Major aortopulmonary collateral arteries (MAPCA) is a rare, congenital (children are born with it) condition where there is not enough blood flow to the lungs. This condition is caused by problems with the pulmonary valves, which may be missing entirely (pulmonary atresia).
Normally, the pulmonary valve sits between the right ventricle and the pulmonary artery. This valve helps move deoxygenated blood from the right ventricle of the heart into the lungs. This is where blood can pick up oxygen before moving to the rest of the body. In children with pulmonary atresia, the valve doesn’t function like it should, which prevents blood from reaching the lungs to receive oxygen. This can lead to cyanotic heart disease (low levels of oxygen in the blood).
In babies with MAPCA, vessels grow off the aorta, the largest blood vessel in the body, before birth. These vessels try to make up for the problems with the pulmonary valves and deliver blood to the lungs. These abnormal, collateral arteries can lead to too much or too little blood going to the lungs.
Babies with MAPCA often have other conditions that can affect how their heart or lungs work, including DiGeorge syndrome, feeding challenges and airway problems. Care, including the timing and order of surgeries and other treatments, is tailored for each child.
MAPCA is a specific kind of tetralogy of Fallot (ToF). ToF is a group of congenital heart defects that can happen together. Rarely, these children may have pulmonary atresia, which can lead to MAPCA. ToF is the most common form of cyanotic heart disease.
Like many kinds of congenital heart disease, there are different genetic factors that can lead to MAPCA. Specific causes are not known. Research is being done to understand the specific genes involved.
MAPCA is most often found during the fetal stage during the 20-week anatomy ultrasound. Pediatric cardiologists can diagnose MAPCA with fetal echocardiography (echo) during fetal development. They will run more tests after birth, including an echo, cardiac CT scan and cardiac catheterization.
MAPCA is a serious condition that needs immediate evaluation. It has a wide range of severity. Children get treatment tailored to their condition. After birth, babies with MAPCA are cared for in the neonatal intensive care unit (NICU). Some babies can go home right away. Others may have heart defects or other conditions that need immediate treatment before they can leave the hospital.
Babies who have too much pulmonary blood flow may have over-circulation symptoms like problems feeding and poor weight gain. Babies with too little flow may be dangerously cyanotic (have low levels of oxygen in their blood). These babies may need immediate intervention to ease their symptoms until they are strong enough to have surgery to fix the issue. These interventions may include:
Babies continue to have frequent cardiology visits throughout their lives. These visits include regular MAPCA cardiac catheterization procedures to make sure they have adequate blood flow to their lungs. Children may have additional surgeries, including stents or shunts, to slow or boost this flow depending on their needs.
For most children with MAPCA, cardiac surgeons will perform unifocalization surgery. This surgery connects the abnormal vessels to the pulmonary arteries to create a single, working pulmonary artery to deliver blood to the lungs.
Children who have enough blood flow to their lungs at birth (not too much or too little) will likely have surgery between 6 and 9 months old.
In severe cases, babies with too much or too little blood flow may have unifocalization surgery early. This surgery can be done from the first day to the first week of life. These children would need an additional MAPCA surgery at 6–9 months old.
MAPCA unifocalization is performed under general anesthesia (while your child is asleep). This procedure is an open-heart surgery.
Children with too much blood flow to the lungs can have surgery to ease blood flow before their unifocalization surgery.
During this minimally invasive procedure, which is done under general anesthesia, pediatric cardiac surgeons place small coils in the child’s abnormal arteries to slow blood flow. Specialists do the MAPCA coiling procedure in the cardiac catheterization lab. A small catheter (wire) is placed in the child’s groin and guided to the abnormal vessels to place the coils.
Children usually go home from the hospital within a few days of this procedure.
After birth, babies with MAPCA can often go home, feed and grow normally. Babies with MAPCA often have other heart defects and conditions that need lifelong follow-up and treatments. This may include open-heart and minimally invasive surgeries as well as diagnostic testing such as echocardiograms, cardiac CTAs and cardiac MRIs. Most patients will need repeat surgeries to improve the connection between their right ventricle and pulmonary artery. They may also need repeated cardiac catheterization for angioplasty (ballooning of the pulmonary artery to increase blood flow).
Long term, following successful surgeries, patients with MAPCA heart defects can live long, unrestricted lives.
Last Updated 03/2026
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