Cardiac Development PDF

M202 Cardiac development Heart primordium (at day 18) The heart starts as endothelial cells dispersed at the cranial end of the mesoderm (Heart primordium) at day 18 Those endothelial cells forms 2 endocardial tube , At first those en...

M202 Cardiac development Heart primordium (at day 18) The heart starts as endothelial cells dispersed at the cranial end of the mesoderm (Heart primordium) at day 18 Those endothelial cells forms 2 endocardial tube , At first those endocardial tubes were closed by epitheliam (epitheloid) then the cells dies till it form a lumen Cardiac tube Pericardiam Then the 2 endocardial tubes fuses d2 lateral folding ,First pericardial cavity is above cardiogrnic area (cardiogenic area was dorsal to pericardial cavity ) after craniocaudal folding the pericardial cavity becomes anterior &. The cardiogenic area became posterior.. Is the process in which the heart tube is shaped as the heart. Or S shaped heart What the parts form Spiral septum Sinoatrial orifice As the heart tube more develops it bends, upon itself: SO, the atrium and sinus venosus become dorsal to the truncus arteriosus, bulbus cordis, and ventricle. By this stage the sinus venosus has developed 2 lateral expansions, called the 2 horns ( right and left horns), and body. Formation of the interatrial septum (partitioning of the common atrium): First A sickle shaped septum primim is formed ,it groows from the roof of common Partitioning of the atrioventricular canal :- First 2 atrium into the endocardial cushions leaving a foramen called osteom primum (serves as a shunt between endocardial cushions appears on the dorsal & ventral walls of atriums) , Septum primim enlarges & fuses with septum AV canal ,they fuse forming septum intermedium which devides intermedium so osteum primim disappear & osteom AV canal into right & left between The primordial atriums & secondum arrises , then septum secondum arises making primordial ventricles. & it begins at the middle of the 4th week an oplique passage between atriums called foramen & ends by the end of the 5th week. ovale (Septum primum acts as it’s valve allow blood passage from right to left) ,in birth the lungs begin to work ,left atrial presure increases so it closes foramen ovale leaving a depression called fossa ovalis made by septum primum & annulas (limbus) ovalis , made by septum secondum. Sinus venoses; has 2 horns right & left , each Left horn atrophies & forms coronary sinus & left horn gets 3 veina :Umbilical vein from common cardiac vein forms oblique vein of left atrium.. placenta ,Vitelline vein from yolk sac & Common While right horn gets absorped forming the posterior cardiac from the fetal body. smooth surface of right atrium (Sinus venerium). Development of the atria The sinus venouses has 2 valves Right & Left , They unit at upper surface making septum superium Left venous valve ,Septum secondum & Septum superior unit to form a part of interatrial septum... the Right venous valve (Superior surface disappears) but inferior surface forms Valve of IVC & valve of coronary sinus & Crista terminalis) Left Pulmonary veins are absorped into left atrium making it’s smooth surface. Note:- Transverse anastomosis between Anterior cardinal veins -> Left brachiocephalic Right cardinal vein above anastomosis -> Right brachiocephalic Right cardinal vein below anastomosis ->Superior vena cava  A spiral septum develops in the truncus arteriosus from truncal ridges , dividing it into aorta and pulmonary trunk. So, now the pulmonary artery joins the right ventricle while the aorta joins the left ventricle. Pulmonary trunk moves right & anterior then left & posterior to aorta When partitioning of the truncus is Interventricular septum ; it’s mascular part formed of almost complete, primordia of the semilunar mascular outgrowth of ventricules ,While membranous part is valves become visible as 3 small tubercle the tubercles hollow out at their upper formed of endocardial cushion , Aorticopulmonry (spiral) septum surface,forming the semilunar valves “cusps”. & Thick mascular part of IV septum. Smooth Posterior part of both ventricles is formed of conus cordus (Middle third of bulbus cordus) ,Rough (Tuberculated) of Right ventricle is formed of Proximal third of bulbus cordis & Rough Left ventricle is formed of Primitive ventricle Congenital anomalis:- 1) Atrial Septal Defects (ASD): D2 Absence of septum primum and septum secundum, Excessive resorption of septum primum & patent foramen ovale (That leads to mixing venous & arterial blood) 2)Ventricular septal defect (VSD) as in Roger’s disease (Absence of membranous part of IV septum). 3) Fallot’s Tetralogy that has: VSD ,Pulmonary stenosis., Overriding of the aorta, Right ventricular hypertrophy. 3)(TGA) OR TRANSPOSITION OF GREAT ARTERIES : TGA is due to abnormal rotation or malformation of the aorticopulmonary septum, so the right ventricle joins the aorta, while the left ventricle joins the pulmonary artery. It is one of the most common cause of cyanotic heart disease in the newborn, Often associated with ASD or VSD. 4) Persistent Truncus Arteriosus: It is due to failure of the development of the aorticopulmonary (spiral) septum. It is usually accompanied with VSD. Videos: https://youtu.be/4H-dSo6IhrM?feature=shared https://youtu.be/a4erhGAqTU4?feature=shared