Introduction:
Congenital heart defects affect the development of the heart leading to structural abnormalities. Proper development of the heart is crucial to maintaining the body’s normal function. Structural defects in the heart can lead to several complications like heart failure, hypertension, respiratory and cardiac infections, abnormal heart rhythms, etc. These defects might occur independently or be associated with a syndrome. Down’s syndrome is the most common cause of congenital heart defects.
What Is Scimitar Syndrome?
Scimitar syndrome was first described by Catherine Neill, a British pediatric cardiologist, in 1960. It is a rare clinical condition characterized by an underdeveloped right lung, abnormal positioning of the heart, and abnormal blood drainage into the systemic circulation.
It is important to know the various parts involved to understand the condition better.
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The pulmonary artery is a blood vessel that carries impure blood from the right side of the heart to the lungs.
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The pulmonary vein is a blood vessel that carries pure blood from the lungs to the left side of the heart.
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Superior vena cava and inferior vena cava are the major blood vessels in the body that carry impure blood from all body parts into the right side of the heart.
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The atrium and ventricles are the upper and lower chambers of the heart, respectively.
In healthy individuals, the impure blood from the right side of the heart travels to the lungs for purification, and the pure blood returns to the left side of the heart via the pulmonary vein.
What Happens in Scimitar Syndrome?
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There is partial or complete deviated blood drainage from the pulmonary vein to the inferior vena cava in Scimitar syndrome.
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The term Scimitar syndrome is derived from the curvilinear shadow created on the chest X-ray by the anomalous pulmonary vein.
Other Characteristics:
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Hypoplasia (immature or underdeveloped right lung).
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Underdeveloped pulmonary artery.
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Sometimes blood from the left side of the heart diverts back into the lungs instead of going into the systemic circulation.
What Causes Scimitar Syndrome?
The exact cause underlying the Scimitar syndrome is not yet identified. In addition, genetic mutations linked explicitly to Scimitar syndrome have not been reported so far.
How Commonly Does Scimitar Syndrome Occur?
It is a rare congenital heart condition that affects one to three infants per 1,00,000 live births. It affects females more than males at a ratio of 2:1. 3 % to 6 % of all partial anomalous pulmonary vein connections are diagnosed as Scimitar syndrome. All cases may not be reported because many patients remain asymptomatic. Cases running in families are also described in many studies.
What Are the Signs and Symptoms of Scimitar Syndrome?
A majority of cases remain asymptomatic or show minor symptoms. If present, the symptoms include:
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Symptoms of heart failure are usually associated with other congenital heart conditions. These include shortness of breath, fatigue, swelling in the legs, irregular and rapid heartbeats, etc.
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Symptoms of recurrent pulmonary infection like cough, throwing up blood while coughing, pressure in the chest, difficulty breathing, fever, etc.
How Is Scimitar Syndrome Diagnosed?
Diagnosis is made by using advanced imaging and scanning techniques.
1. Plain Radiography:
Plain radiography is a valuable aid in the diagnosis of congenital heart diseases. This is because it can detect structural defects in the heart based on physiology. However, there is always a risk of radiation exposure. The plain chest radiographs reveal a small, underdeveloped lung with an anomalous vein seen as a tube-like structure parallel to the right side of the heart in the shape of a Turkish sword (scimitar).
2. CT (Computed Tomography):
Computed tomography can produce high-quality three-dimensional images and detect the heart's structural defects accurately. Therefore, it has a supplementary role in diagnosing and differentiating between the normal and pathologic features.
3. MRI (Magnetic Resonance Imaging):
MRI is used to evaluate the structure of the heart, its chambers, valves, blood vessels, and its surrounding structures. It also detects an abnormality in the blood flow patterns, and hence it is helpful to detect Scimitar syndrome.
4. Echocardiography:
It is a commonly used tool in pediatric cases as it is non-invasive. It provides information regarding the structural abnormalities as well as the position of the heart and blood vessels.
5. Angiography:
A special three-dimensional angiography utilizes rotational volumetric imaging for enhanced spatial visualization of complex cardiac structures.
How Is Scimitar Syndrome Treated?
If patients are symptomatic, surgery is the treatment of choice. Correction of the abnormality should be done if there is a significant connection between the right and left chambers of the heart. A tunnel or baffle is created in the blood vessels to redirect the flow of blood. As an alternative, the abnormally positioned vein can be reimplanted in the right place.
What Are the Risks Associated With Scimitar Syndrome?
The persistent presence of a connection between the right and left chambers can lead to pulmonary hypertension (a type of blood pressure that affects the right side of the heart and lungs). Eisenmenger phenomenon is another complication that develops due to unrepaired congenital defects of the heart.
Conclusion:
Scimitar syndrome is a condition characterized by a small right lung, abnormal position of the heart, and abnormal blood drainage into the systemic circulation. It affects one to three infants per 1,00,000 live births. It affects females more than males at a ratio of 2:1. A majority of cases remain asymptomatic or show minor symptoms. If present, the symptoms include shortness of breath, fatigue, swelling in the legs, irregular and rapid heartbeats, etc. Diagnosis is made by using advanced imaging and scanning techniques, and if patients are symptomatic, surgery is the treatment of choice.
