--- title: Congenitally corrected transposition of the great arteries description: What congenitally corrected transposition of the great arteries is, how it differs from ordinary transposition, why the systemic ventricle weakens over the years and AV block can occur, how the defect is found and treated, and when urgent help is needed. type: disease preset: av-block-third-degree wiggers: false afterTreatment: false aliases: - ccTGA - Congenitally corrected TGA - Corrected transposition of the great arteries - Corrected transposition of the great vessels - L-transposition - L-TGA - Ventricular inversion - Atrioventricular discordance sources: - tier: guideline org: minzdrav-rf title: Дискордантное предсердно-желудочковое соединение year: 2024 url: https://cr.minzdrav.gov.ru/view-cr/35_2 - 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: Congenitally Corrected Transposition of the Great Arteries year: 2023 url: https://www.msdmanuals.com/professional/pediatrics/congenital-cardiovascular-anomalies/congenitally-corrected-transposition-of-the-great-arteries sources_checked: 2026-10-13 review: null --- Congenitally corrected transposition of the great arteries (ccTGA; the Russian Ministry of Health guideline calls it corrected transposition of the great vessels) is a congenital heart defect in which two connections are abnormal at once: between the atria and the ventricles, and between the ventricles and the great arteries. The right atrium is connected to the morphologic left ventricle, which gives rise to the pulmonary artery, and the left atrium to the morphologic right ventricle, which gives rise to the aorta. The two "errors" cancel each other out, so blood flows in the right direction: venous blood goes to the lungs and arterial blood to the body. That is why the circulation is called "corrected". But it is the morphologic right ventricle that pumps blood into the aorta and to the whole body, while the left ventricle works for the lungs. Because of this, and because other defects often come with it, symptoms and complications almost always appear over time. It is a rare defect: according to the MSD Manual it accounts for about 0.5% of all congenital heart defects, and according to the Russian Ministry of Health guideline for less than 1%. This defect is not the same as [transposition of the great arteries](../transposition-of-the-great-arteries/) (d-TGA). In d-TGA only the arteries are switched, the two circulations run in parallel, the baby turns severely blue right after birth, and surgery is needed in the first week of life. In corrected transposition the blood follows the correct route. And when the defect is isolated, without other heart defects, complications rarely develop before adulthood.

Normally the atria and ventricles are connected correctly, and blood follows its usual route: venous blood to the lungs, arterial blood to the body. The valve that leads into the morphologic right ventricle is the tricuspid valve, and the one that leads into the morphologic left ventricle is the mitral valve. The diagram is drawn as seen from the front: the right side of the heart is on the left, and the left side on the right.

In corrected transposition the right atrium is connected to the morphologic left ventricle, which gives rise to the pulmonary artery, and the left atrium to the morphologic right ventricle, which gives rise to the aorta. The valves stay with their ventricles: the tricuspid valve leads into the systemic (morphologic right) ventricle, and the mitral valve into the venous one. The morphologic right ventricle lies on the left, and the aorta lies in front of and to the left of the pulmonary artery. Blood follows the usual route, but it is the right ventricle that pumps it into the aorta. In this defect the tricuspid valve is almost always abnormal, and blood often leaks back through it into the left atrium, a leak that grows over time.

