Layers in a blastocyst
Outer cell is tophoblast Inner cell is Embryoblast Central cavity is called blastocyst
External: epiblast which gives rise of embryonic disc Internal: hypoblast
precordial cells are in epiblast portion of embryonic disc on either side of the primitive stread. They migrate downward to give rise of intraembryonic mesoderm
formation of the three layers 1) endo 2) mesoderm - which contains the precardial cells that migrate anteriorly and laterally (cranially) 3) ectoderm
what happens on day 16 gestation
precardiac cells are most cranial and surround neural plate in the cardiogenic area.
where are cardiac cells dervied
Day 19 in gestation
cardiogenic cells migrate ventrally to forebrain and foregut. Formation of two endothelial lined heart tubes begins and the splancnic mesoderm surrounds the heart cells
Day 21 and 22
cardiac cells fuse due to cephalic and lateral folding to form the primitive heart tube. and heart begins to beat
when do the heart tubes begin to form? when do they fuse?
day 19 - form and fuse by day 22
when does the heart start to beat?
what cells give rise to the endocardium
endothelial layer of heart tub
what cells give rise to the myocardium
outer tube mesoderm
what cells give rise to the epicardium
outer tube mesoderm
where is the cardiac jelly
in between endocardium and myocardium to facilitate in looping and separation
General order form head to tail of the cardiac loop
Dorsal Aorta - Truncus - Conus - Bulbus Cordis - Primitive Ventricle - antrioventricular sulcus - primitive atria - sinus venosus
what does the truncus form?
aortic sac and aorta, Pulmonic trunk, Aortic and pulmonic valves
what does the conus from?
infundibula of ventricles
what does the bulbus cordis form?
what does the primitive ventricle form?
What does the atrioventricular sulcus form?
what forms the aorta and pulmonary a.?
what forms the trabeculated RV
what forms the trabeculated LV
Looping stage days
day 23-25 loops right. Cranial to caudal and posterior to anterior.
Blood flow at day 25
Entry itno sinus venosus via three veins. 1) Umbillical 2) vitelline 3) cardinal
From the placenta
from the yolk sac
From the embryo
What happens to the umbillical vein?
Right disappears, Left forms ductus venosus
what happens to the vitelline vein?
R form the superior mesenteric artery distal and proximal suprahepatic a. and IVC L forms hepatic sinusoids
what happens to the cardinal veins?
R fors SVC, brachiocephalic V and innominate L forms ligament of marshall
how do the pulmonary veins form?
splanchnic plexus forms the pulmonary venous plexus --> pulmonary veins. An endothelial projection form LA connects to pulmonary venous venous plexus to form a common pulmonary vein that branches into R and L
Cushions in the conus
Dextrodorsal conal crest Sinistroventral conal crest
Cushions in the truncus
Dextrosuperior CC Sinistroinferior Right and Left intercalated swellings
Sinistroventral conal crest is contiuous with..
the sinstrosuperior conal crest of the truncus
dextrosuperior conal crest is continuous with..
the dextrodorsal conal crest of the conus
which is unique about the great artery formation?
it happens in a rotation. So pulmonary outlet in to the right and anterior of the aortic.
Right intercalated swelling forms part what valve?
Left intercalated swelling forms part of what valve?
pulmonic cusp (anterior)
when do the great arteries form?
what doe the aortic arches give rise to?
vascullature of head, neck and upper thorax
First aortic arch
gives rise to maxillary and external carotid a. First to disappear
Second aortic arch
proximal disappears and distal gives rise to stapedial a.
3rd aortic arch
4th aortic arch
Right gives rise to Right brachiocephalic and rt. subclavian. Left gives rise to transverse aortic arch
5th aortic arch
6th aortic arch
Proximal Right: Proximal Pulm a. Proximal Left: pulmonary a. Distal L: ductus arteriosus
what arch gives rise to the external carotid a.
what arch gives rise to the maxillary a.
what arch gives rise to the cartod a.
3rd (1st external carotid)
what arch gives rise to the right brachiocephalic a.?
