“Cardiac Development’ by Lisa McCabe for OPENPediatrics


Cardiac development, by Lisa McCabe. Hello, my name is Lisa McCabe. I’m a clinical
nurse specialist at Children’s Hospital Boston in the cardiovascular program. I will
be discussing with you today Cardiac development. The information I swill share is consistent
with our practice here at Children’s Hospital Boston. You may want to adapt this information
to your own institutional practice. Fetal Development. During the first week of fetal life, the fertilized
egg develops into a blastocyte and implants in the mother’s uterus. During the second
week of fetal life, the blastocyte implants deeper into the uterine wall, and a primitive
placenta begins to form. During the third week of fetal life, the primitive umbilical
cord develops. Also at this time, the blastocyte develops into a three-layered disk. The three
layers are: the endoderm, mesoderm and ectoderm. Specific body systems will develop from each
layer. The endoderm, or inner layer, gives rise to the primitive intestinal tube, mucous
membranes, glands, lung buds, urinary tract, and yolk sac. The mesoderm, of middle layer,
gives rise to the heart and vascular system, the dermis, subcutaneous tissue, muscles,
skeleton, sex glands, lymph glands, kidneys, connective tissue, and blood cells. And finally
the ectoderm, or outer layer, gives rises to the epidermis, hair, sebaceous glands,
sweat glands, and nervous system. Cardiogenesis. Early in the development, the primitive heart
develops two tubes that merge into one tube. The single tube begins to swell, and develops
into various anatomic features of the heart. The heart begins o beat by week three. In
normal cardiac development, the cardiac tube will twist and turns on itself in a rightward
direction. This is called dextral-looping. This results in the right ventricle developing
on the right side of the heart and the left ventricle developing on the left side of the
heart. Abnormal looping in a leftward direction is called leval-looping. This results in the
right ventricle developing on the left side of the heart and the left ventricle developing
on the right side of the heart. Atrial Septation. Entering into the fifth week of fetal life,
the atrial septum and ventricular septum begins to form. The atrial septum grows in layers,
and includes the tissues of septum premium, septum secondo, and endocardial cushion tissue.
The endocardial cushion tissue is located in the middle of the heart. From this tissue
arises the tricuspid valve, mitral valve, part of the atrial septum, and part of the
ventricular septum. Septum prium grows downward between the right and left atrium, and eventually
fuses with the endocardial cushion tissues. The septum secudnum grows parallel to septum
primum. Both septum primum and septum secundum develop with holes in them to create a passageway
for blood to flow from right atrium to left atrium through the foramen ovale. As long
as the pressures on the right atrium are higher than pressures in the left atrium, the passage
will stay open to allow the blood to flow from right to left.
Errors may occur during atrial septation. A secundum atrial septal defect is an opening
in the middle of the atrial septum, produce when the tissue of septum primum does not
reach septum secundum adequately to completely close the wall or when a tiny hole is left
in the septum primum as the tissues grow. A primum atrial septal defect is an opening
in the lower part of the atrial septum, near the tricuspid and mitral valves. It results
from problems in the growth of the endocardial cushion tissues. A defect here is often associated
with a defect in the mitral valve, as well as tricuspid valve. The most severe form of
this is an atrial ventricular canal defect. Truncal Septation. The aorta and pulmonary artery develop from
a single tubular structure: the truncus arteriosis. Two areas of thickened tissue project into
the lumen of this tube on the right and left side. As they continue to grow in size, these
ridges meet and fuse to form the septum, which takes a spiral course toward the end of this
tube. This septum divides the truncus into two vessels: the aorta and the pulmonary artery.
The conal tissue involved in the septation of the truncus arteriosis also directs placement
of the aorta and pulmonary artery over their related ventricles. Ventricular Septation. By the fifth week of fetal life, the atria
completely separate into the right atrium and left atrium. Also at this time, the ventricular
septum continues to develop. The muscular portion of the ventricular septum develops
from the apex of the common ventricle. The membranous septum develops from the endocardial
cushion tissues. Conal tissue contributes to the complete closure of the septum between
the aortic and pulmonary valves. Errors may occur during ventricular septation. Muscular
defects can occur in any portion of the muscular septum. Small defects often close on their
own as the tissues develop. Membranous defects are located behind the septal leaflet of the
tricuspid valve. Sub-pulmonary defects are caused by deficiency of the conal septum.
Atrial ventricular canal type defects are caused by defects in the endocardial cushion
tissues of the intraventricular septum. Arch Formation. The aorta and pulmonary artery and their branching
vessels are formed from the brachial arch arteries. Initially there are six pairs of
brachial arch arteries. The first, second, and fifth pairs disappear, forming ligaments
that hold the heart in place. The third aortic arch forms the common carotid artery, external
carotid artery, and internal carotid artery. The fourth aortic arch forms part of the final
aortic arch, as well as the proximal portion of the right subclavian artery. The sixth
aortic arch produces the proximal segment of the branch pulmonary arteries, the ductus
arteriosis, and provides pulmonary blood flow via the branch that develops lung buds. Errors
may occur in arch formation that result in the following defects: coarctation of the
aorta, interrupted aortic arch, aortic atresia, patent ductus arteriosis, and vascular ring.
In just a few short weeks, the human heart has undergone major development. By the third
week of fetal life, the heart is beating. BY day 44, the fetal heart resembles the postnatal
heart in structure and function. It will continue to grow and develop over the next 30 to 32
weeks. Many of the features that may results in a heart defect, however, have also begun
to develop. Please help us improve the content by providing
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42 thoughts on ““Cardiac Development’ by Lisa McCabe for OPENPediatrics

  1. That was the best video, I have seen. I have to sat Thank you very much. Maybe you can a real-time animation at the end of how it goes from tubes to the human heart and adding labels would also be nice.

  2. As embryogenesis is a complex process Animated embryo topics are always welcome. And this is really good. there are many more embryology heading over which students like animated lesson e.g. CNS, GUT rotation, development of placenta, facial development, pharyngeal arches, urogenital system.

  3. this was great! i love the illustrations. you voice is really cute auntie. 🙂 really great supplement in my readings when i cant imagine it anymore. please upload more videos, now thinking getting in to pediatrics.

  4. This is a great video especially for medstudents trying to learn embryo with professors that don't know how to teach. I would love if you could put tables for what the Brachial Arch Arteries become or form and for what problem in the embryo causes the heart defect seen in infants and also possible treatments. Lastly information on the inferior and superior endocardial cushions would be great. Thanks so much, I will watch this a few times, very nice video

  5. This is amazing. Would be lovely if it was more detailed and the speaker was drawing the heart while explaining, thats helps alot!

  6. really wonderful video. I happened onto it by pure luck and I was really happy. I am going to watch it again. This video gives a good overview for medical students. Thanks for the all the hard work.

  7. Heart will beat by week 4 of development not 3 as i read in first aid book edition 2017 thanks for this amazing video

  8. Dextral looping was so fast that difficult to understand what is happening in its posterior portion.. I think it would be better in 3D image..

    And the video is very helful..❤

  9. very helpful, maybe just a little more of the truncus arteriosus formation with the aortic branches. I really like the explanation of the normal formation and then what could go wrong with them. I hope you make more, visualizing it helps tremendously when trying to study to test on it. Thanks for the video.

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