Pediatric Complete Atrioventricular Septal Defects Clinical Presentation

Updated: Sep 13, 2019
  • Author: Michael D Pettersen, MD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Tachypnea, repeated respiratory infections, poor feeding, and failure to thrive are frequent symptoms in patients with complete atrioventricular septal defect (AVSD) and large left-to-right shunts. These symptoms are usually present by 6-8 weeks and due to blood flow through the large interventricular communication with or without incompetence of the common atrioventricular valve.

Pulmonary vascular disease results from damage caused by excessive pulmonary flow and elevated pulmonary artery pressure due to the large ventricular septal defect (VSD). Irreversible pulmonary vascular disease may be present by age 2 years or, in rare cases, earlier. The pulmonary vascular disease may occur earlier in infants with Down syndrome.



General physical examination may show characteristics of Down syndrome, including flat facial profile, upslanting palpebral fissures, prominent inner epicanthal folds, Brushfield spots, protuberant tongue, abnormal palmar creases, and fifth finger clinobrachydactyly. Inspection may reveal pallor or Harrison grooves (horizontal depression along lower border of chest at diaphragm insertion site due to chronic tachypnea). [26] Failure to thrive is common due to excessive metabolic cardiovascular requirements and poor caloric intake (due to tachypnea).

The cardiac examination is remarkable for and overactive precordium. The volume and pressure overload on the right ventricle result in a prominent systolic heave along the left sternal border and subxiphoid regions. The pulmonary component of the second heart sound may be palpable at the left second intercostal space. Regurgitation of the atrioventricular valve may uncommonly result in a palpable apical thrill.

The first heart sound is single and often accentuated. The second heart sound is narrowly split, with an accentuated pulmonary component. A crescendo-decrescendo murmur may be audible at the upper left sternal border due to increased blood flow through a normal pulmonary valve. A mid diastolic rumble may be audible at the lower left sternal border and apex due to the increased flow across the common atrioventricular valve. A holosystolic murmur is often appreciated at the apex due to atrioventricular valve insufficiency. Because the VSD in complete atrioventricular septal defect is large and unrestrictive, it is not usually associated with a separate murmur.

When pulmonary vascular resistance (PVR) is elevated, the systolic murmur may not be prominent, and the diastolic rumble may disappear, reflecting less left-to-right shunt. This finding can occur in the infant in whom PVR has never fallen or in the older child with developing pulmonary vascular obstructive disease (PVOD), for whom the improvement in congestive heart failure (CHF) symptoms is an ominous finding.

In patients with advanced PVOD, the left parasternal impulse is prominent, S2 may be palpable, and the systolic murmur may be soft and short or even may be absent. A high-pitched decrescendo diastolic murmur of pulmonary insufficiency (Graham Steell murmur) may be detected at the left upper sternal border, reflecting severely elevated PVR.

Factors that can influence hemodynamics in Down syndrome include chronic nasopharyngeal obstruction, relative hypoventilation, carbon dioxide retention, and sleep apnea. Nonspecific CHF signs that may be seen include hepatosplenomegaly, pulmonary rales, and tachypnea. Skull erosion and striations have been noted from venous distension and increased blood volume.



The exact cause atrioventricular septal defects is not known. The majority of the defects may be explained by multifactorial inheritance hypothesis. [27]

Trisomy 21 (Down syndrome) is the most frequently associated genetic abnormality with complete atrioventricular septal defect, although it may also occur in association with trisomy 13 and trisomy 18. In patients without trisomy 21 who have common atrioventricular canal (CAVC) defects, a genetic locus on chromosome 1 can account for the disorder in some families. [28]

Interstitial deletion on chromosome 16 may be associated with atrioventricular septal defect. Endocardial cushion tissue seems to function as an adhesive for myocardial structures. Fibroblasts of endocardial cushions in trisomy 21 tend to be more adhesive, possibly leading to cardiac malformations. Atrioventricular septal defect may be seen with other less common syndromes, such as Dandy-Walker malformation, Joubert syndrome, and Ritscher-Schintal (craniocerebellocardiac) syndrome. An orocardiodigital syndrome consisting of tongue hamartomas, polysyndactyly, and atrioventricular septal defect has been described.

Atrioventricular septal defect is one of several cardiac abnormalities commonly seen with heterotaxy syndromes (asplenia and occasionally with polysplenia). Other rare combinations include atrioventricular septal defect with total anomalous pulmonary venous return and atrioventricular septal defect with Ebstein anomaly. Uncommon associations with atrioventricular septal defect include DiGeorge syndrome and coloboma of the eye, heart defects, atresia of the choanae, renal anomalies and retardation of growth and/or development, genital anomalies in males such as micropenis or cryptorchidism, and ear abnormalities or deafness (CHARGE) syndrome.

The presence of vascular endothelial growth factor (VEGF) gene mutations has been associated with atrioventricular septal defect. [29] The prevalence of the VEGF +405C allele was higher in patients with CHD than in control subjects (0.42 vs 0.21; P < .05). The presence of VEGF +405C presented increased risk for CHD (odds ratio [OR], 1.72; 95% CI, 1.32–2.26).

Advanced maternal age is a risk factor for Down syndrome, and at least two thirds of patients with uncomplicated atrioventricular septal defect have trisomy 21.