Lec 24 Congenital Heart Disease Flashcards
What is most common congenital defect?
bicuspid aortic valve
What are the 3 major cardiac segments and their 2 interconnecting segments?
3 cardiac segments: atria, ventricles, great arteries
interconnecting:
AV canal connects aria and ventricles
conus truncus connects ventricles and great arteries
When does formation of CV system begin?
week 3 of development
When can heart beat spontaneously?
step1
by wk 4 of development
What are the 4 chambers of the primitive heart tube in order?
step1
- truncus arteriosus
- bulbus cordis
- primitive ventricle
- primitive atrium
- sinus venosus
WHat does the truncus arteriosis give rise to?
step1
ascending aorta and pulmonary trunk [including A/P valves]
What does the bulbis cordis give rise to?
step1
smooth parts of left and right ventricles = the outlfow tracts
gives rise to infundibulum/conus = muscle under pulm valve
in class he said RV, above answer from text book/first aid
What does the primitive ventricle give rise to?
step1
trabeculated parts of left and right ventricles
in class he said left ventricle. above answer is from text book/ first aid
What does the primitive atria give rise to?
step1
trabeculated part of left and right atria
in class he said appendages of mature heart
What does the primitive pulmonary vein give rise to?
step1
smooth part of left atrium
What does the primitive sinus venosus give rise to?
step1
left horn –> coronary sinus
right horn –> smooth part of right atrium
What do the right common cardinal and right anterior cardinal veins give rise to?
step1
SVC
What happens in normal cardiac looping?
step1
establishes L-R polarity
normal = loops to the right [D looping] so atrium and sinus venosus above/behind truncus arteriosus, bulbus cordis, and ventricle
bulbus cordis to right of atrium
What is shape of R and L atrium appendages?
R atrium appendage = big broad triangular base
L atrium appendage = smaller finger-like = crenellated
What does the AV canal become?
tricuspid and mitral valves
What is process of atrial septation?
step1
- septum primum grows down from roof of atrium creating ostium primum = space between leading edge of septum and endocardial cushions of AV canal
- holes form in center of septurm primum and coalesce to form ostium secundum
- septum primum fuses with endocardial cushions of AV thus closing ostium primum
- septum secundum develops to the right of septum primum and grows down from roof and covers ostium secundum.
- septum secundum eventually fuses partially with endocardial cushions, leaves oval-shaped opening = foramen ovale
- superior edge of septum primum regresses gradually, leaves lower edge of septum primum as flap-like valve that allows only R to L flow through foramen ovale
- during gestation: blood shunts R to L b/c pressure in fetal RA higher; postnatally pressure gradient changes; valve closes soon after birth
What is process of ventricular septation?
step1
- muscular ridge begins to grow from bottom of ventricle and forms primitive ventricular septum. opening = interventricular foramen
- bulbar ridges form in bulbus cordis and truncus arteriosus; ridges fuse in midline and spiral 180 to form aorticopulmonary septum that divides bulbus cordis and truncus arteriosus into pulm artery and aorta
- aorticulpomonary septum fuses with muscular ventricular septum to form membranous interventricular septum thus closing the interventricular foramen
- growth of endocardial cushions separates atria from ventricles and contributes to both atrial septation and membranous portion of IV septum
What is process of outflow tract formation?
step1
truncus arteriosus rotates
neural crest derived mesenchymal and endocardial cell migration and proliferation in bulbus cordis and truncus arteriorus to form bulbar ridges
bulbar ridges spiral 180 and fuse to form aorticopulmonary septum
aorticopulmonary septum divides bulbus cordis and truncus arteriosus into pulmonary and aortic
What is patent foramen ovale?
step1
caused by failure of septum primum and septum secundum to fuse after birth; usually left untreated
What is process of aortic/pulm valve development?
step1
form from endocardial cushions of outflow tract = outgrowths of subendocardial mesenchymal tissue that eventually form the 3 cusps
occur just as aorticopulmonary septum is being completed
What is process of mitral/tricuspid valve development?
step1
derived from fused endocardial cushions of AV canal
What is path of fetal circulation?
step1
- oxygenated blood enters fetus through umbilical vein
- about 1/2 of blood in umbilical vein –> bypasses hepatic circulation directly into IVC via ductus venosus
- other 1/2 goes through hepatic circulation and then IVC
- thus IVC is mix of well-oxygenated + less oxygenated
- blood goes to heart
- most IVC blood reaches RA –> foramen ovale –> LA and pumped out aorta to head and body
- most SVC deoxygenated blood enters RA from SVC and goes through RV –> pulmonary trunk
- -> most then through ductus arteriosus –> descending aorta
some –> pulm –> lungs –> back through left heart circuit
Is blood in SVC or IVC more oxygenated in fetal circ?
step1
IVC = more oxygenated
What happens to IVC blood vs SVC blood in fetal circulation?
step1
IVC –> mostly goes from RA through foramen ovale to LA and pumped to head/body via aorta
SVC –> mostly RA –> RV –> pulmonary artery then mostly goes –> ductus arteriosus –> descending aorta –> lower body –> umbilical arteries –> placenta for gas exchange
the rest of the IVC/SVC blood that does not follow these paths goes the normal adult path through heart and pulmonary circulation; but this is just a small percent of the blood b/c of high resistance in pulm vessels
foramen ovale opening overrides opening of IVC into right atrium so preferentially IVC blood is shunted vs SVC blood is not really
Does RV or LV provide most of total CO of fetal circulation?
RV provides 2/3 of fetal CO
What drug can you give to close PDA [patent ductus arteriosus]?
step1
indomethacin
What drug can you give to keep patent ductus arteriosus open?
step1
prostaglandins E1/E2
What does umbilical vein become postnatally?
step1
ligamentum teres hepatis = contained in falciform ligamen
What does ductus arteriosus become postnatally?
step1
ligamentum arteriosum
What does ductus venosus become postnatally?
step1
ligamentum venosum
What does foramen ovale become postnatally?
step1
fossa ovalis
What do umbilical arteries become postnatally?
step1
medial umbilical ligaments
What morphological features characterize the right atrium?
- broad triangular shaped appendage
- usually receives connection of hepatic IVC
- coronary sinus opens into morphologically right atrium
- more trabeculae than LA
What morphological features characterize the left atrium?
- smaller finger-like [crenellated] appendage
- septum wall contains flap valve of foramen ovale [derived from septum primum]
How can you distinguish pulmonary valve from aortic valve morphologically?
you can’t! they have identical morphology you can only judge based on connectivity
What morphological features characterized the tricuspid valve?
by definition = the valve that serves the morphologically right ventricle regardless of its leaflet morphology
- typically trileaflet; broad direct attachments of septal leaflet to septum by multiple fine chordae
“septophilic”
What morphological features characterized the mitral valve?
by definition = the valve that serves the morphologically left ventricle regardless of its leaflet morphology
- typically two leaflets = anterior and posterior are connected by chordae to two free wall papillary muscles
- not connected to septum
“septophobic”
What morphological features characterized the left ventricle?
- bullet shape
- smooth septal wall = smooth near top
- AV valve [mitral] has no connections to septum = free wall valve
- near free edge have fine trabeculation
What morphological features characterized the right ventricle?
- pyramidal shape
- more trabeculae than in LV
- AV valve [tricuspid] is heavily attached on septal surface
- moderator band cross from septum to RV wall