4th fight aortic arch
what arch gives rise to the Rt subclavian a?
4th right aortic arch
what arch gives rise to the transverse aortic arch?
left 4th aortic arch
what gives rise to the proximal pulmonic artery?
Proximal Right and left 6th aortic arch
what gives rise to the ductus arteriosis?
distal L 6th aortic arch
connects placenta with hepatic artery at IV before going into RA. Mixes oxygenated blood from placenta with deoxygenated blood from fetal circulation
what portion of blood pumped into the RA gets pumped out RV?
2/3 - gets pumped through the pulmonary valve (not all into the lungs though). 1/3 goes through foramen ovale into the LA.
shunt from Right pulmonary A to the aorta.
what percent of Ventricular blood goes through the ductus arteriosus?
55-60%; only 6-8% goes through the lungs
Risk factors for patent ductus arteriosus?
Premature if less than 29 weeks or under 1000 grams has higher than 70% incidence. High elevation. Maternal rubella infection
Usual closure of ductus arteriosus
occurs 10-15 hours with functional closure, then anatomic closure 2-3 weeks old. >98% are closed completely at 1 year
Functional closure vs. Anatomic closure of ductus arteriosus.
Functional: contraction and cellular migration to lumen of medial smooth muscle. Anatomical: vascular remodeling. Proliferation of elastic membrane of ductus imtima and media to form mucoid lakes that form a **hyaline mass to occlude y lumen.
why does the ductus close?
ductus has fewer elastic fibers than aortic or pulmonic arteries. Increase in pulmonary artery oxygen pressure causes contraction of spiral muscle fibers
why does the ductus stay open?
prostaglandin due to metabolism of arachidnoic acid (PGE2) from local or placental source.
when does the septum form?
atrial septum formation
septum primium begins to grow towards the valve and closes the ostium primum. Ostium secundum is due to apoptosis in the primum. The septum secundum in the RA begins to grown and sovers the ostium secundum to from the foramen ovale which is a one way shunt from Right to left.
Ventricular septum formation
fusion of the septum primus from the atrium with the endothelial cushions and primitive intraventricular septum. Superior and inferior endocardial cushions fuse and leave two aterioventricular canals.
Right endocardial cushion forms
Tricuspid valve and ventricular spteum
Left endocardial cushion forms
mitral valve and ventricular septum
Membranous part of IV spteum
Right under aortic valve. thinner area forms the inferior endothelial cushion
Superior Endocardial cushion
Left surface of the outlet protion of the intraventricular septum Part of MV
Inferior endocardial cushion froms..
Inlet protion of IV septum membranous part of septum Part of Tricuspid and mitral valve
Right endocardial cushion forms
part of tricuspid valve
Left endothelial cushion forms
posterior leaflet of mitral valve.
what cushions form the mitral valve?
Superior, inferior and left endocardial cushions
what cushions form the tricuspid valve?
Right and Inferior endocardial cushions
Epidemiology of Congenital heart Defects
5-8/1000 Boys over girls Equal for races and parental ages
Risk factors of congenital heart defects
Maternal diabetes (X3), Family Hx with first degree relative. Recommended with fetal echo - focus on structural abnormalities
Most common congenital heart defects
VSD> PDA > TOF >ADS> Coarch
Percentage for VSD
Shunt type for PDA
Left to right shunt from Aorta into pulmonary artery. Decreased pressure relative to aorta of pulmonary a cause flow back to lungs.
Risk factors of PDA
maternal rubella, premature, high elevation at birth
Magnitude of PDA shunt is based on..
size, resistance and pressure in aorta and pulmonary A.
What is the long term structural heart changes in PDA
overload of LA and LV due to increase pulmonary blood flow to cause dilation and heart failure.
