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?
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by wk 4 of development
What are the 4 chambers of the primitive heart tube in order?
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- truncus arteriosus
- bulbus cordis
- primitive ventricle
- primitive atrium
- sinus venosus
WHat does the truncus arteriosis give rise to?
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ascending aorta and pulmonary trunk [including A/P valves]
What does the bulbis cordis give rise to?
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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?
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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?
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trabeculated part of left and right atria
in class he said appendages of mature heart
What does the primitive pulmonary vein give rise to?
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smooth part of left atrium
What does the primitive sinus venosus give rise to?
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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?
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SVC
What happens in normal cardiac looping?
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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?
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- 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?
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- 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?
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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?
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caused by failure of septum primum and septum secundum to fuse after birth; usually left untreated
What is process of aortic/pulm valve development?
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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?
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derived from fused endocardial cushions of AV canal
What is path of fetal circulation?
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- 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?
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IVC = more oxygenated
What happens to IVC blood vs SVC blood in fetal circulation?
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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]?
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indomethacin
What drug can you give to keep patent ductus arteriosus open?
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prostaglandins E1/E2
What does umbilical vein become postnatally?
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ligamentum teres hepatis = contained in falciform ligamen
What does ductus arteriosus become postnatally?
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ligamentum arteriosum
What does ductus venosus become postnatally?
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ligamentum venosum
What does foramen ovale become postnatally?
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fossa ovalis
What do umbilical arteries become postnatally?
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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
What are the 3 types of atrial situs?
- situs solitus = RA on right and receives IVC; LA is left as well as attachments of septum primum + flap valve of foramen ovale
[+ stomach/spleen on left, liver on right + R lung 3 lobes + L lung 2 lobes] - situs inversus = RA on left and receives IVC; LA is right as well as attachments of septum primum [+ stomach/spleen on right, liver on left + R lung 2 lobes + L lung 3 lobes]
- situs ambiguus = ambiguous which is RA/LA and weird spatial organization of rest of ab/chest
What causes dextrocardia [situs inversus totalis]?
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defect in left-right dyenin
What are 2 major signs of kartagener syndrome?
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- situs inversus totalis [dextrocardia]
- primary ciliary dyskinesia [immotile cilia]
What are the types of ventricular situs?
D-looped = normal if solitus atria; RV to right of LV
L-looped = inverted = abnormal for solitus atria but normal for situs inversus atria; RV to left of LV
X-looped = single ventricle, can’t figure out ventricular situs or loope
How do you determine which direction [L or D] looping if its confusing based on chirality?
If D-looped –> RV is right-handed
If L-looped –> RV is left handed
technique for handedness: from hand in RV –> place thumb through tricuspid, palm on septal surface, finger out semilunar valve
What are two types of great artery situs?
normally related great arteries = have 4 characteristics of normal relation
malposition of great arteries = abnormally interrelated; 4 types DALP
What are the 4 characteristics of normally related great arteries?
- aorta arises in fibrous continuity with mitral valve [no muscle/conus separates them]
- pulmonary valve separated from tricuscpid valve by subpulmonary muscle [= conus]
- normal alignments of great arteries –> LV aligned with aorta; RV with PA
4.
- if situs solitus –> aortic valve right and posterior of pulm valve
- if situs inversus –> aortic valve left and posterior of pulm valve
What are the four nomenclature types of malpositions of great arteries?
- D = aortic valve right and anterior to pulm
- A = aortic valve directly anterior to pulm
- L = aortic valve left and anterior to pulm
- P = aortic valve posterior to pulm irrespective of L-R positioin
What different letters can you use to describe great arteries situs?
S or I if they are normally related and thus
- S = aortic valve right of pulm valve and
- L = aortic valve left of pulm valve
D or A or L or P if some malposition
- D = aortic valve right and anterior to pulm
- A = aortic valve directly anterior to pulm
- L = aortic valve left and anterior to pulm
- P = aortic valve posterior to pulm irrespective of L-R positioin
What is AV discordance? What are the 2 types?
- right atrium connects abnormally with left ventricle = atrio-ventricular discordance
- solitus atria and L looped ventricles
- inversus atria and d looped ventricles
What is VA-discordance? What are the 4 types?
