--- title: Pulmonary atresia with ventricular septal defect description: What pulmonary atresia with ventricular septal defect is, how it differs from tetralogy of Fallot, how blood reaches the lungs in this defect, how it is found and treated and when urgent help is needed. type: disease aliases: - PA-VSD - PA/VSD - Pulmonary atresia with VSD sources: - tier: guideline org: minzdrav-rf title: Атрезия легочной артерии с дефектом межжелудочковой перегородки (АЛА с ДМЖП) year: 2024 url: https://cr.minzdrav.gov.ru/view-cr/47_3 - tier: guideline org: esc title: 2020 ESC Guidelines for the management of adult congenital heart disease year: 2020 doi: 10.1093/eurheartj/ehaa554 url: https://doi.org/10.1093/eurheartj/ehaa554 - tier: reference org: msd-manuals title: Overview of Congenital Cardiovascular Anomalies year: 2025 url: https://www.msdmanuals.com/professional/pediatrics/congenital-cardiovascular-anomalies/overview-of-congenital-cardiovascular-anomalies sources_checked: 2026-10-13 review: null --- Pulmonary atresia with ventricular septal defect (PA-VSD) is a complex congenital heart defect in which there is no direct connection between the right ventricle and the pulmonary artery: the outflow of blood from the right ventricle to the lungs is closed. In addition, there is a large hole under the aorta in the wall between the ventricles, the aorta is shifted to the right, and the wall of the right ventricle is thickened. The main feature of the defect is a lack of oxygen in the blood and a bluish colour of the skin (cyanosis). The defect resembles [tetralogy of Fallot](../tetralogy-of-fallot/), but differs from it in the most important way. 1. The internal structure of the heart is the same as in tetralogy of Fallot, but there is no direct route for blood from the right ventricle to the pulmonary arteries. 2. So blood reaches the lungs by a roundabout route: from the right ventricle through the septal defect into the left ventricle and the aorta, and only from there through an open arterial duct or through collateral vessels. 3. The pulmonary arteries themselves may be underdeveloped or absent, and there are very many anatomical variants. 4. The hypercyanotic spells typical of tetralogy of Fallot do not occur in this defect. 5. When the pulmonary arteries are favourably formed, the operation is similar to tetralogy of Fallot repair; in other cases treatment is done in several stages. 6. In adults after surgery, the problems are similar to those after tetralogy of Fallot repair. Do not confuse this defect with [pulmonary atresia with intact ventricular septum](../pulmonary-atresia-with-intact-ventricular-septum/): there the wall between the ventricles is intact.

Normally none of these changes is present: blood goes from the right ventricle straight into the pulmonary artery and through its branches to the lungs, and the aorta arises from the left ventricle. The arterial duct, a vessel between the pulmonary artery and the aorta that the fetus needs, closes after birth.

The diagram shows one of the variants of the defect. The outflow from the right ventricle ends blindly, the pulmonary arteries are thin, there is a large septal defect under the aorta, the aorta is shifted and sits over it, and the right ventricular wall is thickened. Blood from the right ventricle passes through the defect, mixes with blood from the left ventricle and goes into the aorta; it reaches the lungs from the aorta, through an open arterial duct and/or through collateral vessels. The structure of the pulmonary arteries and the sources of blood flow to the lungs vary greatly from patient to patient.

