Great Vessel development Flashcards
where does the aortic arteries arise from embryologically and how many arches are there at the beginning
the aortic sac, and there are 6 pairs of aortic arches that are formed within the pharyngeal arches via vasculogenesis and angiogenesis
what are the three ways that these primitive system changes into the adult pattern we have today
hypertrophy of some vessels (AA 3, 4, 6)
addition of new vessels (external carotid and distal parts of pulmonary artery
loss of some vessel segments
what are the intersegmental arteries and how are they formed
Intersegmental arteries form via vasculogenes (within the paraaxial mesoderm) and connect the dorsal aorta together
these vessels run between the somites and then go on to interconnect to one another cranially and caudally
What happens to the fate of the Dorsal Intersegmental arteries
Cervical: 7intersegments
- United by the longitudinal anastomosis and then the roots of 1-6 drop out and the 7th one remains
- these left over longitudinal anastomsis become the vertebral arteries
- the 7th intersegmental artery remains on the left and forms the left subclavian artery and the right it forms a portion of the right subclavian
Thoracic: 12 intersegmentals
-superior and inferior thoracic anastomosis between the intersegmentals contribute to the formation of the internal thoracic arteries and while the intersegmentals them selves contribute to the intercostal arteries
Lumbar: 5 intersegments
-lumbar anastamosis involved in making the epigastric and iliac vessels
Fate of the Aortic Arches: I and II
Arches I and IIeventually break up and reorganize
small part of AA I may contribute to maxillary artery
a part of AA II becomes the stapedial arteries
Fate of the Aortic Arches: III
Carotid Arch, main feeder to the head
will form the common carotid and proximal portion of internal carotid
remainder of internal carotid comes from the dorsal aorta while the external carotid is a sprout from AA III
Fate of the Aortic Arches: IV
hypertrophies and becomes very large
Left:
- Forms part of the aortic arch (aortic sac forms first part, 2nd part is the IV, left dorsal aorta and proximal to distal to the 7th intersegmental artery forms the 3rd and 4th parts
- spiral septum of the outflow tract insures connection of left AAIV to the left ventricle
- on the left the 7th intersegmental makes the entire left subclavian artery
Right:
- forms the proximal part of the right subclavian artery
- the 7th dorsal intersegmental artery makes the distal portion
- the right AA IV makes the proximal portion and intervening dorsal aorta makes the rest
Fate of the Aortic Arches: V
Never forms
Fate of the Aortic Arches:VI
pulmonary arteries
-each side forms new outgrowth that enters the mesenchyme of the luung (intrapulmonary portion)
-both formed from the proximal portion of Aortic sac and VI
since the heart will descend as the body grows it will pull the recurrent laryngeal nerve with it, however since on the right side the distal part of VI is loss it will only wrap around VI on the left side
Fate of the dorsal aorta
portion between the AA III and the AA IV is called the carotid duct and this portion is obliterated
right dorsal aorta will also disappear between the right 7th intersegmental artery and its junctions with the left dorsal aorta
the remaining caudal segments of the right and left dorsal aorta fuse to form the descending thoracic and abdominal aorta
Fate of the Vitelline arteries
vessels supplying the yolk sac eventually form the GI vasculature
fate of the umbilical arteries
paired ventral branches of the dorsal aorta course the placenta and have connections with the developing bladder
a new connection is made between the 5th lumbar intersegmental arteries and the distal umbilical arteries and then the original proximal connections to the dorsal aortic regress in the embryo
after birth the distal end of umbilical arteries is obiterated (part heading to the umbilical cord at the umbilicus) and become the medial umbilical ligaments a
the more proximal portion off the 5th lumbar intersegmental arteries (iliac vessels) are still referred to as umbilical arteries in the adult with the superior vesicular arteries branching off them to supply the bladder
what are the shunts of the fetal circulation
Oxygen rich blood bypasses much of the liver via the ductus venosum and enters the inferior vena cava and RA
much of the blood also passes through the foramen ovalis into the LA and only a bit of blood enters the RV
most of the superior vena cava blood is directed into the right ventricle which will then go into the pulmonary trunk and sneak into the descending aorta via the ductus arteriosus
(only 10 percent of blood makes it to the pulmonary circuit)
what areas in the fetus recieve the most oxygenated blood
since the blood from the umbilical vein dumps right into the RA and into the LV
the most oxygenated blood will go to the head, neck , and upper limb since it comes from the ascending Aorta
medium oxygenated will go to the rest since blood from the ductus arteriosus mixes with the descending aorta
Abnormalities of Great vessels: Patent ductus arteriosus
in fetus, prostagladins keep the ductus arteriosus open prior to birth
affter birth a drop in prostagladins and increase in endothelin release wiill stimulate smooth muscle contraction of the ductus arteriosus about 10 - 15 hours after birth
-if this doesnt happen 1/2 to 1/3 of blood going into the aorta will be shunted to the pulmonary circulation due to the lower pressure, and blood will circulate their 2-3 times
