Cardiovascular embryology Flashcards
Primitive ATRIUM GIVES RISE TO?
Trabeculated part of left and right atria
Primitive ventricle gives rise to?
Trabeculated part of left and right ventricles
Primitive pulmonary vein gives rise to?
Smooth part of the left atrium
Left horn of sinus venosus gives rise to?
Coronary sinus
Right horn of sinus venosus gives rise to?
Smooth part of the right atrium (sinus venarum)
Right common cardinal vein and right anterior cardinal vein gives rise to?
Superior vena cava
SVC AKA
Superior vena cava
What is the first functional organ in vertebrate embryos?
Heart, it beats spontaneously by week 4 of development
Describe cardiac looping
Primary heart tube loops to establish left-right polarity, begins in week 4 of gestation
Describe Kartagener syndrome
A primary ciliary dyskinesia, Defect in left-right Dynein (involved in L/R asymmetry) can lead to Dextrocardia as seen in Kartagener Syndrome
Describe the septation of the atria
- Septum primum grows toward endocardial cushions, narrowing foramen primum
- Foramen secundum forms in septum primum (foramen primum disappears)
- Septum secundum develops as foramen secundum maintains the R-L shunt
- Septum secundum expands and covers most of the foramen secundum, the residual foramen is the foramen ovale
- Remaining portion of septum primum forms valve of foramen ovale
- Septum secundum and septum primum fuse to form the atrial septum
- Foramen ovale usually closes soon after birth because of increased LA pressure
Diagram pg 274
What causes patent foramen ovale?
Caused by failure of septum primum and septum secundum to fuse after birth
Clinical pearl of patent foramen ovale
Can lead to paradoxical emboli (venous thromboemboli that enter systemic arterial circulation) similar to those resulting from an ASD
Describe septation of the ventricles
- Muscular interventricular septum forms. The opening is called interventricular foramen
- Aorticopulmonary septum rotates and fuses with muscular ventricular septum to form membranous interventricular septum, closing interventricular foramen
- Growth of the endocardial cushions separates atria from ventricles and contributes to both atrial septation and membranous portion of the interventricular septum
- Diagram pg 275
What is the most common congenital cardiac anomaly?
Ventricular septal defect
Describe ventricular septal defect
Most common cardiac anomaly, usually occurs in the membranous septum
Describe outflow tract formation
Neural crest and endocardial cell migrations -> truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum -> ascending aorta and pulmonary trunk
What are the conotruncal abnormalities associated with failure of neural crest cells to migrate?
Transposition of the great vessels
Tetralogy of Fallot
Persistent truncus arteriosus
What is the pathophysiological etiology resulting in Transposition of the great vessels?
conotruncal abnormalities associated with failure of neural crest cells to migrate
What is the pathophysiological etiology resulting in Tetralogy of Fallot?
conotruncal abnormalities associated with failure of neural crest cells to migrate
What is the pathophysiological etiology resulting in Persistent truncus arteriosus?
conotruncal abnormalities associated with failure of neural crest cells to migrate
What is the aortic valve derived from?
Derived from the endocardial cushions of outflow tract
What is the pulmonary valve derived from?
Derived from the endocardial cushions of outflow tract
What is the mitral valve derived from?
Derived from fused endocardial cushions of the AV canal
What is the tricuspid valve derived from?
Derived from fused endocardial cushions of the AV canal
Describe the possible valvular anomalies
May be stenotic, regurgitant, atretic (tricuspid atresia), or displaced (e.g. Ebstein anomaly)
What are the important shunts in the fetal circulation?
Ductus venosus
Foramen Ovale
Ductus arteriosus
Describe O2 saturation in the umbilical arteries and veins
Umbilical vein PO2 = 30 mmHg and 80% saturation, umbilical arteries have low O2 saturation
Describe the importance of the ductus venosus
Blood entering the fetus through the umbilical vein is conducted through the ductus venosus into the IVC
bypassing the portal circulation
Describe the importance of foramen ovale
Most of the highly oxygenated blood reaching the heart via the IVC us directed through the foramen ovale and pumped into the aorta to supply the head and the body
Describe the importance of Ductus arteriosus
Deoxygenated blood from the SVC passes through the RA -> RV -> main pulmonary artery -> ductus arteriosus -> descending aorta; shunt is due to high fetal pulmonary resistance (due partly to low O2 tension)
Describe the changes at birth
At birth, the infant takes a breath -> reduced resistance in pulmonary vasculature -> increased left atrial pressure vs right atrial pressure -> foramen ovale closes (now referred to as the fossa ovalis)
Also, leads to increase in O2 (from respiration) and a decrease in prostaglandins (from placental separation) -> closure of ductus arteriosus
What is the fate of the ductus arteriosus?
Becomes the ligamentum arteriosum (remnant of the ductus arteriosus)
What makes the ductus arteriosus close?
Indomethacin helps close the PDA -> ligamentum arteriosum (remnant of ductus arteriosus)
What drugs make the ductus arteriosus stay open?
Prostaglandins E1, E2 kEEp the PDA open
What is the Urachus?
Urachus is part of the allantoic duct between bladder and umbilicus
Allanotis -> urachus postnatal derivative
Median umbilical ligament
Ductus arteriosus postnatal derivative
Ligamentum arteriosum
Ductus venosum postnatal derivative
Ligamentum venosum
Foramen ovale postnatal derivative
Fossa ovalis
Notochord postnatal derivative
Nucleus pulposus
Umbilical arteries postnatal derivative
Medial umbilical ligaments
Umbilical vein postnatal derivative
Ligamentum teres hepatis (round ligament) (contained in falciform ligamentum)
