History
Infants and young children with atrial septal defects (ASDs) are typically asymptomatic. Most atrial septal defects are diagnosed after a suspicious murmur is detected during a routine health-maintenance examination.
Even in symptomatic children with atrial septal defects, clinical manifestations are often subtle and nonspecific. Some children with atrial septal defects have poor weight gain, they remain somewhat small, and they may have exertional dyspnea or frequent upper respiratory tract infections.
Relatively severe symptoms, such as arrhythmia, pulmonary artery hypertension, and pulmonary vascular obstructive disease (PVOD), are rare in children with atrial septal defects. Some infants and young children with large defects may present with symptoms of congestive heart failure (CHF), especially if they have an associated lesion (eg, patent ductus arteriosus) or lung disease (eg, bronchopulmonary dysplasia and/or chronic lung disease).
Physical Examination
Most children with atrial septal defects (ASDs) are asymptomatic. In developed countries, the diagnosis is usually made during an evaluation of a suspicious murmur or during an evaluation of fatigue and exercise intolerance. Atrial septal defects that are not diagnosed in childhood can result in problems in adulthood.
Upon initial evaluation, many children with atrial septal defects appear completely healthy; however, careful physical examination often yields clues to the diagnosis.
Patients with atrial septal defects may have a precordial bulge, a prominent right ventricular cardiac impulse, and palpable pulmonary artery pulsations. All of these are signs of increased blood flow through the right side of the heart and pulmonary vascular bed.
Upon auscultation of the individual with atrial septal defect, the first heart sound may be normal or split. The sound associated with closure of the tricuspid valve may be accentuated if blood flow across the pulmonic valve is increased and leads to a midsystolic pulmonary ejection murmur. This sound is best appreciated at the upper left sternal border and may be transmitted to the lung fields.
Although the second heart sound may be normal in newborns with atrial septal defects, it becomes widely split and fixed over time as pressures on the right side of the heart decrease. This fixed splitting occurs as the result of increased capacitance in the pulmonary vascular bed, leading to low pulmonary impedance and, therefore, a long hangout interval after the end of right ventricular systole. Fixed splitting of S2 is an important diagnostic finding in atrial-level shunting.
A large shunt increases flow across the tricuspid valve, and the patient with atrial septal defect is likely to have a mid-diastolic rumble at the left sternal border.
Mitral valve prolapse occurs with increased frequency in the presence of atrial septal defect and may be caused by compression of the left side of the heart secondary to enlargement of the right side. In patients with mitral valve prolapse, an apical holosystolic or late systolic murmur often is heard radiating to the axilla. A midsystolic click may be present, but this murmur can be difficult to detect in some patients with atrial septal defects.
Pulmonary vascular resistance (PVR) may increase through childhood, adolescence, and adulthood, resulting in PVOD. The rise in PVR and pulmonary artery pressure results in right ventricular hypertrophy, which, in turn, reduces right ventricular compliance and may subsequently reduce the degree of left-to-right shunting.
Upon physical examination, patients may have a prominent right ventricular impulse, but the previously noted diastolic tricuspid flow rumble and the systolic ejection murmur in the pulmonic area may be diminished. The wide splitting of the second heart sound may narrow, and the pulmonic component of the second heart sound may become loud, with intensity equal to that of the aortic component.
In all patients with common atrium, right-to-left shunting occurs, resulting in cyanosis, although this may be mild due to preferential streaming of blood across the respective atrioventricular (AV) valves.
In adults with an unrecognized atrial septal defect, the left-to-right shunt may worsen if systemic arterial hypertension develops. The result may be left ventricular hypertrophy, reduced left ventricular compliance, and increased left-to-right shunt.
-
Subcostal echocardiographic view of a child with a secundum atrial septal defect (ASD). Note the position of the defect in the atrial septum. LA = left atrium; RA = right atrium; SVC = superior vena cava.
-
Subcostal long-axis view of the same child as in the previous image with a secundum atrial septal defect (ASD). LA = left atrium; RA = right atrium; RUPV = right upper pulmonary vein.
-
Parasternal short axis view of a child with a secundum atrial septal defect (ASD). AO = aorta; LA = left atrium; RA = right atrium.
-
Apical echocardiographic view of a primum atrial septal defect (ASD). Note the position of the defect when compared with a secundum ASD. LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle.
-
Apical echocardiographic view of a primum atrial septal defect (ASD). Note that the atrioventricular valves are at the same level (instead of mild apical displacement of the tricuspid valve), which is seen in the spectrum of atrioventricular canal defects. LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle.
-
Apical color Doppler echocardiographic view of a primum atrial septal defect (ASD). Note the flow across the defect from the left atrium to the right atrium (RA), and note the mitral regurgitation (MR) through a cleft in the anterior leaflet of the mitral valve. LV = left ventricle; MV = mitral valve.
-
Subcostal short-axis view of a child with a sinus venosus atrial septal defect (ASD). Note the position of the defect compared with that of a secundum or primum ASD. Also note the anomalous position of the right upper pulmonary vein (RUPV). LA = left atrium; RA = right atrium.
-
Electrocardiographs (ECGs) from a child with a secundum atrial septal defect (ASD). Note the right-axis deviation and rSR' pattern in lead V1.
-
Electrocardiogram (ECG) from a child with a primum atrial septal defect (ASD). Note the left-axis deviation with a counterclockwise vector of depolarization (small q waves in leads I and aVL) and right ventricular hypertrophy and/or volume overload (rSR' pattern and upright T wave in lead V1).
