---
title: Pulmonary atresia with intact ventricular septum
description: What pulmonary atresia with an intact ventricular septum is, why the right ventricle is often underdeveloped in this defect, how it is found, which treatment approaches the sources describe and when urgent help is needed.
type: disease
aliases:
  - PA/IVS
  - PA-IVS
  - pulmonary atresia with an intact ventricular septum
sources:
  - 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: Other Congenital Cardiac Anomalies
    year: 2023
    url: https://www.msdmanuals.com/professional/pediatrics/congenital-cardiovascular-anomalies/other-congenital-cardiac-anomalies
  - 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: 2026-10-14
review: null
---

Pulmonary atresia with intact ventricular septum (PA/IVS) is a congenital heart defect in which the <Structure id="pulmonary-valve">pulmonary valve</Structure> is not properly formed and does not let blood pass from the heart to the lungs, while the <Structure id="interventricular-septum">wall between the ventricles</Structure> is intact.<Cite n={2} /> Often the <Structure id="tricuspid-valve">tricuspid valve</Structure> and the <Structure id="right-ventricle">right ventricle</Structure> are underdeveloped as well.<Cite n={2} /> It is a "blue" defect: the newborn's skin looks bluish (cyanosis).<Cite n={[2, 3]} />

It is a different defect from [pulmonary atresia with ventricular septal defect](../pulmonary-atresia-with-ventricular-septal-defect/): there the wall between the ventricles has a hole, while here it is intact.<Cite n={[1, 2]} /> The European Society of Cardiology (ESC) guidelines place variants of this defect among the hypoplastic right heart syndromes, a group of defects in which one ventricle is so small that the circulation cannot be divided between two ventricles (see the article on [single ventricle](../single-ventricle/)).<Cite n={1} />

<Diagram name="pulmonary-atresia-with-intact-ventricular-septum">
  <p slot="normal">
    Normally blood goes from the right ventricle through the valve into the pulmonary artery and
    along its branches to the lungs, and from the left ventricle into the aorta.<Cite n={[1, 2, 3]} /> The
    arterial duct, a vessel between the pulmonary artery and the aorta that the fetus needs, closes
    after birth.<Cite n={3} />
  </p>
  <p slot="disease">
    The diagram shows one of the variants of the defect. The pulmonary valve does not let blood out of
    the right ventricle, the ventricle itself is small, and the wall between the ventricles is
    intact.<Cite n={2} /> Blood reaches the pulmonary artery from the aorta through the open arterial
    duct: the baby's life right after birth depends on it.<Cite n={[2, 3]} /> The structure of the
    heart in this defect varies: the right ventricle is often underdeveloped, but not in everyone.<Cite n={[1, 2]} />
  </p>
</Diagram>

## Why it happens

<Patient>

The defect forms before birth. A ventricle of the fetus grows normally only if enough blood flows into it and out of it.<Cite n={2} /> When the way out through the pulmonary valve is closed, the right ventricle and the tricuspid valve often stay underdeveloped.<Cite n={2} />

The coronary arteries, which supply the heart itself, are also often changed: there may be fistulas, abnormal connections between the coronary arteries and the small right ventricle, and narrowings of the coronary arteries.<Cite n={2} /> These changes largely determine the outlook and which operation is possible.<Cite n={2} />

</Patient>

<Student>

Pulmonary valve atresia with an intact ventricular septum frequently occurs together with hypoplasia of the tricuspid valve and the RV; MSD attributes this to the fact that normal ventricular growth in fetal life depends on adequate inflow and outflow of that ventricle.<Cite n={2} /> Coronary arterial abnormalities, particularly fistulous connections of the coronary arteries to the hypoplastic RV and coronary artery stenoses, are common and have a major impact on prognosis and surgical options.<Cite n={2} />

In the ESC guidelines on adults with congenital heart disease (CHD), pulmonary atresia (all forms) is classed as CHD of severe complexity.<Cite n={1} /> ESC places PA/IVS variants among the hypoplastic right heart syndrome variants, that is, in the univentricular heart group: one ventricle is missing or hypoplastic and thus not amenable to biventricular repair.<Cite n={1} />

</Student>

<HeartModel highlight={['pulmonary-valve', 'right-ventricle', 'tricuspid-valve']} />

The 3D model shows a normal heart, with the pulmonary valve, the right ventricle and the tricuspid valve highlighted: the parts that the defect changes.

