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.

Up to ~85% of people with NS have one of the following heart defects:

- Pulmonary valvular stenosis (50–60%)

- Septal defects: atrial (10–25%) or ventricular (5–20%)

- Hypertrophic cardiomyopathy (12–35%)

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

As discussed earlier, Shone’s syndrome is a rare disorder that is often detected in very young children. The children tend to show symptoms like fatigue, nocturnal cough, and reduced cardiac output by the age of two years. They also develop wheezing due to the exudation of fluid into the lungsCitation needed.

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).

Noonan syndrome (NS) is a relatively common autosomal dominant congenital disorder and is named after Jacqueline Noonan, a pediatric cardiologist. It is referred to as the male version of Turner's syndrome; however, the genetic causes of Noonan syndrome and Turner syndrome are distinct and both males and females are affected. The principal features include congenital heart defect (typicall pulmonary valve stenosis with dysplastic pulmonary valve also atrial septal defect and hypertrophic cardiomyopathy), short stature, learning problems, pectus excavatum, impaired blood clotting, and a characteristic configuration of facial features including a webbed neck and a flat nose bridge. NS is a RASopathy, and is one of several disorders that are caused by a disruption of RAS-MAPK signaling pathway.

It is believed that between approximately 1 in 1,000 and 1 in 2,500 children worldwide are born with NS. It is one of the most common genetic syndromes associated with congenital heart disease, similar in frequency to Down syndrome. However, the range and severity of features can vary greatly in patients with NS. Therefore, the syndrome is not always identified at an early age.

Signs/symptoms of tricuspid insufficiency are generally those of right-sided heart failure, such as ascites and peripheral edema.

Tricuspid insufficiency may lead to the presence of a pansystolic heart murmur. Such a murmur is usually of low frequency and best heard low on the lower left sternal border. As with most right-sided phenomena, it tends to increase with inspiration, and decrease with expiration. This is known as Carvallo's sign. However, the murmur may be inaudible indicating the relatively low pressures in the right side of the heart. A third heart sound may also be present, also heard with inspiration at the lower sternal border.

In addition to the possible ausculatory findings above, there are other signs indicating the presence of tricuspid regurgitation. There may be giant C-V waves in the jugular pulse and a palpably (and sometimes visibly) pulsatile liver on abdominal exam. Since the murmur of tricupsid regurgitation may be faint or inaudible, these signs can be helpful in establishing the diagnosis.

Symptoms of aortic insufficiency are similar to those of heart failure and include the following:

- Dyspnea on exertion

- Orthopnea

- Paroxysmal nocturnal dyspnea

- Palpitations

- Angina pectoris

- Cyanosis (in acute cases)

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.

Heyde's syndrome is a syndrome of gastrointestinal bleeding from angiodysplasia in the presence of aortic stenosis.

It is named after Edward C. Heyde, MD who first noted the association in 1958. It is caused by the induction of Von Willebrand disease type IIA (vWD-2A) by a depletion of Von Willebrand factor (vWF) in blood flowing through the narrowed valvular stenosis.

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.

Signs and symptoms of mitral stenosis include the following:

- Heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea (PND)

- Palpitations

- Chest pain

- Hemoptysis

- Thromboembolism in later stages when the left atrial volume is increased (i.e., dilation). The latter leads to increase risk of atrial fibrillation, which increases the risk of blood stasis (motionless). This increases the risk of coagulation.

- Ascites and edema and hepatomegaly (if right-side heart failure develops)

Fatigue and weakness increase with exercise and pregnancy.

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

- Heart murmur

- Cyanosis

- Dyspnea

- Dizziness

- Upper thorax pain

- Developmental disorders

The carcinoid syndrome occurs in approximately 5% of carcinoid tumors and

becomes manifest when vasoactive substances from the tumors enter the systemic circulation escaping hepatic degradation. Interestingly, if the primary tumor is from the GI tract (hence releasing serotonin into the hepatic portal circulation), carcinoid syndrome generally does not occur until the disease is so advanced that it overwhelms the liver's ability to metabolize the released serotonin.

- Flushing: The most important clinical finding is flushing of the skin, usually of the head and the upper part of thorax.

- Diarrhea: When the diarrhea is intense and explosive, it may lead to electrolyte disturbance and dehydration.

- Abdominal pain: Due to desmoplastic reaction of the mesentery or hepatic metastases.

- Bronchoconstriction, which may be histamine-induced, affects a smaller number of patients and often accompanies flushing.

