AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Background

Atrial septal defect (ASD) is one of the most common congenital cardiac abnormalities identified in adults. Most ASDs, however, are detected in the pediatric population and corrected at that time.¹

There are 3 types of ASD:

• Ostium secundum: Most often, ASD involves the fossa ovalis, is midseptal in location, and is of the ostium secundum type.² This type of ASD is a true deficiency of the interatrial septum and is distinct from the frequently identified patent foramen ovale.³
• Ostium primum: Ostium primum ASDs involve atrial and ventricular septa. Primum defects do not always involve the ventricular septum. If both the atrial and ventricular septa are involved, the defect is called an atrioventricular canal or atrioventricular septal defect.
• Sinus venosus: The third form of ASD involves defects of the sinus venosus type that are high in the atrial septum near the junction with the superior vena cava (SVC)

Patients with ASD usually are asymptomatic early in life, although occasional reports exist of congestive heart failure (CHF) and recurrent pneumonia in infancy. Common findings include a prominent right ventricular cardiac impulse and palpable pulmonary artery pulsation. The first heart sound is normal or split, with accentuation of the tricuspid valve closure sound. Two-dimensional echocardiography, supplemented by conventional or color-coded Doppler flow and/or contrast echocardiography, has superseded cardiac catheterization as the confirmatory test for ASD.

In contrast to adults, children with the sinus venosus or secundum types of ASD rarely require treatment for CHF, atrial fibrillation, or supraventricular tachycardia. Although the risk of infective subacute bacterial endocarditis is low, antibiotics should be administered prophylactically before dental procedures. Operative repair is recommended for all patients with uncomplicated ASD in whom significant left-to-right shunting exists (ie, in patients with pulmonary flow/systemic flow ratios exceeding approximately 1.5:1). Ideally, the repair should be performed early (ie, by age 2-4 years). Surgical mortality is less than 1%, and results generally are excellent.

(See also the eMedicine articles Atrial Septal Defect, Ostium Secundum, Atrial Septal Defect, Ostium Primum, and Atrial Septal Defect, Patent Foramen Ovale, as well as Atrial Septal Defect: Pathophysiology, Diagnosis, and Treatment and Transcatheter Closure of Atrial-Septal Defects and Patent Foramen Ovale in Adults: Optimal Anatomic Adaptation of Occlusion Device, on Medscape.)

Pathophysiology

Anatomic sites

• Patent foramen ovale: A widely patent foramen ovale may be considered an acquired form of ASD that occurs especially when a disparity exists between the size of the foramen ovale and the length of its valve.³
• Classification of ASD according to anatomic site is as follows:
  • Mid - Ostium secundum ASD
  • Low - Septum primum ASD (or partial arteriovenous [AV] canal defect)
  • High - Sinus venosus–type ASD
• Lesions of ASD may have the following associated abnormalities:
• • Ostium secundum defects are encountered most frequently and involve the fossa ovalis. From 10-20% of patients also may have prolapse of the mitral valve as an associated anomaly.
  • Ostium primum atrial septal anomalies are a form of atrioventricular septal defect. Lutembacher syndrome involves a rare combination of ASD and mitral stenosis. Mitral stenosis occurs almost invariably as a result of acquired rheumatic valvulitis.
  • Sinus venosus–type defect involves the high atrial septum and may be created by a defect in the wall that normally separates the pulmonary veins from the right lung, SVC, and right atrium. Thus, sinus venosus–type defect may be associated with partial anomalous pulmonary venous drainage.

Hemodynamics

The magnitude of the left-to-right shunt through an ASD depends on the following factors:

• Size of the defect
• Relative compliance of the ventricles
• Relative resistance in both the pulmonary and systemic circulations

In patients with a small ASD or a patent foramen ovale,³ the left atrial pressure may exceed the right by several millimeters of mercury, while the mean pressures in both atria are nearly identical when the defect is large.

Left-to-right shunting occurs predominantly in late ventricular systole and early diastole, with some augmentation during atrial contraction. The shunt results in diastolic overloading of the right ventricle and increased pulmonary blood flow.