## Symptoms

<Patient>

The main sign is a bluish tinge to the baby's skin and lips.<Cite n={2} /> Before birth the arterial duct is open; after birth it usually starts to close within the first 10–15 hours of life.<Cite n={3} /> In this defect blood reaches the lungs through the duct, so the newborn's survival depends on the duct staying open.<Cite n={[2, 3]} />

</Patient>

<Student>

Auscultation may reveal a murmur of tricuspid regurgitation or of a patent ductus arteriosus (PDA).<Cite n={2} /> According to MSD, persistent cyanosis in cyanotic CHD in general can lead to polycythaemia, clubbing, thromboembolism (including stroke), bleeding disorders and brain abscess.<Cite n={3} />

</Student>

## How it is diagnosed

<Patient>

The defect may be found before birth on an ultrasound scan of the fetus; if not, it is diagnosed after birth with an ultrasound scan of the heart (echocardiography).<Cite n={2} /> The MSD Manual recommends pulse oximetry for all newborns before they leave hospital: a sensor on the right hand and on a foot measures how much oxygen the blood carries, so that critical heart defects are not missed.<Cite n={3} />

</Patient>

<Student>

In a newborn with a murmur, cyanosis, abnormal pulses or signs of heart failure, CHD is confirmed with echocardiography; in selected cases cardiac MRI or CT angiography clarifies the anatomy, and cardiac catheterisation with angiocardiography is occasionally needed and is generally done for therapeutic purposes (MSD data for CHD in general).<Cite n={3} />

Cyanosis in a newborn also occurs in critical [pulmonary valve stenosis](../pulmonary-valve-stenosis/): there the valve is narrowed, and the cyanosis is due to right-to-left atrial shunting through a patent foramen ovale.<Cite n={2} />

</Student>

## How it is treated

<Patient>

An operation cannot be avoided: surgery is always required for this defect.<Cite n={2} /> Until the operation, doctors keep the arterial duct open with a medicine given into a vein.<Cite n={3} />

Which operation is possible depends largely on the size of the right ventricle and the structure of the coronary arteries.<Cite n={[1, 2]} /> If the right ventricle is too small to divide the circulation between two ventricles, treatment follows the [single ventricle](../single-ventricle/) path: the usual final step is the Fontan operation, which is often done in two stages, the first being the Glenn operation. After a Fontan operation, venous blood flows to the lungs bypassing the ventricles, and the single working ventricle pumps blood only to the organs of the body.<Cite n={[1, 2]} /> Which operations a particular child needs, and when, is decided by paediatric heart surgeons.

</Patient>

<Student>

When the RV is hypoplastic and not amenable to biventricular repair, ESC places these PA/IVS variants in the univentricular heart group.<Cite n={1} /> For the univentricular heart in general, ESC states that by adulthood the vast majority of patients have undergone a systemic-to-pulmonary artery shunt, a cavopulmonary connection (Glenn operation) or, now preferably, a Fontan operation or one of its modifications.<Cite n={1} /> The Fontan operation separates the systemic and pulmonary venous returns without a subpulmonary ventricle; this circulation is frequently established in two stages.<Cite n={1} />

According to ESC, after the Fontan operation the majority of patients do well during childhood and adolescence, although exercise capacity is reduced when measured objectively; a premature decline in cardiovascular performance, with reduced survival, is inevitable even in patients with the best Fontan result.<Cite n={1} /> These data apply to all patients after the Fontan operation, not only to patients with PA/IVS.

</Student>

## When to call an ambulance

Acute severe heart failure or cyanosis in the first week of life is a medical emergency.<Cite n={3} /> If a newborn's bluish colour suddenly gets worse, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK).

Persistent cyanosis can lead to a stroke.<Cite n={3} /> For signs of a stroke (sudden weakness or numbness on one side of the body, trouble speaking, a drooping face), call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) at once. As with any heart condition, call an ambulance for fainting, chest pain or severe shortness of breath: this is the site's general safety rule, repeated at the bottom of every page.

<Quiz />