At birth, the ductus arteriosus is still open, and there is higher than normal resistance to blood flow in the lungs. This allows for adequate oxygenation via mixing between the atria and a normal appearance at birth. When the ductus begins to close and pulmonary vascular resistance decreases, blood flow through the ductus is restricted and flow to the lungs is increased, reducing oxygen delivery to the systemic circulation. This results in cyanosis and respiratory distress which can progress to cardiogenic shock. The first symptoms are cyanosis that does not respond to oxygen administration or poor feeding. Peripheral pulses may be weak and extremities cool to the touch.

HLHS often co-occurs with low birth weight and premature birth.

In neonates with a small atrial septal defect, termed "restrictive", there is inadequate mixing of oxygenated and deoxygenated blood. These neonates quickly decompensate and develop acidosis and cyanosis.

On EKG, right axis deviation and right ventricular hypertrophy are common, but not indicative of HLHS. Chest x-ray may show a large heart (cardiomegaly) or increased pulmonary vasculature. Neonates with HLHS do not typically have a heart murmur, but in some cases, a pulmonary flow murmur or tricuspid regurgitation murmur may be audible.

Co-occurring tricuspid regurgitation or right ventricular dysfunction can cause hepatomegaly to develop.

A right ventricular outflow tract obstruction (RVOTO) may be due to a defect in the pulmonic valve, the supravalvar region, the infundibulum, or the pulmonary artery.

- Pulmonary atresia

- Pulmonary valve stenosis

- Hypoplastic right heart syndrome

- Tetralogy of Fallot

There are numerous types, differentiated by the extent of the defect. These types are:

- Type I: simple defects leading to communication between the ascending aorta and pulmonic trunk

- Type II: defects that extend to the origin of the right pulmonary artery

- Type III: anomalous origin of the right pulmonary artery from the ascending aorta

It is also classified as simple or complex. Simple defects are those that do not require surgical repair, occur with no other defects, or those that require minor stright-forward repair (ductus arteriosus, atrial septal defect). Complex defects are those that occur with other anatomical anomalies or require non-standard repair.

A left ventricular outflow tract obstruction (LVOTO) may be due to a defect in the aortic valve, or a defect located at the subvalvar or supravalvar level.

- Aortic valve stenosis

- Supravalvar aortic stenosis

- Coarctation of the aorta

- Hypoplastic left heart syndrome

Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs. The pulmonary valve is located on the right side of the heart between the right ventricle and pulmonary artery. In a normal functioning heart, the opening to the pulmonary valve has three flaps that open and close

In congenital heart defects such as pulmonary atresia, one finds that these structural abnormalities can include the valves of the heart, as well as, the walls and arteries/veins near the heart muscle. Consequently, blood flow due to the aforementioned structural abnormalities, is affected, either by blocking or altering the flow of blood through the human cardiac muscle.

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

Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped. It may affect the left ventricle, aorta, aortic valve, or mitral valve.

The symptoms/signs of pulmonary atresia that will occur in babies are consistent with cyanosis, some fatigue and some shortness of breath (eating may be a problem as well).

In the case of pulmonary atresia with ventricular septal defect, one finds that decreased pulmonary blood flow may cause associated defects such as:

- Tricuspid atresia

- Tetralogy of Fallot (severe)

- RV w/ double-outlet

In mild cases, children may show no signs or symptoms at first and their condition may not be diagnosed until later in life. Some children born with coarctation of the aorta have other heart defects too, such as aortic stenosis, ventricular septal defect, patent ductus arteriosus or mitral valve abnormalities.

Coarctation is about twice as common in boys as it is in girls. It is common in girls who have Turner syndrome.

Symptoms may be absent with mild narrowings (coarctation). When present, they include: difficulty breathing, poor appetite or trouble feeding, failure to thrive. Later on, children may develop symptoms related to problems with blood flow and an enlarged heart. They may experience dizziness or shortness of breath, faint or near-fainting episodes, chest pain, abnormal tiredness or fatigue, headaches, or nosebleeds. They have cold legs and feet or have pain in their legs with exercise (intermittent claudication).

In more severe cases, where severe coarctations, babies may develop serious problems soon after birth because not enough blood can get through the aorta to the rest of their body.

Arterial hypertension in the arms with low blood pressure in the lower extremities is classic. In the lower extremities, weak pulses in the femoral arteries and arteries of the feet are found.

The coarctation typically occurs after the left subclavian artery. However, if situated before it, blood flow to the left arm is compromised and asynchronous or radial pulses of different "strength" may be detected (normal on the right arm, weak or delayed on the left), termed "radio-radial delay". In these cases, a difference between the normal radial pulse in the right arm and the delayed femoral pulse in the legs (either side) may be apparent, whilst no such delay would be appreciated with palpation of both delayed left arm and either femoral pulses. On the other hand, a coarctation occurring after the left subclavian artery will produce synchronous radial pulses, but "radio-femoral delay" will be present under palpation in either arm (both arm pulses are normal compared to the delayed leg pulses).

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.

