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Journal of the American Academy of Physician Assistants:
doi: 10.1097/01.JAA.0000430348.81563.f1
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Atrial septal defect

Thompson, Erin MPH, MMS, PA-C

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Author Information

Erin Thompson is a PA working in emergency medicine at Wake Forest University Baptist Medical Center in Winston-Salem, North Carolina. The author has indicated no relationships to disclose relating to the content of this article.

Dawn Colomb-Lippa, MHS, PA-C; Amy M. Klingler, MS, PA-C, department editors.

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GENERAL FEATURES

* Atrial septal defect (ASD) is a congenital heart defect that enables blood flow between the left and right atria through a defect in the interatrial septum.

* Occurs due to failure of foramen ovale to close despite change in pulmonary pressure at birth, a condition known as a patent foramen ovale

* Results in mixing of arterial (high oxygen content) and venous (low oxygen content) blood

* The mixing of blood can cause a left-to-right shunt that can reverse to a right-to-left shunt over time. This complication is known as Eisenmenger syndrome.

* Right-to-left shunts cause more complications, such as right heart failure and pulmonary hypertension.

* ASDs are present in 1.64 of every 1,000 live births.

* ASDs compose 35% to 40% of congenital heart defects, making them the second most common congenital heart defect.

* The male to female ratio is 1:2.

* Familial recurrence rate is about 10%.

* Ostium secundum, an opening in the atrial wall at the site of the foramen ovale, is the most common type of ASD.

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CLINICAL ASSESSMENT

* Most patients with ASDs are diagnosed in utero or early childhood due to advances in ultrasonography and auscultation during the physical exam.

* Symptoms of ASD are related to size of the defect.

* Small to medium ASDs may not cause symptoms in early childhood.

* Infants with large ASDs may have cyanosis, heart failure, recurrent respiratory infections, or failure to thrive.

* Adults who were not diagnosed in childhood typically present by their 30s or 40s with

* Dyspnea on exertion

* New-onset heart failure

* Stroke

* Atrial fibrillation

* In patients who have long-standing ASD, a switch to a right-to-left shunt may result in cyanosis evident on physical exam.

* The findings on physical examination depend on the size and location of the defect.

* Palpation of the precordium: right ventricular heave most noticeable on the left sternal border. A left upper sternal border impulse may be noted if the patient has pulmonary hypertension.

* Heart sounds: A wide, fixed, split S2 is characteristic of ASD and is best evaluated when the patient is sitting or standing.

* Additional murmurs that may be auscultated include:

* Mid-systolic pulmonary flow or ejection murmur, noted in larger left-to-right shunts

* A low-pitched diastolic murmur, which can be heard when the pulmonary artery has dilated

* A late apical or holosystolic murmur radiating to the axilla, found in patients with mitral regurgitation due to ASD

* A diastolic rumble increased with inspiration can be noted in patients with left-to-right shunts, and is caused by increased flow across the tricuspid valve.

* An S4 will be noted in patients with pulmonary hypertension due to ASD.

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DIAGNOSIS

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* Echocardiogram

* Test of choice for diagnosis

* Transthoracic echocardiogram (TTE) with color Doppler will show jet of blood from left to right atrium.

* A bubble study can be conducted. Bubbles moving from right to left atrium indicate that right atrial pressure is higher.

* Transesophageal echocardiogram may be required if the ASD is not visualized on TTE or to aid in sizing and determining concomitant abnormalities.

* Chest X-ray

* May be normal

* Later in life, may show enlarged cardiac silhouette and pulmonary edema

* In patients with sinus venous defect (a defect close to the superior or inferior vena cava), the “scimitar sign” may be seen. This is a vertical, curved right-sided pericardiac linear density that increases in width as it approaches the right cardiophrenic angle.

* ECG

* Prolonged PR interval in patients with first-degree heart block

* Incomplete right bundle branch block

* Notched R wave in inferior leads

* Left axis deviation of QRS, most commonly seen in primum ASDs, which are communications present at the level of the mitral or triscupid valves

* Right axis deviation of QRS (ostium secundum ASD)

* Left axis deviation of P wave (sinus venous defect)

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TREATMENT

* Treatment options are determined based on time of discovery and size and location of defect.

* Patients with significant pulmonary hypertension are best treated symptomatically for heart failure.

* Surgical correction is ideal before pulmonary hypertension develops, and has the lowest risk of complications when performed in patients<25y. Closure may be performed as open heart surgery or, more common, percutaneously.

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COMPLICATIONS

* Decompression sickness

* Paradoxical emboli

* Eisenmenger syndrome

* Pulmonary hypertension

* Right-sided heart failure

* Atrial fibrillation or flutter.

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© 2013 American Academy of Physician Assistants.

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