From the Guidelines
The most common murmur seen in patients with Down syndrome is an atrioventricular septal defect (AVSD). This is due to the high prevalence of congenital heart defects in individuals with Down syndrome, with approximately 40% having some form of cardiac abnormality 1. The association between Down syndrome and AVSD is well-established, with AVSD occurring in approximately 40-60% of individuals with Down syndrome. Key characteristics of AVSD include:
- Abnormalities in the center of the heart where the atria and ventricles meet
- A systolic murmur heard best at the left sternal border, often accompanied by a fixed split second heart sound
- The potential for complications such as pulmonary hypertension and heart failure if left untreated Early detection through routine cardiac screening is essential for all newborns with Down syndrome, even in the absence of obvious symptoms, to ensure timely surgical correction and prevent long-term morbidity and mortality 1.
From the Research
Most Common Murmur in Down Syndrome
- The most common murmur seen in patients with Down syndrome is associated with atrioventricular septal defects (AVSD) 2, 3.
- AVSD is a type of congenital heart defect that occurs when there is a hole in the wall between the heart's chambers, and the valves between the chambers do not form properly.
- Studies have shown that patients with Down syndrome are more likely to have AVSD, with a prevalence of 33% in one study 2.
- Another study found that 54.7% of patients with AVSD had Down syndrome, and that these patients were more likely to have pulmonary hypertension, but less likely to have arrhythmias 3.
Associated Cardiac Malformations
- Patients with Down syndrome and ventricular septal defect (VSD) are more likely to have inlet VSD and a cleft of the mitral valve 4.
- Muscular and subpulmonary VSD are less common in patients with Down syndrome 4.
- Left-ventricular inflow and outflow obstructions are more common in patients without Down syndrome 4.
Clinical Significance
- The presence of a murmur in a patient with Down syndrome should prompt further evaluation for underlying cardiac defects, particularly AVSD and VSD 2, 3, 4.
- Early diagnosis and treatment of these defects can improve outcomes and reduce the risk of complications, such as pulmonary hypertension and heart failure 2, 3.