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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
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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)
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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)
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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
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Interventricular septal defects
- N.C.
- Acyanotic: left to right shunt
- Perimembranous defects
- muscle part forms fine
- pulmonary hypertension-soem blood goes to pulmonary trunk
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"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
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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"
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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
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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
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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
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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
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1st arch
- External carotid
- Maxillary
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2nd arch
- Stems of stapedial arteries
- External carotid
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Aortic sac
- Common carotid (proximal 3rd arch)
- Pulmonary trunk
- Base of arch of aorta
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3rd arch
- Common carotid
- Internal carotid
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4th arch
- left: medial portion of arch of aorta
- Right: proximal Rt. subclavian, distal Rt. subclavian, Rt. dorsal aorta
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6th arch
- Pulmonary arteries
- -left distal ductus arteriosus-P.T. to aorta
- -right distal degenerates
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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
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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)
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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
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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
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Inferior Vena Cava
- hepatic segment: Rt. vitelline/hepatic veins and sinuses
- Prerenal: Rt. subcardinal
- Renal: Subcardinal-supracaradinal anastomosis
- Postrenal: Rt. supracardinal
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Malformations of Inferior Vena Cava
- Persistent left sacrocardinal vein-going into renal
- double superior vena cava
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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
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