Scimitar Syndrome

What is Scimitar Syndrome?

Scimitar syndrome is an unusual birth defect that affects the heart. It’s known by several other names, including congenital venolobar syndrome, Halasz syndrome, mirror-image lung syndrome, hypogenetic lung syndrome, and vena cava bronchovascular syndrome. This condition is a type of partial anomalous pulmonary venous return, which is a heart defect that causes some of the blood in the body to flow in the wrong direction. The syndrome gets its name from its distinctive feature that resembles a “scimitar,” a type of curved sword from the Middle East or Turkey.

This condition is characterized by four unique features:

1) Abnormal curved vein drainage from the right lung to a large vein called the inferior vena cava, which can be partially or entirely off course.

2) An unusual degree of underdevelopment (hypoplasia) of the right lung and the pulmonary artery, a major blood vessel supplying the lungs.

3) The shifting of the heart’s position slightly to the right side, termed as dextraposition.

4) An abnormal supply of blood from the body’s main arteries to the lung on the same side.

Also, people with this condition may have other heart defects like holes in the wall that separates the upper chambers of the heart (atrial septal defects), or unusual blood vessels connecting the aorta and pulmonary artery (aortopulmonary collaterals).

Scimitar syndrome was first reported by George Cooper in 1836 when he found it during the post-mortem of a 10-month-old baby. The first diagnosis using imaging tools called cardiac catheterization was done by Dotter and his team in 1949. The first surgery for this condition took place in 1950, carried out by Drake and Lynch, where they removed the lower part of the right lung. The first corrective surgery, in which an attempt was made to correct the structural problem, happened in 1956 by Kirklin and others. Schramel and his team later recognized two variations of scimitar syndrome.

What Causes Scimitar Syndrome?

Scimitar syndrome is a condition that isn’t fully understood yet. However, medical experts believe it may be caused by a developmental defect when the lung bud is forming early in embryo development. The process of how exactly this happens is still unknown.

Risk Factors and Frequency for Scimitar Syndrome

Anomalous pulmonary venous connection is estimated to occur in 1 to 3 out of every 100,000 live births, but the actual occurrence could be higher. This condition is more common in females, with twice as many female cases as males. Moreover, among all those who have a partial anomalous pulmonary venous connection, 3% to 6% will present with it.

Signs and Symptoms of Scimitar Syndrome

Scimitar syndrome is a health condition that can show up differently from person to person. Some people may not have any symptoms and only discover their condition during a check-up, while others may have serious symptoms such as heart failure and breathing difficulties. Scimitar syndrome can appear in two main forms: one that shows up in infancy and one that is noticed in childhood or adulthood.

The condition can be divided into three categories:

Those that come with other serious heart problems
Those without significant heart issues, which can either show up in infants or present milder symptoms in older children and adults

Common heart problems that go along with Scimitar syndrome include a hole in the wall separating two chambers of the heart (atrial septal defect, seen in 80% of the cases), an open blood vessel that usually closes after birth (patent ductus arteriosus, found in 75% of cases), another type of hole in the heart’s wall (ventricular septal defect, present in 30%) and a narrowed blood vessel (pulmonary vein stenosis, found in 20%). Some patients may also have multiple heart-related conditions that can cause a lack of oxygen in the body.

The infant version of Scimitar syndrome often comes with other inborn defects and serious complications. These infants are usually diagnosed within the first few months of life and may have rapid breathing and heart failure. They may have a mortality rate of up to 45%. They might have issues like:

Abnormal blood flow to the lower right lung
Blood shunting through associated heart defects
Norrowing of the blood vessels that drain the lungs
Increased blood flow from the left to the right in the lung’s blood vessels
Underdeveloped lungs leading to increased blood pressure in the lungs

These infants might have lung infections, particularly in the right lower lung, bronchiectasis (a chronic condition where the walls of the bronchi are thickened from inflammation and infection) and other lung conditions.

The type that shows up in older children and adults is usually milder. Individuals with this type may often find out about their condition by chance during a check-up for an unexplained enlargement of the right side of the heart or frequent lung infections, mainly on the right side. Half of these patients may have an enlarged right ventricle due to mildly elevated blood pressure in the lung arteries and right-sided volume overload, which can lead to a specific type of heart block.

Testing for Scimitar Syndrome

Scimitar syndrome is a condition that’s primarily detected through imaging methods and is characterized by a distinctive abnormal chest X-ray. The X-ray reveals certain unique features such as the shadow of a descending pulmonary vein down the right side of the heart, a smaller than average lung, and a heart positioned towards the right side. Also, the heart cavity or the lungs might have shifted from their normal position due to lack of air in lungs or the absence of a lung.

Echocardiography, an imaging test of the heart, is a better initial test in the diagnosis of Scimitar syndrome. This test provides a detailed look at the Scimitar vein, a special vein that’s unique to this syndrome, any unusual blood supply to the right lung, and other potential heart defects that might be present in patients with severe symptoms. Fetal echocardiography, which is used to visualize a baby’s heart before birth, can assist with early diagnosis by showing an obstructed blood flow pathway in the lungs, confluence (a point where two things merge) behind the right chamber of the heart, and a vertical vein. Unlike the usual blood flow in pulmonary veins which happens in two or three phases and has a reverse flow during the heart’s contraction, the Scimitar vein has a single-phase flow throughout the whole cardiac cycle and does not experience reverse flow.

