Signs and symptoms are related to type and severity of the heart defect. Symptoms frequently present early in life, but it is possible for some CHDs to go undetected throughout life. Some children have no signs while others may exhibit shortness of breath, cyanosis, fainting, heart murmur, under-development of limbs and muscles, poor feeding or growth, or respiratory infections. Congenital heart defects cause abnormal heart structure resulting in production of certain sounds called heart murmur. These can sometimes be detected by auscultation; however, not all heart murmurs are caused by congenital heart defects.

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.

For many people cardiomegaly is asymptomatic. For others, if the enlarged heart begins to affect the body's ability to pump blood effectively, then symptoms associated with congestive heart failure may arise.

- Heart palpitations – irregular beating of the heart, usually associated with a valve issue inside the heart.

- Severe shortness of breath (especially when physically active) – irregularly unable to catch one's breath.

- Chest pain

- Fatigue

- Swelling in legs

- Increased abdominal girth

- Weight gain

- Edema – swelling

- Fainting

Subjects' symptoms from non-compaction cardiomyopathy range widely. It is possible to be diagnosed with the condition, yet not to have any of the symptoms associated with heart disease. Likewise it possible to have severe heart failure, which even though the condition is present from birth, may only manifest itself later in life. Differences in symptoms between adults and children are also prevalent with adults more likely to have heart failure and children from depression of systolic function.

Common symptoms associated with a reduced pumping performance of the heart include:

- Breathlessness

- Fatigue

- Swelling of the ankles

- Limited physical capacity and exercise intolerance

Two conditions though that are more prevalent in noncompaction cardiomyopathy are: tachyarrhythmia which can lead to sudden cardiac death and clotting of the blood in the heart.

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.

Among some of the symptoms consistent with pulmonary valve stenosis are the following:

- Heart murmur

- Cyanosis

- Dyspnea

- Dizziness

- Upper thorax pain

- Developmental disorders

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.

Valvular heart disease is any disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left and the pulmonary and tricuspid valves on the right). These conditions occur largely as a consequence of aging, but may also be the result of congenital (inborn) abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy.

Anatomically, the valves are part of the dense connective tissue of the heart known as the cardiac skeleton and are responsible for the regulation of blood flow through the heart and great vessels. Valve failure or dysfunction can result in diminished heart functionality, though the particular consequences are dependent on the type and severity of valvular disease. Treatment of damaged valves may involve medication alone, but often involves surgical valve repair (valvuloplasty) or replacement (insertion of an artificial heart valve).

Symptoms related to aortic stenosis depend on the degree of stenosis. Most people with mild to moderate aortic stenosis do not have symptoms. Symptoms usually present in individuals with severe aortic stenosis, though they may occur in those with mild to moderate aortic stenosis as well. The three main symptoms of aortic stenosis are loss of consciousness, anginal chest pain and shortness of breath with activity or other symptoms of heart failure such as shortness of breath while lying flat, episodes of shortness of breath at night, or swollen legs and feet. It may also be accompanied by the characteristic "Dresden china" appearance of pallor with a light flush.

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.

Cardiomegaly is a medical condition in which the heart is enlarged. It is more commonly referred to as an enlarged heart. The causes of cardiomegaly may vary. Many times this condition results from high blood pressure (hypertension) or coronary artery disease. An enlarged heart may not pump blood effectively, resulting in congestive heart failure. Cardiomegaly may improve over time, but many people with an enlarged heart need lifelong treatment with medications. Having an immediate family member who has or had cardiomegaly may indicate that a person is more susceptible to getting this condition. Cardiomegaly is not a disease but rather a condition that can result from a host of other diseases such as obesity or coronary artery disease. Recent studies suggest that cardiomegaly is associated with a higher risk of sudden cardiac death (SCD).

Angina in setting of heart failure also increases the risk of death. In people with angina, the 5-year mortality rate is 50% if the aortic valve is not replaced.

