
The management of adults with congenital heart disease, including those with Down syndrome, requires careful attention to coexisting diseases and special care issues, as outlined in 1. Regular screening for hypothyroidism, leukemia, Alzheimer’s disease, depression, atlantoaxial subluxation, obesity, and sleep apnea is essential for individuals with Down syndrome. The risks of anesthesia and procedures need to be carefully reviewed by CHD specialists and discussed with the patient.
From the Research
Cardiac Defects in Down Syndrome
The most common cardiac defects in Down syndrome (Trisomy 21) are:
- Atrio-ventricular septal defect (AVSD) 2, 3, 4
- Ventricular septal defect (VSD) 2, 5, 6, 4
- Atrial septal defect (ASD) 2, 6, 4
- Patent ductus arteriosus (PDA) 2, 6
- Tetralogy of Fallot (TOF) 2, 5, 6, 4
Prevalence of Cardiac Defects
The prevalence of cardiac defects in Down syndrome is high, with studies reporting:
- 49.8% of patients with Down syndrome having congenital heart disease (CHD) 2
- 61.3% of patients with Down syndrome having CHD 6
- 44% of patients with Down syndrome having major cardiac defects 4
Characteristics of Cardiac Defects
Studies have shown that:
- AVSD is more common in patients with Down syndrome, with outlet extension of the ventricular component of the defect and outlet septum anterior malalignment being characteristic features 3
- VSD is the most common lesion in some studies, with better prognosis than AVSD 2
- Tetralogy of Fallot is more frequent in patients with Down syndrome 3, 4