Atrial Septal Defect

Background

An atrial septal defect (ASD) is one of the more commonly recognized congenital cardiac anomalies presenting in adults. It is characterized by an abnormal connection between the upper chambers of the heart, allowing for mixing of oxygenated and deoxygenated blood—thus, a defect or hole in the interatrial septum allows pulmonary venous return (oxygenated blood) from the left atrium to pass directly to the right atrium (left-to-right shunt). While often diagnosed in childhood, the clinical presentation of some ASDs may be subtle, thus delaying diagnosis until adulthood.

Other times, deoxygenated blood from the right atrium can traverse the defect and enter the systemic circulation (right-to-left shunt). Depending on the size and site of the defect, compliance/pressures of the atria and ventricles, and associated anomalies, this can result in a spectrum of disease ranging from no significant cardiac sequelae to major conditions as a result of right-sided volume overload. Small ASDs may not produce any noticeable signs or symptoms, whereas large defects may lead to significant issues with right ventricular enlargement and resultant heart failure and poor growth in childhood or pulmonary arterial hypertension and atrial arrhythmias in adulthood.

With the routine use of echocardiography, the detection and, therefore, the incidence of ASD is increased compared to earlier incidence studies using catheterization, surgery, or autopsy for diagnosis.^{[1, 2]} For some ASDs, the subtle physical examination findings and often minimal symptoms during the first 1-3 decades of life may contribute to a delay in diagnosis until adulthood. However, the majority of ASDs (>70%) are detected by the fifth decade of life. If an ASD is hemodynamically significant, earlier intervention is recommended.

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Pathophysiology

The magnitude of the left-to-right shunt across the atrial septal defect (ASD) depends on the defect size, the relative compliance of the ventricles (ie, determinates of left atrial [LA] and right atrial [RA] pressures), and the relative resistance of the ventricles (ie, in both the pulmonary and systemic circulation. With a small ASD, the LA pressure may exceed the RA pressure by several millimeters of mercury (mm Hg), whereas with a large ASD, mean atrial pressures are nearly identical. Shunting across the interatrial septum is usually left-to-right and occurs predominantly in late ventricular systole and early diastole/atrial systole. Some additional augmentation likely occurs during atrial systole; however, a transient and small right-to-left shunt can occur, especially during respiratory periods of decreasing intrathoracic pressure, even in the absence of pulmonary arterial hypertension.

The chronic left-to-right shunt results in diastolic volume loading of the right ventricle (RV) and increased pulmonary blood flow. Over time, this chronically increased blood flow will affect the pulmonary vascular resistance (PVR) and filling/geometry of the RV and interventricular septum (IVS). Often through early childhood, the volume load is usually well tolerated even though pulmonary blood flow may be more than double the systemic blood flow (Qp:Qs >2) and the PVR remains normal. However, altered ventricular compliance with age can result in an increased left-to-right shunt, contributing to higher pulmonary blood flow and symptoms of pulmonary overcirculation (eg, increased respiratory effort, fatigue, decreased exercise tolerance, poor growth). RV enlargement shifts the interventricular septum toward the left ventricle (LV) during diastole, which will then decrease LV filling and may raise LV end-diastolic pressure, causing lower cardiac output and increased left-to-right shunting.^[3]

A chronic, significant left-to-right shunt can permanently alter the PVR, leading to pulmonary arterial hypertension and, eventually, reversal of shunt (now becoming right to left), also known as Eisenmenger syndrome.

Owing to an increase in plasma volume during pregnancy, shunt volume can increase, also leading to symptoms. However, pulmonary artery pressures usually remain normal.

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Etiology

Atrial septal defects (ASDs) are a congenital cardiac disorder caused by the spontaneous malformation of the interatrial septum. Embryologically, there are three tissue planes that eventually fuse to septate the atria: the septum primum, the septum secundum, and the atrioventricular (AV) canal septum (ie, the endocardial cushions that separate the atria and the ventricles). Initially, there is a common atrium, and the septum primum arises from the superior surface and grows inferiorly toward the AV canal septum. The fusion between these two structures closes the orifice (ostium primum), separating the right and left atria. In addition, the septum secundum forms, arising as an invagination from the rightward aspect of the atrial wall. Defects in the atrial septum result from abnormalities of this process.

Note the following types of ASD:

• Patent foramen ovale: This type of ASD results from a residual flap connection between the septum primum and the septum secundum. The septum secundum grows leftward until the seventh week of gestation and then stops before completely fusing with the septum primum, leaving a posterior and inferior gap known as the fossa ovalis. This connection is normal in all fetuses, allowing oxygenated umbilical venous blood to traverse the atrial septum into the left side of the heart for ejection to the systemic circulation. After birth, left atrial pressures increase due to the expansion of the lungs and higher systemic vascular resistance. This pushes the flap closed and many seal shut. However, approximately 25% of foramen ovales remain patent into adulthood.^[4]
• Ostium secundum ASD: Before the septum primum can completely fuse with the AV canal septum, small perforations develop and coalesce in the superior portion of the septum primum, leading to a secundum ASD. The combination of excessive resorption of the septum primum from apoptosis and incomplete development of the septum secundum produce a large ostium secundum ASD.
• Ostium primum ASD: These defects are caused by incomplete fusion of septum primum with the endocardial cushion. The defect lies immediately adjacent to the AV valves, either of which may be deformed and incompetent. In most cases, only the anterior or septal leaflet of the mitral valve is displaced, and it is commonly cleft. The tricuspid valve is usually not involved.

The remaining two defects do not actually involve a true defect in the interatrial septum but physiologically behave similarly, allowing for atrial mixing of blood:

• Sinus venosus ASD: Abnormal fusion between the embryologic sinus venosus and the atrium causes these defects. In most cases, the defect lies superior in the atrial septum near the entry of superior vena cava. Often there is associated anomalous drainage of the right superior pulmonary vein. The relatively uncommon inferior type is associated with partial anomalous drainage of the right inferior pulmonary vein. Anomalous drainage can be into the right atrium, the superior vena cava, or the inferior vena cava.
• Coronary sinus ASD: The coronary sinus defect is characterized by unroofed coronary sinus and persistent left superior vena cava that drains into the left atrium. A dilated coronary sinus often suggests this defect. This can result in desaturation due to right-to-left shunt into the left atrium. The diagnosis can be made by injecting a contrast agent into the left upper extremity; coronary sinus opacification precedes right atrial opacification.

