Embryology and Congenital Heart Defects Flashcards Preview

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Flashcards in Embryology and Congenital Heart Defects Deck (158):
1

Layers in a blastocyst

Outer cell is tophoblast Inner cell is Embryoblast Central cavity is called blastocyst

2

Embyoblast layers

External: epiblast which gives rise of embryonic disc Internal: hypoblast

3

Blastocyst stage

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

4

Gastrula Stage

formation of the three layers 1) endo 2) mesoderm - which contains the precardial cells that migrate anteriorly and laterally (cranially) 3) ectoderm

5

what happens on day 16 gestation

precardiac cells are most cranial and surround neural plate in the cardiogenic area.

6

where are cardiac cells dervied

mesoderm

7

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

8

Day 21 and 22

cardiac cells fuse due to cephalic and lateral folding to form the primitive heart tube. and heart begins to beat

9

when do the heart tubes begin to form? when do they fuse?

day 19 - form and fuse by day 22

10

when does the heart start to beat?

day 22

11

what cells give rise to the endocardium

endothelial layer of heart tub

12

what cells give rise to the myocardium

outer tube mesoderm

13

what cells give rise to the epicardium

outer tube mesoderm

14

where is the cardiac jelly

in between endocardium and myocardium to facilitate in looping and separation

15

General order form head to tail of the cardiac loop

Dorsal Aorta - Truncus - Conus - Bulbus Cordis - Primitive Ventricle - antrioventricular sulcus - primitive atria - sinus venosus

16

what does the truncus form?

aortic sac and aorta, Pulmonic trunk, Aortic and pulmonic valves

17

what does the conus from?

infundibula of ventricles

18

what does the bulbus cordis form?

Trabeculated RV

19

what does the primitive ventricle form?

Traveculated LV

20

What does the atrioventricular sulcus form?

IV septum

21

what forms the aorta and pulmonary a.?

Truncus

22

what forms the trabeculated RV

Bulbus cordis

23

what forms the trabeculated LV

Primitive ventricle

24

Looping stage days

Day 23-25

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Looping stage

day 23-25 loops right. Cranial to caudal and posterior to anterior.

26

Blood flow at day 25

Entry itno sinus venosus via three veins. 1) Umbillical 2) vitelline 3) cardinal

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Umbillical Vein

From the placenta

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Vitelline vein

from the yolk sac

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Cardinal Vein

From the embryo

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What happens to the umbillical vein?

Right disappears, Left forms ductus venosus

31

what happens to the vitelline vein?

R form the superior mesenteric artery distal and proximal suprahepatic a. and IVC L forms hepatic sinusoids

32

what happens to the cardinal veins?

R fors SVC, brachiocephalic V and innominate L forms ligament of marshall

33

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

34

Cushions in the conus

Dextrodorsal conal crest Sinistroventral conal crest

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Cushions in the truncus

Dextrosuperior CC Sinistroinferior Right and Left intercalated swellings

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Sinistroventral conal crest is contiuous with..

the sinstrosuperior conal crest of the truncus

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dextrosuperior conal crest is continuous with..

the dextrodorsal conal crest of the conus

38

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.

39

Right intercalated swelling forms part what valve?

aortic cusp

40

Left intercalated swelling forms part of what valve?

pulmonic cusp (anterior)

41

when do the great arteries form?

35-56 day

42

what doe the aortic arches give rise to?

vascullature of head, neck and upper thorax

43

First aortic arch

gives rise to maxillary and external carotid a. First to disappear

44

Second aortic arch

proximal disappears and distal gives rise to stapedial a.

45

3rd aortic arch

carotid a.

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4th aortic arch

Right gives rise to Right brachiocephalic and rt. subclavian. Left gives rise to transverse aortic arch

47

5th aortic arch

disappears

48

6th aortic arch

Proximal Right: Proximal Pulm a. Proximal Left: pulmonary a. Distal L: ductus arteriosus

49

what arch gives rise to the external carotid a.