During the first few days and weeks of life, pulmonary resistance normally decreases, while systemic resistance increases. This results in increased right ventricular emptying. Left ventricular (LV) emptying diminishes at the same time, causing a rise in the left-to-right shunt.

Early in infancy, left-to-right shunt flow through even a large interatrial defect is limited by both the reduced chamber compliance of the hypertrophied right ventricle and the elevated pulmonary and reduced systemic vascular resistance.

Even in the older infant or child, pulmonary vascular resistance commonly is normal or low, and the volume load is well tolerated, even though pulmonary blood flow may be 2-5 times greater than systemic flow.

A transient and small right-to-left shunt occurring with the onset of LV contraction, especially during respiratory periods of decreasing intrathoracic pressure, is common in patients with ostium secundum defect, even in the absence of pulmonary hypertension.

Frequency

United States

ASD is one of the most commonly recognized congenital cardiac anomalies in adults. AV septal defects account for 4-5% of congenital heart defects.

International

Prevalence of ASD internationally parallels that found in the United States.

Mortality/Morbidity

• Patients with ASD usually are asymptomatic early in life.
• Occasional reports exist of patients presenting with CHF and recurrent pneumonia in infancy. More commonly, children may experience easy fatigability and exertional dyspnea. They tend to be somewhat underdeveloped physically and prone to respiratory infection.
• Atrial arrhythmias, pulmonary arterial hypertension, and CHF are quite rare in children, in contrast to the common appearance of these conditions in adults with ASD.

Race

No particular racial predilection is noted.

Sex

No clear sex predilection exists.

Age

ASD is one of the most common congenital cardiac anomalies detected in both children and adults. ASD is diagnosed less frequently in infants and young children because of the absence of significant symptoms early on. More often than not, older children and young adults present with heart murmurs and recurrent respiratory infections. Among adults, the diagnosis most often is made beyond middle age as long-term sequelae begin to develop, such as atrial arrhythmias, pulmonary hypertension, and congestive heart failure.

Anatomy

Anatomic sites of interatrial defects include (1) high atrial septum, which is seen in sinus venosus–type ASD; (2) midatrial septum, which represents common secundum ASD, and (3) low atrial septum, which represents septum primum ASD (or partial AV canal defect).

Embryologically, the left side of the atrial septum is derived from the septum primum, which possesses an opening termed the interatrial ostium secundum. The ostium secundum lies forward and superior to the position of the foramen ovale. The foramen ovale is formed by the septum secundum and occupies the right side of the atrial septum. Tissue of the septum primum lying to the left of the foramen ovale serves as a flap valve, which usually becomes fused postnatally with the side of the foramen ovale, yielding an anatomically closed or sealed foramen.

Probe patency, or an incomplete seal of the foramen ovale, occurs in approximately 25% of adults. A widely patent foramen ovale may be considered to be an acquired form of ASD that occurs especially when a disproportion exists between the size of the foramen ovale and the effective length of its valve. Enlargement of the foramen ovale per se is associated commonly with obstructive lesions on the right side of the heart, while a short valve relative to the size of the foramen often is seen in large-volume left-to-right shunts in which left atrial dilatation is prominent.

Clinical Details

Clinical history

• Patients with ASD usually are asymptomatic early in life, although occasional reports exist of CHF and recurrent pneumonia occurring in infancy.
• Children with ASD may experience easy fatigability and exertional dyspnea. They tend to be somewhat underdeveloped physically and prone to respiratory infection.
• Atrial arrhythmias, pulmonary arterial hypertension, development of pulmonary vascular obstruction, and heart failure are exceedingly uncommon in the pediatric age range. In contrast, these conditions are seen commonly in adults with ASD.
• In children, the diagnosis often is entertained after a heart murmur is detected on routine physical examination, prompting a more extensive cardiac evaluation.

