• Cardiovascular Embryology
– Describe cardiovascular embryology
– Discuss aspects of cardiovascular
embryology with pathologic consequence
HUMAN EMBRYO: WEEK 3
•
Woodburne RT and Burkel W. Essentials of Human Anatomy. Oxford Press 1994
• Cardiogenic mesoderm forms the primitive
heart tube with endocardium at
approximately 3 weeks
• The myocardium and epicardium develop
from mesoderm surrounding the primitive
heart tube
• Hematopoiesis begins in the yolk sac wall
about the third week of development
• Erythrocytes produced in the yolk sac
have nuclei
• Blood formation does not begin inside the
embryo until fifth week
• Angiogenesis starts at the beginning of the
third week
• Blood vessels first start to develop in the
extraembryonic mesoderm of the yolk sac,
connecting stalk and chorion
• Blood vessels develop in the embryo
about two days later
VENOUS-ARTERIAL CELL TYPE
DIFFERENTIATION
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•
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As in humans, angioblast precursors reside in the mesoderm in
zebrafish
Increased expression of gridlock (grl), an artery-restricted gene,
ablates arteries and leads to development of veins and expression
of venous marker EphB4 receptor (ephb4)
Decreased creased notch signalling also leads to increased grl and
venous development
“notch-grl pathway controls assembly of the first embryonic artery,
apparently by adjudicating an arterial versus venous cell fate
decision”
ZhongTP et al.
Nature. 2001 Nov 8;414(6860):216-20
EMBRYONIC CIRCULATION
• J. Villenue, MD, McGill
http://sprojects.mmi.mcgill.ca/embryology/cvs/
VENOUS EMBRYOLOGY
VENOUS EMBRYOLOGY
• Infrahepatic IVC develops between the 6th
and 8th weeks
• Requires partial regression of three paired
embryonic veins: the posterior cardinal,
the subcardinal and the supracardinal
veins
• A left IVC results from regression of the
right supracardinal vein with persistence of
the left supracardinal vein. The prevalence
is 0.2%–0.5%
•
http://radiographics.rsnajnls.org/cgi/co
ntent/full/20/3/639
• Right anterior cardinal vein:
superior vena cava
• Right common cardinal vein
superior vena cava
• Right posterior cardinal vein
azygous vein
• Right anterior cardinal vein:
left brachiocephalic vein
• Left horn of sinus venosus:
coronary sinus
• Superior vena cava anomalies (including
double superior vena cava and left-sided
superior vena cava).
• Inferior vena cava anomalies (including
transposition or left-sided inferior vena
cava, retroaortic left renal vein,
circumaortic left renal vein, retrocaval
ureter and absent suprarenal inferior vena
cava).
•
radiopaedia.org/.../703/IVC_left_thumb.jpg
VASCULAR MALFORMATIONS
•
Mulliken JB, Glowaki J Hemangiomas and vascular malformations in infants and children: a
classification based on endothelial characteristics. Plast Reconstr Surg 69:412--422, 1982
• Vascular malformations: congenital lesions
with normal endothelial turnover
• Hemangiomas: neoplastic lesions with
endothelial hyperplasia
Vascular Malformations
• Klippel-Trenaunay syndrome is
characterized by a triad of port-wine stain,
varicose veins, and bony and soft tissue
hypertrophy involving an extremity
• Predisposition to thrombophlebitis and
thrombotic events in as many as 25% of
patients
ARTERIAL EMBRYOLOGY
• Six pairs of pharyngeal arches develop
from 6-8 weeks
– 1 and 2nd arches involute
– 3rd: common and internal carotid arteries
– 4th: L aortic arch; R subclavian a
– 5th: no derivatives
– 6th: pulmonary arteries and ductus arteriosus
Diagrams showing transformation of the early aortic arch pattern
(6–8 weeks) into the adult pattern.
Moore KL. The developing human: clinically orientated embryology
WB Saunders Company, 1982.
DOUBLE AORTIC ARCH
• Is a vascular web encircling the trachea
and esophagus
• Occurs due to persistence of part of the 6th
pharyngeal arch
• Band 22q11 deletion is common as are
associated abnormalities including TOF
• Treatment requires thoracotomy and
division of the minor arch
http://www.emedicine.com/ped/topic2541.htm#Multimediamedia1
DOUBLE AORTIC ARCH
DSYPHAGIA LUSORIA: Retroesophageal right subclacvian artery
• Congenital extremity arterial anomalies:
– persistent sciatic artery
– popliteal entrapment syndrome
PERSISTENT SCIATIC ARTERY
• Is an artery that usually regresses during
development of fetal circulation
• Incidence: 0.02%
• Can present as a gluteal mass and is
prone to aneurysmal degeneration and
emboli
• Originates from an internal iliac and travels
posterior to the femoral head
Persistent Sciatic Artery
• Classified as complete: in continuity from
the internal iliac artery to the popliteal
artery) with varying degrees of superficial
femoral artery development
• Incomplete interrupted superiorly at the
internal iliac artery or inferiorly at the
popliteal artery with an intact superficial
femoral artery
•
home.flash.net/~drrad/tf/090197.htm
Popliteal Entrapment Syndrome
• Conclusions:
• Complex and partially understood
mechanisms determine the embryology of
the cardiovascular system
• Additional understanding of these
mechanisms will improve our ability to
treat or avert the clinical consequences of
embryologic derangements in the
cardiovascular system