Transposition of the great vessels

Congenital heart defect affecting the great arteries

Transposition of the Great Vessels
Synonyms	d-TGA, Congenital heart defect - transposition
Pronounce
Field	Pediatric cardiology, Cardiothoracic surgery
Symptoms	Cyanosis, rapid breathing, difficulty feeding, heart murmur
Complications	Heart failure, pulmonary hypertension, arrhythmias
Onset	Congenital (present at birth)
Duration	Lifelong condition (requires surgical correction)
Types	Dextro-Transposition of the great arteries (d-TGA), Levo-Transposition of the great arteries (l-TGA)
Causes	Genetic and environmental factors
Risks	Maternal diabetes, genetic syndromes, prenatal infections
Diagnosis	Echocardiography, Chest X-ray, Electrocardiogram, Cardiac catheterization
Differential diagnosis	Tetralogy of Fallot, Total anomalous pulmonary venous return, Double outlet right ventricle
Prevention	Prenatal care, avoidance of teratogenic exposures
Treatment	Arterial switch operation, Atrial switch operation, prostaglandin therapy
Medication	Prostaglandins, diuretics (supportive care)
Prognosis	Good with early surgical correction; lifelong follow-up required
Frequency	1 in 3,000 to 5,000 live births
Deaths	High mortality if untreated

Normal heart anatomy vs. d-TGA

Chest X-ray showing the "egg-on-a-string" sign.

Transposition of the Great Vessels (TGV) is a group of congenital heart defects involving an abnormal arrangement of the great vessels, including the aorta and pulmonary artery. It is a severe cyanotic congenital heart defect (CHD), meaning it causes a lack of oxygen in the body due to improper blood circulation.

The condition is primarily classified into dextro-Transposition of the Great Arteries (d-TGA) and levo-Transposition of the Great Arteries (l-TGA). It is one of the most common congenital heart defects requiring early surgical intervention.

Types

Subcostal echocardiographic view showing discordant ventriculoarterial connections.

Transposition of the Great Vessels results in altered circulatory patterns, leading to cyanosis (bluish discoloration due to low oxygen levels). There are two major forms:

Dextro-Transposition of the Great Arteries (d-TGA)

Main article: Dextro-Transposition of the Great Arteries

• Most common form of TGV
• The aorta arises from the right ventricle, and the pulmonary artery arises from the left ventricle.
• This creates two separate, non-mixing circulatory loops, preventing oxygen-rich blood from reaching the body.
• Cyanosis appears shortly after birth due to a lack of oxygenated blood circulation.
• Requires surgical intervention (arterial switch operation) within the first weeks of life.

Levo-Transposition of the Great Arteries (l-TGA)

Main article: Levo-Transposition of the Great Arteries

• Also called "congenitally corrected TGA" (ccTGA).
• The ventricles and great arteries are transposed, but blood circulation remains normal because both atrioventricular and ventriculoarterial connections are reversed.
• Often asymptomatic at birth, but may lead to heart failure, arrhythmias, or valve dysfunction later in life.

Symptoms and Signs

Symptoms depend on the type of transposition and any associated heart defects.

Common symptoms include:

• Cyanosis (bluish skin color)
• Rapid breathing (tachypnea)
• Difficulty feeding
• Heart murmur
• Poor weight gain
• Weak pulse or poor perfusion

If untreated, complications such as heart failure and pulmonary hypertension can occur.

Risk Factors

Several factors increase the risk of transposition of the great vessels:

• Maternal diabetes
• Genetic syndromes (e.g., 22q11.2 deletion syndrome)
• Prenatal infections (e.g., rubella)
• Exposure to teratogens (e.g., alcohol, certain medications)
• Family history of congenital heart defects

Diagnosis

Early diagnosis is essential, usually made before or shortly after birth using imaging and clinical tests.

• Fetal echocardiography – Detects TGV in utero.
• Postnatal echocardiography – Confirms the diagnosis and detects associated defects.
• Chest X-ray – Classic “egg-on-a-string” appearance due to an enlarged heart and narrowed mediastinum.
• Electrocardiogram (ECG) – Non-specific but may show right ventricular hypertrophy.
• Cardiac catheterization – Occasionally needed for detailed structural analysis.

Treatment

Pre-Surgical Management 1. Prostaglandin E1 (Alprostadil) – Keeps the ductus arteriosus open to allow blood mixing. 2. Balloon Atrial Septostomy (Rashkind procedure) – Enlarges the foramen ovale to allow better oxygenation.

Surgical Interventions

1. 1. Arterial Switch Operation (ASO)

• Preferred surgery for d-TGA.
• Aorta and pulmonary artery are reconnected to the correct ventricles.
• Performed within first two weeks of life.
• Excellent long-term outcomes.

1. 2. Atrial Switch Operations (Mustard or Senning Procedure)

• Alternative for older patients who missed early intervention.
• Creates an intra-atrial baffle to direct blood flow.
• Higher risk of arrhythmias and right ventricular failure.

1. 3. Double Switch Operation (for l-TGA)

• Performed in levo-TGA cases with ventricular dysfunction.
• Corrects both ventricular and arterial malposition.

Post-Surgical Care

• Regular cardiology follow-ups
• Lifelong monitoring for arrhythmias, valve dysfunction, or heart failure
• Exercise restrictions may be needed for some patients.

Prognosis

• Without surgery: High mortality within the first year of life.
• With surgical correction:
• 90% survival rate into adulthood.
• Most children lead normal lives but require lifelong cardiac monitoring.
• Risk of late complications (e.g., arrhythmias, heart failure) remains.

Prevention

While not always preventable, some measures can reduce risks:

• Proper prenatal care
• Diabetes management during pregnancy
• Avoiding teratogens and infections during pregnancy
• Genetic counseling for families with congenital heart disease history

See Also

• Dextro-Transposition of the great arteries
• Levo-Transposition of the great arteries
• Mustard procedure

This article is a medical stub. You can help WikiMD by expanding it!
Most recent articles Ongoing trials	Wikipedia