Physical examination

Common findings include the following:

• Prominent right ventricular cardiac impulse may be found.
• Palpable pulmonary artery pulsation may be found.
• The first heart sound is normal or split, with accentuation of the tricuspid valve closure sound.
• Increased flow across the pulmonic valve is responsible for a midsystolic pulmonary ejection murmur.
• The second heart sound is widely split and is relatively fixed in relation to respiration in patients with normal pulmonary pressures and low pulmonary vascular impedance because of a delay in pulmonic valve closure. With pulmonary hypertension, the splitting interval is a function of the electromechanical intervals of each ventricle; wide splitting occurs with shortening of the left and/or lengthening of the right ventricular electromechanical interval.
• If the shunt is large, increased blood flow across the tricuspid valve is responsible for a middiastolic rumbling murmur at the lower left sternal border.
• In patients with associated prolapse of the mitral valve, an apical holosystolic or late systolic murmur radiating to the axilla often is heard, but a midsystolic click may be difficult to discern. Moreover, LV precordial overactivity usually is absent because mitral regurgitation is mild in most patients.
• In the teenage patient, physical findings may be altered when an increase in pulmonary vascular resistance results in diminution of the left-to-right shunt.
  • Both the pulmonary and the tricuspid murmurs decrease in intensity.
  • The pulmonic component of the second heart sound becomes accentuated.
  • The 2 components of the second heart sound may fuse.
  • A diastolic murmur of pulmonic incompetence appears.
  • Cyanosis and clubbing accompany development of a right-to-left shunt.

Electrocardiographic results

• Ostium secundum ASD: In patients with an ostium secundum defect, electrocardiogram (ECG) results usually demonstrate the following:
  • Right-axis deviation
  • Right ventricular hypertrophy
  • rSR' pattern in the right precordial leads with a normal QRS duration (Whether the delay in right ventricular activation is a manifestation of right ventricular volume overload or a true conduction delay in the right bundle branch and peripheral Purkinje system is not clear.)
• Septum primum ASD: ECG results in patients with a primum defect may demonstrate the following:
  • Left-axis deviation of the P wave in the frontal plane (manifested by a negative P wave in lead III) may be noted.
  • Left-axis deviation and counterclockwise rotation of the QRS suggest the presence of either an ostium primum defect or a secundum ASD in association with mitral valve prolapse.
  • Prolongation of the PR interval may be seen with all types of ASDs, including ostium primum defect. The prolonged conduction time may be related to both the increased size of the atrium and the increased distance for internodal conduction produced by the defect.
  • In ostium primum ASD, ECG results are characteristic and demonstrate a right ventricular conduction defect accompanied by left anterior division block, left-axis deviation, and superior orientation and counterclockwise rotation of the QRS loop in the frontal plane.

Preferred Examination

• Chest radiography: Chest radiographs usually demonstrate nonspecific findings, such as enlargement of the right atrium, right ventricle, pulmonary vasculature, left atrium, and proximal segment of the SVC.
• CT scan: Findings on CT scans, particularly the ultrafast CT scan, are specific; however, the CT scanner is less portable than the echocardiogram machine. Findings include clear separation of the atrial septa. Size of the cardiac chambers can be measured accurately.
• Magnetic resonance imaging: MRI, especially cine MRI, has a sensitivity and specificity of over 90% in delineating septal defects; however, greater portability and more widespread use of echocardiography have resulted in a very limited role for MRI in patients with ASD.

Echocardiogram

Echocardiography is the preferred examination.^{4, 5, 6, 7} Echocardiographic features include the following:

• Pulmonary arterial and right ventricular dilatation and anterior systolic (paradoxic) septal motion (if significant right ventricular volume overload is present) may be noted.
• ASD may be visualized directly using 2-dimensional (2D) echo imaging, especially from a subcostal view.
• Transesophageal color-coded Doppler echocardiography (TEE) provides excellent visualization of defects of the atrial septum.
• Associated mitral valve prolapse also may be identified using echocardiographic examination.

Supplemented by conventional or color-coded Doppler flow and/or contrast echocardiography, 2D echocardiography has superseded cardiac catheterization as the confirmatory test for ASD. Cardiac catheterization is used if inconsistencies exist in the clinical data or if significant pulmonary hypertension is suggested.

Cardiac catheterization

Using cardiac catheterization, diagnosis may be confirmed easily by passing the catheter across the atrial defect. The site at which the catheter crosses, if high in the cardiac silhouette, may suggest a sinus venosus defect. If the defect is mid septal in location, a patent foramen ovale or ostium secundum defect is indicated. If the defect is low septal, a primum defect is indicated.