Clinical Signs of PDA
Small: asymptomatic Large: respiratory problems, pulmonary edema, Left sided CHF, feeding intolerance, renal insufficiency, intraventricular hemorrhage, rarely death. If found in older infant/child: hoarse cry due to largyngeal nerve, hx of pneumonia, failure to thrive, increased WOB, diaphoresis,
Physical Exam with PDA
Wide pulse pressure and bounding pulses (can feel in hands). Hyperactive precrodium increased WOB Continuous murmur on LUSB in both systolic and diastolic
CXR for PDE
normal if asymptomatic Pulmonary edema with dilated LA and LV for severe symptomatic
Treatment of symptomatic PDA in infants
NSAIDS (IV indomethacin or IV ibuprofen) if fail, surgery
Treatment of symptomatic vs. asymptomatic child with PDA
Sym: percutaneous occlusion in the Cath lab Asymptomatic with murmur: percutaneous occlusion.
what is the biggest risk of PDA?
pulmonary hypertension and subacute bacterial endocarditis if untreated
Types of ASD
Ostium Secundum and Steum Secundum
most common type of ASD - too large a central hole to becovered
second type of ASD: due to inadequte development to cover regular size ostium secundum
Magnitude of ASD is determined by
size and resistance of LV and RV. Moves from LA to RA because it is more compliant and lower resistance.
Clinical Presentation of ASD
RARE in infancy because LV is approximately equal to RV pressure due to fluid filled lungs. Long term: pulmonary hypertension, atrial arrhythmia, CHF
PE of ASD
large: increased respiratory rate, sweating, hepatomegaly Murmur that is not due to shunt blood flow. Systolic ejection murmur and disatolic rumble with side split S2
Systolic ejection murmur in ASD is due to
excess flow across Pulmonary valve
Diastolic murmur in ASD is due to
excess flow across tricuspid valve
Systolic Ejection murmur due to excess flow across PV Diastolic rumble due to excess flow across TV Split S2 (accentuated with both exhalation and inhalation) due to increased RV pressure
CXR on ASD
Variable size heart, pulmonary artery elargement, pulmonary vascular markings
Treatment of ASD
in infants: diuretics Adults or children or symptomatic infants: fix the hole!
75% due to preimembranous portion 10% due to muscular Some due to infundibular
magnitude of VSD
size and systemic and pulmonic vascular resistance
Pathophysiology of VSD
left to right shunt, increased lung flow, increased LA flow, increased EDV, increased muscle length, increased contraction, increased LV output.
Clinical Presentation of VSD
asymptomatic until pulmonary pressure decreases significnatly (delayed at elevation). Large VSD: causes respiratory distress, diaphoresis, failure to thrive Small VSD: tachypnea, diaphoresis
PE of VSD large vs. small
large: active precordium, holosystolic murmur, diastolic murmur 2nd heart sound delay small: normal precordial cells, normal S2, early systolic murmur. no diastolic murmur.
Murmur in VSD
Holosystolic murmur represents shunting of blood form LV to RV. Decreases to early systolic in small VSDs. Diastolic murmur represtsns increased flow across MV in large VSD cases. Delayed S2 due to increased RV volume in large VSDs
Is a quiet VSD murmur good?
not necessary - could mean equalization of LV and RV pressures OR increased Pulmonary Vascular Resistance.
Is a loud VSD murmur bad?
not necessarily - could bean closure or increase in pressure change.
CXR in VSD
RV and LV hypertrophy, pulmonary edema, enlarged pulmonary a.
which murmur, ASD or VSD, is due to blood flow in shunt?
long term remodeling in VSD
RV and LV hypertrophy - no dilation because blood goes directly into pulmonary a.
Treatment of VSD
Diuretics for HF or pulmonary edema Surgery if persistent symptoms despite treatment, poor growth, or secondary complications.
when it starts a Left to right shunt, but pulmonary hypertension gets so severe that RV pressure exceeds LV to shunt from Right to left and cuase cynaosis and clubbing.
Tetralogy of Fallot
cyatonic defect with Pulmonary Stenosis, RVH, Aorta overrides VSD to receive blood from LV and RV, and VSD. RV pressure equals LV pressure, but flow in from right to left.
