Left to right shunting heart defects include:

- Ventricular septal defect (VSD) (30% of all congenital heart defects)

- Atrial septal defect (ASD)

- Atrioventricular septal defect (AVSD)

- Patent ductus arteriosus (PDA)

- Previously, Patent ductus arteriosus (PDA) was listed as acyanotic but in actuality it can be cyanotic due to pulmonary hypertension resulting from the high pressure aorta pumping blood into the pulmonary trunk, which then results in damage to the lungs which can then result in pulmonary hypertension as well as shunting of blood back to the right ventricle. This consequently results in less oxygenation of blood due to alveolar damage as well as oxygenated blood shunting back to the right side of the heart, not allowing the oxygenated blood to pass through the pulmonary vein and back to the left atrium.

- (Edit - this is called Eisenmenger's syndrome and can occur with Atrial septal defect and ventricular septal defect as well (actually more common in ASD and VSD) therefore PDA can still be listed as acyanotic as, acutely, it is)

Others:

- levo-Transposition of the great arteries (l-TGA)

Acyanotic heart defects without shunting include:

- Pulmonary stenosis (a narrowing of the pulmonary valve)

- Aortic stenosis

- Coarctation of the aorta

Obstruction defects occur when heart valves, arteries, or veins are abnormally narrow or blocked. Common defects include pulmonic stenosis, aortic stenosis, and coarctation of the aorta, with other types such as bicuspid aortic valve stenosis and subaortic stenosis being comparatively rare. Any narrowing or blockage can cause heart enlargement or hypertension.

Cyanotic heart defects are called such because they result in cyanosis, a bluish-grey discoloration of the skin due to a lack of oxygen in the body. Such defects include persistent truncus arteriosus, total anomalous pulmonary venous connection, tetralogy of Fallot, transposition of the great vessels, and tricuspid atresia.

Persistent truncus arteriosus (or Patent truncus arteriosus or Common arterial trunk), is a rare form of congenital heart disease that presents at birth. In this condition, the embryological structure known as the truncus arteriosus fails to properly divide into the pulmonary trunk and aorta. This results in one arterial trunk arising from the heart and providing mixed blood to the coronary arteries, pulmonary arteries, and systemic circulation.

Anatomical changes associated with this disorder includes:

- single artery arising from the two ventricles which gives rise to both the aortic and pulmonary vessels

- abnormal truncal valve

- right sided aortic arch in about 30% of cases (not shown)

- large ventricular septal defect

- pulmonary hypertension

- complete mixing occurring at level of the great vessel

- right-to-left shunting of blood

d vessels can present a large variety of , and/or . The effects may range from a change in blood pressure to an interruption in circulation, depending on the nature and degree of the misplacement and which vessels are involved.

Although "transposed" literally means "swapped", many types of TGV involve vessels that are in abnormal positions, while not actually being swapped with each other. The terms TGV and TGA are most commonly used in reference to dextro-TGA – in which the arteries "are" in swapped positions; however, both terms are also commonly used, though to a slightly lesser extent, in reference to levo-TGA – in which both the arteries and the ventricles are swapped; while other defects in this category are almost never referred to by either of these terms.

In dextro-Transposition of the great arteries (dextro-TGA) deoxygenated blood from the right heart is pumped immediately through the aorta and circulated to the body and the heart itself, bypassing the lungs altogether, while the left heart pumps oxygenated blood continuously back into the lungs through the pulmonary artery. In effect, two separate "circular" (parallel) circulatory systems are created. It is called a cyanotic congenital heart defect (CHD) because the newborn infant turns blue from lack of oxygen.

Simple l-TGA does not immediately produce any visually identifiable symptoms, but since each ventricle is intended to handle different blood pressures, the right ventricle may eventually hypertrophy due to increased pressure and produce symptoms such as dyspnea or fatigue.

Complex l-TGA may produce immediate or more quickly-developed symptoms, depending on the nature, degree and number of accompanying defect(s). If a right-to-left or bidirectional shunt is present, the list of symptoms may include mild cyanosis.

