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Atrial Septal Defect (ASD): Symptoms, Diagnosis, and Closure Treatment

What Is an Atrial Septal Defect?

An atrial septal defect (ASD) is a congenital opening in the wall separating the right and left atria of the heart.

It is commonly described as a "hole in the heart."

Normally, the two atria are separated by an intact septum.

In patients with ASD, blood usually flows from the left atrium into the right atrium, increasing blood flow to the lungs.

A significant ASD may cause enlargement of the right heart chambers over time.

Small ASDs may have little hemodynamic effect, while larger defects can affect cardiac function.

Not every ASD requires closure. Treatment decisions depend on the hemodynamic effects of the defect and the patient's clinical characteristics, not simply its diameter.

What Are the Types of Atrial Septal Defect?

1. Secundum ASD

Secundum ASD is the most common type.

It is located in the central part of the atrial septum, near the fossa ovalis.

Many secundum ASDs with suitable anatomy can be closed using a catheter-based procedure.

2. Primum ASD

Primum ASD is located in the lower portion of the atrial septum.

It is frequently associated with atrioventricular valve abnormalities.

Surgical treatment is generally required.

3. Sinus Venosus ASD

Sinus venosus defects are usually located near the junction of the superior or inferior vena cava with the right atrium.

They may be associated with anomalous pulmonary venous drainage.

Surgical repair is commonly performed, although transcatheter treatment may be feasible for selected superior sinus venosus defects in experienced centers.

4. Coronary Sinus Defect

This is a rare type of interatrial communication involving the coronary sinus.

Treatment depends on the specific anatomy.

What Are the Symptoms of ASD?

Small ASDs may remain asymptomatic for many years.

Larger defects or defects diagnosed in adulthood may cause:

  • Shortness of breath during exertion
  • Fatigue
  • Reduced exercise tolerance
  • Palpitations
  • Atrial fibrillation or atrial flutter
  • Recurrent respiratory infections
  • Leg swelling in advanced disease
  • Symptoms of right-sided heart failure

Some ASDs are discovered incidentally during echocardiography.

What Causes ASD?

ASD develops when the atrial septum does not form completely during fetal heart development.

In most patients, the exact cause is unknown.

Some ASDs may be associated with genetic syndromes or familial congenital heart disease.

How Does ASD Affect the Heart?

A significant left-to-right shunt increases blood flow through the right heart and pulmonary circulation.

Over time, this may lead to:

  • Right atrial enlargement
  • Right ventricular enlargement
  • Tricuspid regurgitation
  • Atrial arrhythmias
  • Increased pulmonary artery pressure
  • Right-sided heart failure

Long-standing significant shunts may cause pulmonary vascular disease in some patients.

In advanced, irreversible pulmonary vascular disease, shunt reversal and Eisenmenger syndrome may develop.

Early recognition and appropriate assessment are therefore important.

How Is ASD Diagnosed?

1. Echocardiography

Echocardiography is the first-line diagnostic method.

It evaluates:

  • Defect location and size
  • Direction of blood flow
  • Right atrial and ventricular dimensions
  • Right ventricular function
  • Estimated pulmonary artery pressure
  • Associated valve abnormalities

2. Transesophageal Echocardiography (TEE)

TEE provides detailed visualization of the atrial septum.

It is particularly important when transcatheter closure is planned.

It assesses:

  • Defect diameter
  • Surrounding tissue rims
  • Multiple defects
  • Relationships with adjacent cardiac structures

3. Three-Dimensional Echocardiography

Three-dimensional imaging can help assess defect shape and device suitability.

4. Cardiac MRI or CT

These methods may be used to evaluate right ventricular volumes, shunt magnitude, and associated anomalous pulmonary venous connections.

5. Right Heart Catheterization

Right heart catheterization may be required when pulmonary hypertension is suspected, particularly to measure pulmonary vascular resistance and assess whether closure is safe.

When Should an ASD Be Closed?

Closure decisions should not be based solely on the defect diameter.

Important factors include:

  • Right ventricular volume overload and enlargement
  • Hemodynamically significant left-to-right shunting
  • Symptoms
  • Pulmonary artery pressure and pulmonary vascular resistance
  • Defect anatomy
  • Associated cardiac conditions

Closure may be recommended when an ASD causes significant right heart volume overload and pulmonary vascular conditions are suitable.

