Mitral valve prolapse
Mitral valve prolapse | |
---|---|
Other names | Floppy mitral valve syndrome, systolic click murmur syndrome, billowing mitral leaflet, Barlow's syndrome Echocardiogram, auscultation |
Frequency | 1 in 40 people, 2-3%[2] of total population in the United States 3.36% in a Taiwanese military study[3] |
Mitral valve prolapse (MVP) is a
The diagnosis of MVP primarily relies on echocardiography, which uses ultrasound to visualize the mitral valve.
MVP is the most common valvular abnormality, and is estimated to affect 2–3% of the population and 1 in 40 people might have it.[4][5][6]
The condition was first described by John Brereton Barlow in 1966.[1] It was subsequently termed mitral valve prolapse by J. Michael Criley.[7] Although mid-systolic click (the sound produced by the prolapsing mitral leaflet) and systolic murmur associated with MVP were observed as early as 1887 by physicians M. Cuffer and M. Barbillon using a stethoscope.[2][8][9]
Signs and symptoms
Murmur
Upon auscultation of an individual with mitral valve prolapse, a mid-systolic click, followed by a late systolic murmur heard best at the apex, is common. The length of the murmur signifies the time period over which blood is leaking back into the left atrium, known as regurgitation. A murmur that lasts throughout the whole of systole is known as a holo-systolic murmur. A murmur that is mid to late systolic, although typically associated with less regurgitation, can still be associated with significant hemodynamic consequences.[10]
In contrast to most other heart murmurs, the murmur of mitral valve prolapse is accentuated by standing and Valsalva maneuver (earlier systolic click and longer murmur) and diminished with squatting (later systolic click and shorter murmur). The only other heart murmur that follows this pattern is the murmur of hypertrophic cardiomyopathy. An MVP murmur can be distinguished from a hypertrophic cardiomyopathy murmur by the presence of a mid-systolic click which is virtually diagnostic of MVP. The handgrip maneuver diminishes the murmur of an MVP and the murmur of hypertrophic cardiomyopathy. The handgrip maneuver also diminishes the duration of the murmur and delays the timing of the mid-systolic click.[11]
Both Valsalva maneuver and standing decrease venous return to the heart thereby decreasing left ventricular diastolic filling (
Mitral valve prolapse syndrome
Historically, the term mitral valve prolapse syndrome has been applied to MVP associated with
Mitral regurgitation
Mitral valve prolapse is frequently associated with mild
The severity of regurgitation in MVP is typically estimated using a grading system:[16][17][18]
- 0 (none or trivial)
- Grade 1 (mild)
- Grade 2 (moderate)
- Grade 3 (moderate to severe)
- Grade 4 (severe)
Cardiac arrhythmia
People with mitral valve prolapse might have arrhythmic mitral valve prolapse which includes higher incidence of ventricular contraction disorders and tachycardia compared to the normal population, although the relationship between both phenomena is not entirely clear.[19] Prolapse of both mitral leaflets and the presence of mitral regurgitation further increases the risk of severe ventricular arrhythmias during exertion, which may not be resolved with surgery. The most common rhythm disorder is ventricular extrasystole, followed by paroxysmal atrial tachycardia.[citation needed]
Sudden cardiac death
Severe mitral valve prolapse and moderate-to-severe mitral regurgitation and reduced left ventricular
Risk factors
MVP can be non-syndromic, isolated, familial and syndromic.
Rheumatic fever is common worldwide and responsible for many cases of damaged heart valves. Chronic rheumatic heart disease is characterized by repeated inflammation with fibrinous resolution. The cardinal anatomic changes of the valve include leaflet thickening, commissural fusion, and shortening and thickening of the tendinous cords.[32] The recurrence of rheumatic fever is relatively common in the absence of maintenance of low dose antibiotics, especially during the first three to five years after the first episode. Heart complications may be long-term and severe, particularly if valves are involved. Rheumatic fever, since the advent of routine penicillin administration for Strep throat, has become less common in developed countries. In the older generation and in much of the less-developed world, valvular disease (including mitral valve prolapse, reinfection in the form of valvular endocarditis, and valve rupture) from undertreated rheumatic fever continues to be a problem.[33]
In an Indian hospital between 2004 and 2005, 4 of 24 endocarditis patients failed to demonstrate classic vegetations. All had rheumatic heart disease (RHD) and presented with prolonged fever. All had severe eccentric mitral regurgitation (MR). (One had severe aortic regurgitation (AR) also.) One had flail posterior mitral leaflet (PML).[34]
The
Each leaflet is composed of three layers of
In diagnostics
Common risk factors in diagnostics for severe, arrhythmic mitral valve prolapse include:
- Electrocardiography - Inferior T wave inversions in II, III, aVF leads, ST-segment depression, QT dispersion, QT prolongation, complex ventricular ectopy (PVCs), PVC-triggered ventricular fibrillation[36][37][38]
- Echocardiography - moderate mitral regurgitation, leaflet thickening, bi-leaflet MVP with redundancy, spiked systolic high-velocity signal (pickelhaube spike) when ≥ 16 cm/s in mitral annular tissue Doppler imaging (TDI), mitral annular disjunction (MAD)[39][40][36][41]
- Cardiac MRI - myocardial/papillary scars (fibrosis), myocardial stretch, systolic curling[36][42]
Histopathology
MVP is understood histologically, as a form of myxomatous degeneration, which is a type of connective tissue changes.[43]
In MVP, the spongiosa layer of the mitral valve leaflets undergoes proliferation, and the cells in this layer multiply and expand. This proliferation is associated with the accumulation of deposits of
Also in people with MVP, there is an increase in the content of
Causes
Genetics
Mitral valve prolapse is a genetically heterogeneous autosomal dominant trait, which can be passed down from one parent to child, who will have a 50% chance to inherit the mutated gene.