## Causes It is a congenital defect: the heart forms this way before birth. How a child will feel depends mainly on the other heart defects that most people with ccTGA have. Most often these are changes in the tricuspid valve, usually resembling [Ebstein anomaly](../ebstein-anomaly/), a [ventricular septal defect](../ventricular-septal-defect/), and narrowing (stenosis) of the pulmonary artery, including [pulmonary valve stenosis](../pulmonary-valve-stenosis/). The conduction system of the heart — the AV node and the bundle of His, which carry the signal to contract from the atria to the ventricles — lies in an unusual position in this defect. That is why conduction problems — [AV block](../av-block/) — are common. Complete AV block may be present at birth or appear later: it develops at a rate of about 2% a year. It is more common after operations — closure of a ventricular septal defect or replacement of the tricuspid valve — and may appear during pregnancy. ccTGA is the combination of atrioventricular and ventriculoarterial discordance; it is this double discordance that gives a normal distribution of blood flow. According to the ESC, the ventricles are inverted: the aorta arises anteriorly from the RV (usually on the left side) and the PA posteriorly from the LV (usually on the right side); these connections may be present with usual or mirror-image atrial arrangement. The AV valve of the systemic (morphologic right) ventricle is morphologically tricuspid and is called the systemic (arterial) AV valve; the valve of the venous ventricle is mitral. According to the ESC, abnormal base–apex orientation, especially dextrocardia, is common (20%). The sources give different frequencies of associated lesions. ESC: associated lesions in 80–90%, VSD in 70%, PS in 40%, and a dysplastic systemic tricuspid valve (e.g. Ebstein-like malformation). The Russian Ministry of Health guideline: associated intracardiac defects in about 80%, tricuspid valve anomalies with significant regurgitation in up to 90%, VSD in 80%. MSD: VSD in more than 60%, PS in 40%. The AV node (sometimes multiple AV nodes) and the bundle of His are abnormally located. According to the Russian Ministry of Health guideline, normal AV conduction is found in only 38% of patients. Other rhythm and conduction disorders include [sick sinus syndrome](../sick-sinus-syndrome/), [atrial fibrillation](../atrial-fibrillation/) and AV re-entrant tachycardia via accessory pathways around the tricuspid annulus. According to the ESC, [Wolff–Parkinson–White syndrome](../wpw-syndrome/) is present in 2–4% of patients. The model shows a normal heart, in which the right ventricle with its tricuspid valve lies on the right. In ccTGA the morphologic right ventricle lies to the left of the morphologic left ventricle. ## Symptoms When the defect is isolated, without other heart defects, complications rarely develop before adulthood. These patients usually come to a doctor because of an unexplained heart murmur or rhythm problems. In infants the defect may show itself as a heart murmur, a bluish colour of the skin, or cyanosis (when a ventricular septal defect is combined with severe narrowing of the pulmonary artery), heart failure (with a large defect), or a slow pulse with symptoms because of congenital complete AV block. People with associated defects most often complain of breathlessness on exertion and tiredness, and sometimes of stabbing pains in the heart area and a bluish colour of the skin. In adults a common concern is the gradual weakening of the systemic right ventricle. It may go unnoticed for a long time, or it may lead to severe [heart failure](../heart-failure/). Heart failure is made worse by increasing leakage through the tricuspid valve — [tricuspid regurgitation](../tricuspid-regurgitation/), which is common in this defect. Late complications, according to the ESC: systemic RV dysfunction and failure, progressive TR (systemic AV valve), LVOTO, complete AV block and, extremely rarely, ventricular tachycardias. Life expectancy is reduced: according to the ESC, about 50% of patients with associated lesions were alive at the age of 40 years, and without associated lesions about 50% were alive at the age of 60 years. Patients die from congestive heart failure or die suddenly, presumably due to VT/VF, regardless of the presence of advanced heart failure. A characteristic finding is a loud second heart sound at the base of the heart to the left of the sternum, due to the anterior and leftward position of the aorta; it can be mistaken for a sign of severe pulmonary hypertension. Murmurs depend on the associated lesions: TR, VSD, PS. ## Diagnosis The main test is a heart ultrasound scan, [echocardiography](../../diagnostic/echocardiography/). It shows that the ventricles have swapped places and finds associated defects. An [ECG](../../diagnostic/ecg/) may show AV block. To find rhythm and conduction problems, a long-term ECG recording is made — [Holter monitoring](../../diagnostic/holter-monitoring/). A chest X-ray may show an unusual position of the heart and the aorta. Cardiac MRI assesses the work of the ventricles more accurately, especially the systemic right ventricle, which is hard to assess by ultrasound. Cardiac catheterisation is done if other tests are not enough. ECG: a prolonged PR interval or complete AV block; early septal activation from right to left causes deep Q waves in II, III, aVF and V1–V3, and reversal of the normal precordial progression shows as a QR pattern in V1 and rS in V6. Echocardiography: the aorta lies to the left of and anterior to the PA, and