[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Chest](https://durgical.com/en/anatomy/region/chest/) › Mitral anterior leaflet [Cardiovascular system](https://durgical.com/en/anatomy/system/cardiovascular-system/) · [Chest](https://durgical.com/en/anatomy/region/chest/) # Mitral anterior leaflet The anterior leaflet is the larger flap of the mitral valve, between the left atrium and ventricle; it covers about two-thirds of the opening. Official name: Anterior leaflet of left atrioventricular valve [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=thorax&select=mitral_anterior_leaflet&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The larger, front leaflet of the mitral valve, attached next to the aortic valve. ## What it does Covers about two-thirds of the valve opening; it closes against the posterior leaflet. ## Key points - Its fibrous continuity with the [aortic left coronary cusp](https://durgical.com/en/anatomy/left-coronary-leaflet/) and [aortic non-coronary cusp](https://durgical.com/en/anatomy/non-coronary-leaflet-of-aortic-valve/) (aortomitral curtain) lets endocarditis and calcium spread between the two valves - Rheumatic mitral stenosis: fused commissures make the leaflet dome in diastole (hockey-stick shape on echo); still frequent in Colombia and Latin America - Mitral stenosis: loud S1, an opening snap after S2 and a low-pitched diastolic rumble at the apex - Systolic anterior motion of this leaflet obstructs the outflow tract in hypertrophic cardiomyopathy ## Key facts **Where** Anteromedial (aortic) leaflet; in fibrous continuity with aortic valve; valve behind left [sternum](https://durgical.com/en/anatomy/sternum/) at 4th [costal cartilage](https://durgical.com/en/anatomy/costal-cartilage/) **Attaches** Mitral annulus; chordae tendineae from both anterolateral and posteromedial papillary muscles **Function** Closes against posterior leaflet in systole; separates LV inflow from outflow tract; mitral area heard at apex ## Relations **In front** Left ventricular outflow tract, leading up to the aortic valve **Behind** [Mitral posterior leaflet](https://durgical.com/en/anatomy/posterior-leaflet-of-left-atrioventricular-valve/), meeting it along the closure line between the anterolateral and posteromedial commissures **Above** [Left atrium](https://durgical.com/en/anatomy/left-atrium/), into which a prolapsing or flail segment bulges in systole **Below** [Chordae tendineae](https://durgical.com/en/anatomy/chordae-tendineae-of-right-atrioventricular-valve/), including the thick strut chords on its ventricular surface, to both [Left ventricle papillary muscles](https://durgical.com/en/anatomy/superior-papillary-muscle-of-left-ventricle/) ## How to find it Mitral area: the apex (left 5th intercostal space, midclavicular line), with the person turned onto the left side. Diastolic rumbles are heard with the bell; regurgitant murmurs are holosystolic and spread to the left axilla. ## On imaging Transthoracic echo: the parasternal long [axis](https://durgical.com/en/anatomy/axis/) shows its length and movement; the short axis at the leaflet tips allows tracing of a stenotic orifice. Transesophageal echo names its segments A1 to A3 (lateral to medial) to plan repair. ## Common problems - Mitral regurgitation (leak): from a prolapsing leaflet, a torn chord or a stretched ventricle; causes breathlessness and atrial fibrillation. - Mitral stenosis (narrowing), mostly after rheumatic fever: still common in parts of Latin America. - Mitral valve prolapse: a floppy leaflet that bulges back; usually mild. ## How it is diagnosed A heart murmur on exam; echocardiogram (transesophageal for detail). ## Treatment - Medicines for symptoms; regular echo follow-up for mild disease. - Surgical repair (preferred when possible) or replacement; catheter-based clip repair for some high-risk patients. ## Clinical notes - Balloon commissurotomy suits rheumatic stenosis with pliable, little-calcified leaflets and no more than mild regurgitation; otherwise surgery is considered - Anterior leaflet prolapse or flail directs the regurgitant jet backward and is harder to repair than posterior prolapse - Transcatheter edge-to-edge repair clips the middle segments of the two leaflets (A2 to P2) together ## Anatomical variants - An accessory scallop of the anterior leaflet is uncommon (about 2.5% in the cited review) ## Development Both mitral leaflets form from the endocardial cushions of the atrioventricular canal; when the cushions fail to fuse (atrioventricular septal defect), this leaflet is cleft. ## Related conditions - [Hunter syndrome (mucopolysaccharidosis type II)](https://durgical.com/en/conditions/hunter-syndrome/) - [Mitral stenosis](https://durgical.com/en/conditions/mitral-stenosis/) - [Hypertrophic cardiomyopathy](https://durgical.com/en/conditions/hypertrophic-cardiomyopathy/) - [Mitral valve prolapse](https://durgical.com/en/conditions/mitral-valve-prolapse/) - [Hypoplastic left heart syndrome](https://durgical.com/en/conditions/hypoplastic-left-heart-syndrome/) - [Marfan syndrome](https://durgical.com/en/conditions/marfan-syndrome/) - [Rheumatic heart disease](https://durgical.com/en/conditions/rheumatic-heart-disease/) - [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/) - [Mitral regurgitation](https://durgical.com/en/conditions/mitral-regurgitation/) ## Test yourself Think of the answer, then tap the question to see it. ## What is the aortomitral curtain, and why does it matter in endocarditis? The fibrous continuity of the mitral anterior leaflet with the left and non-coronary aortic cusps; infection and calcium can spread between the two valves. ## What are the auscultatory signs of mitral stenosis? A loud S1, an opening snap after S2 and a low-pitched diastolic rumble at the apex, heard with the bell, the person turned onto the left side. ## What causes the «hockey-stick» shape of the mitral anterior leaflet on echo? Rheumatic mitral stenosis: fused commissures make the leaflet dome in diastole. ## How does the mitral anterior leaflet obstruct the outflow tract in hypertrophic cardiomyopathy? By systolic anterior motion: the leaflet moves toward the septum in systole and narrows the left ventricular outflow tract. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/anterior-leaflet-of-left-atrioventricular-valve/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** cuspis anterior valvae atrioventricularis sinistrae TA2 3989 **Official Spanish (DeCS)** Cúspide anterior de la válvula mitral DeCS D008943 **English (TA2)** Anterior leaflet of left atrioventricular valve **Also called** aortic leaflet of left atrioventricular valve · anterior cusp of left atrioventricular valve · cuspis ventralis valvulae bicuspidalis · septal leaflet of lefta atrioventricular valve ## Related - [Left atrium](https://durgical.com/en/anatomy/left-atrium/) - [Aortic non-coronary cusp](https://durgical.com/en/anatomy/non-coronary-leaflet-of-aortic-valve/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=9132); [Anatomy, Thorax, Mitral Valve](https://www.ncbi.nlm.nih.gov/books/NBK549884/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/anterior-leaflet-of-left-atrioventricular-valve/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/anterior-leaflet-of-left-atrioventricular-valve/