Fetal heart development Flashcards
(30 cards)
From which germ layer does the heart develop?
Mesoderm (specifically, cardiogenic mesoderm from lateral plate mesoderm)
What is one of the earliest differentiating and functioning organs in the embryo?
The heart
What gives rise to the paired endocardial heart tubes?
Angiogenic cell clusters from cardiogenic mesoderm
What embryonic process fuses the endocardial heart tubes?
Lateral folding of the embryo
Name the segments of the primitive heart tube (cranial to caudal)
Truncus arteriosus → Bulbus cordis → Primitive ventricle → Primitive atrium → Sinus venosus
What does the bulbus cordis give rise to?
Right ventricle and ventricular outflow tracts
What forms from the truncus arteriosus?
Proximal aorta and pulmonary artery
When does heart folding occur?
Days 23–28
What is the role of endocardial cushions?
Divide the atrioventricular canal into left and right canals
What is the role of the septum primum and septum secundum in atrial septation?
They form the interatrial septum; their overlap forms the foramen ovale
What is the function of the foramen ovale in fetal circulation?
Shunts blood from right atrium to left atrium, bypassing the lungs
What causes the foramen ovale to close after birth?
Increased pressure in the left atrium compared to the right atrium.
What is a common cause of Atrial Septal Defect (ASD)?
Incomplete fusion of septum primum and septum secundum.
What complication can arise from a large Atrial Septal Defect (ASD)?
Pulmonary hypertension and right ventricular hypertrophy due to left-to-right shunt
What forms the muscular and membranous parts of the interventricular septum?
Muscular part: grows from the primitive ventricle floor; Membranous part: from endocardial cushions
What is the most common congenital heart defect?
Ventricular Septal Defect (VSD), especially membranous type (90%)
What structure forms the aorta and pulmonary trunk separation?
Truncoconal swellings that spiral and fuse.
What does the primitive ventricle give rise to?
left ventricle
What does the primitive atria give rise to?
left and right atria
What does sinus venosus give rise to?
smooth part of right atrium + coronary sinus
Name the three fetal shunts and their functions
Ductus venosus: Umbilical vein to IVC (bypasses liver)
Foramen ovale: RA to LA (bypasses lungs)
Ductus arteriosus: Pulmonary trunk to aorta (bypasses lungs)
What do the fetal shunts become postnatally?
Ductus venosus → Ligamentum venosum
Foramen ovale → Fossa ovalis
Ductus arteriosus → Ligamentum arteriosum
List 4 acyanotic congenital heart lesions.
ASD, VSD, PDA, Coarctation of the aorta (usually)
How is Patent Ductus Arteriosus (PDA) typically treated in infants?
Prostaglandin inhibitors/NSAIDs (e.g., Indomethacin or ibuprofen); surgical clip if persistent after 3 months
