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41 Cards in this Set

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  • Back
When is the primitive vertebrate cardiovascular plan present by?
Week 4
Where does the first wave of hematopoiesis occur?
Extra-embryonic yolk sac

Leads to production of primitive embryonic nucleated red blood cells in blood islands
What are the 3 phases of embryonic hematopoiesis?
1. Primordial - yolk sac followed by aorta-gonad-mesonephros
2. Hepatosplenothymic - weeks 4-8
3. Medullolymphatic - week 9--> (by 5th month in utero bone marrow has become major site of hematopoiesis)
Which gene is essential for blood formation?
What are the two ways in which blood vessels are formed?
1. Vasculogenesis - blood vessels arise from coalescence of hemangioblasts, which arise from blood islands
2. Angiogenesis - vessel formation via branches arising from existing vessels

Major vessels form via vasculogenesis
What are the steps in vasculogenesis?
FGF binds to mesenchymal cells-->hemangioblasts
VEGF elicits regional change in blood islands
Central cells become hematopoietic stem cells
Peripheral cells differentiate into angioblasts--> endothelium of blood vessels
How does vascular development occur?
Once the vascular bed (primary capillary plexus) is established, VEGF then regulates formation of additional vasculature via angiogensis
What is the embryonic vascular circuit?
Series of aortic arches that connect to dorsal aorta
Blood drained by anterior and posterior cardinal veins
What are the extraembryonic vascular circuits?
Vitelline - supply and drain yolk sac

Umbilical (placental) - umbilical vein carries oxygenated blood from placenta
What is the adult structure that corresponds with the Truncus Arteriosus?
Pulmonary Trunk
What is the adult structure that corresponds with the Bulbus Cordis?
Smooth part of right ventricle (conus cordis)
Smooth part of left ventricle (aortic vestibule)
What is the adult structure that corresponds with the primitive ventricle?
Trabeculated part of right and left ventricles
What is the adult structure that corresponds with the primitive atrium?
Trabeculated part of right and left atria (auricles)
What is the adult structure that corresponds with the sinus venosus?
Smooth part of right atrium (sinus venarum)
Coronary sinus
Oblique vein of left atrium
How does the heart go from a tube to its recognized form?
Cardiac looping
The heart bends on itself, forming a bulboventricular loop
What is dextrocardia?
Heart bends to the left instead of the right
Heart displaced to the right with transposition of heart and great vessels
Most common positional abnormality
What are endocardial cushions?
Dorsal and ventral blocks of tissue grow together

Their formation and fusion is the critical first step in the development of the 4-chambered heart
What is common AV canal?
Defect in endocardial cushions
Enlarged pulmonary trunk
Less resistance in the pulmonary circulation than in the systemic circulation
How is the interventricular septum formed?
Muscular portion develops in the midline on the floor of the primitive ventricle
Grows upward towards endocaardial cushions and down growing bulbar ridges
What are ventricular septal defects?
Opening between L & R ventricles, associated shunting of blood
4 types based on position and severity
25% of all congenital heart defects
Most occur in muscular portion (these spontaneously close)
How is the atrial septum formed?
Septum primum forms almost to ECC, but before it fuses it forms foramen secundum
Septum primum then fuses with ECC (closes foramen primum)
Septum secundum forms, creating valve of forman ovale
What are atrial septal defects?
Common atrium
Ostium (foramen) primum defects - similar to ECC defects
Secundum type - involve foramen ovale and septum primum
Sinus Venosus - usually near opening of SVC
Fairly common, present in 10-15% of patients with congenital cardiac anomalies
What occurs in the changes of the sinus venosus?
Right horn enlarges as blood is shunted from L-->R
Move all systemic inflow to the right side
Describe the shunt for the vitelline veins.
Veins become incorporated into liver as hepatic sinusoids, hepatic veins, part of IVC and some of the veins that drain the GI tract
Describe the shunt for the umbilical vein.
Loses direct connection with heart (ligamentum teres hepatis)
Joins large venous shunt - ductus venosus
What is the ductus venosus?
Connects umbilical vein with IVC
Bypasses the liver and diverts oxygenated blood into the heart
What is the shunt involving the cardinal veins?
Anterior cardinal veins become connected
Anastomosis becomes left brachiocephalic vein
Right anterior cardinal and common cardinal become SVC
What does the crista terminalis mark the division between?
Embryonic sins venosus and embryonic primitive atrium (auricles)
Describe the partitioning of the great vessels.
Tissue forming aorticopulmonary septum twists inside the truncus arteriosus so that pulmonary trunk connects with right ventricle and aorta connects with left ventricle
More complex = increased possibility of errors
What is Eisenmenger's Syndrome?
Equal division of truncus, incomplete fusions of bulbar ridges inferiorly --> VSD
Initial L-->R shunt, increased pulmonary blood flow and hypertension
Proliferation in intima and media to narrow lumen
Increased pulmonary resistance causes R-->L shunt and cyanosis
What is Tetrology of Fallot?
Pulmonary stenosis
Overriding aorta
Rt. ventricular hypertrophy
How many pairs of aortic arches are there?
6 pairs

Connect aortic sac/TA to dorsal aortae
Which derivations of the aortic arches form the aorta and the ductus arteriosus?
IV - aorta
VI - ductus arteriosus, also the pulmonary arteries
How are pulmonary veins formed?
Form independently, are not remade
Venous drainage channels from lungs converge to form single vessel-->left atrium
As atrium expands, tissue of the vein is incorporated into the wall
What is Total Anomalous Pulmonary Venous Return (TAPVR)?
Rare congenital malformation in which all four pulmonary veins do not connect normally to the left atrium
Instead, all four pulmonary veins drain abnormally to the right atrium by way of an abnormal (anomalous) connection
What are the types of TAPVR?
Supracardiac - pulmonary veins drain to rt. atrium via SVC
Cardiac - pulmonary veins come together behind heart and then drain to rt. atrium through coronary sinus
Infracardiac - pulmonary veins drain to the rt. atrium through the liver (hepatic) veins and the IVC
T/F: All types of TAPVR must have an ASD.

Because none of the pulmonary veins connect normally to the left side of the heart, blood must be shunted from rt. atrium across the ASD
What is right aortic arch?
Persistence of right 4th arch distal to the right subclavian
Left segment caudal to left subclavian disappears
Situs inversus complex
What is double aortic arch?
Segment of right 4th aortic arch caudal to the right subclavian persists
Vascular ring around trachea and esophagus
What is coarctation of the aorta?
Coarctation of the aorta distal to the left subclavian
Typically near the ductus arteriosus: postductal (adult) or preductal (infantile)
Collateral circulation often includes the ITA and branches
What is ectopia cordis?
Heart forms outside the body