Pediatric Cardiology

Atrial Septal Defect (ASD): Symptoms, Causes and Treatment Options

Posted on by Prof. Dr. İbrahim Cansaran TANIDIR

Atrial septal defect (ASD) is a congenital structural opening in the wall between the right and left upper chambers of the heart. It is commonly known as a hole in the heart and causes blood to mix.

In a healthy circulatory system, the passage between these chambers is completely closed. However, when an anatomical opening is present, oxygen-rich blood from the left side leaks directly into the right side, altering the fundamental dynamics of circulation.

This tissue deficiency, present since birth, forces the right side of the heart and the pulmonary blood vessels to work with extra effort. It is an important cardiovascular condition that directly affects the body’s hemodynamic balance.

Over time, this ongoing imbalance may strain the structural elasticity of the heart muscle. Early detection is important for preserving the heart’s original structure and ensuring that the circulatory system continues to function properly.

What Is ASD (Atrial Septal Defect), Known as a Hole in the Heart, and How Does It Develop?

The human heart is an extremely complex and remarkable organ whose initial structure begins to form during the earliest weeks of development in the mother’s womb. Initially consisting of a single cavity, this structure gradually begins to divide into chambers as the weeks progress. Between the two upper chambers, the right and left atria, there is a natural passage that physiologically needs to remain open throughout fetal life. Since the fetus does not yet breathe using its own lungs, oxygen-rich blood coming from the mother must be pumped directly to the brain and then throughout the body without passing through the lungs. Therefore, this opening in the heart is not a disease while the baby is in the womb but a vital passage necessary for survival.

When birth occurs and the baby takes its first breath, pressure balances within the chest change within seconds. As the lungs fill with air, this opening between the atria normally closes like a valve, becoming functionally closed in the early period and then completely fusing over the following months to form a solid wall. However, in some cases, this closure process remains incomplete due to minor differences in the cellular mechanisms responsible for growth and fusion. The membranes that should form the wall may not grow sufficiently or may become excessively thin, leaving an opening in the middle.

The causes of this structural condition are not always clearly known. It can often develop through a combination of environmental factors and random genetic changes, even when there has never been a family history of heart disease. On the other hand, clinical practice has shown that certain genetic backgrounds predispose children to this condition. The frequency of this opening is higher among children with Down syndrome or certain specific genetic conditions affecting both the heart and skeletal system than in the general population.

What Are the Types of ASD (Atrial Septal Defect) with Different Structural Characteristics?

This opening in the heart does not develop in the same location or in the same way in every child. The location of the deficiency in the wall is one of the most critical factors determining how the condition will progress and which treatment approach will be selected. The main types classified according to their anatomical location are:

  • Secundum
  • Primum
  • Sinus venosus
  • Coronary sinus

Secundum-type defects account for the vast majority of all cases and are located in the very center of the wall between the heart’s atria. The most important characteristic of this region is the presence of healthy heart tissue surrounding the opening, much like a doorframe. This surrounding healthy tissue creates a secure area where devices used in nonsurgical treatment methods can be anchored during subsequent procedures.

The primum type occurs in the lower part of the wall, in a highly sensitive region adjacent to the heart’s ventricles and valves. Tissue deficiency in this area may often be accompanied by structural clefts in the heart valves. Because there is no firm surrounding rim to support a device and the valves may also require intervention, surgical methods are generally considered in these cases.

The sinus venosus type develops at the points where the major veins carrying deoxygenated blood from the upper and lower parts of the body connect to the heart. This form may also be accompanied by additional anatomical differences, such as the vessels carrying oxygen-rich blood from the lungs connecting to the heart at an incorrect location. The coronary sinus type is another form that occurs in the region where the vessels draining the heart muscle itself converge and is very rarely encountered in clinical practice. While surgery was previously the only treatment option for these types of defects, treatment can now also be performed in selected suitable patients using stents placed through angiographic procedures.

How Does ASD (Atrial Septal Defect) Between the Atria Affect Blood Circulation?

The left side of the heart has a highly muscular structure that operates under high pressure because it is responsible for pumping oxygen-rich blood from the lungs throughout the body. The right side of the heart, however, is responsible only for sending deoxygenated blood collected from the body to the nearby lungs and therefore works against much lower pressure. When there is an opening in the wall between them, it is a physical principle that fluid always tends to flow from an area of higher pressure toward an area of lower pressure.

Some of the oxygen-rich, high-pressure blood collected in the left atrium leaks through this hole and returns to the right side of the heart instead of being pumped into the body. This means that the right side of the heart and the vessels leading to the lungs must handle a greater blood volume than normal. A volume of blood far exceeding the amount that should normally pass through the pulmonary valve fills the right side of the heart.