Genetics

ASD may occur on a familial basis. Holt-Oram syndrome, characterized by an autosomal dominant pattern of inheritance and deformities of the upper limbs (most often, absent or hypoplastic radii), has been attributed to a single gene defect in TBX5.^[5]  The penetrance is nearly 100% for Holt-Oram syndrome. Approximately 40% of Holt-Oram cases are due to new mutations. An estimated 58% of individuals with Holt-Oram syndrome have ASD.^[2]

Ellis van Creveld syndrome is an autosomal recessive disorder associated with skeletal dysplasia characterized by short limbs, short ribs, postaxial polydactyly, dysplastic nails and teeth, and a common atrium, occurring in 60% of affected individuals.^[6]

Mutations in the cardiac transcription factor NKX2.5 have been attributed to the syndrome familial ASD associated with progressive atrioventricular block.^{[7, 8, 9]} This syndrome is an autosomal dominant trait with a high degree of penetrance but no associated skeletal abnormalities.

Variants in the GATA4 gene have also been implicated in ASD.^{[8, 10]} Relatively recently, a novel mutation at the methylation position of GATA4 (c.A899C, p.K300T) was reported in association with ASD.^[10]

Wang et al reported that downregulation of the following genes in ASD may affect heart atrial septum formation, cardiomyocyte proliferation, and cardiac muscle development^[8] :

• Cardiac specific transcriptional factors GATA4 and NKX2-5
• Extracellular signal molecules VEGFA and BMP10
• Cardiac sarcomeric proteins MYL2, MYL3, MYH7, TNNT1, and TNNT3

The investigators noted that dysregulation of these genes during heart septum morphogenesis may lead to cell cycle as the dominant pathway among downregulated genes, with the potential for the decreased expression of the proteins included in the cell cycle then disturbing cardiomyocyte growth and differentiation during atrial septum formation.^[8]

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Epidemiology

In the last half century, there has been an increasing prevalence of congenital heart disease and atrial septal defects (ASDs), with the former diagnosed in an estimated 9 per 1000 live births and the latter in 1.6 per 1000 live births.^[2]  

The three major types of ASD account for 10% of all congenital heart disease and as much as 25-30% of congenital heart disease presenting in adulthood.^[11] The most common types of ASD include the following:

• Ostium secundum: The most common type of ASD accounting for 80% of all ASD cases,^{[11, 12]} representing approximately 7% of all congenital cardiac defects and 30-40% of all congenital heart disease in patients older than 40 years.
• Ostium primum: The second most common type of ASD accounts for 15-20% of all ASDs.^{[11, 12]} Primum ASD is a form of atrioventricular septal defect and is commonly associated with mitral valve abnormalities.
• Sinus venosus: The least common of the three, sinus venosus (SV) ASD is seen in 5-6% of all ASDs.^{[11, 12]}  The defect is located along the superior aspect of the atrial septum. Anomalous connection of the right-sided pulmonary veins is common and should be expected. Alternate imaging is generally required.

Sex- and age-related demographics

ASD occurs in about 25% of children.^[2] There is a female-to-male ratio of approximately 2:1. The recurrence rate of ASD in the offspring of women with ASD is 4-6%; in males with ASD, it is 1.5-3.5%.^[12]

Patients with ASD can be asymptomatic through infancy and childhood, although the timing of clinical presentation depends on the degree of left-to-right shunt. Symptoms become more common with advancing age. By age 40 years, 9 in 10 untreated patients exhibit exertional dyspnea, fatigue, palpitations, sustained arrhythmia, or indications of heart failure.^[13]

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History

The atrial septal defect (ASD) malformation can go undiagnosed for decades due to subtle physical examination findings and a lack of symptoms.^{[2, 12]} 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.

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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. Fixed splitting of S₂ is the classic distinguishing physical exam feature of ASD.
• 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 mid-diastolic 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

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Laboratory Studies

No specific laboratory blood tests are required in the workup of atrial septal defects (ASDs), although plasma B-type natriuretic peptide (BNP) levels have been positively correlated with the degree of shunting present.^[14]

Routine laboratory studies should be performed in patients undergoing intervention for ASD, such as the following:

• Complete blood cell (CBC) count
• Type and screen
• Metabolic profile or chemistry panel
• Coagulation studies (prothrombin time [PT] and activated partial thromboplastin time [aPTT])

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Imaging Studies

Chest radiography

In the presence of a clinically significant left-to-right shunt, chest radiographs most often show cardiomegaly because of dilatation of the right atrium and right ventricular chambers.

The pulmonary artery is prominent, and pulmonary vascular markings are increased in the lung fields.

Left atrial enlargement is rare, generally occurring only if another lesion is present, such as clinically significant mitral regurgitation. On occasion, proximal dilatation of the superior vena cava can be seen in sinus venosus defect.

Echocardiography

Echocardiography is the first-line imaging modality in congenital heart disease.^[12]

Transthoracic (TTE) and transesophageal echocardiography (TEE)

The preferred imaging modality is TTE, and, if needed, TEE (often in conjunction with 3-dimensional [3-D] echocardiography).

An uncertain diagnosis can be clarified with 2-D TTE, which provides direct noninvasive visualization of most types of atrial septal defects (ASDs), including evaluation of the right atrium, right ventricle, and pulmonary arteries, as well as other associated abnormalities, and is thus the gold standard for assessment of ASDs.^[2] The subcostal view is often the most beneficial. One exception is the diagnosis of a sinus venosus defect, for which TEE—or advanced imaging with cardiac magnetic resonance (CMR) imaging or cardiac computed tomographic angiography (CTA)—may be needed to image the defect and associated lesions like anomalous pulmonary veins. TEEs and an echocardiogram are shown below:

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Atrial Septal Defect. Parasternal short axis: Right ventricular (RV) dilatation with RV pressure overload as evidenced by flattening of the interventr....

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Atrial Septal Defect. Transesophageal echocardiogram: Moderate-large atrial septal defect with left-to-right shunt across the interatrial septum. Ao =....

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Atrial Septal Defect. Apical four-chamber view. ASD = atrial septal defect; LA = left atrium; RA = right atrium; RV = right ventricle; TR = tricuspid ....

