Congenital aortopulmonary artery fistula is a very rare heart blood vessel defect present from birth. In very simple words, it means there is an abnormal passage between the aorta and the pulmonary artery. The aorta is the big blood vessel that sends oxygen-rich blood to the body. The pulmonary artery carries blood from the heart to the lungs. Because of the abnormal connection, blood may move from the high-pressure aorta into the lower-pressure pulmonary artery. This can make too much blood go to the lungs and can slowly overload the heart. In medical literature, the congenital form is often discussed under the very closely related term aortopulmonary window or aortopulmonary septal defect, which is a direct abnormal connection between the ascending aorta and the pulmonary artery present at birth. [1] [2]
Congenital aortopulmonary artery fistula is a very rare birth defect in which there is an abnormal connection between the aorta and the pulmonary artery. In most modern heart references, the closest standard name is aortopulmonary window. Because the aorta has higher pressure, blood is pushed into the pulmonary artery, so too much blood goes to the lungs and then returns to the left side of the heart. This can cause fast breathing, poor feeding, sweating, poor weight gain, heart failure, and later pulmonary hypertension if the defect is not closed early. Early repair usually gives a very good outcome.
This is the most important treatment point: medicine alone does not cure the fistula. The main treatment is early closure, usually by surgery, and in selected cases by catheter device closure. Drugs are used only as support before repair, after repair, or when complications such as heart failure, pulmonary hypertension, or rhythm problems are present.
This problem is different from many acquired fistulas that happen later because of infection, surgery, trauma, or aneurysm. In the congenital form, doctors believe the defect starts early in fetal development when the normal tissue wall that should fully separate the aorta from the pulmonary artery does not form correctly. If the connection is large, a baby may develop fast breathing, sweating with feeds, poor weight gain, repeated chest infections, heart failure, or pulmonary hypertension. If the opening is small, the person may have few symptoms and the condition may be found later by a murmur or a heart scan. [3] [4] [5]
Another names
Another names used for this condition include aortopulmonary fistula, congenital aortopulmonary fistula, aortopulmonary window, aortopulmonary septal defect, and sometimes AP window in short. Some authors use “fistula” and “window” differently, but in simple clinical discussion they both describe an abnormal communication between the aorta and pulmonary artery. [6] [7]
Types
Type 1, proximal type. The abnormal opening is near the semilunar valves, in the part of the great vessels closest to the heart. This is one of the common classifications and means the defect is in the proximal ascending aorta and main pulmonary artery area. [8]
Type 2, distal type. The opening is farther away from the valves, in a more distal part of the connection between the vessels. [8]
Type 3, total type. The communication is large and extends through most of the wall between the aorta and pulmonary artery. [8]
Intermediate type. Some reports describe an intermediate form that does not fit neatly into the first three groups. [9]
Causes
The exact cause is often unknown. Because it is congenital, the “causes” below are best understood as development problems, associated defects, or factors linked with the condition, not always proven direct causes. [10]
1) Failure of normal embryonic separation of the aorta and pulmonary artery. This is the main developmental explanation. Early in fetal life, the outflow tract should divide into two separate great arteries. If this separation is incomplete, an abnormal connection can remain. [10]
2) Abnormal formation of the aortopulmonary septum. The septum is the tissue partition that should separate the two vessels. If it forms poorly, a window or fistula-like opening may stay present. [10]
3) Defective conotruncal ridge fusion. Some reviews explain that the opposing ridges in the outflow tract may fail to fuse properly, leading to this rare defect. [10]
4) Spiral septum maldevelopment. The spiral septum helps create the normal separate outflow channels. Abnormal development may leave the vessels partly connected. [10]
5) Isolated sporadic developmental error. In many babies, there is no family history and no clear outside trigger. The defect may happen as a sporadic fetal developmental mistake. [1] [10]