leads to extra work load for the LV and it will hypertrophy
lead to pulmonary congestion due to the increased blood flow their and eventually congestive heart failure
after 1-3 years can hear a murmur
there is an increased risk for this in the fetus if the mother has a rubella infection
treatment is grostaglandin inhibitor or surgery
Abnormalities of Great vessels: Coarctation of the aorta and the two types
Aortic lumen below the orgin of the left subclavian artery is narrowed due to abnormal thickening of the aortic wall
More frequent in turners syndrome
Constriction may be before or after ductus arteriosus
Postductal: sometimes not noticed because collateral circulation is established through collateral ciculation is established through intercostal (intersegmental) arteries and internal thoracic arteries
Preductal: Collaterals usually not well developed
after birth, a little or no blood gets to lower body and legs unless the duuctus arteriosus remains open
-Many times child dies if surgery is not performed to correct this
Abnormalities of Great vessels: Aberrant orgin of right subclavian
Right subclavian is formed by distal portion of right dorsal aorta and 7th intersegmental artery
right AA IV and proximal part of right dorsal aorta are obliterated
this may cause problems in swallowing (dysphagia) and respiration (dyspnea) because right dorsal aorta must cross esophagus to reach the right upper limb
usually asymptomatic
Abnormalities of Great vessels: double aortic arch
Vascular ring surrounding trachea and esophagus
may lead to esophageal dysfunction nd strangulation of trachea
Abnormalities of Great vessels: right aortic arch
the left AA IV and Left dorsal aorta are completely obliterated and replaced by corresponding vessels on right
may cause complaints of dysphagia and dyspnea if the left subclavian artery passes behind the esophagus and the ligamentum arteriosum passes in front of the trachea to reach the right side
Abnormalities of Great vessels: Interrupted aortic arch
similar to an abnormal right subclavian except the left AA IV disappears as well
ductus arteriosus remains open and descending aorta and subclavian arteries are supplied with blood of low O2 content
aortic trunk supplies the two common carotid arteries, often seen in DiGeorge syndrome
life threatening unless one intervenes
what are the three main venous systems
Vitelline: carries blood from yolk sac to sinus venosus
Umbilical: orginates in chronic villi of placenta carrying O2 rich blood
Cardinal: drains body of the embryo
What is the fate of the vitelline veins?
initially empty into sinus horn and as they pass through the septum transversum they become surrounded by liver primordia
as the liver develops the vitelline veins form a vascular plexus (hepatic sinusoids) within the primordia liver
as the left sinus venosus is reduced in size, the blood flow of the left vitelline and the left umbilical is channeled toward the right side within the liver
the proximal portion of the right vitelline vein forms the right hepatocardiac channel that eventually forms the terminal part of the inferior vena cava
the proximal parts of the left vitelline vein (left hepatocardiac channel) will disappear
inferior parts of vitelline veins regress except for that contributing to the portal vein, superior and inferior mesenteric vein and splenic vein
what is the fate of the umbilical veins
since vessels pass on either side of the liver they become connected to hepatic sinusoid, proximal part of both sides and remainder of distal right umbilical vein disappears so the left umbilical vein is the only one carrying placental blood to liver
with increased placental circulation, a direct communication is formed between the left umbilical vein and right hepatocardiac channel called the ductus venosus
the ductus venosus allows most of the blood to bypass the sinusodial plexus of liver
Prostaglandins have a role in maintaining patency of duuctus venosus during fetal life
After birth, the left umbilical vein and ductus venosus disappear forming the ligamentum teres hepatis and ligamentum venosum
how does the cardinal vein work in the fetus
Anterior and posterior cardinal vein are the early drainage system of the body
they will both join to form the common cardinal vein before entering the sinus horn
anastamoses between the left and right anterior cardinal vein drains most of the head and neck into the cardinal vein on the right side
Anterior cardinal vein
an anastomosis between right and left anterior cardinal vein forms the left brachiocephalic vein, superior vena cava forms from right common cacrdinal vein
the connection of the left anterior cardinal with the left common cardinal vein is lost as the left brachiocephalic vein develops. much of the left cardinal vein regresses along with the left sinus horn with remnants forming the coronary sinus
abnormal anterior cardinal vein development can lead to the Superior vena cava draining into the heart via the coronary sinus
Posterior cardinal vein
connected to parallel sets of veins called the subcardinal and supracardinal veins, as these new set of veins develop much of the original posterior cardinal veins regress
subcardinal: will form veins primarily associated with the kidney and gonads and contributes to formation of abdominal inferior vena cava
supracardinal: (body wall) will form portions of inferior vena cava and azygos system as well as veins draining the body wall