3-D computed tomography (CT) and cardiac-gated magnetic resonance imaging (MRI) are the best diagnostic tools as they provide a detailed view of the unusual pulmonary vein, its course, how it connects, and where it drains. These imaging techniques are particularly useful in identifying a horseshoe lung, a rare lung malformation. Cine MRI and 3-D MR angiography using contrast help to quantify the blood flow in the pulmonary veins and assist in determining the ratio of blood flow from the lungs to the body. These imaging modalities provide a complete anatomical and functional diagnosis, reducing the need for more invasive procedures.

Cardiac catheterization and angiography, which are more invasive studies, are the most definitive diagnostic tests for confirming Scimitar syndrome, but they’re not always necessary. They provide detailed information about the resistance in the pulmonary blood vessels, the degree of the shift from left-to-right in heart’s functioning, and the exact anatomy of the anomalous vein. They also reveal the degree of high blood pressure in the lung arteries, the structure of the pulmonary arteries, any accompanying heart defects and any additional blood vessels supplying the lung originating from the aorta, the main artery of the body.

Treatment Options for Scimitar Syndrome

Scimitar syndrome is a rare congenital heart disease that may need various medical professionals to work together for successful treatment. The disorder may occur in two types: the infantile and the childhood/adult form, each requiring varying treatment options.

Infantile form tends to show symptoms of heart failure. In such cases, doctors start immediate treatments to help buy time and allow the patient to grow. During this time, doctors will use a procedure called angiography to stop blood flow in the abnormal arteries from the main blood vessel to the right lung. This reduces the amount of blood being improperly rerouted, thus lowering the pressure in lung arteries. However, if the patient has additional heart-related issues, an early surgical intervention may be necessary.

The childhood/adult form usually needs surgical intervention. This may be done when a patient shows symptoms or if the flow of blood from the lungs to the body’s system is more than 1.5 times the standard rate.

Several surgical treatments are available for Scimitar syndrome, entirely dependent on the individual case and the surgeon’s preference. These include either removing the part of the lung drained by the faulty vein (called the scimitar vein) or a corrective approach for blood flow redirection. Surgical redirection can be accomplished through different techniques like tunnel creation or direct vein re-implantation to the left atrium, which receives oxygenated blood from the lungs. Some methods may require suspending the circulation (circulatory arrest).

Procedures for blood flow redirection range from attaching the scimitar vein directly to the left atrium or by separating and reattaching the scimitar vein into the right atrium, and redirecting blood flow through an artificial opening to the left atrium. If a complication called stenosis occurs, where the blood vessels narrow, it can be treated using a balloon inflation procedure.

Different methods may be used to build a tunnel to redirect the blood flow from the faulty lung vein (the anomalous pulmonary vein) to the left atrium. One involves creating a tunnel using a wall of the heart chamber (patch), while another uses the free wall of the right atrium; both require circulatory arrest for accurate stitching of an artificial barrier within the heart (intra-atrial baffle). Other surgical techniques involve no use of barriers (baffles) or pump machine and involve direct re-implantations of the scimitar vein into the left atrium. Alternatively, a tube graft can relay the vein to the left atrium. Some techniques may use grafts to create a link between the scimitar vein and the left atrium; but in such cases, the long-term effectiveness of the grafts is not well-known, making some physicians recommend blood thinners to keep the grafts functioning.

Surgical procedures that involve removing a lung lobe (lobectomy) or the entire lung (pneumonectomy) are only applied when a patient presents with persistent conditions like frequent infections, extensive damage to the bronchial tubes (bronchiectasis), blood-filled cough (hemoptysis), significantly underdeveloped right lung, or blood coagulation in the intra-atrial baffles.

There are other conditions that can produce similar results on medical imaging. These conditions include:

An unusual artery linked to an underdeveloped right lung and non-developed pulmonary artery
An abnormal wandering vein draining from an underdeveloped right lung to the left part of the heart
A lung mass with blood supply from the body’s main circulatory system
A lung tissue that’s separate from the main lung and has its own blood supply

What to expect with Scimitar Syndrome

In the past, the outlook for infants with this condition was not very good. Today, however, things have greatly improved thanks to early diagnosis and advanced surgical techniques. The results now are often positive, with a very low rate of complications or death following corrective surgery.

Possible Complications When Diagnosed with Scimitar Syndrome

After undergoing surgery, there is a high chance of experiencing blocked blood flow in the lung and reduced blood flow to the right lung. The risks of post-surgery complications, death, and the need for follow-up surgeries rise when you have high blood pressure in the lung arteries and related defects.

Possible Risks:

Blocked blood flow in the lung
Reduced blood flow to the right lung
Increased post-surgery complications
Possibility of death
Need for more surgeries
Increased risks when you have high blood pressure in the lung arteries
Increased risks when you have related defects

Preventing Scimitar Syndrome

Patients should be informed about the different treatment options available to them. It’s crucial that the team managing their case includes professionals from different fields. This way, patients will have all the information they need to make educated decisions about their treatment.