Oximetry

Serial determinations of oxygen saturation or indicator dilution curve techniques may be used to estimate the magnitude of the shunt. In the absence of pulmonary hypertension, pressures on the right side of the heart often are normal, despite a large shunt.

When a high oxygen saturation is found in the SVC or when the catheter enters pulmonary veins directly from the right atrium, a sinus venosus defect is likely, and indicator dilution curves and selective angiography aid in identifying the number and location of the anomalous veins. Partial anomalous pulmonary venous connection, although usually associated with a sinus venosus defect, may accompany secundum defects.

Left ventricular angiography

Selective LV angiography identifies prolapse of the mitral valve and allows assessment of the magnitude of the mitral regurgitation that may be present in these patients.

In ostium primum ASD, the interatrial septal tissue is absent in the region of the crest of the interventricular septum; the trileaflet configuration of the mitral valve also may be identified. The subxiphoid long-axis view of the LV outflow tract shows the characteristic gooseneck deformity in a manner similar to that of a right anterior oblique LV angiogram.

Electrophysiologic abnormalities

Intracardiac electrophysiologic studies reveal a high incidence of intrinsic dysfunction of the sinoatrial and atrioventricular nodes, which persists after surgical repair. These intrinsic nodal abnormalities are more common in sinus venosus defects than in ostium secundum defects.

Limitations of Techniques

Occasionally, echocardiographic results may fail to provide adequate information in the presence of high pulmonary pressures or associated structural abnormalities (ie, mitral regurgitation).

Limitations exist for the use of MRI in critically ill neonates because of the lack of portability and the difficulties in treating occasional patients in the MRI environment. Portability is not necessarily a problem for CT or MRI in evaluation of ASD, because most patients are not usually that sick. Echocardiography provides very good results and is cheaper. In addition, no ionizing radiation is used.

DIFFERENTIALS

Section 3 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Other Problems to Be Considered

Partial anomalous pulmonary venous return
Arteriovenous canal defect
Lutembacher syndrome
Patent foramen ovale

RADIOGRAPH

Section 4 of 12  

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• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Chest radiographs usually reveal the following findings:

• Enlargement of the right atrium and ventricle may be demonstrated.
• Dilatation of the pulmonary artery and its branches may be demonstrated.
• Increased pulmonary vascular markings may be demonstrated. In general pulmonary arterial overcirculation is almost always noted when at least a 2:1 shunt is present.
• The vascular pedicle (ascending aorta and arch and SVC shadow) is small. Dilatation of the proximal portion of the SVC occasionally is noted in patients with a sinus venosus defect.
• Left atrial dilatation is extremely rare (the left atrium is decompressed by the ASD) but may be observed when significant mitral regurgitation exists. The left ventricle is normal.

Degree of Confidence

The degree of confidence is reasonably good if there are typical radiographic findings, but confirmation with echocardiography is usually necessary.

False Positives/Negatives

An ASD should be differentiated from other etiologies of acyanotic heart disease with increased pulmonary vascularity. Left atrial enlargement is seen in ventricular septal defects and patent ductus arteriosus, not in ASDs.

CT SCAN

Section 5 of 12  

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• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Ultrafast CT scans provide quite accurate findings in defining ASDs.⁸

• Transverse tomography provides clear spatial separation of the inflow and outflow portions of the atrial and ventricular septa.
• As a result of the absence of overlying structures defined on CT scans and the 3-dimensional (3D) nature of ultrafast CT acquisition, the size of the atria and ventricles can be measured.

Degree of Confidence

The degree of confidence is quite good.

False Positives/Negatives

Although many cardiac anomalies, such as septal defects, have been demonstrated using CT or ultrafast CT scans, these techniques have not found widespread use owing to the ease and the usual diagnostic superiority of 2D echocardiography and, more recently, MRI.

