CV Development Flashcards
What pairs of tubes form the initial tube that becomes the heart?
Endocardial tubes
What derm layer forms around the initial tube that becomes the myocardial mantle?
Mesoderm
When does the myocardial mantle begin beating?
22 days
What are the 5 initial regions of the endocardial tube & myocardium?
Inferiorly to Superiorly:
Sinus Venosus (2)
Primitive atrium
Ventricle
Bulbus cordis
Aortic sac
What does the aortic sac eventually become?
Aorta & Pulmonary artery
What does the Bulbus cordis eventually become?
R ventricle, Proximal aorta & pulmonary trunk
What does the primitive ventricle eventually become?
L ventricle
What does the primitive atrium eventually become?
R & L auricles, L atrium
What does the left and right sinus venosus eventually become?
R atrium, Vena cavae, coronary sinus
What are the 4 steps to making a 4-chambered heart?
- Sinus venosus and primitive atrium separate into the R and L atrium.
- Primitive ventricle separates from bulbus cordis to form L and R ventricle.
- Primitive atrium separates from primitive ventricle.
- Conus cordis and truncus arteriosus develop internal partitions to become the proximal aorta and pulmonary trunk.
What is the hole between the atria known as?
Foramen ovale
What 4 things make up the wall that separate the atria?
Septum secundum and primum
Ostium secundum and primum
How much of the US population is estimated to still have a PFO? (patent foramen ovale)
25%
When is having a PFO a concern? What does it cause?
When you have increased R heart pressure. This can cause clots to skip from the R atrium straight to the L atrium, sending a clot into your arteries.
What separates the two ventricles from each other during development?
Muscular portion of the interventricular septum.
What two primitive structures become the L and R ventricles?
Primitive ventricle = L ventricle
Bulbus Cordis = R ventricle
What is the final key in separating the two ventricles during development?
Endocardial cushions, which make up the superior part of the interventricular septum and are made from the membranous portion of the interventricular septum.
Note: They also contribute to forming the pulmonary and aortic valves.
What is the most common congenital heart defect? (CHD)
A ventricular septal defect (VSD), estimated to make up 25% of all CHDs.
What are the 3 types of VSDs and who is most at risk?
Perimembranous (most common)
Muscular (less common)
Supracristal (rare)
Siblings have 3x the risk.
Expansion of what divides the common AV canal?
Endocardial cushions, separating it into L&R AV canals.
Note: imagine pinching a tube vertically in the center so it makes two holes, left and right.