Major Aortopulmonary Collateral Arteries

Introduction:

The major aortopulmonary collateral arteries are common and are about fifty to seventy percent identified in patients. The development of the collateral arteries occurs in cases of congenital heart defects.

What Are Major Aortopulmonary Collateral Arteries?

• The major aortopulmonary collateral arteries, also known as MAPCAs or systemic-to-pulmonary collaterals, are abnormal blood vessels that develop in individuals with certain congenital heart defects.

• Normally, the pulmonary arteries carry deoxygenated blood from the heart to the lungs, picking up oxygen and returning it to the heart to be pumped to the rest of the body. However, in some cases, the pulmonary arteries may be underdeveloped or completely absent. When this happens, blood can not flow to the lungs as it should, and the body compensates by developing alternative routes for blood to reach the lungs.

• MAPCAs are those alternative routes. They are arteries originating from the aorta or other systemic arteries and connecting to the pulmonary arteries or lung tissue, allowing blood to bypass the underdeveloped or absent pulmonary arteries and reach the lungs.

In Which Conditions Are the Major Aortopulmonary Collateral Arteries Seen?

These collaterals provide an alternative route for blood to flow from the systemic circulation (the aorta and its branches) into the lungs, bypassing normal pulmonary circulation.

MAPCAs can occur in a variety of congenital heart defects, including:

• Tetralogy of Fallot: This is a heart defect characterized by a combination of four abnormalities, including a ventricular septal defect, an overriding aorta, pulmonary stenosis, and right ventricular hypertrophy. MAPCAs may develop as a compensatory mechanism in response to pulmonary stenosis, restricting lung blood flow.

• Pulmonary Atresia With a Ventricular Septal Defect: In this defect, the pulmonary valve is completely blocked or absent, preventing blood from flowing into the lungs. As a result, MAPCAs may develop to provide an alternative route for blood to reach the lungs.

• Double Outlet Right Ventricle: This is a defect in the pulmonary artery and the aorta arising from the right ventricle. In some cases, MAPCAs may develop to provide additional blood flow to the lungs.

• Transposition of the Great Arteries: In this defect, the aorta and pulmonary artery positions are switched so that the left ventricle gives way to the pulmonary artery. In contrast, the right ventricle gives way to the aorta. MAPCAs may develop to provide additional blood flow to the lungs, which is necessary for survival.

Overall, the development of MAPCAs is a complex process involving various signaling pathways and molecular mechanisms. The formation of these collaterals can have both beneficial and detrimental effects on circulation, and their management requires careful evaluation and treatment by a team of specialists.

What Are the Types of Major Aortopulmonary Collateral Arteries?

Major aortopulmonary collateral arteries (MAPCAs) are extra blood vessels that develop in the lungs in some congenital heart defects, particularly in the condition known as pulmonary atresia with the ventricular septal defect. Different types of MAPCAs can vary in origin, course, distribution, and relationship with other blood vessels. Here are some of the main types:

• Systemic to Pulmonary Artery Collaterals: These MAPCAs arise from the systemic arteries (such as the subclavian or bronchial arteries) and supply blood to the pulmonary circulation. They can have a direct or indirect connection to the pulmonary arteries.

• Aortic Arch Collaterals: These MAPCAs arise from the aortic arch or branches and supply blood to pulmonary circulation. They can include the left subclavian artery, the innominate artery, or the descending thoracic aorta.

• Ductus Arteriosus Collaterals: These MAPCAs arise from the ductus arteriosus, a fetal blood vessel that normally closes shortly after birth. They can supply blood to the pulmonary arteries or systemic circulation.

• Coronary to Pulmonary Artery Collaterals: These MAPCAs arise from the coronary arteries, which supply blood to the heart muscle. They can have a direct or indirect connection to the pulmonary arteries.

• Pulmonary Artery Collaterals: These MAPCAs arise from the pulmonary arteries themselves and supply blood to other areas of the lungs that are not receiving adequate blood flow.

The anatomy of MAPCAs can be complex and variable, and their identification and management require specialized imaging and treatment techniques.

What Is the Diagnosis of Major Aortopulmonary Collateral Arteries?

The diagnosis of MAPCAs is typically made through imaging tests such as echocardiography, cardiac MRI, or cardiac CT. These tests can visualize abnormal blood vessels and show how they are connected to the aorta and pulmonary arteries. The diagnosis may also involve a cardiac catheterization procedure, which allows a more detailed evaluation of the blood vessels and can sometimes be used to treat the condition.

What Is the Treatment of Major Aortopulmonary Collateral Arteries?

• These abnormal blood vessels can affect the normal blood flow to the lungs, leading to respiratory distress, heart failure, and other serious complications.

• The treatment of MAPCAs depends on the specific type and severity of the heart defect, as well as the age and overall health of the patient. The treatment options for MAPCAs include surgical repair, interventional catheterization, or a combination.

• Surgical repair of MAPCAs may involve either complete repair of the underlying heart defect or isolation and ligation of the MAPCAs. In some cases, a combination of both approaches may be necessary. The specific surgical technique will depend on the patient's case.

• Interventional catheterization may be used to treat MAPCAs in some cases, particularly in younger patients or unsuitable for surgery. The surgery involves placing a catheter into a blood vessel in the groin and guided to the MAPCAs. The MAPCAs are then treated with various techniques, including balloon angioplasty, stent placement, or embolization.

• Overall, treating MAPCAs requires a multidisciplinary approach involving a team of experienced cardiologists, cardiac surgeons, and other healthcare professionals. Treatment aims to optimize blood flow to the lungs and prevent complications associated with MAPCAs.

Conclusion:

However, MAPCAs can also lead to complications like heart failure, pulmonary hypertension, and respiratory infections. In some cases, treatment of MAPCAs may involve surgical or catheter-based interventions to address any potential issues. Overall, the presence of MAPCAs requires careful evaluation by a healthcare provider with experience in congenital heart disease management. The treatment approach will depend on the specific case and may involve a combination of medical therapy and interventions to address complications.