An acyanotic heart defect, also known as non-cyanotic heart defect, is a class of congenital heart defects. In these, blood is shunted (flows) from the left side of the heart to the right side of the heart due to a structural defect (hole) in the interventricular septum. People often retain normal levels of oxyhemoglobin saturation in systemic circulation.

This term is outdated, because a person with an acyanotic heart defect may show cyanosis (turn blue due to insufficient oxygen in the blood).

In a normal heart, oxygen-depleted ("blue") blood is pumped from the right side of the heart, through the pulmonary artery, to the lungs where it is oxygenated. The oxygen-rich ("red") blood then returns to the left heart, via the pulmonary veins, and is pumped through the aorta to the rest of the body, including the heart muscle itself.

With d-TGA, deoxygenated blood from the right heart is pumped immediately through the aorta and circulated to the body and the heart itself, bypassing the lungs altogether, while the left heart pumps oxygenated blood continuously back into the lungs through the pulmonary artery. In effect, two separate "circular" (parallel) circulatory systems are created, rather than the "figure 8" (in series) circulation of a normal cardio-pulmonary system.

d-TGA is often accompanied by other heart defects, the most common type being shunts such as atrial septal defect (ASD) including patent foramen ovale (PFO), ventricular septal defect (VSD), and patent ductus arteriosus (PDA). Stenosis of valves or vessels may also be present.

When no other heart defects are present it is called 'simple' d-TGA; when other defects are present it is called 'complex' d-TGA.

Although it may seem counterintuitive, complex d-TGA presents better chance of survival and less developmental risks than simple d-TGA, as well as usually requiring fewer invasive palliative procedures. This is because the left-to-right and bidirectional shunting caused by the defects common to complex d-TGA allow a higher amount of oxygen-rich blood to enter the systemic circulation. However, complex d-TGA may cause a very slight increase to length and risk of the corrective surgery, as most or all other heart defects will normally be repaired at the same time, and the heart becomes "irritated" the more it is manipulated.

DORV occurs in multiple forms, with variability of great artery position and size, as well as of ventricular septal defect (VSD) location. It can occur with or without transposition of the great arteries. The clinical manifestations are similarly variable, depending on how the anatomical defects affect the physiology of the heart, in terms of altering the normal flow of blood from the RV and left ventricle (LV) to the aorta and pulmonary artery. For example:

Double aortic arch (DAA) is a relatively rare congenital cardiovascular malformation. DAA is an of the aortic arch in which two aortic arches form a complete vascular ring that can compress the trachea and/or esophagus. Most commonly there is a larger (dominant) right arch behind and a smaller (hypoplastic) left aortic arch in front of the trachea/esophagus. The two arches join to form the descending aorta which is usually on the left side (but may be right-sided or in the midline). In some cases the end of the smaller left aortic arch closes (left atretic arch) and the vascular tissue becomes a fibrous cord. Although in these cases a complete ring of two patent aortic arches is not present, the term ‘vascular ring’ is the accepted generic term even in these anomalies.

The symptoms are related to the compression of the trachea, esophagus or both by the complete vascular ring. Diagnosis can often be suspected or made by chest x-ray, barium esophagram, or echocardiography. Computed tomography (CT) or magnetic resonance imaging (MRI) show the relationship of the aortic arches to the trachea and esophagus and also the degree of tracheal narrowing. Bronchoscopy can be useful in internally assessing the degree of tracheomalacia. Treatment is surgical and is indicated in all symptomatic patients. In the current era the risk of mortality or significant morbidity after surgical division of the lesser arch is low. However, the preoperative degree of tracheomalacia has an important impact on postoperative recovery. In certain patients it may take several months (up to 1–2 years) for the obstructive respiratory symptoms (wheezing) to disappear.