A pulmonary-to-systemic flow ratio (Qp/Qs) of 1.5 or greater is an important finding but is not sufficient on its own.

Closure may be harmful in certain patients with advanced, irreversible pulmonary vascular disease.

How Is Transcatheter ASD Closure Performed?

Suitable secundum ASDs can often be closed without open-heart surgery.

The procedure is usually performed through a vein in the groin.

Procedure Steps

  1. A catheter is introduced through the femoral vein.
  2. The defect is assessed using echocardiographic and fluoroscopic guidance.
  3. An appropriately sized closure device is selected.
  4. The device is positioned across the atrial septal opening.
  5. Device stability and its relationship with surrounding structures are checked.
  6. Once satisfactory positioning is confirmed, the device is released.

Over time, the device becomes covered by the patient's own tissue.

Which Devices Are Used for ASD Closure?

Different types of transcatheter ASD occluders are available, commonly consisting of two discs.

Device selection depends on:

  • Defect size
  • Defect shape
  • Adequacy of surrounding tissue rims
  • Presence of multiple defects
  • Relationship with nearby valves and vessels

Not every ASD is suitable for transcatheter closure.

Large defects or inadequate surrounding tissue may make surgical treatment more appropriate.

What Are the Risks of ASD Closure?

Transcatheter ASD closure has a high success rate in appropriately selected patients at experienced centers.

However, possible complications include:

  • Bleeding or vascular complications
  • Transient arrhythmias
  • Device displacement or embolization
  • Residual shunting
  • Device-related thrombus
  • Rarely, cardiac erosion or perforation

These complications are uncommon but should be discussed before the procedure.

How Is Surgical ASD Closure Performed?

Surgical closure may be required when catheter-based treatment is unsuitable.

The defect is closed using direct sutures or a surgical patch.

Surgery is generally preferred for primum ASD, many sinus venosus defects, and ASDs associated with other structural abnormalities requiring repair.

How Long Is the Hospital Stay After ASD Closure?

Following uncomplicated transcatheter ASD closure, many patients remain in the hospital for approximately one day.

Selected patients may be discharged the following day.

Hospitalization is generally longer after surgical repair.

Are Medications Needed After ASD Closure?

Antiplatelet medication is commonly prescribed for a period after device closure to reduce the risk of device-related thrombus.

The regimen and duration depend on the device and individual patient factors.

Temporary infective endocarditis prophylaxis may also be indicated after device implantation.

Is Follow-Up Necessary After ASD Closure?

Yes.

Follow-up examinations assess:

  • Device position
  • Residual shunting
  • Right heart chamber dimensions
  • Cardiac rhythm
  • Valve function

Right ventricular remodeling may take time, particularly in patients treated during adulthood.

Some atrial arrhythmias may persist despite successful closure.

What Is the Difference Between ASD and PFO?

ASD and patent foramen ovale (PFO) are different conditions.

ASD represents a true deficiency of tissue in the atrial septum.

PFO is a persistent fetal communication that normally closes after birth.

ASD commonly causes right heart volume overload through left-to-right shunting.

PFO is more commonly considered in relation to paradoxical embolism and stroke in selected patients.

Therefore, the indications for ASD closure and PFO closure differ.

Can Patients Return to Normal Life After ASD Closure?

Many patients return to normal activities following successful ASD closure.

Timely treatment, before irreversible pulmonary vascular disease or significant cardiac damage develops, is important for favorable long-term outcomes.

When Should You Consult a Cardiologist?

Patients with unexplained breathlessness, fatigue, palpitations, right heart enlargement, or suspected congenital heart disease should undergo cardiology evaluation.

Sudden severe breathlessness, fainting, chest pain, or stroke symptoms require immediate emergency medical attention.

Assoc. Prof. Sezen Bağlan Uzunget, MD
Cardiologist

This content is provided for general educational purposes. ASD diagnosis, suitability for transcatheter closure, and surgical treatment decisions should be individualized according to anatomical and hemodynamic findings.