the great arteries are parallel; there is mitral–pulmonary continuity and no tricuspid–aortic continuity, a pattern typical of transposition; the left-sided ventricle has the marked trabeculation typical of the RV, and the tricuspid valve, unlike the mitral valve, has chordal attachments to the septum. Chest X-ray: a straight left heart border due to the position of the ascending aorta, dextroposition or mesocardia. CMR is indicated for quantification of ventricular volumes, mass and EF, because echocardiographic assessment of systolic function in the systemic RV is difficult and less reliable. Catheterisation is indicated when non-invasive assessment is inconclusive or pulmonary hypertension requires evaluation. ## Treatment There is no evidence that medicines for heart failure improve the outlook in people with a systemic right ventricle, so prescribing them to everyone "as a precaution" is not recommended. If heart failure has already appeared, diuretics relieve the symptoms. In complete AV block a pacemaker is fitted. Associated defects are often operated on: a ventricular septal defect is closed, narrowing of the pulmonary artery is relieved. After such operations it is still the right ventricle that pumps blood to the body, so their effect may be temporary: the risk that the systemic right ventricle will weaken remains. If the tricuspid valve leaks badly and surgery is needed, it is, as a rule, replaced with a prosthesis: the valve itself can rarely be repaired. The decision to operate depends on symptoms and on how well the systemic right ventricle works. There is also a "double switch" operation: the blood is rerouted so that the left ventricle pumps it to the body again. The Russian Ministry of Health guideline advises this anatomical repair where it is possible. According to the ESC, in children with a failing systemic right ventricle it is an established treatment option, but in adults this approach is very rarely successful. Adults with moderate or severe weakening of the right ventricle and a risk of dangerous ventricular arrhythmias may need an implantable cardioverter-defibrillator, and in severe cases a heart transplant. Lifelong follow-up in a specialised congenital heart disease centre, once a year, is needed. After surgery an ECG, Holter monitoring and a heart ultrasound scan are done once a year. Excessive physical exertion should be avoided. The Russian Ministry of Health guideline advises prevention of [infective endocarditis](../infective-endocarditis/) before dental and other procedures that damage the skin or mucous membranes, and agreeing such procedures with a cardiologist in advance. The ESC limits such prevention to people at high risk of endocarditis, for example those with a prosthetic valve. Vaccination against flu and pneumococcal infection is recommended. According to the ESC, the risk of pregnancy depends on how well the person feels, on the function of the ventricle and the tricuspid valve, on rhythm problems (especially AV block) and on associated defects. The doctor decides what treatment is needed in each case. There are no data that ACE inhibitors, ARBs, beta-blockers or aldosterone antagonists, alone or in combination, improve outcome; their routine prescription to prevent heart failure or improve outcome is not recommended. In more symptomatic patients, "classical" heart failure medications or ARBs may provide some benefit. In complete AV block, AV sequential pacing is the standard; biventricular pacing should be considered in case of complete AV block or a ventricular pacing requirement of more than 40% (IIa C). Repair of the systemic AV valve is rarely feasible; as a rule, valve replacement is the treatment of choice. ESC: in symptomatic patients with severe TR and preserved or mildly impaired systemic RV systolic function (EF more than 40%), TV replacement is indicated (I C); in asymptomatic patients it should be considered with progressive dilatation or mildly impaired function of the systemic RV (IIa C); in symptomatic patients with an EF of 40% or less it may be considered (IIb C). According to the Russian Ministry of Health guideline, the "double switch" combines an atrial switch (Senning or Mustard) with an arterial switch when there is no PS, or with a Rastelli operation when there is PS. ## When to call an ambulance The Russian Ministry of Health guideline lists the reasons for emergency admission to hospital: high-grade AV block, a sudden increase in cyanosis or breathlessness, and the appearance of signs of severe heart failure. If cyanosis or breathlessness suddenly gets worse or signs of severe heart failure appear, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK). How AV block shows itself and when it needs urgent help is explained in the article on [AV block](../av-block/). 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. If tiredness, breathlessness, cyanosis or swelling appear or suddenly get worse, the abdomen gets bigger, or there are heart rhythm problems, fainting or signs of nervous system damage — loss of vision, hearing or speech, numbness of an arm or leg, paralysis, even if brief — and also with an acute respiratory infection or a fever of unclear cause, the Russian Ministry of Health guideline advises seeing a cardiologist as soon as possible, outside the usual schedule. But if there are signs of a stroke (sudden weakness or numbness of an arm or leg, difficulty speaking, a drooping face) or the person loses consciousness, do not wait for the cardiologist appointment: call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) straight away.