WordNet

control consisting of a mechanical device for controlling the flow of a fluid
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
one of the paired hinged shells of certain molluscs and of brachiopods
the entire one-piece shell of a snail and certain other molluscs
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
having two cusps or points (especially a molar tooth); "bicuspid teeth"; "bicuspid leaves" (同)bicuspidate
(of brass instruments) having valves

PrepTutorEJDIC

(液体・ガスなどの流れを調節する)『バルブ』,弁 / (血液の流れを調節する)弁,弁膜 / (管楽器の)バルブ / (2枚貝の)から,貝がら / 《英》真空管
(歯などが)2つの尖(せん)部(突起)を持つ / 小臼歯(きゅうし)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/06/12 07:03:11」(JST)

wiki en

The mitral valve (also known as the bicuspid valve or left atrioventricular valve) is a dual-flap (bi- from the Latin, meaning double, and mitral- from the Latin, meaning shaped like a mitre) valve in the heart that lies between the left atrium (LA) and the left ventricle (LV). The mitral valve (not to be confused with the congenital bicuspid aortic valve) and the tricuspid valve are known collectively as the atrioventricular valves because they lie between the atria and the ventricles of the heart and control the flow of blood.

During diastole, a normally-functioning mitral valve opens as a result of increased pressure from the left atrium as it fills with blood (preloading). As atrial pressure increases above that of the left ventricle, the mitral valve opens. Opening facilitates the passive flow of blood into the left ventricle. Diastole ends with atrial contraction, which ejects the final 20% of blood that is transferred from the left atrium to the left ventricle. This amount of blood is known as end diastolic volume (EDV), and the mitral valve closes at the end of atrial contraction to prevent a reversal of blood flow.

Anatomy [edit]

Operative view of the mitral valve with a chordal rupture "fail" of the anterior leaflet

The mitral valve is typically 4–6 cm² in area. It has two cusps, or leaflets, (the anteromedial leaflet and the posterolateral leaflet) that guard the opening. The opening is surrounded by a fibrous ring known as the mitral valve annulus. (The orientation of the two leaflets resemble a bishop's mitre, whence the valve receives its name.^[1]) The anterior cusp protects approximately two-thirds of the valve (imagine a crescent moon within the circle, where the crescent represents the posterior cusp). Note that although the anterior leaflet takes up a larger part of the ring and rises higher, the posterior leaflet has a larger surface area. These valve leaflets are prevented from prolapsing into the left atrium by the action of tendons attached to the posterior surface of the valve, chordae tendineae.

The inelastic chordae tendineae are attached at one end to the papillary muscles and the other to the valve cusps. Papillary muscles are fingerlike projections from the wall of the left ventricle. Chordae tendineae from each muscle are attached to both leaflets of the mitral valve. Thus, when the left ventricle contracts, the intraventricular pressure forces the valve to close, while the tendons keep the leaflets coapting together and prevent the valve from opening in the wrong direction (thus preventing blood to flow back to the left atrium). Each chord has a different thickness. The thinnest ones are attached to the free leaflet margin, whereas thickest ones (strut chords) are attached quite away from the free margin. This disposition has important effects on systolic stress distribution physiology ^[2]

Normal physiology [edit]

During left ventricular diastole, after the pressure drops in the left ventricle due to relaxation of the ventricular myocardium, the mitral valve opens, and blood travels from the left atrium to the left ventricle. About 70-80% of the blood that travels across the mitral valve occurs during the early filling phase of the left ventricle. This early filling phase is due to active relaxation of the ventricular myocardium, causing a pressure gradient that allows a rapid flow of blood from the left atrium, across the mitral valve. This early filling across the mitral valve is seen on doppler echocardiography of the mitral valve as the E wave.

After the E wave, there is a period of slow filling of the ventricle.

Left atrial contraction (left atrial systole) (during left ventricular diastole) causes added blood to flow across the mitral valve immediately before left ventricular systole. This late flow across the open mitral valve is seen on doppler echocardiography of the mitral valve as the A wave. The late filling of the LV contributes about 20% to the volume in the left ventricle prior to ventricular systole, and is known as the atrial kick.

The mitral annulus changes in shape and size during the cardiac cycle. It is smaller at the end of atrial systole due to the contraction of the left atrium around it, like a sphincter. This reduction in annulus size at the end of atrial systole may be important for the proper coapting of the leaflets of the mitral valve when the left ventricle contracts and pumps blood.^[3] Leaking valves can be corrected by mitral valve annuloplasty, a common surgical procedure that aims at restoring proper leaflet coaptation.

On Auscultation [edit]

The closing of the mitral valve and the tricuspid valve constitutes the first heart sound (S1). It is not actually the valve closure which produces a sound but rather the sudden cessation of blood flow caused by the closure of the mitral and tricuspid valves. The mitral valve opening is normally not heard except in Mitral Stenosis (narrowing of the valve) as the Opening Snap. Flow of blood into the heart during rapid filling is not normally heard except in certain pathological states where it constitutes the third heart sound (S3).