Symptoms are caused by vascular compression of the airway, esophagus or both. Presentation is often within the first month (neonatal period) and usually within the first 6 months of life. Starting at birth an inspiratory and expiratory stridor (high pitch noise from turbulent airflow in trachea) may be present often in combination with an expiratory wheeze. The severity of the stridor may depend on the patient’s body position. It can be worse when the baby is lying on his back rather than its side. Sometimes the stridor can be relieved by extending the neck (lifting the chin up). Parents may notice that the baby’s cry is hoarse and the breathing noisy. Frequently a persistent cough is present. When the airway obstruction is significant there may be episodes of severe cyanosis (“blue baby”) that can lead to unconsciousness. Recurrent respiratory infections are common and secondary pulmonary secretions can further increase the airway obstruction.

Secondary to compression of the esophagus babies often feed poorly. They may have difficulties in swallowing liquids with choking or regurgitating and increased respiratory obstruction during feeding. Older patients might refuse to take solid food, although most infants with severe symptoms nowadays are operated upon before they are offered solid food.

Occasionally patients with double aortic arches present late (during later childhood or adulthood). Symptoms may mimic asthma.

l-TGA is often accompanied by other heart defects, the most common type being shunts such as atrial septal defect (ASD) including patent foramen ovale (PFO), ventricular septal defect (VSD), and patent ductus arteriosus (PDA). Stenosis of valves or vessels may also be present.

When no other heart defects are present it is called 'simple' l-TGA; when other defects are present it is called 'complex' l-TGA.

An enlargement of the aorta may occur; an increased risk of abnormality is seen in babies of women taking lithium during the first trimester of pregnancy (though some have questioned this) and in those with Wolff-Parkinson-White syndrome.

The annulus of the valve is still in the normal position. The valve leaflets, however, are to a varying degree, attached to the walls and septum of the right ventricle. A subsequent 'atrialization' of a portion of the morphologic right ventricle (which is then contiguous with the right atrium) is seen. This causes the right atrium to be large and the anatomic right ventricle to be small in size.

- S3 heart sound

- S4 heart sound

- Triple or quadruple gallop due to widely split S1 and S2 sounds plus a loud S3 and/or S4

- Systolic murmur of tricuspid regurgitation = Holosystolic or early systolic murmur along the lower left sternal border depending on the severity of the regurgitation

- Right atrial hypertrophy

- Right ventricular conduction defects

- Wolff-Parkinson-White syndrome often accompanies

Double outlet right ventricle (DORV) is a form of congenital heart disease where both of the great arteries connect (in whole or in part) to the right ventricle (RV). In some cases it is found that this occurs on the left side of the heart rather than the right side.

Pulmonary and tricuspid valve diseases are right heart diseases. Pulmonary valve diseases are the least common heart valve disease in adults.

Pulmonary valve stenosis is often the result of congenital malformations and is observed in isolation or as part of a larger pathologic process, as in Tetralogy of Fallot, Noonan syndrome, and congenital rubella syndrome . Unless the degree of stenosis is severe individuals with pulmonary stenosis usually have excellent outcomes and treatment options. Often patients do not require intervention until later in adulthood as a consequence of calcification that occurs with aging.

Pulmonary valve insufficiency occurs commonly in healthy individuals to a very mild extent and does not require intervention. More appreciable insufficiency it is typically the result of damage to the valve due to cardiac catheterization, aortic balloon pump insertion, or other surgical manipulations. Additionally, insufficiency may be the result of carcinoid syndrome, inflammatory processes such a rheumatoid disease or endocarditis, or congenital malformations. It may also be secondary to severe pulmonary hypertension.

Tricuspid valve stenosis without co-occurrent regurgitation is highly uncommon and typically the result of rheumatic disease. It may also be the result of congenital abnormalities, carcinoid syndrome, obstructive right atrial tumors (typically lipomas or myxomas), or hypereosinophilic syndromes.

