CV Embryo

Ascending Aorta and Pulmonary Trunk

• Smooth Parts (outflow tracts) of Ventricles
• Right → Conus Arteriosus
• Left → Aortic Vestibule

Atrial Septum, Membranous Intraventricular Septum, AV & Semilunar Valces

Trabeculated parts of the atria

Trabeculated parts of the ventricles

Smooth part of the right atrium (sinus venarum)

Superior Vena Cava

L/R Assymetry that can lead to dextrocardia (seen in Kartagener Syndrome - primary ciliary dyskinesia)

• Early looping - inherent
• convergence - alignment of atrioventricular and conoventricular canal
• wedging - conoventricular canal between tricuspid and mitral valves
• Repositioning - atrioventricular canal straddles L/R Ventricles

establish left-right polarity

Week 4 of gestation

• 1. Septum Primum grows towards endocardial cusions - foramen primum is formed
• 2. Foramen secundum opens up in septum primum (apoptosis) and septum primum continues to grow closing foramen primum
• 3. Septum secundum develops
• 4. Septum secundum expands and covers most of foramen secundum -residual opening is foramen ovale
• 5. Septums fuse to form the atrial septum
• 6. Foramen ovale usually closes at birth due to increased LA pressure

• failure of septum primum and secundum to fuse after birth
• most left untreated but can lead to a paradoxical embolus

• 1. Muscular Interventricular septum forms with an opening called the interventricular foramen
• 2. Aorticopulmonary septum rotates and fuses with muscular ventricular septum to form the membranous interventricular septum closing the interventricular foramen
• 3. growth of endocardial cushions separates the atria from the ventricles and contributes to both atrial septation and membranous portion of the interventricular septum

most common cardiac congenital anomaly (25%) and usually occurs in the membranous portion of the septum

Neural crest and endocardial cell migrations → truncal and bulbar ridges that spiral and fuse to form the aorticopulmonary septum → aorta and pulmonary trunk

• Transposition of the Great Vessels
• Tetralogy of Fallot
• Persistent Truncus Arteriosus

endocardial cushions of the outflow tract

fused endocardial cushions of the AV canal

• Stenosis
• Regurgitation
• Atretic
• Displased - Ebstein

• Lateral Plate Mesoderm splits into somatic and splanchnic
• Splanchnic becomes the pericardial cavity
• Precardiac mesoderm distributes into the splanchnic mesoderm which become heart forming regions that fuse with lateral folding at the midline

Urachus →Median Umbilical Ligament

Ligamentum Arteriosum

Ligamentum Venosum

Fossa Ovalis

Nucleus Pulposus

Medial Umbilical Ligaments

Ligamentum Teres (contained in the falciform ligament)

• shunt oxygenated blood from the umbilical vein to the IVC bypassing the liver
• Mixing will then occur at the IVC

• Path for oxygenated blood from the IVC to enter the LA and then be pumped to the rest of the body through the aorta
• Some mixing may occur in the RA but not a lot

• Deoxygenated blood from the SVC moves through the tricuspid valve to the RV and then through the Pulmonary Trunk.
• Blood then passes through the PDA to the Aorta after the branches going to the head and upper body
• Reserves the best oxygenation for the brain and then mixing occurs in the aorta

• Upon inhalation the lungs expand decreasing the resistance in the lungs
• Increased pressure in the pulmonary arteries then allows blood to circulate through the lungs
• Increased Pressure in the LA due to the return of blood through the pulmonary veins slams the foramen ovale closed 
• increased O2 and decreased PGs (from separation of the placenta) encourage closing of the PDA

PGE1 and PGE2

Indomethacin