Mitral valve

Additional images [edit]

Section of the heart showing the ventricular septum. (Bicuspid valve visible at center.)
Front of thorax, showing surface relations of bones, lungs (purple), pleura (blue), and heart (red outline). Heart valves are labeled with "B", "T", "A", and "P".
Apical view of valves
Cross-sectional view of mitral valve between left atrium (upper chamber) and left ventricle (lower chamber), which shows parts of walls of left atrium and left ventricle that are next to the mitral valve.

References [edit]

^ Stedman's/LWW 1539731
^ Nazari S, Carli F, Salvi S, et al. (Apr 2000). "Patterns of systolic stress distribution on mitral valve anterior leaflet chordal apparatus. A structural mechanical theoretical analysis". J Cardiovasc Surg (Torino) 41 (2): 193–202. PMID 10901521.
^ Pai RG, Varadarajan P, Tanimoto M (2003). "Effect of atrial fibrillation on the dynamics of mitral annular area". The Journal of Heart Valve Disease 12 (1): 31–7. PMID 12578332. Retrieved 2010-03-04.

External links [edit]

SUNY Figs 20:07-03 - "Valves of the heart."
Mitral Valve Repair at The Mount Sinai Hospital - "Mitral Valve Function"
Surgical Anatomy of the Mitral Valve at echoincontext.com
Mitral Valve Repair at Englewood Hospital and Medical Center - Mitral Valve Repair
Mitral Valve Surgery reference site
Cardiac Valve Animations - Perioperative Interactive Education Group - Cardiac Valve Animations

UpToDate Contents

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1. 成人における大動脈二尖弁疾患のマネージメント management of adults with bicuspid aortic valve disease
2. 成人における大動脈二尖弁の臨床症状および診断 clinical manifestations and diagnosis of bicuspid aortic valve in adults
3. 大動脈弁の心エコー評価 echocardiographic evaluation of the aortic valve
4. 大動脈二尖弁の女性における妊娠 pregnancy in women with a bicuspid aortic valve
5. 成人における慢性大動脈弁閉鎖不全症の経過およびマネージメント course and management of chronic aortic regurgitation in adults

English Journal

Physical therapy for a child with sudden-onset choreoathetosis: a case report.

Smith HJ.Author information Physical Therapy Department, Franciscan Hospital for Children, Brighton, Massachusetts.AbstractPURPOSE: This case report describes the physical therapy examination, intervention, and outcomes for a 5-year-old girl who developed choreoathetosis following mitral valve repair.
Pediatric physical therapy : the official publication of the Section on Pediatrics of the American Physical Therapy Association.Pediatr Phys Ther.2014 Spring;26(1):85-93. doi: 10.1097/PEP.0000000000000010.
PURPOSE: This case report describes the physical therapy examination, intervention, and outcomes for a 5-year-old girl who developed choreoathetosis following mitral valve repair.CASE DESCRIPTION: This child was admitted to an inpatient short-term rehabilitation program with marked choreoathetosis a
PMID 24356324

Comparison of the Effectiveness of Transcatheter Aortic Valve Implantation in Patients With Stenotic Bicuspid Versus Tricuspid Aortic Valves (from the German TAVI Registry).

Bauer T1, Linke A2, Sievert H3, Kahlert P4, Hambrecht R5, Nickenig G6, Hauptmann KE7, Sack S8, Gerckens U9, Schneider S10, Zeymer U11, Zahn R12.Author information 1Abteilung für Kardiologie, Herzzentrum, Ludwigshafen, Germany; Universitätsklinik Gießen, Gießen, Germany. Electronic address: bauer-timm@gmx.de.2Klinik für Kardiologie, Herzzentrum, Leipzig, Germany.3CardioVasculäres Centrum Frankfurt, Katharinenkrankenhaus, Frankfurt, Germany.4Klinik für Kardiologie, Universitätsklinikum, Essen, Germany.5Abteilung für Kardiologie, Herzzentrum, Bremen, Germany.6Klinik für Kardiologie, Universitätsklinikum, Bonn, Germany.7Abteilung für Kardiologie, Krankenhaus der Barmherzigen Brüder, Trier, Germany.8Abteilung für Kardiologie, Klinikum München Schwabing, München, Germany.9Abteilung für Kardiologie, Gemeinschaftskrankenhaus Bonn, Bonn, Germany.10Stiftung Institut für Herzinfarktforschung, Ludwigshafen, Germany.11Abteilung für Kardiologie, Herzzentrum, Ludwigshafen, Germany; Stiftung Institut für Herzinfarktforschung, Ludwigshafen, Germany.12Abteilung für Kardiologie, Herzzentrum, Ludwigshafen, Germany.AbstractPatients with bicuspid aortic valves (BAVs) are considered a relative contraindication to transcatheter aortic valve implantation (TAVI). One of the main reasons is the presumed risk for residual aortic regurgitation (AR). However, case reports and small case series have suggested that TAVI can be successfully performed with acceptable clinical outcomes in high-risk patients with BAV. Within the large German TAVI Registry, we sought to evaluate TAVI in older high-risk patients with BAV. From January 2009 to June 2010, a total of 1,424 patients with severe aortic stenosis undergoing TAVI were prospectively enrolled into the German TAVI Registry. For the present analysis, patients with valve-in-valve procedures were excluded and those with BAV (n = 38, 3%) were compared with those with tricuspid aortic valve (TAV; n = 1357, 97%). Patient characteristics did not markedly differ and procedural success was very high in both groups. There was a higher rate of relevant AR (≥II) after TAVI among patients with BAV (25 vs 15%, p = 0.05), whereas pacemakers were more often implanted in patients with TAV (17% vs 35%, p = 0.02). Thirty-day mortality rate was similar in both cohorts (11% vs 11%). In a Cox proportional regression analysis, BAV was not associated with higher 1-year mortality rate (hazard ratio 0.64, 95% confidence interval 0.29 to 1.41). In selected patients with BAV, TAVI can be performed with a satisfactory clinical result. Although the risk for relevant AR seems to be greater among patients with BAV, 30-day and 1-year mortality rates were not elevated compared with patients with TAV.
The American journal of cardiology.Am J Cardiol.2014 Feb 1;113(3):518-21. doi: 10.1016/j.amjcard.2013.10.023. Epub 2013 Nov 9.
Patients with bicuspid aortic valves (BAVs) are considered a relative contraindication to transcatheter aortic valve implantation (TAVI). One of the main reasons is the presumed risk for residual aortic regurgitation (AR). However, case reports and small case series have suggested that TAVI can be s
PMID 24342758