MRI

Section 6 of 12  

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• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

MRI has several important attributes that make it intrinsically advantageous for helping with cardiovascular diagnoses.^{9, 10, 11}

• A high natural contrast exists between the blood pool and the cardiovascular structures because of the lack of signal from flowing blood using the spin-echo MRI technique or because of the bright signal from blood using the gradient-echo (cine) MRI technique.
• A wide range of soft-tissue contrast provides the potential for the characterization of myocardial tissue.
• Imaging can be performed in any plane, including those parallel and perpendicular to the major axes of the ventricles.
• Morphologic information is provided by ECG and respiratory-gated spin-echo and cine MRI scans.
• Ventricular volumes, mass, and function can be obtained by using cine MRI scans.
• Shunt volumes, valvular function, and pressure gradients across valves and conduits can be estimated using velocity-encoded cine MRI (velocity-flow mapping).
• Since the slice thickness can be reduced to 2-3 mm, using 3D volume techniques, MRI can be used to display morphology of the heart in infants.

New capabilities of MRI include the following:

• Cine MRI can provide multiple images per cardiac cycle so that ventricular function can be evaluated.
• Velocity-encoded cine MRI allows measurement of blood flow and velocity in the aorta and pulmonary artery and across valves and conduits.
• MR angiography permits high-resolution 3D examination of vessels and can noninvasively establish the presence of anomalous pulmonary veins that lead to shunting.

Degree of Confidence

Sensitivity and specificity of more than 90% for the identification of atrial level abnormalities have been reported, including in ostia secundum and primum ASDs and anomalous pulmonary venous connections. Much of the diagnostic information provided by MRI also can be demonstrated by 2D echocardiography.

False Positives/Negatives

As has been recognized, a thin fossa ovalis can be confused with an ostium secundum ASD on static MRI images. On static images, an ASD has increased thickness of the septum at the edges of the defect, while the edges of the defect in a fossa ovalis are very thin. Avoiding this misinterpretation may be possible by using cine MRI techniques, which demonstrate a flow void extending into the right atrium due to a left-to-right shunt from the ASD.

Clinical use of MRI capabilities is influenced by the widespread application of echocardiography and Doppler techniques for many of the same purposes. Consequently, the current clinical role of MRI is to supplement information acquired by echocardiography.

The role of MRI in the evaluation of congenital heart disease is still evolving. Experience in large numbers of patients has not yet been achieved; therefore, widespread familiarity with the technique and its attributes, limitations, and indications does not exist.

ULTRASOUND

Section 7 of 12  

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• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Echocardiographic features include the following:

• Pulmonary arterial and right ventricular dilatation may be noted.
• Anterior systolic (paradoxic) or flat interventricular septal motion may be noted if significant right ventricular volume overload is present. The defect may be visualized directly by 2D echo imaging, particularly from a subcostal view of the interatrial septum.
• TEE provides excellent visualization of defects of the atrial septum.
• Associated mitral valve prolapse may be identified.
• In ostium primum ASD, 2D echocardiography is considered the standard for the diagnosis. Important features include the following:
  • Enlargement of both the right ventricle and pulmonary arteries
  • Systolic anterior ventricular septal motion
  • Prolonged mitral-septal apposition in diastole
  • Various abnormalities in mitral valve motion
• The defect is visualized easily from the precordial, apical, and subxiphoid positions, with subxiphoid views best demonstrating the relation between the atrial defect, AV valves, and interventricular septum. Interatrial septal tissue is absent in the region of the crest of the interventricular septum; the trileaflet configuration of the mitral valve also may be identified.
• The subxiphoid long-axis view of the LV outflow tract exhibits the gooseneck deformity similar to that seen on a right anterior oblique LV angiogram.
• Echocardiography is particularly useful for detecting and characterizing a double-orifice mitral valve, an association that occurs in approximately 3% of patients with ostium primum atrial defect.
• Echocardiography allows detection of single LV papillary muscle, hypoplasia of the left ventricle, and coarctation of the aorta, seen especially in symptomatic infants with an ostium primum atrial defect but without trisomy 21.

Degree of Confidence

The degree of confidence is very good. Supplemented by conventional or color-coded Doppler flow and/or contrast echocardiography, 2D echocardiography has supplanted cardiac catheterization as the confirmatory test for ASD.