Research has shown an association between MVP and primary cilia defects.[5] Studies have identified mutations in the Zinc finger protein DZIP1 gene which regulates ciliogenesis; the same problem was found in mice who also developed MVP with this gene. It was found that primary cilia loss during development results in progressive myxomatous degeneration and profound mitral valve pathology.[45][46]
Myxomatous degeneration of the mitral valve is a genetic abnormality that is mapped to the Xq28 gene.[2][47] And additionally to FLNA.[23]
Other genes that have been associated with MVP include:
- 13.q31.3-q32.1[2][48]
- 16p12.1-p11.2[2][49][50]
- Ch16p11.2-p12.1[50][51]
- 11p15.4[2][48]
- DCHS1[52][53][23]
Genetic and chromosome defect causes of MVP are complex and currently not fully understood. Further research is needed to fully identify all of the genes and genetic mechanisms involved in the development of MVP.
Other
Recent studies have suggested an association between MVP and the upregulation of
Withdrawn drug such as
In a 2023 study a potential link between the use of
Diagnosis
Echocardiography is the most useful method of diagnosing a prolapsed mitral valve. Two- and three-dimensional echocardiography is particularly valuable as they allow visualization of the mitral leaflets relative to the mitral annulus. This allows measurement of the leaflet thickness and their displacement relative to the annulus. Thickening of the mitral leaflets >5 mm and leaflet displacement >2 mm above the annular plane in parasternal long-axis view indicates classic mitral valve prolapse.[29]
Prolapsed mitral valves are classified into several subtypes, based on leaflet thickness, type of connection to the mitral annulus, and concavity. Subtypes can be described as classic, nonclassic, symmetric, asymmetric, flail, or non-flail.[29]
All measurements below refer to adult patients; applying them to children may be misleading.[citation needed]
Classic versus nonclassic
Prolapse occurs when the mitral valve leaflets are displaced more than 2
Symmetric versus asymmetric
Classical prolapse may be subdivided into symmetric and asymmetric, referring to the point at which leaflet tips join the mitral annulus. In symmetric coaptation, leaflet tips meet at a common point on the annulus. Asymmetric coaptation is marked by one leaflet displaced toward the atrium with respect to the other. Patients with asymmetric prolapse are susceptible to severe deterioration of the mitral valve, with the possible rupture of the chordae tendineae and the development of a flail leaflet.[29]
Flail versus non-flail
Asymmetric prolapse is further subdivided into flail and non-flail. Flail prolapse occurs when a leaflet tip turns outward, becoming concave toward the left atrium, causing the deterioration of the mitral valve. The severity of flail leaflet varies, ranging from tip eversion to chordal rupture. Dissociation of leaflet and chordae tendineae provides for unrestricted motion of the leaflet (hence "flail leaflet"). Thus patients with flail leaflets have a higher prevalence of mitral regurgitation than those with the non-flail subtype.[29]
Treatment
Individuals with mitral valve prolapse, particularly those without symptoms, often require no treatment.[58] Those with mitral valve prolapse and symptoms of dysautonomia (palpitations, chest pain) may benefit from beta-blockers (e.g., propranolol, metoprolol, bisoprolol). People with prior stroke or atrial fibrillation may require blood thinners, such as aspirin or warfarin. In rare instances when mitral valve prolapse is associated with severe mitral regurgitation, surgical repair or replacement of the mitral valve may be necessary. Mitral valve repair is generally considered preferable to replacement. Current ACC/AHA guidelines promote repair of mitral valve in people before symptoms of heart failure develop. Symptomatic people, those with evidence of diminished left ventricular function, or those with left ventricular dilatation need urgent attention.[59]
Prevention of infective endocarditis
Individuals with MVP are at higher risk of bacterial infection of the heart, called
Many organisms responsible for endocarditis are slow-growing and may not be easily identified on routine blood cultures (these fastidious organisms require special culture media to grow). These include the
Prognosis
Generally, MVP is benign. However, MVP patients with a murmur, not just an isolated click, have an increased mortality rate of 15-20%.[62] The major predictors of mortality are the severity of mitral regurgitation and reduction in ejection fraction.[63]
Close monitoring and treatment, if necessary, is recommended for those with severe MVP to prevent complications and reduce the risk of mortality. In most cases, individuals with MVP can lead a normal and healthy life with minimal symptoms.