Minor tricuspid insufficiency is common in healthy individuals. In more severe cases it is a consequence of dilation of the right ventricle, leading to displacement of the papillary muscles which control the valve's ability to close. Dilation of the right ventricle occurs secondary to ventricular septal defects, right to left shunting of blood, eisenmenger syndrome, hyperthyroidism, and pulmonary stenosis. Tricuspid insufficiency may also be the result of congenital defects of the tricuspid valve, such as Ebstein's anomaly.

Heart valve dysplasia is a congenital heart defect which affects the aortic, pulmonary, mitral, and tricuspid heart valves. Dysplasia of the mitral and tricuspid valves can cause leakage of blood or stenosis.

Dysplasia of the mitral and tricuspid valves - also known as the atrioventricular (AV) valves - can appear as thickened, shortened, or notched valves. The chordae tendinae can be fused or thickened. The papillary muscles can be enlarged or atrophied. The cause is unknown, but genetics play a large role. Dogs and cats with tricuspid valve dysplasia often also have an open foramen ovale, an atrial septal defect, or inflammation of the right atrial epicardium. In dogs, tricuspid valve dysplasia can be similar to Ebstein's anomaly in humans.

Mitral valve stenosis is one of the most common congenital heart defects in cats. In dogs, it is most commonly found in Great Danes, German Shepherd Dogs, Bull Terriers, Golden Retrievers, Newfoundlands, and Mastiffs. Tricuspid valve dysplasia is most common in the Old English Sheepdog, German Shepherd Dog, Weimaraner, Labrador Retriever, Great Pyrenees, and sometimes the Papillon. It is inherited in the Labrador Retriever.

The disease and symptoms are similar to progression of acquired valve disease in older dogs. Valve leakage leads to heart enlargement, arrhythmias, and congestive heart failure. Heart valve dysplasia can be tolerated for years or progress to heart failure in the first year of life. Diagnosis is with an echocardiogram. The prognosis is poor with significant heart enlargement.

Taussig–Bing syndrome (after Helen B. Taussig and Richard Bing) is a cyanotic congenital heart defect in which the patient has both double outlet right ventricle (DORV) and subpulmonic ventricular septal defect (VSD).

In DORV, instead of the normal situation where blood from the left ventricle (LV) flows out to the aorta and blood from the right ventricle (RV) flows out to the pulmonary artery, both aorta and pulmonary artery are connected to the RV, and the only path for blood from the LV is across the VSD. When the VSD is subpulmonic (sitting just below the pulmonary artery), the LV blood then flows preferentially to the pulmonary artery. Then the RV blood, by default, flows mainly to the aorta.

The clinical manifestations of a Taussig-Bing anomaly, therefore, are much like those of dextro-Transposition of the great arteries (but the surgical repair is different). It can be corrected surgically also with the arterial switch operation (ASO).

It is managed with Rastelli procedure.

Cyanotic heart defect is a group-type of congenital heart defect (CHD) that occurs due to deoxygenated blood bypassing the lungs and entering the systemic circulation or a mixture of oxygenated and unoxygenated blood entering the systemic circulation. It is caused by structural defects of the heart (i.e.: right-to-left, bidirectional shunting, malposition of the great arteries), or any condition which increases pulmonary vascular resistance. The result being the development of collateral circulation.

Anomalous aortic origin of a coronary artery (AAOCA) from the inappropriate sinus of Valsalva with an interarterial, intraconal, or intramural course is a rare heart defect associated with an increased risk of sudden death in children.

In 2009, The Congenital Heart Surgeons' Society (CHSS) established a North American Registry in order to study a large multi-institutional cohort of patients with AAOCA. This initiative is intended to generate new knowledge concerning the natural history of AAOCA, to describe the outcomes of surgical intervention versus observation in children and young adults with AAOCA, and to generate evidence to support risk stratification among patients with AAOCA and eventually suggest evidence-based guidelines for management.

The following table includes the main types of valvular stenosis and regurgitation. Major types of valvular heart disease not included in the table include mitral valve prolapse, rheumatic heart disease and endocarditis.