DK2985_C000 1..28 - AlSharqia Echo Club

Congenital Heart Disease 545Congenital MS can be classified according to whichcomponent of the mitral valve apparatus is abnormal,including leaflets, annulus, chordae, or papillary muscles(13). Most cases, however, involve variable combinationsof structural anomalies, including annulus hypoplasia,thickened rolled leaflet margins, commissural fusion, shortenedand thickened chordae tendineae, fibrous obliterationof the interchordal spaces (Fig. 24.27), abnormalchordal insertion, papillary muscle hypoplasia, anddecreased interpapillary muscle distance or fusion. Echocardiographically,the mitral valve leaflets appearthickened, dysplastic, and echo-dense; they move poorlyand dome during LV diastolic filling. The subvalvularmitral apparatus similarly presents an echo-dense,crowded appearance.The parachute mitral valve represents about half of theMS diagnosed in pediatric patients (Fig. 24.27). It ischaracterized by insertion of all the chordae tendineaeinto a single papillary muscle group. The mitral valve leafletsalso appear dense, with restricted motion. The chordaeare generally shortened and thickened. The anatomy of thepapillary muscles is highly variable. A single papillarymuscle in the LV, the hallmark of this lesion, may beidentified in the four-chamber view, the transgastricshort- and long-axis views. The parachute mitral valve isoften associated with other anomalies which constitutethe Shone’s syndrome, that is, a supravalvular mitralring, subaortic stenosis, and coarctation of the aorta.(A)(B)(C)(D)(E)Nearly 70% of parachute mitral valves are associatedwith a supravalvular mitral ring while 60% present asignificant diastolic pressure gradient.The supravalvular mitral ring rarely occurs as anisolated finding. In most instances, other anomalies arefound such as parachute mitral valve, subaortic stenosis,or coarctation of the aorta. A supravalvular ring is alsofound with 20% of congenital MS with two anatomicalpapillary muscles. It originates from a collection of connectivetissue arising from the atrial surface of the mitralleaflets and consequently encroaches on the mitral valveorifice. It may be closely adherent to the anterior mitralvalve leaflet. The ring itself causes a significant obstructionin only 10% of cases. In the other case, the ringdoes not add significant obstruction to the associatedmitral valve stenosis.TEE in Mitral Stenosis (Table 24.2)The mitral valve is best evaluated with the midesophagealfour- and two-chamber, and long-axis viewsusing 2D and color-flow imaging, as well as Dopplerdetermination of mitral inflow diastolic pressure gradient.The transgastric views can also help to better evaluate thesubvalvular apparatus.2. Cleft Mitral ValveThis rare anomaly of the mitral valve, often associatedwith significant MR, usually involves the anterior leafletbut cases affecting the posterior leaflet have also beenreported (Figs. 24.11 and 24.12). Attachments of thechordae tendineae arising from the margins of the cleftto the ventricular septum may cause LVOT obstruction.The most commonly associated congenital cardiacanomalies include ASD, VSD, and transposition of thegreat arteries.Figure 24.27 (A, B) Double-orifice mitral valve: (A) leftatrial and (B) cut-away atrioventricular views: More commonly,the smaller of the two orifices is in the right lateral position; thedegree of stenosis is variable. (C–E) Stenotic parachute mitral.(C) Cut-away atrioventricular view: a single papillary muscleor fused papillary muscles usually arise from the posterior leftventricular wall. (D) Left atrial views: the dotted lines showthe areas of proposed leaflet fenestrations and papillary muscleincision to open the ventricular inlet. Leaflet fenestrations areperformed to maximize unrestricted blood flow into the left ventricleduring diastole while preserving enough valvular tissue foreffective coaptation during systole. (E) The fused papillarymuscle is being incised to facilitate valvular mobility. [Withpermission from Zias et al. (13).]TEE in Cleft Mitral Valve (Table 24.2)The TEE plane which best demonstrates the cleftanterior leaflet is the transgastric basal short-axis view ofthe LV at the level of the mitral valve. The cleft appearsas a break in the continuity of the anterior leaflet whichdivides it into a medial and a lateral portion. In true cleftof the mitral valve, the cleft is pointing towards theLVOT while the atrioventricular septum is intact and theTV is normally inserted lower than the mitral valve. Incontrast, in atrioventricular septal defects, the so-called“mitral valve cleft” constituted by the space between theanterior and posterior bridging leaflets rather points mediallytowards the inlet ventricular septum (Fig. 24.11).Incomplete cleft or mitral valve defect can also be seen(see Fig. 17.22).