In any patient with an ASD, particularly a sinus venosus defect, seek out anomalies of systemic and pulmonary venous connections. These can be clearly identified by 2-D imaging. Right atrial and right ventricular enlargement without identification of the cause should prompt consideration of additional imaging or other modalities to ascertain the cause. TTE may be suboptimal in some patients with poor echocardiographic windows. In such patients, TEE can provide excellent definition of the atrial septum.

TEE is also useful in guiding device placement during catheter ASD occlusion procedures and in providing immediate intraoperative assurance that defect closure is accomplished. Real-time 3-D TEE can also provide detailed and precise information regarding the selection of the appropriate occluder device, as well as facilitate the transcatheter occlusion by guiding the catheter through the often challenging patient anatomy.^[15]

In a retrospective study that analyzed data from 83 patients with ASD and a dilated right ventricle who underwent transcatheter closure as well as 3-D echocardiography and cardiac magnetic resonance imaging (CMRI) to assess the accuracy of shunt volume of these modalities compared with that of 2-D pulsed Doppler quantification and of the gold standard 2-D phase contrast (2-DPC) CMRI, Yanagi et al found a more accurate assessment of the pulmonary flow (Qp)–to–systemic flow (Qs) ratio (Qp:Qc) with full-volume volumetric 3-D echocardiography than by full-volume volumetric CMR or 2-D pulsed Doppler.^[16]

Contrast echocardiography

Contrast echocardiography (primarily agitated saline, but commercial microbubble preparations are available) can provide additional confirmation of the presence of a shunt lesion. With Valsalva maneuvers or just with transiently increasing right atrial volume/pressure, one can visualize evidence of a right-to-left shunt by visualizing microcavitation bubbles appearing "early" in the left atrium and the left ventricle (after 1-2 beats). Note: If the microcavitation bubbles only appear "late" in the left atrium, (after ≥3 beats), consider pulmonary arteriovenous malformations as the cause, rather than an ASD. A left-to-right shunt can be detected as a negative contrast washout effect in the right atrium.

Color Doppler echocardiography

Color Doppler echocardiography is also helpful in demonstrating flow across the atrial septum. It typically shows a biphasic (systolic and diastolic) pattern with a small right-to-left shunt at the beginning of systole. Pulse wave (PW) or continuous wave (CW) Doppler can help determine the relative pressure differences between the atria. Doppler echocardiography is valuable for estimating right ventricular (and pulmonary arterial when there is no associated right ventricular outflow tract obstruction) systolic pressure when a tricuspid regurgitant jet is present. This technique is also useful in evaluating patients for obstruction to pulmonary venous return.

CMRI and computed tomography (CT) scanning

CMRI has successfully been used to identify the size and position of ASD. However, its utility is limited for small defects. A major advantage of MRI is the ability to quantify right ventricular size/volume and function. Using flow quantification techniques, one can also compute Qp:Qs to quantify the magnitude of the shunt. Furthermore, MRI and MR angiography have the ability to not only identify the systemic and pulmonary venous return but also measure pulmonary arterial sizes.

Likewise, CT scanning can precisely define systemic and pulmonary venous return, but it only provides qualitative information about right heart chamber sizes. With its higher spatial resolution, CT scanning may be better at defining the anatomic characteristics of some ASDs compared with MRI. However, by its very nature, this modality does expose the patient to some ionizing radiation.

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Other Tests

Electrocardiography

Characteristic findings in patients with secundum atrial septal defect (ASD) are a normal sinus rhythm, right-axis deviation, and an rSR' pattern in V_1, an interventricular conduction delay or right bundle branch block (which represents delayed posterobasal activation of the ventricular septum and enlargement of the right ventricular outflow tract).

Left-axis deviation and an rSR' pattern in V_1, an interventricular conduction delay or right bundle branch block suggests an ostium primum defect. Left-axis deviation and negative P wave in lead III suggest sinus venosus defect.

Increasing pulmonary hypertension can cause loss of the rSR' pattern in V₁ and a tall monophasic R wave with a deeply inverted T wave.

A prolonged P-R interval can be seen in familial ASD or ostium primum secondary to left atrial enlargement and an increased distance for internodal conduction produced by the defect itself. Displacement of the AV node in a posteroinferior direction in some patients or an enlarged right atrium has also been reported.

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Procedures

When noninvasive techniques demonstrate the presence of an uncomplicated atrial septal defect (ASD) in a child, routine cardiac catheterization for diagnosis is unnecessary.

However, cardiac catheterization may be useful if the clinical data are inconsistent, if clinically significant pulmonary arterial hypertension is suspected, or if concurrent coronary artery disease must be assessed in patients older than 40 years. Catheterization is also a viable alternative for intervention for secundum ASD.

The diagnosis of ASD may be confirmed by directly passing the catheter through the defect. Note the following:

• Serial oxygen saturation measurements can be used to estimate the magnitude of the shunt.
• In young patients, right heart pressures are often normal despite a large shunt.
• If high oxygen saturation is present in the superior vena cava or if the catheter enters a pulmonary vein directly from the right atrium, sinus venosus type is likely.
• Partial anomalous pulmonary venous return is usually associated with sinus venosus defect, but it may also accompany the ostium secundum type.

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Approach Considerations

Atrial septal defect (ASD) is a disorder to be addressed surgically or through transcatheter percutaneous closure.^[17] No specific or definitive medical therapy is available. However, patients with significant volume overload or atrial arrhythmias may require specific pharmacologic therapy, such as diuretics or antiarrhythmics.

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Surgical Indications and Contraindications

Indications

The decision to repair any kind of atrial septal defect (ASD) is based on clinical and echocardiographic information, including the size and location of the ASD, the magnitude and hemodynamic impact of the left-to-right shunt, and the presence and degree of pulmonary arterial hypertension. In general, elective closure is advised for all ASDs with evidence of right ventricular overload or with a clinically significant shunt (pulmonary flow [Qp]–to–systemic flow [Qs] ratio >1.5^[2] ). Lack of symptoms is not a contraindication for repair.

