Cardiac Diseases (Other Than Mitral Valve Anomalies) Congenital complete heart block Functional, dissociation Persistent LSVC to coronary sinus Vestibule impingement Atrioventricular septal defect Common AV valve, cleft Shone syndrome Parachute, supramitral ring ALCAPA Functional (ischemic) Hypoplastic left heart syndrome Mitral hypoplasia/atresia Noncardiac Diseases Ehlers-Danlos syndrome, Marfan Prolapse, annular dilation syndrome Metabolic diseases Mucopolysaccharidoses Thickening (accumulation of muccopolysaccharides) Sialidosis, galactosialidosis Thickening (accumulation of glycoproteins) Gaucher disease, Fabry disease Thickening (accumulation of sphingolipids) Sandhoff disease Thickening (accumulation of gangliosides) Mitochondrial myopathies Prolapse Neuromuscular diseases Steinert disease Prolapse Arthrogryposis multiplex congenita Calcification, functional Hutchinson-Gilford progeria Calcification Sickle cell hemoglobinopathy Acquired Heart Diseases Dilated cardiomyopathy Hypertrophic cardiomyopathy Myocarditis Infectious Autoimmune (SLE, polyarteritis nodosa) Percutaneous procedures (valvoplasty/valve implantation, ablation procedures) Surgical procedures (repair, replacement) Systemic arteriovenous fistula Cardiac tumors (left atrial, left ventricular) Kawasaki disease Rheumatic heart disease 24 27 31 44, 45 46 69 Regurgitation 58 59 Regurgitation, stenosis Regurgitation, stenosis Regurgitation, stenosis Regurgitation, stenosis Regurgitation 59 Functional (volume overload) Regurgitation Stenosis Regurgitation, stenosis Regurgitation Functional Systolic anterior motion Regurgitation Regurgitation Functional Fibrinoid changes in the connective tissue, functional Traumatic, patient-prosthesis mismatch Regurgitation Regurgitation Regurgitation, stenosis 18 Traumatic, failed repair, patientprosthesis mismatch Functional (volume overload) Inflow obstruction, subvalvar/valvar lesion Valvitis, functional (ischemia) Thickening, calcification, elongated/ruptured cords Leaflet perforation, ruptured cords Functional Regurgitation, stenosis Regurgitation Regurgitation, stenosis Regurgitation Regurgitation, stenosis Regurgitation Regurgitation 16 26 Mitral atresia Prolapse Mitral atresia Regurgitation, obstruction Obstruction Regurgitation Obstruction Infective endocarditis Systemic hypertension (severe, with cardiac failure) ASSOCIATION WITH CONGENITAL HEART DISEASES Isomerism Common AV valve, atresia Levoatrial cardinal vein Atrial septal defect Cor triatriatum sinister Regurgitation Stenosis Regurgitation Stenosis Regurgitation Stenosis/obstruction 61 61 63 50 52 53 55 56 60 27 29 30 Ebstein anomaly Congenitally corrected transposition of the great arteries Double-outlet right ventricle Double-inlet ventricle Criss-cross heart, superoinferior ventricle Prolapse Straddling, overriding, prolapse Regurgitation Regurgitation 33 38 Straddling, overriding, imperforation, parachute, cleft, common AV valve Straddling Straddling, overriding Stenosis/obstruction, 39 regurgitation Regurgitation 69 Regurgitation 49 ALCAPA, Anomalous left coronary artery from the pulmonary artery; AV, atrioventricular; LSVC, left superior vena cava; SLE, systemic lupus erythematosus Morphogenesis of the Mitral Valve As with the anatomy, it is convenient to consider development of the mitral valve in terms of its leaflets, tendinous cords, and papillary muscles We now know from studies investigating the lineage of the constituents of developing atrioventricular valves that the leaflets have never had a myocardial heritage.1 They are derived from the cushions that, initially, are formed within the atrioventricular canal When first seen, only two such cushions are present, located superiorly and inferiorly within the atrioventricular canal The canal, at this early stage of development, opens exclusively into the developing left ventricle, with the right ventricle supporting the entirety of the outflow tract (see also Chapter 3) The myocardium of the atrioventricular canal produces continuity between the developing atrial and ventricular chambers throughout the circumference of the canal (Fig 34.1) FIG 34.1 Initial appearances of the atrioventricular cushions formed within the atrioventricular canal of the developing heart These images are taken from a dataset prepared from a mouse embryo sacrificed at embryologic day 10.5 Left, “Four-chamber” section Right, Long-axis section across the canal At this initial stage, the canal empties exclusively into the developing left ventricle Note the canal myocardium surrounding the cushions, which are positioned superiorly and inferiorly within the canal With ongoing development, there is expansion of the canal such that the