False Positives/Negatives

Echocardiography may fail to provide adequate information in patients with associated structural cardiac abnormalities.

NUCLEAR MEDICINE

Section 8 of 12  

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• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Nuclear imaging may be useful in some patients for assessing cardiac function.

Equilibrium radionuclide angiocardiography

In equilibrium radionuclide angiocardiography (ERNA), ECG is used to define the temporal relation between the nuclear data and the components of the cardiac cycle. Several hundred heartbeats are sampled, accumulated, quantified, and displayed in an endless-loop cine format for qualitative visual interpretation and analysis.

Equilibrium blood pool is labeled using technetium-99m. Following a single labeling procedure, serial studies can be obtained for periods ranging from 4-6 hours. Conventional Anger scintillation cameras are used for these studies. Data from the left anterior oblique view also are used for qualitative analysis of global LV function. Using a count-based approach, the LV ejection fraction and other indices of filling and ejection are calculated by using the LV radioactivity present at various points throughout the cardiac cycle. Right ventricular function is evaluated best using first-pass techniques.

First-pass radionuclide angiocardiography

The first-pass radionuclide angiocardiography (FPRNA) technique involves sampling for only seconds during the initial transit of the bolus through the central circulation. High-frequency components of this radioactive passage are recorded and analyzed quantitatively. Analyzing right and left ventricular function independently during this brief transit is possible. Regional function also can be assessed from generated outlines of ventricular silhouettes. For the most part, technetium-99m radiopharmaceuticals are used for first-pass studies.

Alternatively, a gated first-pass technique can be used at the time of tracer injection for a subsequent equilibrium study. Right ventricular ejection fraction is a highly afterload-dependent measure. The finding of abnormal right ventricular ejection in the absence of intrinsic right ventricular disease is excellent evidence of acquired pulmonary hypertension.

Degree of Confidence

In ERNA imaging, since radioactivity is present within the entire intravascular space, it is necessary to correct for the contribution of activity in adjacent intravascular structures to the overall measured LV radioactivity. Major contributions to this background activity come from the lungs and left atrium.

False Positives/Negatives

In contrast to the equilibrium study, the choice of scintillation camera for the first-pass study (FPRNA) is critical. Instrumentation must be used that provides high sensitivity with respect to count-rate acquisition. If system linearity is lacking and major dead-time losses occur, then data are inaccurate. Several technical issues are relevant to performance of first-pass studies. The injection technique must be impeccable; it is necessary to have a compact radionuclide bolus without streaming. Injections can be made from either the jugular or the antecubital venous systems. The presence of major arrhythmia during the evaluation invalidates the data.

ANGIOGRAPHY

Section 9 of 12  

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• Ultrasound
• Nuclear Medicine
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• Intervention
• Multimedia
• References

Findings

LV angiography in the right anterior oblique view may show the characteristic gooseneck deformity in patients with a primum defect.¹²

Degree of Confidence

The degree of confidence is fair.

False Positives/Negatives

Findings in LV angiography are characteristic of ASD.

INTERVENTION

Section 10 of 12  

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• Ultrasound
• Nuclear Medicine
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• Intervention
• Multimedia
• References

ASD does not avail itself to any particular radiologic intervention. Medical and surgical treatments applicable to patients with various forms of ASD are as follows:

