Embryo-Cardiac Abnormalities and Great Vessels

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  1. Statistic on cardiac abnormalities
    • 5:1000 to 8:1000 births
    • 1/3 severe
    • high frequency
    • due to septation events
    • occurs during the 2nd to 8th week of development
    • usually multifactorial
  2. Classification of cardiac abnormalities
    • Acyanotic-no shunt or left to right shunt
    • high pressure and oxygenated blood to low pressure and deoxygenated blood
    • Cyanotic-right to left shuntturn blue due to diluting oxygen quality from low pressure and deoxygenated blood mixing with high pressure and oxygenated blood
    • No shunt (acyanotic)-abnormalities of aortic arches (due to remodeling) or coarctation of aorta (narrowing of aorta; near ductus artereosus-small connection between aorta and pulmonary trunk)
  3. Persistent ductus arteriosus (PDA)
    • Acyanotic: Left to right shunt
    • high pressure blood in aorta goes into pulmonary trunk (prevent overload)
    • can destroy capillary beds in lungs
    • pressure-pulmonary hypertension
    • usually closes within 96 hours-ligamentum arteriosum (normal adult)
  4. Interatrial septal defects
    • mesoderm
    • Acyanotic: left to right shunt
    • F1, persistence of foramen primum (mesoderm)-remains open
    • F2, defect foramen secundum and septum secundum relationship
    • Probe Patency of foramen ovale, misalignment of foramen ovale and foramen secundum-causes a little amount of blood to go back (left to right)-small murmur
  5. Interventricular septal defects
    • N.C.
    • Acyanotic: left to right shunt
    • Perimembranous defects
    • muscle part forms fine
    • pulmonary hypertension-soem blood goes to pulmonary trunk
  6. "Corrected" transposition of the great vessels
    • RARE
    • Acyanotic: left to right shunt
    • Rt. atrium-Lf. ventricle; L.f. atrium-Rt. ventricle
    • Rt. ventricle-aorta
    • Lf. Ventricle-pulmonary trunk
    • Interventricular septal defect
    • Reversed rotation of heart-dextrocardia-causes pulmonary hypertension
    • Improper septation of outflow tract (N.C.)-no spiral
  7. Complete transposition of great vessels
    • Cyanotic: right to left shunt
    • Septal defects (N.C.)-allows them to live-with intraventricular septum (membranous part) would create a closed septum and wouldn't get oxygen since the blood would never go to the lung
    • Persistent ductus arteriosus
    • No spiral during septation (N.C.)
    • Great vessesl from "wrong ventricles"
  8. Truncus arteriosus communis
    • mesoderm
    • Cyanotic: right to left shunt
    • single great vessel-N.C.-no septation
    • interventricular septal defect (N.C.)
    • mixing of blood-not enough oxygen
  9. Tetralogy of Fallot
    • cyanotic: right to left shunt
    • pulmonary stenosis-tiny pulmonary trunk (N.C.)
    • over-riding oarta (N.C.)
    • interventricular septal defect (N.C.)
    • right ventricular hypertropy-after a few months after working hard to get blood to pulmonary trunk
    • root cause: septation of outflow tract (N.C.)
    • very serious, and very common
  10. Artery development
    • Vasculogenesis: emergence of bloood vessels de novo in the early embryo (mesoderm)-lateral plate
    • Angiogenesis: development of blood vessels from pre-existing vessels
    • end of 3rd week: vasculogenesis begins
    • -isolated accumulations unite to form plexuses (in yolk sac or outflow tract)
    • -channels form within plexuses
    • -channels enlarge and unite to form arteries and veins
  11. Fourth week-arteries
    • First aortic arch formed
    • Paired dorsal aorta
    • Fused dorsal aorta
    • -ventral segmental arteries: splanchnic layer of lateral plate mesoderm and endoderm (G.I. tract): celiac a., superior mesentaric a. (SMA), inferior mesentaric a. (IMA)
    • -lateral segmental arteries: intermediate mesoderm derivatives: renal a. and gonadal a.
    • -dorsal segmental arteries: supply derivatives of somites-vertebral a.; somites-depimere (back muscles) and hypomere (all others)
    • Days 26-32: formation of rudiments of remaining aortic arches (2-6)
    • Days 32-37: completion of aortic arches
    • *remodeling and most oxygen rich blood shunted to head/brain
  12. 1st arch
    • External carotid
    • Maxillary
  13. 2nd arch
    • Stems of stapedial arteries
    • External carotid
  14. Aortic sac
    • Common carotid (proximal 3rd arch)
    • Pulmonary trunk
    • Base of arch of aorta
  15. 3rd arch
    • Common carotid
    • Internal carotid
  16. 4th arch
    • left: medial portion of arch of aorta
    • Right: proximal Rt. subclavian, distal Rt. subclavian, Rt. dorsal aorta
  17. 6th arch
    • Pulmonary arteries
    • -left distal ductus arteriosus-P.T. to aorta
    • -right distal degenerates
  18. Veins
    • meso-lateral plate
    • remodeling of the inflow to the heart: weeks 4-8
    • -cardinals (anterior, posterior, and common)-O2 blood back to heart from head and body
    • -vitelline-from yolk stalk and yolk sac-back to sinus venosus: RBC and liver
    • -umbilical-oxygenated blood from placenta-highest pressure
    • -sinus venosus-inflow tract
  19. Fate of Vitelline Vein
    • Proximal to heart
    • -left vein degenerates
    • -right vein persists
    • Within Liver
    • -right forms hepatic vein (part of inferior vena cava)
    • -right and left form portal vein (from gut)
  20. Fate of umbilical vein
    • Rt. degenerates entirely
    • Lf. perists
    • -proximal degerates
    • -within liver forms ductus venosus (bypass system to bypass liver in infants)
    • -distal persists in embryo providing placental return
  21. Fate of Cardinal veins
    • Anterior--drainage from crainial territory
    • -Rt. forms internal jugular and superior vena cava
    • -Lf. forms Lf. brachiocephalic
    • Posterior--drainage from body wall
    • -Posterior system degenerates except for root of azygos and common iliac
    • -Replaced by subcardinal and supracardinal veins
  22. Inferior Vena Cava
    • hepatic segment: Rt. vitelline/hepatic veins and sinuses
    • Prerenal: Rt. subcardinal
    • Renal: Subcardinal-supracaradinal anastomosis
    • Postrenal: Rt. supracardinal
  23. Malformations of Inferior Vena Cava
    • Persistent left sacrocardinal vein-going into renal
    • double superior vena cava
  24. 4 changes from fetal circulation to neonatal circulation
    • 1. Left umbilical remnant of liver
    • 2. ductus venosum-ligament venosum
    • 3. foramen ovale-fossa ovale
    • 4. ductus arteriosum-ligament arteniosum
Card Set:
Embryo-Cardiac Abnormalities and Great Vessels
2011-10-30 01:19:40

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