- LV is aligned with pulm vessels or RA with aorta; includes problems of great arterial malposition = ventriculo-arterial discordance
- transposition of great arteries [TGA] = great arteries switches over septum;
- —- RV –> aorta; LV –> pulm artery
- double outlet right ventricle [DORV] =
- —– RV –> Ao + PA; LV –> VSD to LV
- double outlet LV [DOLV] =
- —- RV –> VSD to LV; LV –> Ao + PA
- anatomically correct malposition [ACM] of great arteries
Do R-to-L or L-to-R shunts cause cyanosis?
R-to-L shunts = blood bypasses the lungs so don’t get enough oxygen
What is a potential long term complication of large L-to-R shunt?
cause pulm artery volume and pressure to increase –> associated with later development of pulmonary arteriolar hypertrophy and elevated plum resistance –> over time the increases plum resistance can cause shunt to reverse and become R to L
== called eisenmenger syndrome
What is transposition of great arteries [TGA]?
great arteries switched over septum;
—– RV –> aorta; LV –> pulm artery
What are two examples of 2 discordances causing physiologically correct circulation
AV + VA discordance –> 2 wrongs make “right”
- — IDD or SLL == SVC/IVC –> RA –> LV –> PA
- -> lungs –> pulm veins –> LA –> RV –> Ao –> body
What does a valve atresia mean?
it means there is no opening = just bar of tissue
What is normal 3 letter code for normal heart?
SDS
S = solitus atria
D = d looped ventricle
S = solitus GA
Where do ASDs normally occur?
normally occur due to inadequate formation of septum secundum = in region of formaen ovale termed an “ostium secundum ASD”
What are the 2 possible types of ASD?
- ostium secundum ASD = in septum secundum
- ostium primum ASD = in inferior part of septum due to septum primum failure
What is a sinus venosus defect?
= unroofind defect w/ absent normal tissue between R pulm vein and R atrium
have similar pathophysiology as true ASD –> results in flow from R pulm veins and LA into RA
What are clinical signs of ASD?
- loud S1
- wide fixed split S2
symptoms range form none to heart failure –> dyspnea, fatigue, palpitations from atrial tachyarrhythmias due to RA enlargement
What is a patent foramen ovale?
not a true ASD = persitence of fetal foramen ovale
different from ASD in that septum unfused in PFO vs septum missing tissue in ASD
What are signs of patent foramen ovale?
usually clinically silent b/c one-way valve functionally closed since LA pressure > > RA P
becomes significant if RA pressure elevated –> pulm HTN or right HF
What is a paradoxical embolism?
thrombus in systemic vein travels to RF and passess across patent foramen ovale to LA and then into systemic arterial circulation
What is pathophysiology in ASD? possible complication?
blood from LA –> RA but not vice versa due to pressure gradients
L to R shunt –> volume overload RA/RV/pulm vasculature –> RV hypertrophy, RA enlargement
can lead to pulm vascular disease, eisenmenger syndrome –> shunt reversal –> cyanosis
What sounds in ASD?
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- loud S1
- wide fixed split S2
- may have systolic murmur at upper left sternal border from increased flow across pulm valve or mid-diastolic at lower-left sternal border from increased flow across tricuspid
What is the most common congenital cardiac defect?
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ventricular septal defect [VSD]
What are symptoms of VSD? what about if its really large?
- aysmptomatic at birth
- may manifest wks later or remain asymptomatic
- most self-resolve
really large –>early CHF, tachypnea, poor feeding, failure to thrive, lower resp tract infections; can cause pulm vascular disease
may lead to eisenmenger –> reverse shunt + cyanosis
What physical finding with VSD?
harsh holosystolic murmur at left sternal border
smaller defect = louder murmur b/c more turbulence of flow
What happens in patent ductus arteriosus? what kind of shunt?
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ductus arteriosus = connects L pulm artery to descending aorta
shunt R to L in fetal period
in neonate: decreased lung resistance –> can cause switch shunt L to R –> RVH and/or LVH and heart failure
What are risk factors for patent ductus arteriosus?
- maternal rubella in 1st trimester
- prematurity
- birth at high altitude
What kind of physical finding in patent ductus arteriosus?
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continuous machine-like murmur
can have lower extremity cyanosis
What effects if eisenmeger syndrome in person with patent ductus arteriosus?
blood flow from pulm artery to descending aorta –> desaturated blood to lower extremities only –> upper extremities not cyanotic; lower extremities are cyanotic
What kind of treatment for PDA?
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give indomethacin “endomethacin ends patency”
= prostaglandin synthesis inhibitor
What should you do to maintain PDA after birth?
give PGE [prostaglandin E”
What usually happens in congenital aortic stenosis?
usually bicuspid aortic valve causing stenosis
What physical exam findings with congenital aortic stenosis?