Prophylaxis
The consensus is that mitral valve prolapse is a non-preventable condition, although some of its complications may occur. Because symptoms rarely appear, the productivity of the patient's life is not affected. The worsening of the disorder can be delayed by avoiding smoking, the use of contraceptives (because they have the risk of clotting) and regulating the amount and type of exercise and nutrition under the supervision of a health professional.[64] The risk of infective endocarditis is considered high in patients with prosthetic heart valves, moderate in those with mitral prolapse concomitant with mitral regurgitation and low in patients with mitral prolapse without other valve disease.[65]
Antibiotic prophylaxis
Those with mitral prolapse are at increased risk of infective endocarditis, a bacterial infection of the heart tissue, as a result of certain routine non-sterile procedures, such as brushing the teeth. However, in April 2007, a study by the American Heart Association had determined that the risks of prescribing antibiotics outweigh the prophylactic antibiotics before invasive surgery, such as dental surgery or biopsy by colonoscopy or bronchoscopy.[66]
Epidemiology
Prior to the strict criteria for the diagnosis of mitral valve prolapse, as described above, the incidence of mitral valve prolapse in the general population varied greatly.[29] Some studies estimated the incidence of mitral valve prolapse at 5 to 15 percent or even higher.[67] One 1985 study suggested MVP in up to 35% of healthy teenagers.[68]
Recent elucidation of mitral valve anatomy and the development of three-dimensional echocardiography have resulted in improved diagnostic criteria, and the true prevalence of MVP based on these criteria is estimated at 2-3%.[4] As a part of the Framingham Heart Study, for example, the prevalence of mitral valve prolapse in Framingham, MA was estimated at 2.4%. There was a near-even split between classic and nonclassic MVP, with no significant age or sex discrimination.[30] MVP is observed in 7% of autopsies in the United States.[62]
In a Taiwanese CHIEF heart study of Asian adult military personnel, it was estimated that out of 2442 people in Hualien aged 18 to 39, mitral valve prolapse occurred in 3.36%. People with MVP had lower body mass index, somatic symptoms related to exercise (chest pain, dyspnea, palpitations during exercise) and systolic click in auscultation. 7 out of 82 participants with MVP had mild pectus excavatum.[3]
Research
In a human and mice study of MVP, a relationship was found between MVP and progressive fibrosis effects on left ventricular structure, which suggests the cause of molecular and cellular changes are a response of papillary and inferobasal myocardium to increased chordal tension from prolapsing mitral valve leaflets.[69]
In animals
In 2019 an experimental adeno-associated virus (AAV)-based gene therapy method was developed by Rejuvenate Bio, a biotechnology company. The method was successfully and effectively used on mice to reverse multiple age-related diseases: heart failure, kidney failure, type 2 diabetes and obesity. The study found that mice experienced a 58% increase in heart function and 75% reduction in kidney degeneration.[70] Rejuvenate Bio later collaborated with Tufts University to use the same method on Cavalier King Charles spaniel to stop the progression of mitral valve disease by stopping the accumulation of scar tissue in the heart. The therapy used a virus to deliver a genetic therapy that blocks the action of a specific protein that contributes to the accumulation of scar tissue.[71][72]
History
The term mitral valve prolapse was coined by J. Michael Criley in 1966 and gained acceptance over the other descriptor of "billowing" of the mitral valve, as described by John Brereton Barlow.[1]
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Further reading
- Frederickson L (1992). Confronting Mitral Valve Prolapse Syndrome. New York, NY: Warner Books. ISBN 978-0-446-39407-9.
- Bludau Scordo KA (2007). Bludau (3rd, rev. and updated ed.). Cincinnati, Ohio: Kardinal Publishing. ISBN 978-1-4243-1576-5.
- Soffer A (2007). Mitral Valve Prolapse: A Comprehensive Patient's Guide to a Happier and Healthier Life. Hollywood, Fl: HealthwoRx. ISBN 978-0-615-15205-9.
External links
- Mitral valve prolapse at Curlie