6) Ventricular septal defect association. Some patients have this lesion together with a ventricular septal defect, which suggests a broader disturbance in heart formation during fetal life. [1] [11]
7) Interrupted aortic arch association. This is an important linked congenital defect. When both are present, the heart problem is more complex and usually needs early treatment. [11] [12]
8) Tetralogy of Fallot association. Rarely, this abnormal aorta-to-pulmonary connection occurs with tetralogy of Fallot, showing overlap in developmental heart defects. [1]
9) Coronary artery anomaly association. Rare abnormal coronary development may occur with the defect, again suggesting shared embryologic disturbance. [1] [11]
10) Aortic arch anomaly association. Abnormal development of the arch vessels can exist along with this lesion and may affect diagnosis and surgery planning. [12] [13]
11) Complex conotruncal congenital heart disease. This lesion may be part of a wider group of outflow tract defects rather than a single isolated abnormality. [1] [10]
12) Genetic or chromosomal influence, suspected but not always proven. Some congenital heart defects arise from genetic changes, although a single consistent gene cause for this exact lesion is not established in every case. [14]
13) Abnormal neural crest cell contribution, suspected mechanism. Neural crest cells help form the great vessels. Disturbed migration or function is one possible developmental explanation used in conotruncal defects. [14]
14) Persistent abnormal fetal vascular connection. In some rare vascular malformations, an embryonic vessel connection does not close as expected. This concept is used to explain certain congenital aortopulmonary communications. [15]
15) Abnormal development of the ascending aorta wall. If the vessel wall does not form normally where separation should occur, an opening may remain. [1] [10]
16) Abnormal development of the main pulmonary artery wall. Similar wall malformation on the pulmonary side can contribute to a persistent communication. [1] [10]
17) Combined great vessel malformation. Sometimes the problem is not just one hole, but a broader abnormal arrangement of the great arteries. [9] [13]
18) Syndromic congenital heart development disorder. Rarely, the lesion may occur in a child who has multiple congenital anomalies, suggesting a wider syndrome even if not always named in every report. [14]
19) Familial tendency to congenital heart disease, possible risk factor. A family history of congenital heart disease can raise overall risk for structural heart defects, though it does not prove this exact lesion will occur. [14]
20) Unknown idiopathic congenital origin. Even after full evaluation, many cases still have no exact direct cause identified. This is common in rare congenital heart defects. [1] [10]
Symptoms
Symptoms depend on the size of the abnormal connection and how much blood shunts from the aorta to the pulmonary artery. A small defect may cause almost no symptoms. A larger defect may act like other major left-to-right shunt lesions and can lead to heart failure and pulmonary hypertension. [3] [16]
1) Fast breathing. Babies may breathe quickly because too much blood goes to the lungs and the heart has to work harder. [3] [16]
2) Shortness of breath. Older infants, children, or adults may feel breathless, especially with feeding, crying, or activity. [3]
3) Poor feeding. Feeding can become tiring because the baby is using extra energy to breathe and pump blood. [17]
4) Sweating during feeding. This is a common sign of infant heart failure in significant congenital shunt lesions. [17]
5) Poor weight gain or failure to thrive. Because feeding is difficult and the body is under stress, normal growth may slow down. [3] [17]
6) Tiredness. The child may look weak, tired, or less active than expected. [17]
7) Recurrent chest infection. Extra lung blood flow can make some children more likely to have repeated respiratory illness. [18]
8) Heart murmur. Many patients are first noticed because a clinician hears an abnormal murmur during examination. [3] [19]
9) Fast heart rate. Tachycardia may happen when the heart tries to keep up with the abnormal circulation. [16] [17]
10) Irritability. Infants may cry more and settle poorly because of breathing difficulty or heart strain. [20]
11) Signs of heart failure. These can include enlarged liver, poor feeding, sweating, rapid breathing, and weak growth. [3] [19]
12) Chest tightness or chest discomfort. This is less common, but some older patients with rare fistulous communications report it. [21]
13) Cyanosis or bluish color. This is not the main early sign in many patients, but it may appear late if pulmonary vascular disease becomes severe. [19]