1st

50

what arch gives rise to the maxillary a.

1st

51

what arch gives rise to the cartod a.

3rd (1st external carotid)

52

what arch gives rise to the right brachiocephalic a.?

4th fight aortic arch

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what arch gives rise to the Rt subclavian a?

4th right aortic arch

54

what arch gives rise to the transverse aortic arch?

left 4th aortic arch

55

what gives rise to the proximal pulmonic artery?

Proximal Right and left 6th aortic arch

56

what gives rise to the ductus arteriosis?

distal L 6th aortic arch

57

Ductus venosus

connects placenta with hepatic artery at IV before going into RA. Mixes oxygenated blood from placenta with deoxygenated blood from fetal circulation

58

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.

59

Ductus arteriosus

shunt from Right pulmonary A to the aorta.

60

what percent of Ventricular blood goes through the ductus arteriosus?

55-60%; only 6-8% goes through the lungs

61

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

62

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

63

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.

64

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

65

why does the ductus stay open?

prostaglandin due to metabolism of arachidnoic acid (PGE2) from local or placental source.

66

when does the septum form?

days 28-42

67

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.

68

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.

69

Right endocardial cushion forms

Tricuspid valve and ventricular spteum

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Left endocardial cushion forms

mitral valve and ventricular septum

71

Membranous part of IV spteum

Right under aortic valve. thinner area forms the inferior endothelial cushion

72

Superior Endocardial cushion

Left surface of the outlet protion of the intraventricular septum Part of MV

73

Inferior endocardial cushion froms..

Inlet protion of IV septum membranous part of septum Part of Tricuspid and mitral valve

74

Right endocardial cushion forms

part of tricuspid valve

75

Left endothelial cushion forms

posterior leaflet of mitral valve.

76

what cushions form the mitral valve?

Superior, inferior and left endocardial cushions

77

what cushions form the tricuspid valve?

Right and Inferior endocardial cushions

78

Epidemiology of Congenital heart Defects

5-8/1000 Boys over girls Equal for races and parental ages

79

Risk factors of congenital heart defects

Maternal diabetes (X3), Family Hx with first degree relative. Recommended with fetal echo - focus on structural abnormalities

80

Most common congenital heart defects

VSD> PDA > TOF >ADS> Coarch

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Percentage for VSD

15.6%

82

PDA percent

5%

83

TOF percent

2.6

84

ASD percent

2.4

85

Coarch percent

1.4

86

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.

87

Risk factors of PDA

maternal rubella, premature, high elevation at birth

88

Magnitude of PDA shunt is based on..

size, resistance and pressure in aorta and pulmonary A.

89

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.

90

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,

91

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

92

CXR for PDE

normal if asymptomatic Pulmonary edema with dilated LA and LV for severe symptomatic

93

Treatment of symptomatic PDA in infants

NSAIDS (IV indomethacin or IV ibuprofen) if fail, surgery

94

Treatment of symptomatic vs. asymptomatic child with PDA

Sym: percutaneous occlusion in the Cath lab Asymptomatic with murmur: percutaneous occlusion.

95

what is the biggest risk of PDA?

pulmonary hypertension and subacute bacterial endocarditis if untreated

96

Types of ASD

Ostium Secundum and Steum Secundum

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Ostium secundum

most common type of ASD - too large a central hole to becovered

98

Spteum secundum

second type of ASD: due to inadequte development to cover regular size ostium secundum

99

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.

100

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

101

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

102

Systolic ejection murmur in ASD is due to

excess flow across Pulmonary valve

103

Diastolic murmur in ASD is due to

excess flow across tricuspid valve

104

ASD Murmur

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

105

CXR on ASD

Variable size heart, pulmonary artery elargement, pulmonary vascular markings

106

Treatment of ASD

in infants: diuretics Adults or children or symptomatic infants: fix the hole!

107

VSD cuases

75% due to preimembranous portion 10% due to muscular Some due to infundibular

108

magnitude of VSD

size and systemic and pulmonic vascular resistance

109

Pathophysiology of VSD

left to right shunt, increased lung flow, increased LA flow, increased EDV, increased muscle length, increased contraction, increased LV output.