During the early years, particularly in childhood, the muscles of the right heart and the pulmonary vessels are highly elastic. The body attempts to tolerate this additional blood volume by absorbing it like a sponge. Although the accumulation of blood on the right side of the heart may initially appear not to cause a significant problem, this additional burden, continuing every second and with every heartbeat, may eventually cause the right heart muscles to become fatigued, stretch, and enlarge.

What Are the Symptoms of ASD (Atrial Septal Defect) Observed in Infants and Children?

When the opening is not very large, the condition often follows a silent course during childhood. Most children may appear very active and healthy in their daily lives. However, when the opening is large and the amount of blood passing into the right heart is high, certain important signs may appear that do not escape careful observation. Possible symptoms include:

Fatigue during breastfeeding

  • Rapid breathing
  • Increased sweating with physical exertion
  • Weight gain lagging behind peers
  • Becoming tired more quickly than peers
  • Susceptibility to respiratory infections
  • Becoming short of breath easily at older ages
  • Rarely, bluish discoloration

For infants, feeding and breastfeeding require as much energy as an exercise stress test does for an adult. An infant whose heart is already strained by an additional blood load may become tired quickly while sucking, beads of sweat may appear on the forehead, and feeding may stop early because of this fatigue. Naturally, this can prevent adequate calorie intake and cause a slowdown in the child’s growth curve.

When the pulmonary vessels contain more blood than normal, the respiratory system may become more sensitive to viruses and bacteria entering from outside. These children may experience more frequent episodes of bronchitis or lung infections, with slightly longer recovery periods. By school age, a child may become tired before their friends while playing, running, or climbing stairs and feel the need to step aside and rest. Sometimes, the condition is discovered only during an incidental examination when the doctor hears a “heart murmur,” the sound of turbulence created as excess blood passes through a valve.

What Problems Can ASD (Atrial Septal Defect) Cause in Later Years If Treatment Is Delayed?

If this condition, which the body tolerates remarkably well during childhood, goes unnoticed or the necessary interventions are not performed on time, it may create the conditions for certain complex problems to develop with advancing age. Possible long-term risks include:

  • Structural deterioration of the pulmonary vessels
  • Pulmonary hypertension (high blood pressure in the lungs)
  • Heart rhythm irregularities
  • Right heart fatigue
  • Blood clot migration (embolism)

Pulmonary vessels exposed to higher-than-normal blood volumes for years gradually attempt to protect themselves against this increased flow. The cells lining the inner surfaces of the vessels begin to thicken, and the vessel walls start to lose their elasticity. This makes it more difficult for blood to flow through the pulmonary vessels and may lead to a condition known as pulmonary hypertension. If this pressure reaches very high levels, the right side of the heart may become so strained that it can no longer effectively send blood to the lungs.

When the structure of the muscle fibers in the right atrium deteriorates after years of filling with excess blood and stretching, the heart’s electrical impulse system may also be affected. At older ages, the likelihood of sudden increases in heart rate or episodes of irregular rhythm known as atrial fibrillation increases.

Another risk concerns possible blood clots in the circulation. A small clot that forms in any vein in the body is normally carried through the right side of the heart to the lungs, where the fine network of pulmonary vessels filters it. However, if an opening exists between the two atria, this clot may temporarily pass through the hole to the left side during situations that increase pressure inside the chest, such as straining or lifting heavy objects. A clot that reaches the left side and travels to the brain or other organs has the potential to cause neurological complications.

Which Tests and Methods Are Used to Establish a Reliable Diagnosis of ASD (Atrial Septal Defect)?

When a heart murmur is heard in a child or complaints associated with physical exertion are present, a clear evaluation can be performed using comfortable methods that do not exhaust children. Commonly used diagnostic methods include:

  • Transthoracic echocardiography
  • Transesophageal echocardiography
  • Electrocardiography
  • Cardiac computed tomography
  • Cardiac MRI
  • Cardiac catheterization

Transthoracic echocardiography forms the foundation of the diagnostic process. This procedure involves examining the heart through the chest using an ultrasound probe over warm gel applied to the skin. Like examining a baby in the mother’s womb, it is a painless, radiation-free, and rapid method. During this examination, the exact location and size of the opening, the direction of blood flow, and the degree of enlargement of the right heart chambers can be clearly observed.

In older children or when the anatomical structure of the opening must be mapped with millimeter precision, transesophageal echocardiography may be used. This involves a thin probe passed through the mouth into the esophagus. Because the esophagus lies directly behind the heart, this method provides very high-resolution, detailed images of the heart’s internal structures.

In addition, electrocardiography (ECG), which maps the heart’s electrical activity, can be used to evaluate the electrical manifestations of volume overload in the right heart. In very specific circumstances or when the pressure in the pulmonary vessels needs to be measured precisely, cardiac catheterization, in which extremely thin wires are advanced to the heart through the groin, can be used to plan treatment much more accurately.