- Secondary restrictive cardiomyopathy: About 50% of patients have cardiac abnormalities classically of the restrictive-type caused by serotonin-induced fibrosis of the valvular endocardium, notably the tricuspid and pulmonary valves, called cardiac fibrosis. This results in a heart with normal rhythm and contractility, but reduced preload and end-diastolic volume. "TIPS" is an acronym for Tricuspid Insufficiency, Pulmonary Stenosis (fibrosis of tricuspid and pulmonary valves).

- Nausea and Vomiting

The left side of the heart is responsible for receiving oxygen-rich blood from the lungs and pumping it forward to the systemic circulation (the rest of the body except for the pulmonary circulation). Failure of the left side of the heart causes blood to back up (be congested) into the lungs, causing respiratory symptoms as well as fatigue due to insufficient supply of oxygenated blood. Common respiratory signs are increased rate of breathing and increased "work" of breathing (non-specific signs of respiratory distress). Rales or crackles, heard initially in the lung bases, and when severe, throughout the lung fields suggest the development of pulmonary edema (fluid in the alveoli). Cyanosis which suggests severe low blood oxygen, is a late sign of extremely severe pulmonary edema.

Additional signs indicating left ventricular failure include a laterally displaced apex beat (which occurs if the heart is enlarged) and a gallop rhythm (additional heart sounds) may be heard as a marker of increased blood flow or increased intra-cardiac pressure. Heart murmurs may indicate the presence of valvular heart disease, either as a cause (e.g. aortic stenosis) or as a result (e.g. mitral regurgitation) of the heart failure.

"Backward" failure of the left ventricle causes congestion of the lungs' blood vessels, and so the symptoms are predominantly respiratory in nature. Backward failure can be subdivided into the failure of the left atrium, the left ventricle or both within the left circuit. The patient will have dyspnea (shortness of breath) on exertion and in severe cases, dyspnea at rest. Increasing breathlessness on lying flat, called orthopnea, occurs. It is often measured in the number of pillows required to lie comfortably, and in orthopnea, the patient may resort to sleeping while sitting up. Another symptom of heart failure is paroxysmal nocturnal dyspnea: a sudden nighttime attack of severe breathlessness, usually several hours after going to sleep. Easy fatigability and exercise intolerance are also common complaints related to respiratory compromise.

"Cardiac asthma" or wheezing may occur.

Compromise of left ventricular "forward" function may result in symptoms of poor systemic circulation such as dizziness, confusion and cool extremities at rest.

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.

Tricuspid insufficiency (TI), a valvular heart disease also called tricuspid regurgitation (TR), refers to the failure of the heart's tricuspid valve to close properly during systole. This defect allows the blood to flow backwards, reducing its efficiency.

Regurgitation may be due to a structural change of components of the tricuspid valve apparatus, a lesion can be primary (intrinsic abnormality) or secondary (right ventricular dilatation).

A mild diastolic murmur can be heard during auscultation caused by the blood flow through the stenotic valve. It is best heard over the left sternal border with rumbling character and tricuspid opening snap with wide-splitting S1. It may increase in intensity with inspiration (Carvallo's sign). The diagnosis will typically be confirmed by an echocardiograph, which will also allow the physician to assess its severity.

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.

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).

The symptoms associated with MI are dependent on which phase of the disease process the individual is in. Individuals with acute MI are typically severely symptomatic and will have the signs and symptoms of acute decompensated congestive heart failure (i.e. shortness of breath, pulmonary edema, orthopnea, and paroxysmal nocturnal dyspnea), as well as symptoms of cardiogenic shock (i.e., shortness of breath at rest). Cardiovascular collapse with shock (cardiogenic shock) may be seen in individuals with acute MI due to papillary muscle rupture, rupture of a chorda tendinea or infective endocarditis of the mitral valve.

Individuals with chronic compensated MI may be asymptomatic for long periods of time, with a normal exercise tolerance and no evidence of heart failure. Over time, however, there may be decompensation and patients can develop volume overload (congestive heart failure). Symptoms of entry into a decompensated phase may include fatigue, shortness of breath particularly on exertion, and leg swelling. Also there may be development of an irregular heart rhythm known as atrial fibrillation.

Findings on clinical examination depend on the severity and duration of MI. The mitral component of the first heart sound is usually soft and with a laterally displaced apex beat, often with heave. The first heart sound is followed by a high-pitched holosystolic murmur at the apex, radiating to the back or clavicular area. Its duration is, as the name suggests, the whole of systole. The loudness of the murmur does not correlate well with the severity of regurgitation. It may be followed by a loud, palpable P, heard best when lying on the left side. A third heart sound is commonly heard.

