WHAT YOU NEED TO KNOW ON CARDIAC EMBRYOLOGY Peer SupportJS View as a slideshow

Main things to know  Heart tube  Make sure you can draw both the primitive and adult heart diagrams (5 swellings)  Atrial septation  Know the order of septal formation (primum, secundum, ovale)  Ventricular septation  Know the different parts and where they arise.  Truncus arteriosus defects  Know the main ones and those that can present with cyanosis

Heart tube  The CVS develops from extra-embryonic mesoderm  Angiogenic cell clusters around the neural plate develop into cords before canalising to form to endocardial tubes (heart tubes)  Lateral folding fuses these tubes into one heart tube  Longitudinal folding relocates the heart, mouth and brain into their adult position.

Heart Tube Swellings

Atrial Septation  A: Septum primum grows from the roof of the common atrium towards the endocardial cushion, leaving an ostium primum (primary foramen)  B: Before this closes, small holes appear in the septum.  C: These holes merge to form ostium secundum (secondary foramen) to allow blood flow between the atria.  D: A stiffer, muscular septum secundum forms immediately to the right, leaving a gap near the endocardial cushion, the foramen ovale  Since its floppy, septum primum becomes the valve for foramen ovale, and while RAP is high, allows R- to-L shunting of blood in utero.  After birth, the foramen ovale closes leaving a depression known as the fossa ovalis. PFO is the most common ASD

Ventricular Septation  Muscular component  Grows from floor of ventricle  Membranous component  Grows down from bulbar ridges and endocardial cushion  VSD are the most common heart congenital anomaly, usually arise in membranous part of ventricular septum  Aorticopulmonary septum forms in the common ventricular outflow from bulbar and truncal ridges in a 180° spiral

Truncus arteriosus defects  Cyanotic  Transposition of Great Arteries most common cyanotic heart defect  Tetralogy of Fallot Pulmonary stenosis, RVH, Overriding aorta, VSD (PROV)  Persistent truncus arteriosus Also just called truncus arteriosus  Critical pulmonary stenosis  Non-cyanotic  ASD  VSD  PDA  Failure of equal division i.e. AS, non-severe PS

Questions  Look into “Embryology” Illustrated Colour Text by Mitchell and Sharma  me