- harsh crescendo-decrescendo systolic mumur loudest at base and raditating to neck
- often preceded by systolic ejection click
- in severe disease have paradoxical splitting
- mumur present from birth = does not depend on postnatal decline in pulm resistance [unlike ASD, VSD, PDA]
What physical exam findings with congenital pulmonary stenosis?
loud late peaking crescendo-decrescendo systolic ejection murmur at upper left steernal border
may have palpable thrill
wide spliitng S2 with soft P2
What is coarctation of the aorta?]
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narrowing of aortic lumen; commonly associated with bicuspid aortic vale
What is infantile vs adult coarctation of the aorta?
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location of aortic narrowing in relation to ductus arteriosus
infantile = proximal to ductus arteriosus insertion “INfantile = IN close to the heart”
adult = distal to ductus arteriosus insertion “aDult = Distal to Ductus”
What disease is infantile coarctations of the aorta associated with?
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turner syndrome
when does infantile coarctation of the aorta usually present?
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usually presents with closure of ductus arteriosus –> can reverse with PGE
What are compensatory mech of aortic coarctation?
- development LV hypertrophy
- dilation of collateral blood vessels from intercostals to bypass coarctation –> notching of ribs
What are symptoms/signs of coarctation of aorta?
- may have symptoms of HF
- differential cyanosis if PDA
- weakness/pain in lower extremities [claudication]
- weak and delayed femoral pulses
- upper extremity hypertension
- rib notching due to collateral circulation
How does upper extremity BP tell you location of coarctation of aorta?
upper extremities > legs –> coarctations is distal to left subclavian artery
right arm > left arm –> coarctations proximal to left subclavian artery
What are the 5 congenital heart defects that cause early cyanosis?
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R to L shunts
the 5 Ts
1. truncus arteriousus [1 vessel]
- transposition [2 switched vessels]
- tricuspid atresia [3 = tri]
- tetralogy of fallot [4 = tetra]
- TAPVR [5 letters in the name] = total anomalous pulmonary venous return
What causes tetralogy of fallot?
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abnormal anterior/superior displacement of infundibular part of IV septurm
What is the most common cause of early childhood cyanosis?
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tetralogy of fallot
What are the 4 anomalies of tetralogy of fallot?
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PROVe
- pulmonary [infundibular] stenosis
- RVH = boot shaped on CXR; in response to high Ao pressure
- overriding aorta
- VSD
How does degree of pulmonary stenosis determine outcome of etetralogy of fallot?
mild PS with big VSD –> acts like a VSD –> L to R shunt –> lungs –> CHF
moderate PS with big VSD –> more resistance to pulm Q –> protects your lungs = just the right amount is protective
severe pulm stenosis –> forces R to L flow across VSD –> hypoxemia/cyanosis “tet spells”
What aspect of tetralogy of fallot is most important for determining prognosis?
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degree of pulmonary stenosis
more stenosis = more R to L shunt
What movement improves tetralogy of fallot cyanosis?
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squatting –> increase SVR –> decrease R to L shunt –> less cyanosis
What is treatment for tetralogy of fallot?
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early surgical correction
What happens in transposition of great arteries?
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LV –> pulm artery and RV –> aorta
have separate systemic and pulm circulations
not compatible with life unless shunt is present [VSD, PDA, patent foramen oval, etc]
What causes transposition of great arteries?
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failure of aorticopulmonary septum to spiral
What is effect of transposition of great arteries?
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- generalized cyanosis w/in first day of live –> die within first few months unless surgical intervention
What is eisenmenger syndrome?
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uncorrected L to R shunt [from VSD, ASD, PDA,] –> increase pulm blood flow –> remodeling of vasculature –> high pulm vasculatrue resistance –> pulm arteriolar HTN and RVH to compensate –> shunt R to L
causes late cyansosi, clubbing, polycythemia
What is total anomalous pulm venous return [TAPVR]?
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pulm veins drain into right heart circulation [SVC, coronary sinus, etc]
associated wtih ASD and sometimes PDA
What is tricuspid atresia? what other defects needed for viability?
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absence of tricuspid valve and hypoplastic RV
need ASD and VSD for viability
What is persistent truncus arteriosus?
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failure of truncus arteriosus to divide into pulm trunk and aorta
most pts have accompanying VSD