Angina in the setting of AS occurs due to left ventricular hypertrophy (LVH) that is caused by the constant production of increased pressure required to overcome the pressure gradient caused by the AS. While the muscular layer of the left ventricle thickens, the arteries that supply the muscle do not get significantly longer or bigger, so the muscle may not receive enough blood supply to meet its oxygen requirement. This ischemia may first be evident during exercise when the heart muscle requires increased blood supply to compensate for the increased workload. The individual may complain of anginal chest pain with exertion. At this stage, a cardiac stress test with imaging may be suggestive of ischemia.

Eventually, however, the heart muscle will require more blood supply at rest than can be supplied by the coronary artery branches. At this point there may be signs of "ventricular strain pattern" (ST segment depression and T wave inversion) on the EKG, suggesting subendocardial ischemia. The subendocardium is the region that is most susceptible to ischemia because it is the most distant from the epicardial coronary arteries.

In regards to the cause of pulmonary valve stenosis a very high percentage are congenital, the right ventricular flow is hindered (or obstructed by this). The cause in turn is divided into: valvular, external and intrinsic (when it is acquired).

In a study (2006) carried out on 53 patients with the condition in Mexico, 42 had been diagnosed with another form of heart disease and only in the most recent 11 cases that ventricular noncompation was diagnosed and this took several echocardiograms to confirm. The most common misdiagnoses were:

- dilated cardiomyopathy: 30 Cases

- congenital heart disease: 6 Cases

- ischemic heart disease: 2 Cases

- disease of the heart valves: 2 Cases

- dilated phase hypertensive cardiomyopathy: 1 Case

- restrictive cardiomyopathy: 1 Case

The high number of misdiagnoses can be attributed to non-compaction cardiomyopathy being first reported in 1990; diagnosis is therefore often overlooked or delayed. Advances in medical imaging equipment have made it easier to diagnose the condition, particularly with the wider use of MRIs.

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]

Abdominal organs, including the liver, stomach, intestinal tract, and spleen may be randomly arranged throughout the left-right axis of the body. Distribution of these organs largely dictates treatment, clinical outcomes, and further evaluation.

The liver is typically symmetrical across the left-right axis in patients with situs ambiguous, which is abnormal. A majority of left atrial isomeric patients have defects throughout the biliary tree, which is responsible for bile production, even when the gall bladder is functional and morphologically normal. This biliary atresia can lead to acute problems such as nutrient malabsorption, pale stools, dark urine, and abdominal swelling. If this condition continues without proper treatment, cirrhosis and liver failure become a major concern. Biliary atresia is not usually observed in patients with right atrial isomerism.

Random positioning of the stomach is often one of the first signals of situs ambiguous upon examination. Malrotation of the entire intestinal tract, or improper folding and bulging of the stomach and intestines, results in bowel obstruction. This impairment leads to vomiting, abdominal distention, mucus and blood in the stool. Patients may also experience abdominal pain. Intestinal malrotation is more commonly identified in patients with right atrial isomerism than in those with left atrial isomerism.

Isomeric patients often experience disruptions to splenic development during embryogenesis, resulting in an overall lack a spleen (asplenia) or development of many spleens (polysplenia). Asplenia is most often observed in patients with right atrial isomerism. Polysplenia results in 90% of patients with left atrial isomerism. Although they have many spleens, each is usually ineffective resulting in functional asplenia. Rarely, left atrial isomeric patients have a single, normal, functional spleen. Patients lacking a functional spleen are in danger of sepsis and must be monitored.

Isomerism of the bronchial tree is not typically damaging and presents no significant clinical complications. Pulmonary valve stenosis results in issues of blood flow to the lungs.

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

There are many cardiovascular diseases involving the blood vessels. They are known as vascular diseases.