Four patients with Sillence type I osteogenesis imperfecta and mild bone fragility, complicated by left ventricular cardiac valvular disease and cardiac tissue fragility caused by type I collagen mutations.

Vandersteen AM, Lund AM, Ferguson DJ, Sawle P, Pollitt RC, Holder SE, Wakeling E, Moat N, Pope FM.Author information Ehlers-Danlos Syndrome National Diagnostic Service, North West London Hospitals NHS Trust, Harrow, Middlesex, United Kingdom.AbstractOsteogenesis imperfecta (OI) type I is a hereditary disorder of connective tissue (HDCT) characterized by blue or gray sclerae, variable short stature, dentinogenesis imperfecta, hearing loss, and recurrent fractures from infancy. We present four examples of OI type I complicated by valvular heart disease and associated with tissue fragility. The diagnosis of a type I collagen disorder was confirmed by abnormal COL1A1 or COL1A2 gene sequencing. One patient was investigated with electrophoresis of collagens from cultured skin fibroblasts, showing structurally abnormal collagen type I, skin biopsy showed unusual histology and abnormal collagen fibril ultra-structure at electron microscopy. The combined clinical, surgical, histological, ultra-structural, and molecular genetic data suggest the type I collagen defect as contributory to cardiac valvular disease. The degree of tissue fragility experienced at cardiac surgery in these individuals, also reported in a small number of similar case reports, suggests that patients with OI type I need careful pre-operative assessment and consideration of the risks and benefits of cardiac surgery. © 2013 Wiley Periodicals, Inc.
American journal of medical genetics. Part A.Am J Med Genet A.2014 Feb;164(2):386-91. doi: 10.1002/ajmg.a.36285. Epub 2013 Dec 5.
Osteogenesis imperfecta (OI) type I is a hereditary disorder of connective tissue (HDCT) characterized by blue or gray sclerae, variable short stature, dentinogenesis imperfecta, hearing loss, and recurrent fractures from infancy. We present four examples of OI type I complicated by valvular heart d
PMID 24311407

Japanese Journal

手術の工夫大動脈二尖弁に対する弁輪拡大大動脈弁置換および上行大動脈置換におけるグラフトの工夫

高原真吾,深沢学,川原優他
胸部外科 65(13), 1135-1138, 2012-12-00
NAID 40019497490

Concomitant aortic valve and ascending aorta replacement with moderate hypothermic circulatory arrest to treat an aortic bicuspid valve with post-stenotic dilatation

HATA Mitsumasa,AKIYAMA Kenji,WAKUI Shinji,TAKASAKA Ayako,SHIONO Motomi
Surgery today : the Japanese journal of surgery 42(9), 913-916, 2012-09-01
NAID 10031032582

Adult Bicuspid Aortic Valve Endocarditis with Extensive Paravalvular Invasion Attributable to Disseminated Varicella Zoster Infection

CHEN Shao-Wei,TSAI Feng-Chun,CHOU An-Hsun
Annals of thoracic and cardiovascular surgery 18(4), 382-384, 2012-08-01
… He later developed an extensively destructive endocarditis affecting a congenital bicuspid aortic valve, accompanied with leaflet perforation, complete atrio-ventricular (AV) block, and invasion of vegetation to both left and right atrium; …
NAID 10031034468

Related Pictures

★リンクテーブル★

リンク元	「僧帽弁」「二尖弁」
関連記事	「bicuspid」「valve」

「僧帽弁」

Mitral valve
	Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow. (Mitral valve labeled at center right.)
	Base of ventricles exposed by removal of the atria. (Bicuspid (mitral) valve visible at bottom left.)
Latin	valva atrioventricularis sinistra, valva mitralis
Gray's	subject #138 534
MeSH	Mitral+Valve