In childhood, spontaneous closure of secundum ASD may occur. However, in adulthood, spontaneous closure is unlikely. Patients may be monitored relatively conservatively for a period before intervention is advised. Considerations and even contraindications to consider no intervention include small size of the defect and shunt, severe pulmonary arterial hypertension, diagnosis during pregnancy (intervention can be deferred until after), severe left or right ventricular dysfunction. Guidelines for the management of adults with congenital heart disease are available.^[18]

For both children and adults, surgical mortality rates for uncomplicated secundum ASD are < 1%.^[11] Because of the lifetime risk associated with ASD, as outlined including paradoxical embolization, there should be ongoing evaluation and review of the indication and risks for closure, even for patients with small shunts. However, such closure remains controversial, because patients with small defects generally have a good prognosis, and the risk of cardiopulmonary bypass may not be warranted. The widespread use of catheter closure of secundum ASD with lower mortality and without cardiopulmonary bypass has raised the question regarding the need to close even small defects.

Long-term prevention of death and complications is best achieved when the ASD is closed before age 25 years and when the systolic pressure in the main pulmonary artery is less than 40 mm Hg. Even in elderly patients with large shunts, surgical closure can be performed at low risk and with good results in reducing symptoms.

Either method of closure, whether transcatheter or surgical, results in excellent hemodynamic outcomes with no significant differences with regard to survival, functional capacity, atrial arrhythmias, or embolic neurologic events.^[19] However, atrial arrhythmia and neurologic events remain long-term risks particularly for patients with preexisting events.^[20] Moreover, independent risk factors for unsuccessful transcatheter closure include smaller retroaortic and inferior rims and the morphologic atrial septal variation of malattached septum primum (MASP).^[21]

Contraindications

Closure of an ASD is not recommended in asymptomatic patients with a clinically insignificant shunt (Qp-Qs ratio < 1.5) and certainly not in those who have severe pulmonary arterial hypertension or irreversible pulmonary vascular occlusive disease who have a reversed shunt with at-rest arterial oxygen saturations of less than 90% (Eisenmenger syndrome). In addition to the high surgical morbidity and mortality risk, closure of a defect in the latter situation may worsen the prognosis by removing the "pop-off" for the RV. Whether the patient whose condition is diagnosed well in the sixth decade of life would benefit from surgical closure remains controversial. However, newer data suggest this age group may also experience significant clinical and hemodynamic improvement from shunt closure, even into their seventh decade.^[22]

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Surgical Care

Criterion standard

The classical surgical approach to an atrial septal defect (ASD) is direct closure of the defect by using an open approach with extracorporeal support. John Gibbon performed the first successful ASD closure by applying this method in 1953. Surgical techniques and equipment have since improved to the point that the mortality rate from this repair approaches zero.^{[23, 24, 25]}

In the usual procedure, a median sternotomy incision is made, and the sternum is split in the midline. Direct arterial and double venous (superior vena cava and inferior vena cava) cannulation are performed. Upon applying cardiopulmonary bypass, the aorta is clamped, and the heart is arrested with a cardioplegia solution. The caval snares are tightened, and the right atrium is opened. Most secundum defects can be closed primarily, using a direct continuous suture of 3-0 or 4-0 polypropylene (Prolene). Some, however, require patch closure.

Caution must be taken when large defects are closed primarily with sutures, because this closure can pucker or distort the atrium, leading to hemodynamic problems or even distortion of the aortic annulus. These ASDs are best closed by using autologous pericardium or synthetic patches made of polyester polymer (Dacron) or polytetrafluoroethylene (PTFE). Care must be taken to completely remove any air or debris from the left atrium and ventricle before cardiopulmonary bypass is discontinued. Depending on the clinical circumstances, temporary pacing wires may be left in place on the right atrium/appendage or ventricle before the chest is closed over the drains.

In an ostium primum defect, surgical closure is more complicated. The patch must be attached to the septum at the juncture of the mitral and tricuspid valves. Mitral valve repair, including closure of the cleft/zone of apposition in the anterior mitral leaflet and, possibly annuloplasty, may be necessary to correct or prevent mitral insufficiency. In rare cases, mitral valve replacement may be required.

In a sinus venosus defect, partial anomalous pulmonary venous return is common, especially for superior/SVC type sinus venosus defects. One or more of the pulmonary veins primarily drains into the right atrium or SVC. The ASD must be patched in such a way as to ensure that the anomalous pulmonary venous drainage is diverted into the left atrium. This patching may be simple or complex, depending on where the anomalous drainage enters. Many innovative techniques have been developed to redirect pulmonary venous flow, and the surgeon should be familiar with several approaches. Pulmonary venous return must not be compromised with the redirection because this invariably causes localized pulmonary venous hypertension.

Minimally invasive approaches

Minimally invasive approaches to the repair of ASD continual to garner significant interest, principally for incisional cosmetic reasons. In most cases, the size of the incision is simply decreased with different approaches to cardiopulmonary bypass. Examples include partial or full submammary skin incision, hemisternotomy, and limited thoracotomy. Surgeon preference and ability to adequately visualize the lesion and cannulate for cardiopulmonary bypass will determine this approach.

Totally endoscopic minimally invasive surgery may be a potential alternative to catheter-based intervention for ASD in patients with an unfavorable anatomy or clinical contraindications.^[26] A retrospective study (2011-2015) that assessed the outcomes of totally endoscopic closure with a glutaraldehyde-treated autologous pericardial patch in 37 Japanese patients with ASD who were deferred from transcatheter intervention found excellent results. The investigators reported no operative deaths nor postprocedure reinterventions for ASD or readmission for heart failure, and follow-up echocardiography did not demonstrate recurrent shunt or calcification of the autologous pericardial patch.^[26]

Percutaneous transcatheter closure

In relatively recent times, secundum ASD have been closed by using a variety of catheter-implanted occlusion devices rather than by direct surgical closure with cardiopulmonary bypass.^[17] Although surgical closure is associated with low morbidity and mortality and excellent long-term results, sternotomy and cardiopulmonary bypass are required, thus driving the interest in a percutaneous option.^[27] ​ These devices are placed percutaneously, usually through a femoral venous approach and are deployed like an umbrella or clamshell with discs on both the left and right atrial side to seal/occlude the septal defect. Procedural guidance is accomplished using a combination of angiographic and TEE and/or 3D echocardiographic techniques. These devices work best for centrally located secundum defects.

Drs King and Mills performed the first transcatheter closure of a secundum ASD in 1976. William Rashkind pioneered the development of percutaneous ASD closure technique in late 1970s. Jim Lock developed the clamshell method in 1989. Around the same time, Sideris started clinical trials with a buttoned device.

