MGA 15 Heart Development Lecture 15 PDF

Notice and Agreement Medical Gross Anatomy – Lecture 15 – Heart Development This session is being recorded Class recordings are distributed for the exclusive use of students in the LMU DeBusk College of Osteopathic Medicine....

Notice and Agreement Medical Gross Anatomy – Lecture 15 – Heart Development This session is being recorded Class recordings are distributed for the exclusive use of students in the LMU DeBusk College of Osteopathic Medicine. Student access to and use of class recordings are conditioned on agreement with the terms and conditions set below. Any student who does not agree to them is prohibited from accessing or making any use of such recordings. Any student accessing class recordings (1) acknowledges the faculty members’ intellectual property rights in recorded lectures and class materials and that distribution of the recordings violates the DCOM Copyright Policy; (2) recognizes the privacy rights of fellow students who speak in class; (3) accepts that distributing, posting, or uploading class recordings to students or any other third party not authorized to receive them or to those outside DCOM is an Honor Code violation; and (4) agrees that recordings are to be accessed and used only as directed by the faculty member(s) teaching the course. ©AK2023  Medical Gross Anatomy Lecture 15: Heart Development 24 August 2023 Adam Kolatorowicz PhD Langman’s Medical Embryology 14th ed. Ch 13 pp 181-204, 216-219 (Ignore all sections on molecular regulation.) Anatomy of the Human Body (Gray, 1918) Fig. 463. Heart of human ©AK2023 embryo of about fourteen days. (From model by His.)  Learning Objectives 1. Describe the formation and positioning of the heart tube. 2. Identify embryonic tissues that give rise to cardiovascular structures. 3. Explain the formation of the cardiac chambers, septa, and valves. 4. Diagnose congenital heart anomalies based on physical exam findings. 5. Compare and contrast circulation before and after birth. ©AK2023 3 Langman's Medical Emb ryology 14th ed. Fig. 13.38 Introduction Cardiovascular system is first major system to function in the embryo Primordial heart and vascular system appear in middle of wk 3 Rapidly growing embryo can no longer satisfy nutritional and oxygen requirements from diffusion LO2 Derived from mesoderm with contributions from neural crest ©AK2023 4 LO1 Formation and Position of Heart Tube Cardiogenic area is originally anterior to future mouth and forebrain Forebrain grows over heart to lie in thorax position Lateral folding of embryo brings paired cardiac tubes together as single tube ©AK2023 The Developing Human 10th ed. Fig. 13-9 5 LO1 Formation and Position of Heart Tube ©AK2023 The Developing Human 10th ed. Fig. 13-8 6  LO1 Langman's Medical Emb ryology 14th ed. Fig. 13.8 day 22 day 23 day 24 Formation of Cardiac Loop ©AK2023 7  Anomaly of Cardiac Looping ©AK2023 The Developing Human 10th ed. Fig. 13-23 8 LO2 Development of Sinus Venosus Quadrangular space that precedes atria Receives all blood from the embryo (L and R sinus horns) Right sinus horn ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.11 9 LO2 Development of Sinus Venosus L horn gets smaller after contributing veins degenerate Remains as coronary sinus R horn enlarges greatly from L to R shunting of blood Develops into valves of IVC and valves of coronary sinus ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.12 10 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  LO3 Septum Formation in Outflow Tract ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.27 21  LO4 transposition of the great vessels (4.8/10,000 births) cyanotic conotruncal septum fails to take spiral course and goes straight down aorta originates from R ventricle and pulmonary a. from L ventricle associated with defect in membranous IV septum and patent ductus arteriosus ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.36 22  LO3 Septum Formation in Ventricles Medial walls expand forming muscular IV septum Membranous part of IV septum closes IV foramen Semilunar Valves – Small tubercles on main truncus swellings form – Upper surface of tubercle is hollowed out to form valves, influenced by neural crest cells Langman's Medical Emb ryology 14th ed. ©AK2023 23 LO4 Ventricular Septal Defects acyanotic 12/10,000 births occur in membranous or muscular portions associated with abnormal partitioning in conotruncal region ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.33 24 LO4 tetralogy of Fallot (9.6/10,000 births) cyanotic unequal division of conus due to anterior displacement of conotruncal septum associated with patent ductus arteriosus and pulmonary stenosis 1 3 2 ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.34 4 25 LO4 persistent truncus arteriosus (0.8/10,000 births) cyanotic conotruncal ridges fail to form, and no division of outflow tract occurs accompanied by defective IV septum ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.35 26  coarctation of the aorta (3.2/10,000 births) LO4 Arterial acyanotic lumen below origin of L subclavian is markedly narrow System caused by intima proliferations Defects preductal or postductal types high upper limb BP, low lower limb BP Langman's Medical Emb ryology 14th ed. Fig. 13.42 ©AK2023 27 LO4 Congenital Heart Anomalies Onset of Direction Type Examples Cyanosis of Shunt Acyanotic Cyanotic ©AK2023 28  Image Credit ©AK2023 29  LO5 Fetal Circulation Pathways A. Oxygenated blood Umbilical v. → ductus venosus → IVC → R atrium → oval foramen → L atrium → L ventricle → aorta → body tissues B. Deoxygenated blood Body tissues → SVC/IVC → R atrium → R ventricle → pulmonary trunk → ductus arteriosus → descending aorta → umbilical aa. ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.52 30 LO5 3 Circulatory Changes After Birth 4 1. Closure of umbilical aa. shortly after birth 2. Closure of umbilical v. and ductus venosus shortly after umbilical aa. 3. Closure of ductus arteriosus immediately after birth 4. Closure of oval foramen at first breath, completes by year 1 2 1 ©AK2023 Langman's Medical Emb ryology 14th ed. Fig. 13.53 31