14) Poor exercise tolerance. Older children may tire quickly with walking, playing, or running. [17]
15) Pulmonary hypertension symptoms. If untreated, the person may develop more severe breathlessness and complications from high pressure in lung vessels. [5] [22]
Diagnostic tests
Doctors usually diagnose this condition by combining the history, physical examination, and heart imaging. Echocardiography is usually the first major test. CT angiography, MRI, and cardiac catheterization can give more detail when needed. [19] [23]
1) General physical examination. The doctor looks at breathing pattern, skin color, growth, activity, feeding difficulty, and signs of distress. This basic exam often gives the first clue that a congenital heart problem may be present. [19]
2) Heart auscultation with stethoscope. The doctor listens for a murmur, abnormal heart sounds, or signs of extra blood flow. A murmur is one of the most common findings in these patients. [3] [16]
3) Pulse examination. The doctor checks pulse rate, strength, and sometimes whether pulses feel bounding, which can happen in significant left-to-right shunts. [16]
4) Blood pressure measurement in all limbs when needed. This helps screen for associated aortic arch defects or circulatory imbalance. [12] [19]
5) Precordial palpation. The examiner places a hand on the chest to feel for a strong heartbeat, parasternal lift, or thrill, which may suggest increased flow or pressure. [19]
6) Growth and nutrition assessment. Weight gain, feeding history, and growth chart review are important because poor growth is a common effect of a large defect. [3] [17]
7) Manual respiratory effort assessment. The clinician checks for chest retractions, nasal flaring, and labored breathing. This is a bedside manual assessment, not a machine test. [20]
8) Pulse oximetry. This simple test measures oxygen saturation in the blood and helps detect low oxygen or serious circulatory problems. [19]
9) Chest X-ray. It can show an enlarged heart and increased blood flow to the lungs, both of which support the diagnosis of a significant shunt. [1] [23]
10) Electrocardiogram or ECG. This electrical heart test may show chamber enlargement, strain, or rhythm effects caused by chronic abnormal blood flow. [23]
11) Transthoracic echocardiography. This is the main first imaging test. It uses ultrasound to show the abnormal connection, heart chamber size, blood flow direction, and pressure effects. [1] [23]
12) Color Doppler echocardiography. Doppler helps doctors actually see the abnormal blood flow jet between the vessels and estimate how large the shunt is. [21] [23]
13) Transesophageal echocardiography or TEE. A probe in the food pipe gives clearer pictures in selected patients, especially when ordinary echo is not enough. [24]
14) Cardiac CT angiography. CT angiography shows the exact anatomy, size, and location of the communication and helps surgical planning. [23] [25]
15) Cardiac MRI. MRI can show anatomy, blood flow, and chamber effects without radiation in selected patients. [24]
16) Cardiac catheterization. This invasive test directly measures pressures and oxygen levels and can confirm the size of the shunt when noninvasive tests are unclear. [1] [23]
17) Angiography during catheterization. Dye is injected to outline the abnormal channel and related vessels very clearly. [21] [24]
18) Blood gas analysis when very sick. In unstable patients, this lab test helps assess oxygenation and acid-base balance, though it does not by itself make the diagnosis. [19]
19) Complete blood count and basic blood tests. These are supportive tests. They help assess infection, anemia, or general illness before intervention, even though they do not directly prove the fistula. [19]
20) Pathological examination after surgery, when tissue is available. Pathology is not always required for diagnosis, but in operated cases it can confirm the structure of the abnormal tissue and rule out other vessel wall disease. [23]
Non-pharmacological treatments
1. Early surgical repair is the standard treatment. The purpose is to close the abnormal channel and stop the harmful left-to-right shunt. The mechanism is simple: once the hole is closed, too much blood no longer rushes into the lungs, so lung pressure and heart volume overload can improve. This is the treatment with the strongest evidence for survival and long-term protection.
2. Transcatheter device closure can be used in carefully selected patients when the anatomy is suitable. The purpose is the same as surgery, but the mechanism is closure from inside the blood vessel using an occluder device. It is less invasive than open-heart surgery, but not every patient is a candidate.
