Valvular heart disease
Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). These conditions occur largely as a consequence of aging,[1] but may also be the result of congenital (inborn) abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy.[2]
Valvular heart disease
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 or valve replacement.
Signs and symptoms[edit]
Aortic stenosis[edit]
Symptoms of aortic stenosis may include heart failure symptoms, such as dyspnea on exertion (most frequent symptom[15]), orthopnea and paroxysmal nocturnal dyspnea,[16] angina pectoris,[16] and syncope, usually exertional.[16]
Medical signs of aortic stenosis include pulsus parvus et tardus, that is, diminished and delayed carotid pulse,[16][15] fourth heart sound,[16] decreased A2 sound,[15] sustained apex beat,[16] precordial thrill.[16] Auscultation may reveal a systolic murmur of a harsh crescendo-decrescendo type, heard in 2nd right intercostal space[15] and radiating to the carotid arteries.[16]
Aortic regurgitation[edit]
Patients with aortic regurgitation may experience heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea, palpitations, and angina pectoris.[16] In acute cases patients may experience cyanosis and circulatory shock.[16]
Medical signs of aortic regurgitation include increased pulse pressure by increased systolic and decreased diastolic blood pressure,[16] but these findings may not be significant if acute.[15] The patient may have a diastolic decrescendo murmur best heard at left sternal border, water hammer pulse, Austin Flint murmur, and a displaced apex beat down and to the left.[16] A third heart sound may be present[16]
Mitral stenosis[edit]
Patients with mitral stenosis may present with heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea, palpitations, chest pain, hemoptysis, thromboembolism, or ascites and edema (if right-sided heart failure develops).[16] Symptoms of mitral stenosis increase with exercise and pregnancy[16]
On auscultation of a patient with mitral stenosis, typically the most prominent sign is a loud S1.[16] Another finding is an opening snap followed by a low-pitched diastolic rumble with presystolic accentuation.[16][15] The opening snap follows closer to the S2 heart tone with worsening stenosis.[16] The murmur is heard best with the bell of the stethoscope[16] lying on the left side[15] and its duration increases with worsening disease.[16] Advanced disease may present with signs of right-sided heart failure such as parasternal heave, jugular venous distension, hepatomegaly, ascites and/or pulmonary hypertension (presenting with a loud P2).[16] Signs increase with exercise and pregnancy.[16]
Mitral regurgitation[edit]
Patients with mitral regurgitation may present with heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea,[16] palpitations,[16] or pulmonary edema.[16]
On auscultation of a patient with mitral stenosis, there may be a holosystolic murmur at the apex, radiating to the back or clavicular area,[16] a third heart sound,[16] and a loud, palpable P2,[16] heard best when lying on the left side.[15] Patients also commonly have atrial fibrillation.[16] Patients may have a laterally displaced apex beat,[16] often with heave[15] In acute cases, the murmur and tachycardia may be only distinctive signs.[15]
Tricuspid regurgitation[edit]
Patients with tricuspid regurgitation may experience symptoms of right-sided heart failure, such as ascites, hepatomegaly, edema and jugular venous distension.[16]
Signs of tricuspid regurgitation include pulsatile liver, prominent V waves and rapid y descents in jugular venous pressure.[16] Auscultatory findings include inspiratory third heart sound at left lower sternal border (LLSB)[16] and a blowing holosystolic murmur at LLSB, intensifying with inspiration, and decreasing with expiration and Valsalva maneuver.[16] Patients may have a parasternal heave along LLSB.[16] Atrial fibrillation is usually present in patients with tricuspid regurgitation[16]
Causes[edit]
Calcific disease[edit]
Calcification of the leaflets of the aortic valve is a common with increasing age, but the mechanism is likely to be more related to increased lipoprotein deposits and inflammation than the "wear and tear" of advance age.[17] Aortic stenosis due to calcification of tricuspid aortic valve with age[16] comprises >50% of the disease. Aortic stenosis due to calcification of a bicuspid aortic valve[16] comprises about 30-40%[15] of the disease. Hypertension, diabetes mellitus, hyperlipoproteinemia and uremia may speed up the process of valvular calcification.[15]
Dysplasia[edit]
Heart valve dysplasia is an error in the development of any of the heart valves, and a common cause of congenital heart defects in humans as well as animals; tetralogy of Fallot is a congenital heart defect with four abnormalities, one of which is stenosis of the pulmonary valve. Ebstein's anomaly is an abnormality of the tricuspid valve, and its presence can lead to tricuspid valve regurgitation.[16][18] A bicuspid aortic valve[16] is an aortic valve with only 2 cusps as opposed to the normal 3. It is present in about 0.5% to 2% of the general population and causes increased calcification due to higher turbulent flow through the valve.[17]
Connective tissue disorders[edit]