Many different transcatheter ASD devices are available and come in a variety of sizes. There has generally not been much change to the basic delivery system of these occluder devices over the last 2 decades or so, with some that can use any available delivery sheath for device delivery and others that need a dedicated delivery system as part of the devices.^[28] Some examples are Amplatzer septal occluder (ASO), CardioSEAL, HELEX septal occluder, Gore septal occluder, and StarFlex devices. First introduced in 1995, the family of Amplatzer septal occluder devices (the ASO and its cousins the PFO Occluder and Cribiform occluder devices) remain the most widely used devices because of ease of implant and its track record for excellent procedural success among a range of orifice sizes and anatomic locations.

Selection of a particular device is difficult because no randomized trials have been conducted to compare designs and outcomes. The risk of device dislodgment, embolization, thrombus formation, erosion, and residual shunt leak has decreased with improvements in operator experience and improved delivery systems and imaging. Importantly, transcatheter devices are currently only indicated in patients with ostium secundum defects; they are not amenable to percutaneous closure of ostium primum, coronary sinus, or sinus venosus defects.^[2]

With this method, during the procedure, the static diameter of the defect is first assessed by using transesophageal echocardiography (TEE). The diameter is then measured with a sizing balloon using the “stop-flow” technique to select the proper diameter of the device. Using this technique, the sizing balloon is inflated until no flow is visible through the defect using TEE. There must be adequate tissue "rims" around the defect (usually superiorly, inferiorly, and by the aorta) to allow the retention discs to keep the device in stable and good position. The dimensional requirements for how much tissue rim is needed vary, depending on device type and operator experience. TEE has been the mainstream technique for device sizing, positioning, and deployment. However, for these procedures, often airway protection and general anesthesia are required. Intracardiac echocardiography has been used for the same purpose.

At any age, ASD closure is followed by symptomatic improvement and regression of positive airway pressure (PAP) and right ventricle size; however, the best outcome is achieved in patients with less functional impairment and less elevated PAP.^[29] Considering the continuous increase in symptoms, right ventricle remodeling, and PAP with age, ASD closure must be recommended irrespective of symptoms early after diagnosis, even in adults of advanced age.^[22]

Furthermore, transcatheter closure appears to have additional benefits regarding hemodynamic improvement compared with surgery. In one study, transcatheter closure with the Amplatzer septal occluder improved the left atrial volume index, the left ventricular myocardial performance index, and the right ventricular myocardial performance index.^[30] The last index was unimpressive after surgery, possibly because of cardiopulmonary bypass.

Another group compared atrial function in 45 patients with a mean age of 9 years after surgery and after percutaneous closure by using strain-rate imaging.^[31] They found that both atrial functions were preserved after transcatheter closure, whereas the same was not seen after surgery. A potential explanation was that an atriotomy scar might have negatively influenced right atrial function, whereas perioperative hypoxia or intraoperative myocardial damage might have altered the deformation properties of the left atrium.

In a study of mid- to long-term follow-up results of successful transcatheter ASD closures in 179 patients older than 40 years, investigators reported improvements in New York Heart Association (NYHA) functional class, pulmonary artery pressure, and cardiac rhythm.^[32] The study covered an 8.8 year period, with a median follow-up of 3.8 ± 2.1 years.

Transcatheter closure of ASDs is now an established practice at most cardiac centers. It is proven safe in experienced hands, it is cost-effective, and it favorably compares to surgical closure with successful implantation rates of more than 96%. Transcatheter closure has been associated with fewer complications, shortened hospitalization, and reduced need for blood products, compared with surgery. A Montreal group found that although transcatheter ASD closure conferred a higher reintervention rate at 5 years (7.9% vs 0.3%), most occurred soon after the procedure and the long-term mortality was similar.^[33]  Thus, the investigators concluded that transcatheter ASD closure is not inferior to surgery, and they believe these data support the practice of using transcatheter ASD closure in the majority of eligible patients.

• References

Postoperative Details

Postsurgical closure of an ASD

Postoperative management after atrial septal defect (ASD) repair is usually standard. Patients are expected to be awake and often extubated shortly after the operation. Drainage tubes are removed from the chest the first morning after surgery, and, except when rhythm problems occur, the pacing wires are removed shortly thereafter. Most patients can eat and ambulate without difficulty on the first postoperative day, and most are discharged by the third or fourth postoperative day. Six months of treatment with an antiplatelet agent like aspirin with or without clopidogrel is recommended to prevent thrombus formation. Endocarditis prophylaxis is indicated for 6 months post procedure assuming no residual shunt is present.

Postcatheter closure of an ASD

Similar to surgical patients, postcatheterization patients will typically be extubated immediately postprocedure and remain hospitalized the night after the catheterization for observation. They are expected to be discharged home the next day. Likewise, at least 6 months of treatment with an antiplatelet agent like aspirin is recommended to prevent thrombus formation. Some centers will even continue antiplatelet therapy for 1-2 years to ensure complete device endothelization. Endocarditis prophylaxis is indicated for 6 months post procedure assuming no residual shunt remains.

• References

Follow-up

Follow-up depends on the method of atrial septal defect (ASD) closure as well coexisting cardiac issues such as arrhythmias, ventricular dysfunction, and comorbidities. Surgical follow-up care is maintained until the patient's wounds are completely healed and normal activities can be resumed; this period rarely exceeds 2-3 months. Postpericardiotomy syndrome (Dressler syndrome) symptoms (fever, chest pain, electrocardiographic changes, pericardial effusion, presence of rub on examination) may be more common after surgical ASD closure than for other cardiac surgical procedures.

