Atrial Septal Defect Clinical Presentation

Updated: May 01, 2017
  • Author: David H Adler, MD, FACC, FSCAI; Chief Editor: Yasmine S Ali, MD, MSCI, FACC, FACP  more...
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The atrial septal defect (ASD) malformation can go undiagnosed for decades due to subtle physical examination findings and a lack of symptoms. Even isolated defects of moderate-to-large size may not cause symptoms in childhood. However, some may have symptoms of easy fatigability, recurrent respiratory infections, or exertional dyspnea. In childhood, the diagnosis is often considered after a heart murmur is detected on routine physical examination or after an abnormal finding is observed on chest radiographs or electrocardiogram (ECG).

If undetected in childhood, symptoms can develop gradually over decades and are largely the result of changing compliance with age, pulmonary arterial hypertension, atrial arrhythmias, and, sometimes, those associated with mitral valve disease in a primum ASD. Virtually all patients with ASD who survive beyond the sixth decade are symptomatic.

Clinical deterioration in older patients occurs by means of several mechanisms, such as the following:

  • First, an age-related decrease in left ventricular compliance augments the left-to-right shunt.

  • Second, atrial arrhythmias, especially atrial fibrillation, but also atrial flutter or paroxysmal atrial tachycardia, increase in frequency after the fourth decade and can precipitate right ventricular failure.

  • Third, most symptomatic adults older than 40 years have mild-to-moderate pulmonary arterial hypertension in the presence of a persistent large left-to-right shunt; therefore, the aging right ventricle is burdened by both pressure and volume overload.

  • Another mechanism for symptoms particularly associated with primum ASD is related to clinically significant mitral regurgitation. Its incidence, extent, and degree of dysfunction increases with age. Mitral valve insufficiency leads to further increase in left atrial pressure and a higher degree of left-to-right shunt.

Overall, the most common presenting symptoms include dyspnea, easy fatigability, palpitations, sustained atrial arrhythmia, syncope, stroke, and/or heart failure. In adults, one of the most common symptoms is the development of palpitations related to atrial arrhythmias.


Physical Examination

The findings on physical examination depend on the degree of left-to-right shunt and its hemodynamic consequences, which, in turn, depends on the size of the defect, the diastolic properties of both ventricles, and the relative resistance of the pulmonary and systemic circulations. Note the following:

  • The patient can have a hyperdynamic right ventricular impulse due to increased diastolic filling and large stroke volume.

  • Palpable pulsation of the pulmonary artery and an ejection click can be detected because of a dilated pulmonary artery.

  • S1 is typically split, and the second component may be increased in intensity, reflecting forceful right ventricular contraction and delayed closure of the tricuspid leaflets.

  • S2 is often widely split and fixed because of reduced respiratory variation due to delayed pulmonic valve closure (seen only if pulmonary artery pressure is normal and pulmonary vascular resistance is low). This characteristic abnormality is found in almost all patients with large left-to-right shunts.

  • Blood flow across the atrial septal defect (ASD) does not cause a murmur at the site of the shunt because no substantial pressure gradient exists between the atria. However, ASD with moderate-to-large left-to-right shunts result in increased right ventricular stroke volume across the pulmonary outflow tract creating a crescendo-decrescendo systolic ejection murmur. This murmur is heard in the second intercostal space at the upper left sternal border.

  • Patients with large left-to-right shunts often have a rumbling middiastolic murmur at the lower left sternal border because of increased flow across the tricuspid valve.

  • Auscultatory findings of the ASD may resemble those of mild valvular or infundibular pulmonic stenosis and idiopathic dilatation of the pulmonary artery. These disorders all manifest as a systolic ejection murmur, but they differ from the ASD by movement of the S2 with respiration, a pulmonary ejection click, or the absence of a tricuspid flow murmur.

  • In patients with an ostium primum defect and an associated cleft of the mitral valve, an apical systolic regurgitant murmur of mitral regurgitation may be present.

  • In patients who develop pulmonary arterial hypertension and right ventricular hypertrophy, a right ventricular S4 may be present. In such cases, the midsystolic pulmonic murmur is softer and shorter, the tricuspid flow murmur is not present, the splitting of S2 is narrowed with accentuated pulmonic component, and murmur of pulmonic regurgitation may become apparent.

  • ASD is an acyanotic lesion. Thus, the patient should be normally saturated. In the rare case of severe pulmonary arterial hypertension, atrial shunt reversal (Eisenmenger syndrome) may occur, leading to cyanosis and clubbing