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Cardiovascular Embryology
pg 262 - 265 from 2016 First Aid for Step 1
43
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Professional
04/23/2018

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Term
Heart Embryology
Definition
Term
The truncus arteriosus gives rise to what?
Definition
Ascending aorta and pulmonary trunk
Term
The bulbus cordis gives rise to what?
Definition
Smooth parts (outflow tract) of left and right ventricles
Term
The endocardial cushion gives rise to what?
Definition
Atrial septum, membranous interventricular septum; AV and semilunar valves
Term
The primitive atrium gives rise to what?
Definition
Trabeculated part of the left and right atria
Term
The primitive ventricle gives rise to what?
Definition
Trabeculated part of left and right ventricles
Term
The primitive pulmonary vein gives rise to what?
Definition
Smooth part of left atrium
Term
The left horn of sinus venosus gives rise to what?
Definition
Coronary sinus
Term
The right horn of sinus venosus gives rise to what?
Definition
Smooth part of right atrium (sinus venarum)
Term
The right common cardinal vein and right anterior cardinal vein gives rise to what?
Definition
Superior vena cava
Term
What is the first functional organ in vertebrate embryos?
Definition
Heart
Term
When does the heart begin to beat spontaneously?
Definition
4 weeks of development
Term
What is heart morphogenesis?
Definition
The process by which a straight tube morphs into the heart.
Term
What is cardiac looping?
Definition
When the primary heart tube loops to establish left-right polarity.
Term
When does cardiac looping begin?
Definition
Cardiac looping begins in week 4 of gestation
Term
A defect in left-right dynein can lead to what?
Definition
Dextrocardia, as seen in Kartagener syndrome (primary ciliary dyskinesia)
Term
Left-right dynein is involved in what?
Definition
L/R asymmetry
Term
Describe the seven steps of atrial septation
Definition
  1. Septum primum grows toward endocardial cushions, narrowing foramen primum.
  2. Foramen secundum forms in septum primum (foramen primum disappears.
  3. Septum secundum develops as foramen secundum maintains left-to-right shunt.
  4. Septum secundum expands and covers most of the foramen secundum. The residual foramen is the foramen ovale.
  5. Remaining portion of septum primum forms valve of foramen ovale.
  6. Septum secundum and septum primum fuse to form the strial septum.
  7. Foramen ovale usually closes soon after birth because of ↑ LA pressure.
Term
What is the etiology of a patent foramen ovale?
Definition
Failure of septum primum and septum secundum to fuse after birth; most are left untreated.
Term
How might a person with patent foramen ovale acquire a paradoxical emboli?
Definition
Venous thromboemboli may form, travel to right atrium, through patent foramen ovale to left atrium, to left ventricle, and out to systemic circulation (carotids)
Term
Describe the steps in ventricular septation
Definition
  1. Muscular interventricular septum form. Openin is called interventricular foramen.
  2. Aorticopulmonary septum rotates and fuses with muscular ventricular septum to form membranous interventricular septum, closing interventricular foramen.
  3. Growth of endocardial cushions separates atria from ventricles and contributes to both atrial septation and membranous portion of the interventricular septum.
Term
What is the most common congenital cardiac anomaly?
Definition
Ventricular septal defect
Term
In which part of septum do VSDs usually occur?
Definition
Membranous septum
Term
Outflow tract formation
Definition
Neural crest and endocardial cell migrations → truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum ascending aorta and pulmonary trunk
Term
What are conotruncal abnormalities associated with?
Definition

Transposition of the great veins

 

Tretalogy of Fallot

 

Persistent truncus arteriosus

Term
Aortic/pulmonic valves derived from what?
Definition
Endocardial cushions of outlfow tract
Term
Mitral/ tricuspid valves derived from what?
Definition
Fused endocardial cushions of the AV canal
Term
What are the types of valvular anomalies?
Definition

Stenotic

Regurgitant

Atretic (tricuspid atresia)

Displaced (eg, Ebstein anomaly)

Term
Fetal Circulation
Definition
Term
What is the PO2 and O2 saturation of blood in the umbilical vein? What about umbilical arteries?
Definition

PO2 = 30 mm Hg

 

OSat = 80%

 

Umbilical arteries have low O2 sats.

Term
Describe fetal blood flow and the 3 important shunts
Definition
  1. Blood entering the fetus through the umbilical vein is conducted via the ductus venosus into the IVC, bypassing hepatic circulation
  2. Most of the highly oxygenated blood reaching heart via the IVC is directed through the foramen ovale and pumped into aorta to supply the head and body.
  3. Deoxygenated blood from the SVC passes through the RA → RV → Main pulmonary artery → Patent ductus arteriosus → descending aorta; shunt is due to high fetal pulmonary resistance (due partly to low O2 tension)
Term
How does the foramen ovale close at birth?
Definition
At birth, infant takes breath; ↓ resistance in pulomnary vasculature → ↑ left atrial pressure vs. right atrial pressure; foramen ovale closes (now called fossa ovalis)
Term
How does the ductus arteriosus close at birth?
Definition
Increased in O2 (from respiration) and decrease in prostaglandins (from placental separation) leads to closure of ductus arteriosus
Term
What meds help close PDA?
Definition
Indomethacin
Term
What helps keep PDA open?
Definition
Prostaglandins Eand E2 kEEp PDA open.
Term
Fetal-postnatal derivatives
Definition
Term
Allantois --> urachus becomes what?
Definition
Median Umbilical Ligaments
Term
Ductus arteriosus becomes what?
Definition
Ligamentum arteriosum
Term
Ductus Venosus becomes what?
Definition
Ligamentum venosum
Term
Foramen ovale become what?
Definition
Fossa ovalis
Term
Notochord becomes what?
Definition
Nucleus pulposus
Term
Umbilical arteries becomes what?
Definition
Medial umbilical ligaments
Term
Umbilical vein becomes what?
Definition
Ligamentum teres hepatis (contained in falciform ligament)
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