Marfan's Syndrome is a connective tissue disorder that can lead to chronic aortic or mitral regurgitation.[16] Osteogenesis imperfecta is a disorder in formation of type I collagen and can also lead to chronic aortic regurgitation.[16]
Inflammatory disorders[edit]
Inflammation of the heart valves due to any cause is called valvular endocarditis; this is usually due to bacterial infection but may also be due to cancer (marantic endocarditis), certain autoimmune conditions (Libman-Sacks endocarditis, seen in systemic lupus erythematosus) and hypereosinophilic syndrome (Loeffler endocarditis). Endocarditis of the valves can lead to regurgitation through that valve, which is seen in the tricuspid, mitral, and aortic valves.[16] Certain medications have been associated with valvular heart disease, most prominently ergotamine derivatives pergolide and cabergoline.[19]
Valvular heart disease resulting from rheumatic fever is referred to as rheumatic heart disease. Acute rheumatic fever, which frequently manifests with carditis and valvulitis,[20] is a late sequela of Group A beta-hemolytic streptococcus infection in the throat, often lagging the initial infection by weeks to months.[21] Cardiac involvement is dependent on the cross-reaction of antibodies directed against M proteins produced by bacteria with human proteins present in the myocardium or endocardium[22][23] (although acute rheumatic fever may present as pancarditis with additional involvement of the pericardium).[24] This results in generalized inflammation in the heart, producing acute erosions and vegetations with fibrin deposition in the mitral valve that may be followed by chronic changes over years to decades, including shortening of the chordae tendinae and thickening or fusion of the mitral leaflets, leading to a severely compromised "buttonhole" or "fish mouth" valve.[25]
In 70% of cases rheumatic heart disease involves only the mitral valve, while 25% of cases involve both the aortic and mitral valves. Involvement of other heart valves without damage to the mitral is exceedingly rare.[23] Mitral stenosis is almost always caused by rheumatic heart disease.[16] Less than 10% of aortic stenosis is caused by rheumatic heart disease.[15][16] Rheumatic fever can also cause chronic mitral and aortic regurgitation.[16]
While developed countries once had a significant burden of rheumatic fever and rheumatic heart disease, medical advances and improved social conditions have dramatically reduced their incidence. Many developing countries, as well as indigenous populations within developed countries, still carry a significant burden of rheumatic fever and rheumatic heart disease[26] and there has been a resurgence in efforts to eradicate the diseases in these populations. Among persons who have experienced rheumatic fever, long-term intramuscular antibiotic therapy is used as secondary prophylaxis against additional streptococcal infections, which can contribute to progression of rheumatic heart disease.[27] In people with severe valvular disease, however, short-term risks of cardiovascular compromise after intramuscular injections may outweigh the benefits, and oral therapy may be considered instead of IM injections in this subset of patients.[28]
Diseases of the aortic root can cause chronic aortic regurgitation. These diseases include syphilitic aortitis, Behçet's disease, and reactive arthritis.[16]
Heart disease[edit]
Tricuspid regurgitation is usually secondary to right ventricular dilation[16] which may be due to left ventricular failure (the most common cause), right ventricular infarction, inferior myocardial infarction,[16] or cor pulmonale[16] Other causes of tricuspid regurgitation include carcinoid syndrome and myxomatous degeneration.[16]
Special populations[edit]
Pregnancy[edit]
The evaluation of individuals with valvular heart disease who are or wish to become pregnant is a difficult issue. Issues that have to be addressed include the risks during pregnancy to the mother and the developing fetus by the presence of maternal valvular heart disease as a pre-existing disease in pregnancy.
Normal physiological changes during pregnancy require, on average, a 50% increase in circulating blood volume that is accompanied by an increase in cardiac output that usually peaks between the midportion of the second and third trimesters.[42] The increased cardiac output is due to an increase in the stroke volume, and a small increase in heart rate, averaging 10 to 20 beats per minute.[42] Additionally uterine circulation and endogenous hormones cause systemic vascular resistance to decrease and a disproportionately lowering of diastolic blood pressure causes a wide pulse pressure.[42] Inferior vena caval
obstruction from a gravid uterus in the supine position can result in an abrupt decrease in cardiac preload, which leads to hypotension with weakness and lightheadedness.[42] During labor and delivery cardiac output increases more in part due to the associated anxiety and pain, as well as due to uterine contractions which will cause an increase in systolic and diastolic blood pressure.[42]
Valvular heart lesions associated with high maternal and fetal risk during pregnancy include:[42]
[42]
In individuals who require an artificial heart valve, consideration must be made for deterioration of the valve over time (for bioprosthetic valves) versus the risks of blood clotting in pregnancy with mechanical valves with the resultant need of drugs in pregnancy in the form of anticoagulation.