What are MAPCAs?
Tetralogy of Fallot (ToF) with pulmonary atresia and major aortopulmonary collateral arteries (MAPCAs) are an extreme form of congenital heart disease. MAPCAs are abnormal pulmonary arteries that form in utero out of necessity because the pulmonary valve is blocked or missing (pulmonary atresia).
If untreated, MAPCAs may lead to too much or too little blood flow to certain segments of the lungs, potentially leading to lung damage or complete loss of function. Most children who have MAPCAs need surgical treatment a few months after birth, along with cardiology care before and after surgery. Boston Children’s is one of the few pediatric hospitals to offer a unique surgery, unifocalization, that can treat MAPCAs.
This front view of an illustrated heart shows foundational cardiovascular elements: the left atrium (LA) and right atrium (RA), left ventricle (LV) and right ventricle (RV), and aorta. It also shows what happens when a child has the complex congenital heart defect tetralogy of Fallot (ToF) with pulmonary atresia and major aortopulmonary collateral arteries (MAPCAs). Several MAPCAs extend from the aorta and branch off around the left pulmonary artery and toward the right side of the heart. Meanwhile, an overriding aortic valve extends over a ventricular septal defect that’s often associated with ToF.
How do MAPCAs affect cardiovascular health?
When a child has MAPCAs, the extra arteries are typically the only source of blood to the lungs. MAPCAs cause cardiovascular issues because they are abnormal; they don’t effectively circulate blood after birth. They are often tiny arteries — sometimes one millimeter or smaller in diameter — and because of their abnormal nature, they may narrow over time.
Children who have MAPCAs may experience:
- Low blood-oxygen levels
- Pulmonary hypertension, abnormally high blood pressure in the lungs that can strain the heart
- Pulmonary congestion (edema), a buildup of fluid in the lungs
- Damage to important small blood vessels in lung tissue
Major Aortopulmonary Collateral Arteries MAPCAs | Symptoms & Causes
What are the symptoms of MAPCAs?
- Cyanosis, bluish color in the skin, lips, and nail beds caused by a lack of oxygen in the blood
- Rapid breathing
- Rapid heart rate
What to know about MAPCAs treatment
There are four things every parent should know about MAPCAs treatment, according to Hannah’s parents. They just saw her get specialized care for the rare cardiovascular condition and are happy she got healthy in time for her first birthday.
Major Aortopulmonary Collateral Arteries MAPCAs | Diagnosis & Treatments
How are MAPCAs diagnosed?
MAPCAs may be detected in utero on a prenatal ultrasound. After you child is born, they can also be evaluated for MAPCAs, along with ToF and pulmonary atresia, with an echocardiogram (cardiac ultrasound). Your child might also have a tomographic angiography (CTA) test to assess the number of MAPCAs and their course.
Finally, before your child has surgery, they will have cardiac catheterization to further evaluate different connections that may be present between pulmonary vessels and look for the presence of peripheral pulmonary artery stenosis (PPAS).
How are MAPCAs treated?
Treatment for ToF depends on a child’s anatomy, oxygen levels, and pulmonary artery development. The cardiology, cardiac surgery, and cardiac imaging specialists of the pulmonary artery reconstruction team at Boston Children’s create personalized, comprehensive treatment plans for each child — combining advanced imaging, interventional catheterization, and surgical reconstruction to create a single, functioning pulmonary artery system.
Cardiac catheterization
If your child needs surgical treatment for ToF with MAPCAs and pulmonary atresia, they will have to first wait a few months to grow and get strong enough for surgery. In the meantime, our team’s interventional cardiologists can perform one of several catheter-based procedures that will improve your child’s blood flow and support their growth.
Those procedures may include:
- Balloon dilation of narrowed arteries to improve blood flow and oxygenation
- Placing a stent within small or blocked vessels to maintain pulmonary blood flow
- Placing pulmonary artery flow restrictors to reduce excessive blood flow to MAPCA vessels
- Placing a pulmonary valve stent to enhance oxygenation before surgical reconstruction
This front view of an illustrated heart shows how unifocalization surgery combines major aortopulmonary collateral arteries (MAPCAs) and natural pulmonary arteries to create a single functioning pulmonary artery system. As part of that reconstruction, homograft patches are used to improve blood flow in the natural arteries and MAPCAs. Also, a right ventricle (RV)- to pulmonary artery (PA)-conduit stabilizes blood flow after a ventricular septal defect (VSD) patch is applied. The illustration also shows the left atrium (LA) and right atrium (RA), left ventricle (LV) and right ventricle, left pulmonary artery, and aorta.
Cardiac surgery
Children typically have to wait for four to six months before having surgery. When your child is ready, our preferred approach is unifocalization with a single-stage complete repair. It is a procedure that carefully joins MAPCAs and natural pulmonary arteries and reconstructs them into a single, functional pulmonary artery system. In many patients, treatment of a ventricular septal defect (VSD) that is associated with ToF can be done as part of the unifocalization procedure if the pulmonary arteries are ready for the VSD to be closed.
Some children, however, need unifocalization in a staged approach if the reconstructed pulmonary arteries are not ready to support normal blood flow. Our cardiac surgeons determine the readiness of the arteries by performing a test during the first operation. If the pulmonary arteries are not ready, the surgery team places a small conduit between them and the right ventricle to protect the arteries from high pressure. If your child needs to follow the staged approach, before the second procedure they may have a catheterization procedure known as pulmonary artery rehabilitation. About six months later, your child will complete the unifocalization process with the second-stage operation that closes the VSD and places a larger conduit between the pulmonary arteries and right ventricle.
MAPCAs are one of the most complicated forms of congenital heart disease, and they present differently in every child. Our team will ensure that your child receives care and treatment that is tailored to meet their specific health needs.
Treating MAPCAs with unifocalization surgery and cardiology care
Our heart team’s specialized care of the rare condition tetralogy of Fallot with MAPCAs reduces the number of operations an infant needs and improves their heart and pulmonary health.