- Coronary artery disease (also known as coronary heart disease and ischemic heart disease)

- Peripheral arterial disease – disease of blood vessels that supply blood to the arms and legs

- Cerebrovascular disease – disease of blood vessels that supply blood to the brain (includes stroke)

- Renal artery stenosis

- Aortic aneurysm

There are also many cardiovascular diseases that involve the heart.

- Cardiomyopathy – diseases of cardiac muscle

- Hypertensive heart disease – diseases of the heart secondary to high blood pressure or hypertension

- Heart failure - a clinical syndrome caused by the inability of the heart to supply sufficient blood to the tissues to meet their metabolic requirements

- Pulmonary heart disease – a failure at the right side of the heart with respiratory system involvement

- Cardiac dysrhythmias – abnormalities of heart rhythm

- Inflammatory heart disease

- Endocarditis – inflammation of the inner layer of the heart, the endocardium. The structures most commonly involved are the heart valves.

- Inflammatory cardiomegaly

- Myocarditis – inflammation of the myocardium, the muscular part of the heart.

- Valvular heart disease

- Congenital heart disease – heart structure malformations existing at birth

- Rheumatic heart disease – heart muscles and valves damage due to rheumatic fever caused by "Streptococcus pyogenes" a group A streptococcal infection.

Patent ductus arteriosus (PDA) is a condition wherein the ductus arteriosus fails to close after birth.

Early symptoms are uncommon, but in the first year of life include increased 'work of breathing' and poor weight gain. An uncorrected PDA may lead to congestive heart failure with increasing age.

The ductus arteriosus is a fetal blood vessel that closes soon after birth. In a PDA, the vessel does not close and remains "patent" (open), resulting in irregular transmission of blood between the aorta and the pulmonary artery. PDA is common in newborns with persistent respiratory problems such as hypoxia, and has a high occurrence in premature newborns. Premature newborns are more likely to be hypoxic and have PDA due to underdevelopment of the heart and lungs.

A PDA allows a portion of the oxygenated blood from the left heart to flow back to the lungs by flowing from the aorta (which has higher pressure) to the pulmonary artery. If this shunt is substantial, the neonate becomes short of breath: the additional fluid returning to the lungs increases lung pressure, which in turn increases the energy required to inflate the lungs. This uses more calories than normal and often interferes with feeding in infancy. This condition, as a constellation of findings, is called congestive heart failure.

In some congenital heart defects (such as in transposition of the great vessels) a PDA may need to remain open, as it is the only way that oxygenated blood can mix with deoxygenated blood. In these cases, prostaglandins are used to keep the DA open until surgical correction of the heart defect is completed.

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.

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.

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.

According to a study in cyanotic congenital heart disease (CCHD) in Sohag University, Upper Egypt. 50 neonates were diagnosed as suffering from cyanotic congenital heart disease (CCHD), they concluded that cyanotic congenital heart disease (CCHD) frequency was significant (9.5%) with D-TGA being the commonest type. Majority of neonates with Cyanotic congenital heart disease (CCHD) showed survival with suitable management.

The symptoms of pulmonary hypertension include the following:

Less common signs/symptoms include non-productive cough and exercise-induced nausea and vomiting. Coughing up of blood may occur in some patients, particularly those with specific subtypes of pulmonary hypertension such as heritable pulmonary arterial hypertension, Eisenmenger syndrome and chronic thromboembolic pulmonary hypertension. Pulmonary venous hypertension typically presents with shortness of breath while lying flat or sleeping (orthopnea or paroxysmal nocturnal dyspnea), while pulmonary arterial hypertension (PAH) typically does not.

Other typical signs of pulmonary hypertension include an accentuated pulmonary component of the second heart sound, a right ventricular third heart sound, and parasternal heave indicating a hypertrophied right atrium. Signs of systemic congestion resulting from right-sided heart failure include jugular venous distension, ascites, and hepatojugular reflux. Evidence of tricuspid insufficiency and pulmonic regurgitation is also sought and, if present, is consistent with the presence of pulmonary hypertension.