110

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

111

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.

112

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

113

Is a quiet VSD murmur good?

not necessary - could mean equalization of LV and RV pressures OR increased Pulmonary Vascular Resistance.

114

Is a loud VSD murmur bad?

not necessarily - could bean closure or increase in pressure change.

115

CXR in VSD

RV and LV hypertrophy, pulmonary edema, enlarged pulmonary a.

116

which murmur, ASD or VSD, is due to blood flow in shunt?

VSD only

117

long term remodeling in VSD

RV and LV hypertrophy - no dilation because blood goes directly into pulmonary a.

118

Treatment of VSD

Diuretics for HF or pulmonary edema Surgery if persistent symptoms despite treatment, poor growth, or secondary complications.

119

Eisenmenger's

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.

120

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.

121

Embryology of TOF

conal crest abnormality to displace infundibular septum anteriorly, rightward, and superiorly

122

Magnitude of TOF

source of pulmonary BF, severity of pulmonary stenosis, balance of RV and LV pressures

123

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)

124

Tet spells

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,

125

why does squatting help in TOF

increases systemic vascular resistance to decreases the Right to left shunt.

126

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

127

Diagnosis of TOF

RV domination of precordial impulse Systolic Pulmonic stenosis murmur RVHypertrophy

128

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

129

If untreated TOF

cyanosis, clubbing, poor enamel and teeth, increased bleeding, limited exercise tolerance, arrhythmias, cerebral abcesses

130

Cerebral Abcesses

complication of TOF and other cyanotic cogential defects. Occurs after 1.5-2 years. Causes unexplained fevers and behavior changes

131

What conditions is coarctation of the aorta associated with?

bicuspid AV and Turners

132

Embryology of CoArch

extension of ductal tissue to aortic arch Subclavian a. distruvance decreased blood flow through isthmus as fetus Intraluminal projection

133

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

134

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

135

CXR of coarch

signs of cardia failure Rib notching from dialted intercostal a. aortic knob post stenotic dilation

136

Untreated Coarch

HF>aortic rupture or dissection>infective endocarditis > cerebral hemorrhage

137

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

138

Pressure and O2 sat for ASD

increased O2 sat in RA vs IVC/SVC

139

Pressure and O2 sat for VSD

increased O2 sat in RV compared to RA

140

Pressure O2 sat for TOF

decreased O2 sat between LA and LV. Increase pressure in RV compared to low PA pressure

141

Primary vs secondary congenital heart defect

primary - genetic secondary - extrinsic or environmental

142

Left to right shunts

ASD, VSD, AVSD

143

Most common left to right shunts

VSD

144

Down syndrome defects

ASD, VSD, AVSD, AV valve malformations

145

Rubella leads to

PDA in child

146

Turner causes...

CoArch, Bicuspid AV, hypoplastic LH

147

Digeorge (del 22) causes.

TOF, truncus arteriosus, aortic arch deficit

148

where is infundibular VSD?

below pulmonary valve

149

What is transpositon of Great vessels assoicated with?

VSD, PFO, PDA

150

infantile Coarch

hypoposia of aortic arch

151

Adult CoArch

infodling of ligamentum arteriosum

152

AV stenosis - congenital

Sub, valvular, and supra which are all due to mineralization and fibrosis.

153

Valvular AV stenosis

atretic or severe, associated with hypoplastic LH syndrome

154

PV stenosis congenital

isoalted or with TOF

155

Moderate congeital Aortic Stenosis

25-49 mmHg decrease intense exercise

156

Intermediate congenital Aortic stenosis

50-79 mmHg Depends on doctor

157

Severe congenital aortic stenosis

>80 mmHg balloon, or valve replacement

158

Hypolastic Left heart

underdevelopment of Aorta, AV, LV, LA, MV to cuase blood flow to go out PDA and leads to cyanosis