• Medical treatment
• • In contrast to adults, children with the sinus venosus or secundum types of ASD seldom require treatment for heart failure or antiarrhythmic medications for atrial fibrillation or supraventricular tachycardia.
  • Respiratory tract infections should be treated promptly.
  • Although the risk of infective endocarditis is low, antibiotics should be administered prophylactically before dental or other surgical procedures.
• Surgical treatment^{1, 13, 14, 15, 16}
• • Surgery should be advised for all patients with uncomplicated ASDs in whom evidence of significant left-to-right shunting exists (ie, in patients who have pulmonary flow/systemic flow ratios exceeding approximately 1.5:1.0).
  • Ideally, surgery should be performed in patients aged 2-4 years.
  • Rarely, an atrial septal aneurysm is seen in association with a secundum-type ASD. Patients may experience spontaneous closure and may be observed more conservatively until they attain an older age before advising operation.
  • The defect is closed by suture or with a patch of prosthetic material with the patient on cardiopulmonary bypass.
  • Early surgical repair is the definitive treatment for the small number of infants and young children with significant symptoms or congestive failure. The surgical mortality rate is less than 1%, and results usually are excellent. Although the mitral valve may be examined directly at operation, it seldom is necessary in childhood to attempt plication or replacement of a ballooning or prolapsing mitral valve.^{14, 17}
  • Surgery should not be performed in patients with small defects and trivial left-to-right shunts (pulmonary flow/systemic flow ratio <1.5:1.0) or in patients with severe pulmonary vascular disease (pulmonary resistance/systemic resistance ratio >0.7:1.0) without a significant left-to-right shunt.
• Transcatheter intervention
• • Still investigational is the use of transcatheter closure by way of a clamshell-configuration double umbrella or a buttoned device (Amplatzer septal occluder; AGA Medical Corp., Plymouth, Minn.) using fluoroscopic or transesophageal echocardiographic imaging guidance.^{18, 19} Intracardiac echocardiographic guidance also is used. A detailed description follows:

    There are currently 2 devices approved under humanitarian device exemption for percutaneous closure of patent foramen ovale in patients with a history of recurrent paradoxical embolus. They are the CardioSEAL (NMT Medical, Boston, Mass.) clamshell device (which we use at Tampa General Hospital) and the Amplatzer atrial device.

    1. The CardioSEAL is a double-umbrella device that is introduced through an 11F introducer. It is therefore most suitable for adults. A new model, the STARflex device, has 2 pentagonal umbrellas and is a little better at self-centering. US clinical trials are under way. Both devices have the CE mark and are widely used in Europe. While they are excellent for PFO, only small ASDs (<22 mm) may be closed with them.
    2. The Amplatzer device is a nitinol double-disk–shaped device with an absorbent center that may be introduced through an 8F introducer; it is better for children. Larger models are also good for ASD and may be used when there is a poor tissue rim, unlike with the CardioSEAL and STARflex devices.^{20, 21}

    In addition, there are 3 other devices:

    1. The ASDOS (Sulzer-Osypka, Grenzach-Wyhlen, Germany) has been used in Europe for over 10 years. It is a double-umbrella device, in which each half is introduced from a different access site. It requires both venous and arterial access and is very tricky to insert. It is rapidly being abandoned.
    2. The Buttoned Device, one of the older devices is still in use in Miami, Fla. It has 2 fabric halves that are held together with wire "buttons." The right atrial half is pushed over the buttons using a pusher to fasten the halves together. It is also being abandoned at most centers. It has never made it beyond the investigational phase.
    3. The HELEX septal occluder (W.L. Gore and Associates, Flagstaff, Ariz.) is a spiral wire and fabric device and may be placed via very small sheaths. It has a very low profile and is tricky to deploy.²²
  • Limitations of this technique include the following:
  • • Difficulties in centering the device
    • The need to use a large-sheath delivery system
    • The need to have more than a 4-mm separation between the edges of the defect and other important cardiac structures
    • The inability to close defects in which the stretched diameter exceeds 22 mm

Medical/Legal Pitfalls

• Diagnosis of ASD should be made early, and operative repair should be performed to achieve the best long-term outcome, because normal myocardial function is preserved in patients in whom defects are closed during early childhood.

Special Concerns

• In patients in whom ASDs were closed during preadolescence or later, a residual, reduced cardiac output response to exercise has been reported in the absence of residual shunts, arrhythmias, or pulmonary hypertension. Therefore, every attempt should be made to establish the diagnosis of ASD as early as possible.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Media file 1:  Atrial septal defect is demonstrated using color Doppler echocardiography.
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Media type:  Image

Media file 2:  Atrial septal defect is seen as a break in the interatrial septum (septum secundum defect).
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Media type:  Image

Media file 3:  Contrast-enhanced CT demonstrating an atrial septal defect. Courtesy of Carter Newton, MD.
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Media type:  CT

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• MRI
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

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Article Last Updated: Dec 18, 2007