3. Admission to a pediatric or congenital heart center is important because rare shunt lesions need expert imaging, anesthesia, and surgery planning. The purpose is safer diagnosis and better timing of repair. The mechanism is specialist evaluation by congenital cardiology and cardiothoracic teams.
4. Oxygen support may be used when breathing is hard or oxygen level is low. The purpose is short-term breathing support, not closure of the fistula. The mechanism is improved oxygen delivery while the heart and lungs are under stress.
5. Careful fluid management helps when the baby has heart failure. The purpose is to reduce lung congestion and swelling. The mechanism is lowering volume overload so the heart works with less stress. This must be physician-guided, especially in infants.
6. High-calorie feeding plans are often needed because infants with heart failure burn more energy and tire during feeds. The purpose is weight gain and growth. The mechanism is giving more calories in smaller, easier feeds.
7. Nasogastric tube feeding may be used if oral feeding is too tiring. The purpose is nutrition support and prevention of growth failure. The mechanism is reducing feeding work while still providing calories.
8. Respiratory support such as CPAP or ventilator care may be needed in severe heart failure before repair. The purpose is to reduce breathing effort. The mechanism is lowering work of breathing and improving gas exchange while the defect is being stabilized.
9. Serial echocardiography is essential. The purpose is to confirm the anatomy, estimate shunt severity, and look for associated defects. The mechanism is ultrasound imaging of the heart and great vessels.
10. Cardiac catheterization in selected cases is used when pulmonary hypertension or operability is unclear. The purpose is to measure pressures and resistance directly. The mechanism is invasive hemodynamic testing.
11. Pulmonary hypertension assessment is a non-drug management step that guides treatment timing. The purpose is to find out whether lung vessels are still reversible. The mechanism is pressure and resistance evaluation by echo and sometimes catheterization.
12. Preoperative nutrition rehabilitation is helpful in babies who are underweight. The purpose is to improve surgical readiness and healing. The mechanism is correcting calorie and protein deficit before the operation.
13. Treatment of associated congenital heart defects is often needed because AP window can occur with other heart anomalies. The purpose is full correction of blood-flow problems. The mechanism depends on the associated lesion.
14. Postoperative ICU monitoring is standard after repair. The purpose is to watch for bleeding, low cardiac output, arrhythmia, and pulmonary hypertensive crisis. The mechanism is continuous close monitoring after closure.
15. Long-term congenital cardiology follow-up is important even after successful repair. The purpose is to check for residual shunt, pulmonary pressure, and heart function. The mechanism is regular exam plus imaging.
16. Activity guidance may be needed in patients with unrepaired shunts, heart failure, or pulmonary hypertension. The purpose is to prevent strain. The mechanism is limiting heavy exertion until the heart team says it is safe.
17. Infection prevention around surgery is part of good care. The purpose is to reduce postoperative complications. The mechanism is sterile procedure, line care, and close follow-up.
18. Family counseling and genetic discussion can help parents understand the defect, surgery timing, and warning signs. The purpose is safer home care and better follow-up. The mechanism is education and planning.
19. Prenatal detection by fetal echocardiography can improve delivery planning in some cases. The purpose is early diagnosis. The mechanism is imaging the fetal outflow tracts before birth.
20. Shared decision-making for surgery versus catheter closure is important because anatomy, age, size, pulmonary pressure, and associated defects matter. The purpose is choosing the safest definitive repair. The mechanism is multidisciplinary review.
Drug treatment
There is no medicine that closes the fistula itself. The drugs below are supportive and are chosen by a cardiologist based on heart failure, pulmonary hypertension, rhythm problems, blood pressure, age, weight, kidney function, and surgery timing. I am giving the most relevant FDA-labeled examples, not 20 disease-specific drugs, because that would not be evidence-based for this rare defect.