In acute cases, the murmur and tachycardia may be the only distinctive signs.

Patients with mitral valve prolapse may have a holosystolic murmur or often a mid-to-late systolic click and a late systolic murmur. Cases with a late systolic regurgitant murmur may still be associated with significant hemodynamic consequences.

Right-sided heart failure is often caused by pulmonary heart disease (cor pulmonale), which is usually caused by difficulties of the pulmonary circulation, such as pulmonary hypertension or pulmonic stenosis.

Physical examination may reveal pitting peripheral edema, ascites, and liver enlargement. Jugular venous pressure is frequently assessed as a marker of fluid status, which can be accentuated by eliciting hepatojugular reflux. If the right ventricular pressure is increased, a parasternal heave may be present, signifying the compensatory increase in contraction strength.

"Backward" failure of the right ventricle leads to congestion of systemic capillaries. This generates excess fluid accumulation in the body. This causes swelling under the skin (termed peripheral edema or anasarca) and usually affects the dependent parts of the body first (causing foot and ankle swelling in people who are standing up, and sacral edema in people who are predominantly lying down). Nocturia (frequent nighttime urination) may occur when fluid from the legs is returned to the bloodstream while lying down at night. In progressively severe cases, ascites (fluid accumulation in the abdominal cavity causing swelling) and liver enlargement may develop. Significant liver congestion may result in impaired liver function (congestive hepatopathy), and jaundice and even coagulopathy (problems of decreased or increased blood clotting) may occur.

Canine subvalvular aortic stenosis (SAS) is an abnormal, congenital heart murmur caused by subaortic stenosis (SAS). There is a high incidence of this condition among Rottweiler dogs.

There is very good evidence that it is heritable, passed on from generation to generation genetically. This genetic trait is what is called polygenic, so that the inheritance is complex. An animal might have the genes for SAS, yet have no actual sign of SAS. Also, an animal might have signs of subaortic stenosis, and yet offspring with signs of SAS may not be seen for a couple of generations. Any animal that has subaortic stenosis should not be bred, because they can definitely pass the defect on to future offspring. There is some controversy as to whether the parents of an animal with SAS should be bred again.

Heart murmurs are graded on a scale of 1 to 6, with one being very mild and six being very serious, with some animals dying before they reach this high stage due to a sudden leap in the grade or through long-term slowing down. Murmurs can exist due to a large number of heart problems (infection, trauma, anemia, etc.; some are innocent, with no cardiac pathology. Tests such as chest X-rays, echocardiography, and electrocardiography can be performed to evaluate the severity of the situation

The condition is usually detected during puppy visits to the veterinarian by hearing a heart murmur during physical examination. A heart murmur is the abnormal sound of blood rushing through one of the heart valves. Instead of just the heartbeat, a whistle of blood flow through a narrowed opening is heard. The puppy will most likely appear normal in all other respects. There is a possibility that the murmur may come and go, or it may develop slowly; this can be determined by frequent checks of a puppy's heart during its first few months. The chance for long-term survival of SAS is low.

Puppies and dogs diagnosed with subaortic stenosis can suffer from heart failure and sudden death. If a dog with SAS develops heart failure, medications can be prescribed to alleviate the clinical signs (sudden/strong lethargicism, continuous heavy panting, rise in temperature etc.)

The OFA has established a Congenital Heart Registry whose guidelines were established by veterinary cardiologists. A dog which auscultates normally at 12 months of age is considered to be free of congenital heart disease; upon confirmation of this, the OFA will issue a certificate.

Carcinoid syndrome is a paraneoplastic syndrome comprising the signs and symptoms that occur secondary to carcinoid tumors. The syndrome includes flushing and diarrhea, and less frequently, heart failure, emesis and bronchoconstriction. It is caused by endogenous secretion of mainly serotonin and kallikrein.

Pulmonic stenosis, also known as pulmonary stenosis, is a dynamic or fixed obstruction of flow from the right ventricle of the heart to the pulmonary artery. It is usually first diagnosed in childhood.

Pulmonic stenosis is usually due to isolated valvular obstruction (pulmonary valve stenosis), but it may be due to subvalvular or supravalvular obstruction, such as infundibular stenosis. It may occur in association with other congenital heart defects as part of more complicated syndromes (for example, tetralogy of Fallot).