## Why it happens The defect forms while the heart is developing in the fetus. The pulmonary trunk, its right and left branches and the vessels inside the lungs develop from different primordia, and any of them may fail to develop. That is why there are many variants of the defect: sometimes only the pulmonary valve is closed, and sometimes there is neither the trunk nor either of its branches. People with this defect often have a 22q11.2 microdeletion, the loss of a small piece of chromosome 22; it can come with particular facial features, nasal speech and developmental delay. There is no direct route from the right ventricle to the lungs, so blood goes there through the aorta. The child's condition depends above all on how large the open arterial duct is and whether there are large collateral vessels: abnormal vessels that arise from the aorta or its branches and carry extra blood to the lungs. If blood reaches the lungs only through the duct, a newborn's life depends on the duct staying open. The outlook without treatment depends on how the blood supply to the lungs is arranged. According to the Russian Ministry of Health paediatric guideline, PA-VSD belongs to the group of conotruncal defects. The anatomical criteria are absence of the PA at various levels, a large subaortic VSD, additional sources of collateral pulmonary blood flow, right ventricular (RV) hypertrophy, dextroposition of the aortic root and a normal relationship between the aorta and the PA trunk. Oxygen saturation is the same in the aorta, the collateral arteries and the PA. The Somerville classification distinguishes four types: I, atresia of the pulmonary valve with a formed trunk and both branches; II, atresia of the valve and the trunk; III, of the valve, the trunk and one PA; IV, of the valve, the trunk and both PAs, with pulmonary blood flow through a network of collaterals. The 1999 classification distinguishes type A (native PAs, flow through a patent ductus arteriosus, PDA), type B (native PAs and collaterals) and type C (no native PAs, flow through collaterals). The ESC describes three variants: confluent, normal-sized PAs supplied by a PDA; confluent but hypoplastic PAs ("seagull" appearance) with multiple major aortopulmonary collateral arteries (MAPCAs); non-confluent or absent PAs supplied by MAPCAs. The most important sources of pulmonary blood flow are the PDA, MAPCAs and bronchial arteries. Associated lesions may include an atrial septal defect, an atrioventricular septal defect (more often in Down syndrome), a right aortic arch and coronary artery anomalies. The ESC classes all forms of pulmonary atresia as congenital heart disease (CHD) of severe complexity. The Russian Ministry of Health paediatric guideline gives the frequency in different ways: in the definition, pulmonary atresia as a whole (with a VSD and in other complex defects) accounts for 2–3% of all CHD; in the section on epidemiology, for 3–5%. The 3D model shows a normal heart: the wall between the ventricles, the pulmonary valve and trunk, and the aorta are highlighted, the places the defect changes. ## Symptoms The main sign is blueness (cyanosis) of the lips and fingertips; the child may be breathless, tire quickly and lag behind in physical development. With a long-standing lack of oxygen, the shape of the fingers and nails changes: the fingertips become rounded and thickened (clubbing) and the nails curve like a watch glass. Marked cyanosis in most cases appears when the child starts to walk, and then usually gets worse. Unlike tetralogy of Fallot, this defect does not cause hypercyanotic spells. Adults who have not had surgery notice breathlessness on exertion and tiredness; their cyanosis gradually gets worse and may be severe even with slight effort. Auscultatory findings are sparse. A continuous (systolic–diastolic) murmur of MAPCAs is heard over the lung fields, and with a functioning PDA a characteristic continuous murmur may be heard; according to the ESC, continuous murmurs over the back point to MAPCAs. The most typical complications are cerebrovascular events in the form of thrombosis or haemorrhage, caused by hypoxaemia, embolism, polycythaemia and increased blood viscosity. In unoperated adults the ESC lists haemoptysis (rupture of small collaterals and/or thrombosis of small PA branches), chronic heart failure, progressive dilation of the ascending aorta with aortic regurgitation (rarely dissection), endocarditis, arrhythmias and sudden cardiac death, and segmental pulmonary arterial hypertension. ## How it is diagnosed The defect is suspected from cyanosis, breathlessness and the examination; changes heard when listening to the heart are often slight. The main test is a heart ultrasound scan (echocardiography) with Doppler: it shows the septal defect, the position of the aorta, the thickening of the right ventricular wall and that the outflow from the right ventricle ends blindly. An ECG and a chest X-ray are also done, and the oxygen level in the blood is measured (pulse oximetry). To see all the sources of blood supply to the lungs and the size of the pulmonary arteries, cardiac catheterisation with angiography (an X-ray examination of the vessels with contrast), computed tomography and sometimes MRI are needed. Typical ECG findings are right axis deviation, RV hypertrophy, incomplete right bundle branch block and signs of right atrial overload. The chest X-ray shows a boot-shaped heart with a concave PA segment and reduced pulmonary vascular markings, increased in places because of large MAPCAs. On echocardiography there is no direct flow from the RV to the PA, the RV outflow tract ends blindly, and colour Doppler shows continuous flow in MAPCAs. Right ventriculography opacifies the occluded RV outflow tract, and contrast passes through the VSD into the