Furosemide is one of the most important support medicines when the defect causes fluid overload or pulmonary congestion. Its purpose is to reduce extra fluid and ease breathing. Its mechanism is loop diuresis in the kidney. FDA labeling supports use for edema associated with heart failure, including pediatric patients. Dose is individualized; common labeled use includes pediatric weight-based dosing and adult oral doses that often start at 20–80 mg depending on need and route. Side effects include dehydration, low potassium, low sodium, kidney stress, and low blood pressure.
Enalapril is used when heart failure and left-sided volume overload are present. Its purpose is to reduce afterload and help the heart pump more efficiently. Its mechanism is ACE inhibition, which lowers angiotensin II and aldosterone activity. FDA labeling supports symptomatic heart failure. Dosing is individualized; timing is usually once or twice daily depending on product and age. Side effects include cough, kidney injury, high potassium, and low blood pressure. It must be used very carefully in infants and only with specialist supervision.
Captopril is another ACE inhibitor sometimes used in infants with heart failure because it can be titrated in small doses. Its purpose and mechanism are similar to enalapril. It is usually given multiple times per day because it is shorter acting. Side effects again include hypotension, kidney dysfunction, cough, rash, and high potassium.
Digoxin may be used in selected patients with heart failure or some rhythm problems. Its purpose is to improve contractility and support the heart’s pumping efficiency. Its mechanism is inhibition of the sodium-potassium ATPase pump, which increases intracellular calcium in heart muscle. FDA labeling includes heart failure and pediatric myocardial contractility support. Dosing is highly age- and kidney-dependent. Side effects include nausea, vomiting, bradycardia, dangerous arrhythmias, and toxicity if blood levels rise too high.
Sildenafil may be considered if pulmonary arterial hypertension develops or persists, especially in congenital shunt disease under specialist care. Its purpose is to lower pulmonary vascular resistance. Its mechanism is PDE-5 inhibition, which raises cGMP and relaxes pulmonary vascular smooth muscle. FDA labeling supports pulmonary arterial hypertension. Dose depends on age and formulation; adult labeling commonly uses 20 mg three times daily, while pediatric use is specialist-guided. Side effects include headache, flushing, low blood pressure, nosebleed, and visual symptoms.
Other medicines may be used in special situations, such as milrinone after surgery for low cardiac output, spironolactone as an added diuretic, oxygen and inhaled nitric oxide for pulmonary hypertensive crisis, antiarrhythmic drugs if rhythm problems appear, and antibiotics when infection is suspected. These are complication-based choices, not standard curative therapy for the fistula itself.
Dietary molecular supplements
No dietary supplement can close this defect, and supplements should never delay repair. They are only considered when there is poor feeding, malnutrition, deficiency, or general cardiovascular support needs. Evidence is much weaker than for surgery.
Omega-3 fatty acids may support general cardiovascular health. Their purpose is not to treat the fistula, but to support heart health and triglyceride control in appropriate patients. The mechanism involves membrane effects, inflammation pathways, and lipid changes. Typical supplemental adult intake often ranges around 1 g/day EPA plus DHA under clinician advice, but infants and children need individualized guidance.
Coenzyme Q10 is sometimes used as a heart-health supplement. Its purpose is possible support of cellular energy production. The mechanism is participation in mitochondrial electron transport. Evidence for heart failure support is mixed and it is not FDA-approved to treat this defect. Typical adult supplemental amounts are often 100–200 mg/day, but use should be clinician-guided.
Iron may be important if iron deficiency or anemia is present, especially in congenital heart disease. Its purpose is to improve oxygen-carrying capacity and growth when deficiency is confirmed. The mechanism is restoration of hemoglobin production. It should only be given after checking iron studies because excess iron can also be harmful.
Vitamin D can be useful when deficiency exists, especially for bone health and overall growth. Its purpose is support of normal calcium balance and development. The mechanism is improved calcium and phosphate handling. It is not a treatment for the fistula and should be dosed based on age and lab status.