For patients who underwent transcatheter-closure, different manufacturers offer different approaches to postprocedure follow-up. It is common to observe a patient overnight after transcatheter closure for clinical and echocardiographic follow-up the day after implantation to rule out possible procedural complications, pericardial effusion, or device embolization. Many centers advocate for reevaluation at 7-10 days and then at 1 month postprocedure, as well at 6-12 months. Beyond that, a cardiologist with congenital experience should continue patient care to monitor for recurrence of the shunt and to ensure that the patient remains free of complications such as endocarditis, arrhythmias, poor cardiac function or pulmonary hypertension. For most patients, an appointment every 1-3 years after the immediate postoperative period is adequate, in large part to follow and evaluate for the aforementioned possible complications. However, the evaluation and recommended interval varies, depending on the anatomic and physiologic stage, per the American Heart Association and American College of Cardiology guidelines.^[34]

• References

Complications

Surgery for an atrial septal defect (ASD) may be associated with a long-term risk of atrial fibrillation or flutter. The risk of infective endocarditis exists, primarily during the first 6 months after surgery. The following complications are also associated with ASD):

• Congestive heart failure
• Arrhythmias
• Pulmonary hypertension
• Cyanosis
• Paradoxical embolization
• Stroke
• Infective endocarditis

The following complications are specifically associated with the use of transcatheter occlusion devices:

• Device embolization and malpositioning: The incidence significantly varies among devices and is related to operator experience and appropriate case selection. With experienced clinicians, the incidence is less than 1%. Device embolization and malpositioning happens as a result of inadequate sizing of the defect or incorrect device placement.
• Postimplantation arrhythmias: The incidence is 1-4% and varies from first- to third-degree AV block and atrial fibrillation. These arrhythmias are usually short-lived and do not require medical treatment. Patients who develop complete heart block are typically hemodynamically stable and do not require pacing. The incidence of arrhythmia appears to be related to the size of the device.
• Thrombus formation: A study of 1000 patients was performed to investigate the incidence of thrombus by performing TEE at 4 weeks and 6 months after the procedure.^[35] The overall incidence was 1.2%; 70% were found at 4 weeks. The lowest incidence was with ASO. Thromboembolic events were seen in 20% of patients with thrombus. In 80-85%, thrombus resolved with heparin and warfarin. Risk factors for thrombogenesis on the device were the type of device, postprocedural atrial fibrillation, incomplete neoendothelialization of the surface of the device, insufficient antithrombotic treatment, and previously undiagnosed hypercoagulability disorders (including aspirin resistance and persistent interatrial septal aneurysm). For prophylaxis, aspirin given for 6 months is a common practice. When combined with clopidogrel, no thrombus was noted at 4 weeks and 6 months in one study of 37 patients.^[36]
• Cardiac perforation: The incidence is 0.1-0.4% for various devices. Oversizing of the device and deficient anterosuperior rims are risk factors for perforation. Technique-related perforation during the procedure is amenable to intervention. Approximately 70% of device-related perforations after technically adequate procedures occur after hospital discharge. A retrospective review of 24 patients revealed that all presented with chest pain, shortness of breath, hemodynamic collapse, or sudden death.^[37] About 76% were female patients, and 70% of the perforations were late. If pericardial effusion is present on predischarge echocardiography, the patient should be hospitalized for 24-48 hours of observation and follow-up echocardiography.^[37]
• Device erosion: Erosion of septal occluder devices occurs in 0.1-0.15% of implants.^[38] Nearly all erosions occur at the dome of atria near the aortic root. Risk factors are a deficient aortic rim and/or superior rim and use of an oversized device. Aortic–right atrial fistula may be the consequence. Although device erosion is rare, the mortality rate is 10%.
• Increased levels of cardiac troponin I: Transcatheter closure induces minor myocardial lesions, the extent of which depends on the size of the ASO. The patient's age is not a factor.^[39]
• Residual shunts: As many as 20% of patients may have a residual shunt persist for 24 hours after the procedure; over 90% of such residual shunts are small. During follow-up, the incidence approaches 0% at 3 years for most series.^{[40, 41]}
• Other complications include pericardial effusion, transient ischemic attack/cerebral vascular event, and sudden death.

• References

Outcome and Prognosis

Natural history

Although life expectancy is not normal for patients with untreated atrial septal defects (ASDs), patients generally survive into adulthood without surgical or percutaneous intervention, and many patients live to an older age. However, natural survival beyond age 40-50 years is less than 50%, and the attrition rate after age 40 years is about 6% per year. Advanced pulmonary hypertension seldom occurs before the second to third decade. Late complications are stroke and atrial fibrillation.

In a study that assessed the lifelong burden of small, unrepaired ASD using data from 723 patients from the Danish National Patient Registry, Udholm confirmed affected individuals have a shorter lifespan, more chronic diseases (especially pulmonary disease, such as pneumonia; stroke; atrial fibrillation), lower exercise tolerance, and greater levels of stress relative to the general population.^[42] Death was most often from heart failure. In a separate study, these investigators analyzed data from 151 patients from the same nationwide registry who had an unrepaired ASD and no documented history of atrial fibrillation and found occult arrhythmias of both atrial and ventricular tachyarrhythmias, which they believed could be due to residua from previous right heart volume overload and incomplete reverse modeling.^[43]

Postsurgical prognosis

Available data on survival of patients with congenital heart disease indicates that they have a lower life expectancy than their healthy counterparts.^[44] However, for postintervention ASD patients, the mortality rate of surgical repair is less than 1%^[45] for patients younger than 45 years without heart failure and who have systolic pulmonary artery pressures less than 60 mm Hg. The morbidity rate is low. The surgical mortality rate increases with increasing age and pulmonary artery pressures.

Surgical repair should be considered for all patients with uncomplicated ASDs with a clinically significant left-to-right shunt. Such repair is ideally completed at age 2-4 years. Early surgical repair is considered in a few infants and young children with clinically significant symptoms or congestive heart failure (CHF).

Surgery before the age 25 years results in a 30-year survival rate comparable to that of age- and sex-matched control subjects. However, at age 25-40 years, surgical survival is reduced, although not significantly if pulmonary artery pressures are normal. If pulmonary artery systolic pressure is higher than 40 mm Hg, late survival is 50% less than that of control rates, although life expectancy in surgically treated older patients is better than that of medically treated patients. Even in select patients older than 60 years with no serious comorbidities, ASDs should be closed as early as possible if an indication is present because surgery improves symptoms–at least in the short term–regardless of pulmonary artery pressure or functional class, as long as the left-to-right shunt remains large.

Although surgical closure of ASDs in adulthood is associated with a significant mortality benefit, its benefit is limited in preventing atrial arrhythmias. The patient's age at the time of closure is the most important predictor of the development of atrial arrhythmia.