Embryology of TOF
conal crest abnormality to displace infundibular septum anteriorly, rightward, and superiorly
Magnitude of TOF
source of pulmonary BF, severity of pulmonary stenosis, balance of RV and LV pressures
Pink vs blue baby in TOF
Pink: if with mild pulmonic stenosis and patent DA Blue if severe stonisis and no PDA (right to left)
hypoxic and hypercyanotic at 2-6 months that is alleviated by squatting. Infundibular spasm to decreased pulmonary Blood flow Usualy triggered by crying, anemia,, dehydration,
why does squatting help in TOF
increases systemic vascular resistance to decreases the Right to left shunt.
Tx of Tet spells
Knees to chest, phenylephrine to increase systemic vascular resistance and pulmonary blood flow, fluids, morphine. Can be prevented by beta blockers
Diagnosis of TOF
RV domination of precordial impulse Systolic Pulmonic stenosis murmur RVHypertrophy
Treatment of TOF
propanolol to prevent tet spells Surgury at 2-4 months to close VSD and open Pulmonary A. at expense of AV Prostaglandin to keep DA open
If untreated TOF
cyanosis, clubbing, poor enamel and teeth, increased bleeding, limited exercise tolerance, arrhythmias, cerebral abcesses
complication of TOF and other cyanotic cogential defects. Occurs after 1.5-2 years. Causes unexplained fevers and behavior changes
What conditions is coarctation of the aorta associated with?
bicuspid AV and Turners
Embryology of CoArch
extension of ductal tissue to aortic arch Subclavian a. distruvance decreased blood flow through isthmus as fetus Intraluminal projection
Clinical presentaiton of coarch
necrotizing enterocolitis, leg claudication with exercise, decreased kidney flow--> rebound hypertension with ductus patent - asymptomatic at 1-2 weeks: tachypnic, diaphoretic, decreased feeding, shock with HF, Lack of femoral pulses Systmic hypertension in childhood
Physical Exam of CoArch
tachycardia, higher BP in arms than legs, pulmonary rales, hypatomegaly, absent or weak femoral pulses. Murmur: systolic click over bicupsid AV soft systolic murmur S2 with S3 gallop
CXR of coarch
signs of cardia failure Rib notching from dialted intercostal a. aortic knob post stenotic dilation
HF>aortic rupture or dissection>infective endocarditis > cerebral hemorrhage
Pressure and O2 sat for PDA
increase in O2 sat between RV and PA Increased diastolic pressure in PA. Increased systolic Pressure in RV, PA, LA, LV, Aorta
Pressure and O2 sat for ASD
increased O2 sat in RA vs IVC/SVC
Pressure and O2 sat for VSD
increased O2 sat in RV compared to RA
Pressure O2 sat for TOF
decreased O2 sat between LA and LV. Increase pressure in RV compared to low PA pressure
Primary vs secondary congenital heart defect
primary - genetic secondary - extrinsic or environmental
Left to right shunts
ASD, VSD, AVSD
Most common left to right shunts
Down syndrome defects
ASD, VSD, AVSD, AV valve malformations
Rubella leads to
PDA in child
CoArch, Bicuspid AV, hypoplastic LH
Digeorge (del 22) causes.
TOF, truncus arteriosus, aortic arch deficit
where is infundibular VSD?
below pulmonary valve
What is transpositon of Great vessels assoicated with?
VSD, PFO, PDA
hypoposia of aortic arch
infodling of ligamentum arteriosum
AV stenosis - congenital
Sub, valvular, and supra which are all due to mineralization and fibrosis.
Valvular AV stenosis
atretic or severe, associated with hypoplastic LH syndrome
PV stenosis congenital
isoalted or with TOF
Moderate congeital Aortic Stenosis
25-49 mmHg decrease intense exercise
Intermediate congenital Aortic stenosis
50-79 mmHg Depends on doctor
Severe congenital aortic stenosis
>80 mmHg balloon, or valve replacement
Hypolastic Left heart
underdevelopment of Aorta, AV, LV, LA, MV to cuase blood flow to go out PDA and leads to cyanosis