Other supportive supplements that may be considered only when a clinician finds deficiency or poor intake include zinc, multivitamins, protein supplements, medium-chain triglyceride formulas, folate, and vitamin B12. These help nutrition, growth, and recovery, not fistula closure.
Regenerative, stem cell, or “immunity booster” drugs
At present, there are no FDA-approved regenerative drugs, stem-cell drugs, or immunity-booster drugs that specifically treat congenital aortopulmonary artery fistula or close the abnormal connection. Standard care is anatomic closure plus supportive cardiac treatment. Claims that supplements or stem cells can replace repair are not evidence-based for this disease.
Surgeries or procedures
1. Open surgical patch closure is the classic procedure. A patch closes the abnormal opening and stops extra flow to the lungs. This is done because untreated large shunts can quickly lead to heart failure and pulmonary vascular disease.
2. Direct surgical closure may be used in selected anatomy when the opening is suitable for direct repair. It is done to remove the shunt and protect the lungs and heart.
3. Transaortic or transpulmonary repair techniques are chosen according to location and size of the defect. They are done to obtain safe exposure and complete closure without damaging nearby structures.
4. Catheter device closure is a minimally invasive interventional procedure for selected patients with favorable anatomy. It is done to avoid open surgery when safe and feasible.
5. Combined repair of associated lesions may be necessary when AP window is present with other congenital defects. It is done because leaving associated defects untreated can continue abnormal blood flow or worsen outcome.
Prevention, when to see a doctor, and food advice
A true congenital fistula usually cannot be fully prevented, but risk reduction may include good prenatal care, diabetes control, avoidance of alcohol and tobacco, avoiding known teratogenic medicines unless a doctor approves them, vaccination and infection prevention before pregnancy, folic acid use, and early fetal scans when risk is high. These steps reduce some birth-defect risks in general, though they do not guarantee prevention of AP window.
A doctor should be seen urgently if a baby has fast breathing, chest retractions, poor feeding, sweating during feeds, poor weight gain, bluish color, repeated chest infections, unusual sleepiness, or signs of heart failure. After repair, urgent review is needed for fever, breathing trouble, poor feeding, swelling, fainting, or worsening exercise tolerance.
What to eat: breast milk if possible, calorie-fortified feeds when prescribed, small frequent feeds, adequate protein, iron-rich foods when age-appropriate, fruits and vegetables, oily fish in older children or adults when safe, and enough fluids as directed by the care team. What to avoid: excess salt, force-feeding, unapproved herbal products, high-sugar junk foods, smoking exposure, and any supplement without clinician advice. The best diet is one that supports growth and does not worsen fluid overload.
FAQs
Is this the same as aortopulmonary window? In many clinical sources, yes, that is the closest standard term.
Can medicines alone cure it? No. They support symptoms, but closure is the definitive treatment.
Is surgery always needed? Most significant defects need early closure.
Can catheter closure replace surgery? In selected anatomy, yes, but not in every patient.
Why is early treatment important? It helps prevent irreversible pulmonary vascular disease and heart failure.
Can this cause pulmonary hypertension? Yes, especially if the shunt is large and untreated.
Can a baby fail to gain weight? Yes, because feeding takes more effort and heart failure raises energy needs.
Is it dangerous in adults if not repaired? Yes. Some late cases present with severe pulmonary hypertension or heart failure.
Are supplements enough? No. Supplements may support nutrition, but they do not close the defect.
Are stem-cell drugs available for this? No FDA-approved stem-cell therapy exists for this defect.
Can echocardiography diagnose it? Usually yes, though some complex cases need catheterization or other imaging.
Can the outcome be good after repair? Yes, especially when treated early.
Can it occur with other heart defects? Yes, associated anomalies are common.
Should families follow up long term? Yes, congenital cardiology follow-up remains important after repair.
What is the single most important message? Do not delay expert congenital heart evaluation, because early definitive closure is the main life-saving treatment.
Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.
The article is written by Team RxHarun and reviewed by the Rx Editorial Board Members
Last Updated: March 05, 2025.