Common symptoms include:

- tachycardia (a heart rate exceeding the normal resting rate)

- respiratory problems

- dyspnea (shortness of breath)

- continuous "machine-like" (also described as "rolling-thunder" and "to-and-fro") heart murmur (usually from aorta to pulmonary artery, with higher flow during systole and lower flow during diastole)

- cardiomegaly (enlarged heart, reflecting ventricular dilation and volume overload)

- left subclavicular thrill

- bounding pulse

- widened pulse pressure

- increased cardiac output

- increased systolic pressure

- poor growth

- differential cyanosis, i.e. cyanosis of the lower extremities but not of the upper body.

Patients typically present in good health, with normal respirations and heart rate. If the PDA is moderate or large, widened pulse pressure and bounding peripheral pulses are frequently present, reflecting increased left ventricular stroke volume and diastolic run-off of blood into the (initially lower-resistance) pulmonary vascular bed. Prominent suprasternal and carotid pulsations may be noted secondary to increased left ventricular stroke volume.

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

Aortopulmonary septal defect is a rare congenital heart disorder accounting for only 0.1-0.3% of congenital heart defects worldwide. It is characterized by a communication between the aortic and pulmonary arteries, with preservation of two normal semilunar valves. It is the result of an incomplete separation of the aorticopulmonary trunk that normally occurs in early fetal development with formation of the spiral septum. Aortopulmonary septal defects occur in isolation in about half of cases, the remainder are associated with more complex heart abnormalities.

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.

Shone's syndrome (also called Shone's Complex, Shone's Anomaly)is a rare congenital heart disease described by Shone in 1963. In the complete form, four left-sided defects are present:

- Supravalvular mitral membrane (SVMM)

- Parachute mitral valve

- Subaortic stenosis (membranous or muscular)

- Coarctation of the aorta

Of these four defects, supravalvular mitral membrane (SVMM) is the first to occur, and triggers the development of the other three defects. Partial complexes, or form fruste, have also been described. The definition is often expanded to include lesions of the left side of the heart not originally ascribed to Shone's syndrome, including mitral and aortic valvular lesions and supravalvular aortic stenosis.

The term parachute mitral valve stems from the morphological appearance of the valve; that is to say, the mitral valve leaflets appear as the canopy of the parachute, the chordae as the strings and the papillary muscle as the harness.

Hypoplasia can affect the heart, typically resulting in the underdevelopment of the right ventricle or the left ventricle. This causes only one side of the heart to be capable of pumping blood to the body and lungs effectively. Hypoplasia of the heart is rare but is the most serious form of CHD. It is called hypoplastic left heart syndrome when it affects the left side of the heart and hypoplastic right heart syndrome when it affects the right side of the heart. In both conditions, the presence of a patent ductus arteriosus (and, when hypoplasia affects the right side of the heart, a patent foramen ovale) is vital to the infant's ability to survive until emergency heart surgery can be performed, since without these pathways blood cannot circulate to the body (or lungs, depending on which side of the heart is defective). Hypoplasia of the heart is generally a cyanotic heart defect.

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.

Children with tetralogy of Fallot may develop "tet spells". These are acute hypoxia spells, characterized by shortness of breath, cyanosis, agitation, and loss of consciousness. This may be initiated by any event leading to decreased oxygen saturation or that causes decreased systemic vascular resistance, leading to increased venous return, which in turn leads to increased shunting through the ventricular septal defect.

Tet spells are characterized by a sudden, marked increase in cyanosis followed by syncope, and may result in hypoxic brain injury and death.

Older children will often squat during a tet spell. This increases systemic vascular resistance and allows for a temporary reversal of the shunt. It increases pressure on the left side of the heart, decreasing the right to left shunt thus decreasing the amount of deoxygenated blood entering the systemic circulation.

Tetralogy of Fallot results in low oxygenation of blood due to the mixing of oxygenated and deoxygenated blood in the left ventricle via the ventricular septal defect (VSD) and preferential flow of the mixed blood from both ventricles through the aorta because of the obstruction to flow through the pulmonary valve. This is known as a right-to-left shunt. The primary symptom is low blood oxygen saturation with or without cyanosis from birth or developing in the first year of life. If the baby is not cyanotic then it is sometimes referred to as a "pink tet". Other symptoms include a heart murmur which may range from almost imperceptible to very loud, difficulty in feeding, failure to gain weight, retarded growth and physical development, dyspnea on exertion, clubbing of the fingers and toes, and polycythemia. The baby may turn blue with breast feeding or crying.

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.

Common symptoms include a grayish-blue (cyanosis) coloration to the skin, lips, fingernails and other parts of the body. Other pronounced symptoms can be rapid/difficulty breathing, poor feeding, cold hands or feet, or being inactive and drowsy. "In a baby with hypoplastic left heart syndrome, if the natural connections between the heart's left and right sides (foramen oval and ductus arteriosus) are allowed to close, he or she may go into shock." Signs of shock can include cool or clammy skin, a weak or rapid pulse, and dilated pupils.

Hypoplastic right heart syndrome is a congenital heart defect in which the right atrium and right ventricle are underdeveloped. This defect causes inadequate blood flow to the lungs and thus, a blue or cyanotic infant.[3]

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:

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).