Transposition of the Great Arteries - An Overview

What Is the Transposition of the Great Arteries?

A complex form of congenital (defect from birth) cardiac abnormality known as translocation of the great arteries (TGA) can be found in some patients. The aorta and the pulmonary artery are the two major arteries that lead blood away from the heart in a healthy heart. These arteries have an abnormal connection to the heart in children who have been diagnosed with TGA:

• The aorta is linked to the right ventricle instead of the left ventricle.

• The pulmonary artery has a connection to the left ventricle as opposed to the right.

What Are the Causes of the Condition?

The cause of TGA is generally unknown.

• No single prevalent genetic defect is associated with it within the population; in most cases, additional family members remain unaffected.

• The blood ejected from the heart and distributed throughout the body has an abnormally low oxygen concentration.

In normal heart pumping, blood returning to the body travels to the lungs to obtain oxygen via the pulmonary artery and the right component of the chambers. The blood is circulated back into the body via the aorta after returning via the heart's left ventricle. In TGA, the venous blood typically travels through the right atrium on its way back to the heart. The aorta forces this blood out before returning to the body. Normally, it would have traveled through the lungs to take in oxygen, but now it does so instead. Cyanosis is the outcome of this blood not being replenished with oxygen regularly.

What Are the Symptoms?

The signs show up soon after birth or right away after birth. The severity of the symptoms can be affected by the type and size of any other heart problems, such as patent ductus arteriosus ( an extra blood vessel found in babies before and right after birth), an atrial septal defect (a birth defect of the heart in which there is a hole in the wall (septum) that divides the upper chambers (atria) of the heart), or a ventricular septal defect (a hole in the heart that is there at birth). Newborns with TGA exhibit cyanosis (low oxygen) and may also experience cardiac failure.

Typical symptoms include:

• Difficulty inhaling.

• Minimal pulse.

• Problems with nutrition.

• Faster heartbeat.

• The skin or whites of their eyes resemble bluish, which is in infants with light skin, or grayish, which is in babies with dark skin.

What Are the Diagnostic Methods?

1. Laboratory Tests

• Abnormal pulse oximetry results show a difference between the upper and lower limbs and are consistent with inadequate intracardiac mixing.

• Patients with transposition of the great arteries (TGA) may benefit from a hyperoxia test ( to determine whether there is a decrease in the quantity of oxygen).

• In individuals with arterial hypoxemia, arterial blood gas measurements are performed on 100 percent oxygen.

2. Cardiovascular Catheterization

Neonatal clinical cardiac catheterization is typically reserved for the subgroup of infants. Sound vibrations to generate heart images do not sufficiently identify the coronary artery anatomy. Additionally, cardiac catheterization could be required to enhance left-to-right shifting at the atrial level. Post-catheterization risks include hemorrhage, vascular disruption, discomfort, nausea, vomiting, and arterial or venous obstruction due to thrombosis or spasm.

3. Imaging of the Chest

The chest image may appear normal when the great arteries are transposed in infants, with appropriate atrial level mixing and ventricular septum integrity. However, some patients may have the recognizable "egg on a string" appearance.

• Extreme cyanosis in newborns will provide the appearance of increased pulmonary vascularity, which suggests insufficient atrial level mixing.

• Cardiomegaly is often associated with increased pulmonary arterial vascular characteristics when a hole in the ventricular septal membrane exists.

4. Echocardiography

• A pulmonary artery divide that emerges downward from the left ventricle can be visible on echocardiography.

• Great artery linkages can be seen in the image taken along the short axis of the parasternal. The aorta crosses the pulmonary artery in an anterior and rightward direction.

• Echocardiography may also identify atrial valve anomalies and ventricular structural abnormalities, including patent ductus arteriosus (a condition in additional blood arteries discovered in newborns before and shortly after birth).

• Many people have abnormal coronary artery anatomy, as echocardiography can reveal the origins and branching of coronary arteries.

