Pediatric Partial and Intermediate Atrioventricular Septal Defects Clinical Presentation

Updated: Jan 24, 2019
  • Author: M Silvana Horenstein, MD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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In the absence of moderate to severe mitral regurgitation (MR) and other associated congenital heart disease (CHD), partial atrioventricular septal defect (AVSD) is often discovered later in childhood when the patient is referred for evaluation of a heart murmur. Also, partial AVSD is less common in Down syndrome than in complete AVSD.

Note the following:

  • The clinical presentation of patients with partial AVSD depends on the degree of MR and on the associated cardiac defects.

  • Other cardiac anomalies that may be associated with partial AVSD include secundum atrial septal defect (ASD), persistent left superior vena cava draining to the coronary sinus, pulmonary stenosis, discrete subaortic stenosis, tricuspid stenosis, tricuspid atresia, coarctation of the aorta, patent ductus arteriosus (PDA), perimembranous ventricular septal defect (VSD), and hypoplastic left ventricle (LV).

  • Children with atrioventricular valve competence usually exhibit no significant symptoms. They are usually referred to a pediatric cardiologist if a heart murmur is detected during routine examination.

  • Substantial left-to-right shunting may exacerbate pulmonary disease and cause frequent lower respiratory infections in some patients. These patients may present with tachypnea, respiratory distress, and inadequate weight gain.

  • Infants with severe MR often demonstrate poor feeding, tachypnea, and labored breathing. Rarely, respiratory distress may be so severe as to require mechanical ventilation.

  • Progressive cardiac enlargement and LV dysfunction cause shocklike symptoms and eventually lead to mortality.

  • Adolescents and young adults may note progressive exercise intolerance.

  • Palpitations caused by atrial arrhythmia become more common in young adulthood, and sustained supraventricular tachycardia, atrial flutter, or atrial fibrillation may trigger the onset of congestive heart failure (CHF) in older patients with AVSD.

  • Hypervolemia of pregnancy may trigger CHF symptoms and complicate pregnancy.


Physical Examination

General appearance

Most children with partial AVSD and minimal MR appear healthy. Patients who have Down syndrome exhibit features typical of the condition.

Patients with severe MR in infancy can manifest tachypnea, retractions, and diaphoresis, especially during and immediately after feeding. Poor caloric intake and excessive metabolic demands lead to growth failure. Older children and adolescents with severe MR may display a prominent left chest as well as a slim (asthenic) build.

Pulmonary and cardiovascular examination

Palpation and auscultatory findings depend on the severity of the left-to-right shunt, the presence of MR, and associated defects (eg, LV outflow obstruction, PDA).

Fine rales or rhonchi, or both, may be heard in the lung fields of older patients with severe MR but are rare in infants.

The partial AVSD provides auscultatory findings that are indistinguishable from those created by any other large ASD. A prominent impulse along the right sternal border, consistent with a right ventricle (RV) lift, may be present. Alternatively, severe MR can cause a prominent apical impulse or thrill.

The classic auscultatory finding associated with an ASD is a constant or fixed splitting of the second heart sound (S2), frequently accompanied by a pulmonary ejection murmur audible at the upper left sternal border.

A large AVSD with substantial left-to-right shunting creates a mid-diastolic rumbling murmur, audible along the lower left sternal border. This often occurs in association with a prominent third heart sound (S3) in that location. These sounds are attributed to an abnormally high flow across the tricuspid component of the atrioventricular valve.

The apical murmur of MR occurs even with a small cleft in the atrioventricular valve. This murmur has a blowing quality and must be differentiated from the murmur caused by a VSD. However, when it occurs with a fixed split S2, this murmur is helpful in differentiating a partial AVSD from a secundum ASD.

Severe MR can also cause a diastolic murmur audible over the apical area, which, in association with the systolic murmur, produces a to-and-fro quality.