Complete atrioventricular septal defect

Complete atrioventricular septal defect (CAVSD), also known as complete atrioventricular canal defect or complete endocardial cushion defect, is a congenital heart malformation characterized by a deficiency of the atrioventricular septum and abnormalities of the atrioventricular valves. In this condition, there is a large hole in the center of the heart involving both the atrial septum (ostium primum atrial septal defect) and the ventricular septum (inlet ventricular septal defect), along with a single common atrioventricular valve instead of separate mitral and tricuspid valves. This allows abnormal mixing of oxygenated and deoxygenated blood between all four heart chambers and leads to excessive blood flow to the lungs. Infants with complete AVSD typically present in the neonatal or early infantile period with symptoms of congestive heart failure, including rapid breathing (tachypnea), poor feeding, failure to thrive, excessive sweating, and recurrent respiratory infections. If left untreated, the increased pulmonary blood flow can lead to irreversible pulmonary vascular disease (Eisenmenger syndrome). A heart murmur is usually detected shortly after birth. The condition is strongly associated with Down syndrome (trisomy 21), with approximately 40-45% of CAVSD cases occurring in individuals with this chromosomal abnormality. It can also occur as an isolated defect or in association with other genetic syndromes such as heterotaxy or Ellis-van Creveld syndrome. The primary treatment for complete AVSD is open-heart surgical repair, which is typically performed between 3 and 6 months of age. Surgery involves closing the atrial and ventricular septal defects with patches and reconstructing two separate atrioventricular valves from the common valve. Prior to surgery, medical management with diuretics, afterload reducers, and nutritional support may be necessary to control heart failure symptoms. Long-term outcomes after surgical repair are generally good, though some patients may require additional surgeries later in life, particularly for residual or recurrent mitral valve regurgitation. Lifelong cardiology follow-up is recommended.

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