In a 2023 review of cause-specific mortality of Finnish patients with simple atrial septal defects (ASD) and up to 50 years of follow-up (1969-2019), Muroke et al noted a higher overall mortality during follow-up not only among these patients compared with their five matched control subjects but also among those who had closed ASDs.^[24] Significantly more deaths occurred due to congenital malformations, other circulatory system diseases, stroke, endocrine and respiratory system diseases, ischemic heart disease, and accidents. The investigators found no mortality difference if the defect was closed before age 30 years.^[24]  

Surgery for sinus venosus ASD is also associated with low morbidity and mortality, and postoperative subjective clinical improvement occurs irrespective of the patient's age at surgery. However, in contrast to ostium secundum ASD, surgery for sinus venosus defect is relatively complex and poses the risks of stenosis of the superior vena cava or pulmonary veins, residual shunting, and dysfunction of the sinoatrial node.

In childhood, right ventricular dimensions decrease, often strikingly, after surgery. However, when adults undergo surgery, the dimensions remain abnormal in approximately 80% of patients. If right ventricular failure and tricuspid regurgitation are present before surgery, late postoperative right atrial and ventricular enlargement is typical, and right ventricular systolic function seldom normalizes. Patients in this situation improve, but they usually remain symptomatic, and their preoperative pulmonary vascular resistance influences their long-term outcome.

A few patients who undergo surgical closure during childhood have late-onset supraventricular arrhythmias, which are believed to be related to patchy fibrosis of the right atrium secondary to dilatation and perhaps dysfunction of the sinus node. In adults, chronic preoperative atrial fibrillation usually persists after surgical repair, but cardioversion followed by antiarrhythmics treatment may be effective. If surgery is performed in patients older than 40 years, the prevalence of atrial arrhythmias is 40-60%.^[12] Indeed, 50% of those with preoperative normal sinus rhythm have late postoperative atrial fibrillation. Intracardiac electrophysiologic studies have shown a high incidence of intrinsic dysfunction of the sinoatrial and AV nodes that persists after surgical repair. These nodal abnormalities are most common in the sinus venosus type than in the secundum type.

Late events, including atrial fibrillation, stroke, and heart failure, are most common in patients undergoing repair in adulthood. This observation emphasizes the benefit of early repair of secundum ASDs in symptomatic patients. The unfavorable prognosis of late repairs is presumably related to long-standing deleterious effect of volume overload on the chambers on the right side, of pulmonary hypertension, and of right atrial enlargement with increased vulnerability to atrial arrhythmias and stroke. About 22% of late deaths are attributed to cerebrovascular events. Older age at repair and preoperative New York Heart Association class III or IV heart failure are independent predictors of late mortality. They are also predictive of atrial fibrillation, for which sinus node dysfunction with bradycardia-dependent atrial arrhythmias, scar-dependent multiple reentries, and atrial enlargement or atrial fibrosis due to increased pulmonary venous pressure with exercise are implicated as potential mechanisms.

In a cohort of 300 minimally symptomatic patients at intervention with either surgical or transcatheter closure, long-term follow-up (median 10 years) shows maintained functional class, but continued arrhythmia risk associated with age at procedure and pre-existing arrhythmia. When controlling for these variables, there was a trend toward more arrhythmia in the surgical cohort. However, embolic events were more common in the transcatheter cohort.^[20]

Prognosis after transcatheter closure

See Surgical Care.

Common comorbidities

Pulmonary hypertension

Pulmonary hypertension (mean pulmonary artery pressure >20 mm Hg or systolic pulmonary artery pressure >50 mm Hg) occurs in 15-20% of patients with ASD. This condition is unusual in young patients, but it is observed in 50% of patients older than 40 years.

In Eisenmenger syndrome—a late and rare complication of isolated secundum ASD that occurs in 5-15% of patients—extreme pulmonary obstruction may result in a reversal of the shunt of blood to a right-to-left flow. Desaturated blood entering the systemic circulation results in systemic hypoxemia and cyanosis.

Right-sided heart failure

Heart failure is due to the cardiac volume overload experienced on the right side of the heart because of left-to-right shunting. In patients of all ages, substantial relief of such a complication is generally observed after the defect is closed.

Atrial fibrillation or atrial flutter

Atrial fibrillation and atrial flutter are uncommon in young patients, although they are reported in as many as 50-60% of patients older than 40 years. Therefore, these arrhythmias occur most frequently with age, and they may become a major cause of morbidity and mortality.

The use of anticoagulants is indicated in patients with atrial fibrillation because of the high risk of stroke. Although atrial fibrillation may be present in patients before surgery, surgery may also cause it.

Stroke

Regardless of their surgical status, 5-10% of patients have thromboembolic events (including stroke and transient ischemic attacks) on long-term follow-up. Even with small defects, paradoxical emboli may occur. Therefore, the presence of an ASD should be considered in any patient with a cerebral or other systemic embolus in whom no left-sided source is demonstrable.

• References

Future and Controversies

With increased experience over the years, transcatheter closure of suitable secundum atrial septal defects (ASDs) has now become preferable to surgical repair. Limitations currently include size and location of the defect.

Perhaps the most innovative approach to surgical closure in many years was accomplished in the form of robotically assisted closure of ASD. Current technology allows for excellent visualization and magnification of internal anatomy, and the ability to perform surgery at a remote distance from the patient is now a reality. However, even with this amazing technology, today's devices will seem crude compared with future computer robots. Improved access and cardiopulmonary bypass technology will most likely make robotically assisted heart surgery a routine procedure in the near future.

See a review by Holzer and Hijazi that discusses delivery systems for transcatheter therapies in patients with congenital heart disease such as ASD, including potential future modifications and changes.^[28]

• References

2018​​ AHA/ACC Adult Congenital Heart Disease Guidelines

The American Heart Association (AHA)/American College of Cardiology (ACC) published updated guidelines for the management of adults with congenital heart disease (ACHD) in 2018,^[34]  updating their initial guidelines published a decade earlier. The guidelines present a new classification system for ACHD. The ACHD anatomic and physiologic classification system uses both anatomic complexity as well as physiologic status.

Anatomic classification includes class I (simple), class II (moderate complexity), and class III (great complexity). The physiologic classification is divided into stages A-D and is similar overall to the AHA heart failure classification. The physiologic classification system takes into account a patient's functional status as well as other factors, including presence of valve disease, pulmonary hypertension, arrhythmias, aortic dilatation, end-organ function, and cyanosis. By incorporating physiology in addition to anatomic categorization into the new ACHD guidelines, the authors hope the guidelines will be more applicable to specific patient situations.