5. Imaging With Magnetic Resonance

• Cardiovascular magnetic resonance imaging (MRI) studies involving Late gadolinium enhancement (LGE), a cardiac magnetic resonance imaging (MRI) technique utilized to characterize cardiac tissue, specifically evaluate the development of myocardial scar tissue and regional myocardial fibrosis, may aid physicians in risk stratification for patients undergoing atrial switch surgery who have undergone translocation of the great arteries.

• MRI scans may help examine the supravalvular pulmonary stenosis, which refers to the narrowing of the artery located immediately after the pulmonary valve, aortic, and branch pulmonary artery regions if severe stenosis is suspected.

What Is the Treatment Method?

1. Medical Assistance: The first line of treatment for transposition of the great arteries involves preserving ductal patency (unobstructed flow via the duct) using continuous intravenous (IV) prostaglandin E1 (PgE1) infusion to encourage pulmonary blood flow, raise left atrial pressure, and encourage left-to-right inter-circulatory mixing at the atrial level. This is crucial for patients with significant atresia or left ventricular outflow tract stenosis. To lower early mortality in babies with transposition in the great arteries.

• Patients with acute oxygen deprivation and poor communication and interaction between the atria should undergo cardiac catheterization or balloon atrial septostomy. Balloon atrial septostomy is a minimally invasive cardiac surgery in which a cardiologist uses a balloon catheter to expand congenital heart abnormalities such as opening atrial structural defect, hence improving atrial level shunt and mixing.

• Metabolic acidosis, which refers to the accumulation of acid in the body caused by renal illness or kidney failure, should be treated in sick newborns by replenishing fluids and administering bicarbonate therapy.

• In cases where both pulmonary edema and severe hypoxemia, which is characterized by an unusually low concentration of oxygen in the blood, are present simultaneously, the use of mechanical ventilation may be necessary.

2. Surgical Procedures

• The patient's age and the presence of related congenital heart lesions determine the surgical method. An arterial switch surgery can be done in one operation for most full-term newborns with straightforward transposition of the major arteries.

Great Artery Transposition With Ventricular Septum Intact

• The most effective procedure for rectifying ventriculoarterial concordance is arteriovenous switch surgery. Nevertheless, translocation might not be feasible if the coronary artery structure is intramural (within the walls of an organ or body cavity); thus, an arterial exchange is not recommended.

• The surgeon constructs the obstruction using the patient's tissue during a senning procedure. Utilizing a synthetic material, the Mustard procedure decreases short-term and surgical death and morbidity.

Ventricular Septal Defect and Great Artery Transposition

Aortic switch and ventricular septal defect repair are advised for the transposition of the great artery.

• Rastelli-type intracardiac repair is an option when the ventricular septal defect is big and nonrestrictive. The Rastelli surgery involves a right ventricle-pulmonary artery channel; waiting till the infant is older and larger may be preferable. When a kid develops severe congestive heart failure in conjunction with growth failure, reparative surgery and restriction of the primary pulmonary artery should be performed within the first few weeks of life.

Transposition of the Great Arteries Is Associated With Ventricular Septal Defect and Pulmonary Vascular Obstructive Disease.

Patients with growing pulmonary vascular resistance may not be surgical candidates. After palliative or reparative treatment, these minor issues are usually diagnosed.

What Is the Complication?

If TGA is not treated, there is the potential for the following complications:

1. Heart valve difficulties.

2. Problems with the heart muscle or the arteries that feed blood to the heart muscle are two of the most common causes of heart failure.

3. Rhythm disturbances in the heart.

4. Insufficiency of the heart.

5. Lung complications.

6. Mortality.

Conclusion

TGA is a complicated congenital cardiac defect that results in cyanosis. It is induced by the discordance between the ventriculoarterial or ventriculoatrial chambers. Dextro-transposition of the great arteries (DTGA) is the most common cause of cyanosis in the first week of life. Advances in early identification, medical treatment, and surgery have increased the recovery rate for this previously fatal disease. After surgery, complications with the heart's framework, function, or rhythm can impede recovery. In some instances, LGTA patients may require close monitoring along with a heart transplant. The long-term effects could involve mild to moderate neuro developmental impairments depending on the disease's type, severity, and duration. For optimal results, physicians must continue monitoring children until adulthood.