Heart Development PDF

LO3 Endocardial cushions – growing masses of endocardium that project into lumen to divide canal Formation of Cardiac Septa Langman's Medical Emb ryology 14th ed. ©AK202...

LO3 Endocardial cushions – growing masses of endocardium that project into lumen to divide canal Formation of Cardiac Septa Langman's Medical Emb ryology 14th ed. ©AK2023 11 LO3 Septum Formation in Common Atrium Septum primum – sickle-shaped crest grows from roof of common atrium toward endocardial cushions in atrioventricular canal Ostium primum – opening between lower rim of septum primum and atrioventricular opening Langman's Medical Emb ryology 14th ed. Fig. 13.16 ©AK2023 12 LO3 Septum Formation in Common Atrium Ostium secundum – merging perforations in septum primum, maintains blood flow between atria Septum secundum – crescent-shaped fold from incorporation of sinus horn in right atrium ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.16 13 LO3 Septum Formation in Common Atrium oval foramen – opening left by the septum secundum, closes off after birth (fossa ovalis) Langman's Medical Emb ryology 14th ed. Fig. 13.16 ©AK2023 14 LO4 Congenital Heart Anomalies Onset of Direction Type Examples Cyanosis of Shunt Late Ds: ASD, VSD, PDA, AV canal Defect Acyanotic L→R “blue kids” Obstructive: CoA of aorta 1,2,3,4: persistent truncus arteriosus, Early transposition of vessels, tricuspid atresia, Cyanotic R→L tetralogy of Fallot “blue babies” Obstructive: Ebstein anomaly ©AK2023 15  LO4 Atrial Septal Defects 6.4/10,000 births 2:1 males ostium secundum defect acyanotic large opening between atria due to excessive cell death and resorption of septum primum inadequate development of septum secundum ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.23 16  Langman's Medical Emb ryology 14th ed. Fig. 13.20 LO3 Septum Formation in AV Canal ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.19 17  LO3 Atrioventricular Valves (Bicuspid and Tricuspid) Local proliferations of mesenchyme become fibrous and form AV valves Muscular cords attaching valves degenerate and replaced by dense CT Valves attached to papillary muscles by chordae tendineae Septum Formation in AV Canal ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.21 18 LO4 Ebstein anomaly 1/200,000 births cyanotic tricuspid valve displaced toward apex of R ventricle causing expanded R atrium and small R ventricle, abnormal valve leaflets ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.26 19  LO3 Septum Formation in Outflow Tract Cardiac neural crest cells migrate to contribute to outflow tract – disruption causes tetralogy of Fallot, pulmonary stenosis, persistent truncus arteriosus, transposition of great vessels Conotruncal ridges grow and divide outflow tract into aortic and pulmonary channels ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.30 20