Frequently asked questions

The prognosis for Scimitar Syndrome has greatly improved thanks to early diagnosis and advanced surgical techniques. The results now are often positive, with a very low rate of complications or death following corrective surgery.

Scimitar syndrome is believed to be caused by a developmental defect during lung bud formation in early embryo development. The exact process of how this happens is still unknown.

Signs and symptoms of Scimitar Syndrome can vary depending on the individual and the type of the condition. Here are the signs and symptoms associated with Scimitar Syndrome: 1. Some individuals may not have any symptoms and only discover their condition during a check-up. 2. Others may experience serious symptoms such as heart failure and breathing difficulties. 3. Scimitar Syndrome can appear in two main forms: one that shows up in infancy and one that is noticed in childhood or adulthood. 4. In the infant version of Scimitar Syndrome, symptoms may include rapid breathing, heart failure, and an increased mortality rate of up to 45%. 5. Common complications in infants with Scimitar Syndrome include abnormal blood flow to the lower right lung, blood shunting through associated heart defects, narrowing of the blood vessels that drain the lungs, increased blood flow from the left to the right in the lung's blood vessels, and underdeveloped lungs leading to increased blood pressure in the lungs. 6. Older children and adults with Scimitar Syndrome may experience milder symptoms, such as unexplained enlargement of the right side of the heart or frequent lung infections, mainly on the right side. 7. Half of these patients may have an enlarged right ventricle due to mildly elevated blood pressure in the lung arteries and right-sided volume overload, which can lead to a specific type of heart block. It is important to note that Scimitar Syndrome can also be associated with other serious heart problems, including atrial septal defect, patent ductus arteriosus, ventricular septal defect, and pulmonary vein stenosis. Some patients may also have multiple heart-related conditions that can cause a lack of oxygen in the body.

The types of tests that are needed for Scimitar Syndrome include: 1. Chest X-ray: This imaging method can reveal unique features such as the shadow of a descending pulmonary vein down the right side of the heart, a smaller than average lung, and a heart positioned towards the right side. 2. Echocardiography: This test provides a detailed look at the Scimitar vein, any unusual blood supply to the right lung, and other potential heart defects that might be present in patients with severe symptoms. 3. Fetal echocardiography: This test can assist with early diagnosis by showing an obstructed blood flow pathway in the lungs, confluence behind the right chamber of the heart, and a vertical vein. 4. 3-D computed tomography (CT) and cardiac-gated magnetic resonance imaging (MRI): These imaging techniques provide a detailed view of the unusual pulmonary vein, its course, how it connects, and where it drains. They are particularly useful in identifying a horseshoe lung. 5. Cardiac catheterization and angiography: These invasive studies provide detailed information about the resistance in the pulmonary blood vessels, the degree of the shift from left-to-right in heart's functioning, and the exact anatomy of the anomalous vein. They also reveal the degree of high blood pressure in the lung arteries, the structure of the pulmonary arteries, any accompanying heart defects, and any additional blood vessels supplying the lung originating from the aorta.

The other conditions that a doctor needs to rule out when diagnosing Scimitar Syndrome are: 1) An unusual artery linked to an underdeveloped right lung and non-developed pulmonary artery. 2) An abnormal wandering vein draining from an underdeveloped right lung to the left part of the heart. 3) A lung mass with blood supply from the body's main circulatory system. 4) A lung tissue that's separate from the main lung and has its own blood supply.

The side effects when treating Scimitar Syndrome may include: - Blocked blood flow in the lung - Reduced blood flow to the right lung - Increased post-surgery complications - Possibility of death - Need for more surgeries - Increased risks when you have high blood pressure in the lung arteries - Increased risks when you have related defects

Cardiologist

Scimitar syndrome is estimated to occur in 1 to 3 out of every 100,000 live births.

Scimitar Syndrome can be treated through various medical interventions, depending on the type of the disease. For the infantile form, immediate treatments are initiated to manage heart failure symptoms. This may involve using angiography to stop blood flow in the abnormal arteries, reducing the pressure in lung arteries. Surgical intervention may be necessary if there are additional heart-related issues. The childhood/adult form usually requires surgical intervention when symptoms are present or if the blood flow from the lungs to the body's system is excessive. Surgical treatments for Scimitar Syndrome include removing the part of the lung drained by the faulty vein or redirecting blood flow through different techniques. Balloon inflation procedures can be used to treat complications such as stenosis. In some cases, lobectomy or pneumonectomy may be necessary if persistent conditions are present.

Scimitar Syndrome is an unusual birth defect that affects the heart, characterized by abnormal curved vein drainage from the right lung to the inferior vena cava, underdevelopment of the right lung and pulmonary artery, shifting of the heart's position to the right side, and abnormal blood supply from the body's main arteries to the lung on the same side. It is also associated with other heart defects such as atrial septal defects and aortopulmonary collaterals.

Congenital Heart Defects Genetic Disorders Pulmonary Artery Pulmonary Hypoplasia