Small secundum ASDs are categorized as class I (simple) lesions, whereas moderate/large defects or sinus venosus defects or primum defects are class 2 (moderately complex) lesions.

If a patient is asymptomatic, they are physiologic class A, but when a patient develops even mild symptoms, they then become class B-D, depending on symptom severity.

Recommendations for closure of ASD

Recommendations for closure of a secundum ASD (by device or surgically) in adults is indicated by these guidelines if there is:

• Impaired functional/exercise capacity
• Right atrial (RA) and/or right ventricular (RV) enlargement
• Pulmonary-to-systemic flow ratio (Qp:Qs) ≥1.5:1

Provided that there is:

1. Absence of cyanosis at rest or during exercise
2. The systolic pulmonary artery (PA) pressure is < 50% of systolic systemic pressure
3. The pulmonary vascular resistance is less than one-third of the systemic vascular resistance (class I, level of evidence [LOE]: B).

For asymptomatic patients, closure is also reasonable with the aforementioned criteria (class IIa, LOE: C).

The same guidelines apply to sinus venosus, primum, and coronary sinus ASDs, although these must be closed surgically (ie, not with a transcatheter-delivered device). Likewise, a concomitant surgical ASD closure should be considered if another related procedure is being performed and the above-mentioned criteria are met.

The guidelines also state the reverse corollary, namely that an ASD should NOT be closed if:

1. PA systolic pressure is more than two thirds of the systolic systemic pressure
2. Pulmonary vascular resistance is over of the systolic systemic pressure, and/or
3. There is a net right-to-left shunt.

The 2008 ACHD guidelines also mention that ASD closure is indicated for paradoxical embolism (class IIa, LOE: C) or orthodeoxia-platypnea syndrome (class IIa, LOE: B).^[18]

• References

2020 European Society of Cardiology Adult Congenital Heart Disease Guidelines

The European Society of Cardiology (ESC) released their updated guidelines on the management of adult congenital heart disease (ACHD) in 2020, a decade after their previous version.^[12]  

Select CHD complexity classifications

Mild CHD complexity includes isolated small atrial septal defect (ASD), ventricular septal defect (VSD), or patent ductus arteriosus (PDA), as well as repaired secundum ASD, sinus venosus defect, VSD, or PDA without residua or sequela (eg, chamber enlargement, ventricular dysfunction, elevated pulmonary arterial pressure [PAP]).

Moderate CHD complexity, whether repaired or not repaired, applies to partial or complete atrioventricular septal defect (AVSD), including primum ASD (excluding pulmonary vascular disease), as well as moderate or large unrepaired ASD secundum  (excluding pulmonary vascular disease).

Severe CHD complexity, whether repaired or not repaired, includes any repaired or not repaired CHD that is associated with pulmonary vascular disease (including Eisenmenger syndrome), as well as any unoperated or palliated cyanotic CHD.

In cases of mild CHD, catheter ablation is recommended over long-term medical therapy for symptomatic, sustained recurrent supraventricular tachycardia (SVT) (atrioventricular node reentrant tachycardia [AVNRT], atrioventricular reentrant tachycardia [AVRT], atrial tachycardia [AT], and intraatrial reentrant tachycardia [IART]), or if SVT may be related to sudden cardiac death (SCD) (class I; recommended).

In cases of moderate and severe CHD, consider catheter ablation for symptomatic, sustained recurrent SVT (AVNRT, AVRT, AT, and IART), or if SVT may be related to SCD, as long as the setting is an experienced center (class IIa; should be considered).

Select revised and new recommendations related to ASDs

Invasive measurement of pulmonary vascular resistance (PVR) is required in the setting of shunt lesions and noninvasive signs of elevated PAP (class I).

In cases of technically suitable secundum ASD, device closure is the recommended method of choice (class I).

In patients with ASD and a pulmonary-to-systemic flow ratio (Qp:Qs) above 1.5:1 on the basis of calculated PVR, the ESC adjusted recommendations for ASD shunt closure are as follows:

• Below 3 Wood units (WU): Class I for ASD, VSD, PDA)
• 3-5 WU: Class IIa for ASD, VSD, PDA)
• At least 5 WU but falling to below 5 WU following targeted treatment for pulmonary arterial hypertension (PAH): Class IIb (may be considered) for ASD (fenestrated closure only)
• At least 5 WU for VSD and PDA (after careful individual decision in expert centers): Class IIb
• At least 5 WU despite targeted PAH treatment: Class III (not recommended) for ASD closure

In the setting of ASD and left ventricular (LV) disease, balloon testing is recommended, with careful assessment of the benefit of eliminating left-to-right shunt versus potential adverse outcomes of ASD closure owing to increased filling pressures (consider closure, fenestrated closure, and no closure) (class I).

In elderly patients with ASD who are not candidates for device closure, assess the risk of surgery against the potential benefit of ASD closure (class I).

In the setting of PVR of at least 5 WU, fenestrated ASD closure may be considered when PVR falls below 5 WU after targeted PAH therapy and significant left-to-right shunt is present (Qp:Qs >1.5) (class IIb).

The ESC does not recommend shunt closure in the setting of PAH (PVR ≥5 WU) presenting with desaturation on exercise (class III).

In the setting of documented systemic embolism likely from paradoxical embolism in those with ASD and Ebstein anomaly, consider isolated device closure of ASD/PFO; prior to intervention, carefully assess to rule out induction of elevated right atrial (RA) pressure or decrease in cardiac output (class IIa). If the main issue is cyanosis (resting O2 saturation < 90%), isolated device closure of ASD/PFO may be considered; again, prior to intervention, carefully assess to rule out induction of elevated RA pressure or decrease in cardiac output (class IIb).

Other recommendations for intervention in native and residual ASD include the following:

• In the setting of evidence of right ventricular (RV) volume overload without PAH (absence of noninvasive signs of PAP increase or invasive confirmation of PVR < 3 WU in the presence of such signs) or LV disease, ASD closure is recommended regardless of symptoms (class I).
• When paradoxical embolism is suspected after other causes have been ruled out, consider ASD closure regardless of size as long as PAH and LV are not present (class IIa).

• References