Inlet ventricular septal defect (VSD): Causes, symptoms, and treatment

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There are four chambers in the heart. The two upper chambers are the atria, and the two lower chambers are the ventricles.

The septum separates these chambers. The ventricular septum is the wall of tissue that separates the two ventricles.

Valves are present in the heart to allow blood to flow into and out of the heart and from one chamber to the next. The four valves in the heart are:

• Tricuspid valve: This valve sits between the right atrium and the right ventricle.
• Pulmonary valve: This valve sits between the right ventricle and the pulmonary artery.
• Mitral valve: This valve sits between the left atrium and the left ventricle.
• Aortic valve: This valve sits between the left ventricle and the aorta.

Medical professionals refer to the tricuspid and mitral valves as inlet valves because these are the valves that open to allow blood to flow into the ventricles.

A person with an inlet VSD has a hole or opening close to the inlet valves in the right ventricular septum.

If an infant has a VSD, blood can flow through the hole, from the left ventricle into the right ventricle. This blood can then travel out into the lung arteries.

A large VSD can cause the heart to pump large amounts of blood into the lung arteries. This can require the heart and lungs to work harder, leading to symptoms of VSD.

Inlet VSD occurs when the hole is close to the tricuspid or mitral valve.

Outlet VSD occurs when the hole is close to the aortic and pulmonary valves, which are the outlet valves.

Both types of VSD cause blood to move from the left ventricle into the right ventricle.

VSDs happen when a developmental problem occurs while the heart is forming inside an embryo. Medical professionals do not fully understand what causes VSDs, but genetic factors may play a role in their development.

Some non-genetic risk factors may contribute to the development of VSDs. These may include:

• maternal infections while the embryo is in the womb, such as:
  • rubella
  • influenza
  • febrile illnesses
• maternal diabetes
• phenylketonuria, an inherited inability to metabolize phenylalanine
• embryonic exposure to:
  • alcohol
  • cannabis
  • cocaine

An infant may show signs of a VSD at birth. However, in some cases an infant may not display symptoms of a VSD for some time.

If the VSD causes a small hole, the hole may close on its own, and an infant may not display any symptoms.

If the VSD causes a larger hole, blood may flow through the hole, from the left ventricle into the right ventricle. This blood can then travel into the lung arteries.

When this happens, an infant may display symptoms. Common symptoms of a VSD include:

• shortness of breath
• fast breathing
• heavy breathing
• sweating
• tiredness during feeding
• the inability to gain weight

A doctor will often diagnose a VSD after an infant is born.

A doctor may hear a heart murmur during a standard physical examination. This can be a sign of a VSD. A heart murmur is a distinct whooshing sound that a doctor can hear when listening to the infant’s heart.

If a doctor suspects that an infant has a VSD, they may use several tests to confirm the diagnosis. An echocardiogram is the most valuable tool for diagnosing a VSD. An echocardiogram is a type of ultrasound that uses high frequency sound waves to create pictures of the infant’s heart.

This can help a doctor see:

• whether there are any other abnormalities in the structure of the heart
• how large the hole is
• how much blood is flowing through the hole

If an infant has a small VSD that does not cause any problems, the hole may close on its own. In this case, a doctor may monitor the infant regularly to ensure that the hole closes.

If a hole does not close or is large, a doctor may suggest treatment to close the hole.

A doctor may choose either cardiac catheterization or open heart surgery to close the hole.

Cardiac catheterization

During cardiac catheterization, a medical professional will insert a catheter through a blood vessel in a person’s groin. A catheter is a piece of flexible tubing. They will then pass this catheter through the blood vessel and into the person’s heart.

The doctor can then insert certain devices through the catheter to check that there are no further abnormalities in the heart and to measure the size of the hole. They can insert a small device called an occluder through the catheter, which they can use to close the hole.

Open heart surgery

During open heart surgery for a VSD, a surgeon will sew a patch over the hole to close it. This patch may be fabric or may consist of pericardium, which is the normal lining around the outside of the heart.

Over time, normal heart lining tissue will cover this patch and it will become a permanent part of the heart.

In some cases, a surgeon may sew the hole closed without a patch.

Medicines for a VSD

In some cases, a child with a VSD may need certain medications. These medications may help:

• strengthen the heart muscle
• lower their blood pressure
• help their body remove extra fluid

Nutritional help for infants with a VSD

Some infants with a VSD may have difficulties with feeding. They may become tired when they feed, which can cause them not to gain weight.

To help an infant with a VSD gain weight, medical professionals may recommend that they consume a high calorie formula.

In other cases, an infant with a VSD may need a feeding tube if they are too tired to feed through their mouth.

An inlet VSD is a condition involving a hole close to the inlet valves in the right ventricular septum of the heart.

If the VSD causes a small hole, this hole may close on its own.

If the VSD causes a larger hole, blood can flow through the hole in the wrong direction, from the left ventricle into the right ventricle. This blood can then travel into the lung arteries. If this happens, an infant may experience shortness of breath, fast breathing, heavy breathing, and tiredness during feeding.

If the hole is large, a doctor may suggest closing it by performing cardiac catheterization or open heart surgery.