How Is Nonsurgical ASD (Atrial Septal Defect) Closure Performed in Children?

Today, the first preferred method for children who meet the appropriate anatomical criteria, generally those with secundum-type defects, is nonsurgical closure performed through the groin. This procedure aims to close the opening without opening the chest and protects pediatric patients from major surgical trauma. For the procedure to be feasible, sufficiently wide margins of healthy tissue (rims) must be present around the opening to provide secure support for the device.

The procedure is performed in fully equipped angiography laboratories, usually under deep sedation or general anesthesia supervised by anesthesiologists to ensure children’s comfort and prevent them from feeling pain. The process begins by entering the vein in the child’s groin using a very thin needle. A flexible plastic sheath is then inserted through this vascular access. With the help of specially designed thin guidewires and catheters, the right atrium of the heart is slowly reached through the blood vessel, and the instruments are advanced through the opening into the left atrium.

Under imaging guidance, the actual size of the opening in its stretched state is measured, and the size of the device to be used is determined. This device is generally manufactured from a special nickel-titanium alloy called “nitinol.” These devices have shape memory and consist of two flat discs (umbrellas) connected at the center, with special fabric inside that blocks blood flow.

The folded device is advanced through the sheath inside the blood vessel until it reaches the heart. Upon reaching the left atrium, the first disc is opened and gently pulled back to rest against the left side of the opening. The waist of the device is then positioned precisely in the center of the hole, and the right disc is opened to complete the placement. The two discs firmly grip the heart tissue surrounding the opening between them. Before the device is completely released, its stability, whether it touches the surrounding valves, and whether blood flow through the opening has stopped are carefully checked using ultrasound and fluoroscopy. If everything is as intended, the device is detached from its delivery connection and left in place, and the procedure is completed by closing the entry point in the groin.

What Are the Advantages of Nonsurgical ASD (Atrial Septal Defect) Closure Compared with Open Surgery?

With advances in medical technology, transcatheter (nonsurgical) methods have become standard procedures and offer significant conveniences for patients and families compared with open-heart surgery. The main advantages of this method include:

  • No incision in the chest
  • No need for a heart-lung machine
  • Short hospital stay
  • Rapid return to normal life
  • No permanent surgical scar on the body

During open-heart surgery, the chest may need to be opened to reach the heart, and the heart may need to be stopped while the body’s circulation is connected to an external pump. This requires a longer stay in intensive care and the hospital due to tissue healing and infection risks. Even after discharge, patients must restrict their physical movements for weeks to allow the bones to heal.

In contrast, the nonsurgical method requires only a small needle entry in the groin area. The procedure is performed while the heart continues beating, without causing major changes in the body’s overall physiological balance. Children usually return directly to their rooms without being admitted to intensive care and, in most cases, can walk home after just one day of precautionary observation. Because there is no surgical incision, preservation of body image is a particularly valuable psychological advantage for children of playing age and adolescents.

What Should Be Considered During Recovery After Successful ASD (Atrial Septal Defect) Treatment?

After the procedure is completed and the patient is discharged, the body begins adapting to the new tissue-compatible device placed in the heart. This period is generally quite comfortable, but there are several important steps that must be carefully monitored during the first few months. Considerations during recovery include:

  • Use of blood thinners
  • Antibiotic prophylaxis to prevent infection
  • Temporarily avoiding high-impact sports
  • Attending scheduled periodic follow-up examinations

Over time, the implanted device begins to be surrounded by the cells lining the inner surface of the heart and becomes covered by a natural tissue layer. This covering process generally takes approximately six months. During these months, it is important to use blood thinners (usually low-dose aspirin) for the duration and at the dosage recommended by the physician to prevent small blood clots from forming on the surface of the device before it is completely covered.

Similarly, until the device becomes integrated with the tissue, preventive antibiotics may be required before tooth extraction or any surgical intervention to prevent bacteria entering the body from accumulating on the device. This precaution is also generally no longer necessary once the inner lining of the heart has completely healed.

Although children can return to their daily activities and games within the first few days, they are asked to temporarily avoid contact sports that may involve strong blows to the chest (such as martial arts or football) during the first weeks, when the device has not yet firmly integrated with the tissue. After this short adaptation period, children can generally participate in all the physical activities and sports they wish without any restrictions.

Cases of atrial septal defect that are diagnosed in a timely manner, evaluated by experienced teams, and treated using appropriately planned methods produce encouraging outcomes by relieving the extra burden on children’s hearts and maximizing their growth potential. When regular follow-up programs are followed, the right side of the heart returns to its former healthy structure, and children can confidently move toward an energetic and healthy future on equal terms with their peers.

Güncellenme Tarihi: 13.10.2026

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