ascending aorta; aortography shows the sources of pulmonary blood supply and their connection with the native PAs. The ESC considers MRI, CT and cardiac catheterisation necessary to define the sources of pulmonary blood flow and the size of the PAs and to assess MAPCAs. ## How it is treated The defect is treated with surgery: according to the Russian Ministry of Health paediatric guideline, every variant of it is an indication for surgery, done as early as possible, most often in the first year of life. The aim is to close the septal defect, create an outflow from the right ventricle into the pulmonary arteries and, if needed, rebuild the blood supply to the lungs so that blood reaches them from a single source, the right ventricle. If the pulmonary arteries are well developed, the operation is similar to tetralogy of Fallot repair; if there is no pulmonary trunk, the outflow from the right ventricle is created with a tube called a conduit. If the pulmonary arteries are small, treatment is done in several stages: first, relieving (palliative) operations increase blood flow to the lungs and prepare for complete repair. If a newborn's arterial duct is closing, doctors keep it open with a medicine, and in a critical condition they may place a stent in the duct. Which operation to do and when is decided by heart surgeons, taking into account the structure of the pulmonary arteries and the child's condition and age; the choice of a palliative operation may be discussed by a team of doctors. After timely surgery the outlook is favourable. A conduit that has narrowed may later be widened with a balloon through a catheter. Follow-up with a cardiologist is needed after surgery too: with a paediatric cardiologist until 18, then at an adult outpatient clinic. For adults with this defect, the ESC recommends follow-up in a specialised adult congenital heart disease centre at least once a year; breathlessness, worsening cyanosis, a change in the heart murmur, signs of heart failure or heart rhythm problems are reasons to be seen sooner. For many adults who have not had surgery, an operation may no longer be suitable because of the complex structure of the lung vessels, and heart surgery itself carries a serious risk of death. Dental and other procedures should be agreed with the cardiologist in advance: prevention of endocarditis may be needed. For adults whose heart test results are excellent, the ESC advises regular exercise, avoiding only extreme static exertion. For women who have had surgery and have good heart function and no rhythm problems, the risk of pregnancy is low; it rises with a lack of oxygen in the blood, pulmonary hypertension, weakened ventricular function, heart failure and arrhythmias. Before pregnancy it is worth checking for a 22q11 microdeletion. There is no consensus on the optimal surgical strategy. According to the Russian Ministry of Health paediatric guideline, complete repair (VSD closure, creation of an outflow from the RV into the PA system and, if needed, unifocalisation of pulmonary blood flow for as many segments as possible) is done as a primary operation when the PA anatomy is favourable, or as a second stage after a palliative intervention. According to the ESC, with confluent, normal-sized PAs and a pulmonary trunk present (usually with valvular atresia), a tetralogy of Fallot-type repair with a transannular patch is possible; with normal-sized PAs and no trunk, repair with an RV–PA conduit; with confluent but hypoplastic PAs, an arterial shunt or RV outflow tract reconstruction without VSD closure is often needed, which may stimulate PA growth, followed by repair with a valved conduit. Palliative interventions (most often systemic-to-pulmonary shunts; in critically ill newborns, PDA stenting) increase pulmonary blood flow and prepare for complete repair. With large collaterals, unifocalisation followed by complete repair is recommended, while single-stage complete repair with MAPCAs and a hypoplastic PA system is not recommended because of fairly high mortality. Endovascular procedures include balloon angioplasty and stenting of collaterals to increase pulmonary blood flow and, in severe haemoptysis, coil embolisation of ruptured collaterals. After repair, a residual VSD shunt, residual PA stenosis, pulmonary regurgitation, and rhythm and conduction disorders are possible; after repair through a transventricular approach the ECG shows complete right bundle branch block. Survival depends on the complexity of the pulmonary vessels and the results of surgery; after palliative interventions only, it is considerably lower: according to the ESC, 60% at 20 years of follow-up. The ESC recommends infective endocarditis prophylaxis only for high-risk patients, including all unoperated patients. ## When to call an ambulance The Russian Ministry of Health paediatric guideline lists as reasons for emergency admission to hospital a sudden increase in cyanosis or breathlessness and worsening heart failure. If a child with this defect suddenly becomes more blue or more breathless, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK). In an adult who has not had surgery, coughing up blood may be caused by a ruptured collateral vessel, and heavy coughing up of blood may need an urgent procedure through a catheter. If someone is coughing up blood, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK). The defect can be complicated by a cerebrovascular event. If there are signs of a stroke (sudden weakness or numbness of one side of the body, difficulty speaking, a drooping face), call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) straight away. As with any heart condition, call an ambulance for fainting, chest pain or severe breathlessness: this is the site's general safety rule, repeated at the bottom of every page.