Congenital Heart Defects Flashcards
1
Q
describe fetal blood flow
A
- RV delivers most of output to placenta for O2 uptake and LV pumps blood to heart, brain and upper body of fetus. Before birth, oxygenation of blood occurs through the placenta and after birth, it occurs through the lungs
- fetus in maintained in a low O2 state (PO2 30-35 mmHg, hemoglobin sat of 60-70%)
- ductus venosus allows majority of blood from umbilical vein to bypass hepatic circulation and pass directly into IVC - to RA where 40% of blood moves through foramen ovale into LA, then passes into LV and ejected into aorta and perfused to head and upper extremities. Venous blood from these areas return back to RA through SVC and into RV and pulm arteries and beccause of high pulm vascular resistance almost 90% of blood ejected into pulm artery gets diverted through ductus arteriosus into descending aorta, blood perfuses lower extremities and is returned to placenta via umbilical arteries
2
Q
epidemiology of congenital birth defects?
A
- 8/1000 live births
- one of leading cause of death in infants
- genetic: microdeletion in long arm of xsome 22, also seen in downs and Turners syndrome
- enviro: maternal diabetes, ETOH, and teratogens
- gender: ASD, VSD, PDA, and pulmonic stenosis more common in girls. Left sided lesions more common in boys
3
Q
Classification of congenital defects?
A
- Acyanotic CHD: pink babies: left to right shunts - cyanotic CHD: blue babies: right to left shunts - obstructive CHD: narrowing structures
4
Q
Types of acyonatic CHD?
A
- left to right cardiac shunts, condition where blood from systemic arterial circulation mixes with systemic venous blood
- ASD
- VSD
- PDA: patent ductus arteriosus
5
Q
Types of cyanotic CHD?
A
- R to L shunt, shunt allows blood to flow from R to L side of heart
- tetralogy of fallot
- transposition of Great arteries
6
Q
Types of obstructive CHD?
A
- obstruction to R side of heart: pulmonic valve stenosis (PVS) - to L side: coarction of aorta congenital aortic stenosis (AS)
7
Q
Shunting of blood in fetus?
A
- shunting of blood occurs b/t R and L atria, through the foramen ovale, and b/t the pulmonary artery and aorta through the ductus arterioles
- the placenta supplies O2 to fetus through umbilical vein to heart, enters IVC then goes in RA
- from RA pushed through foramen ovale into LA
- Blood in LA is from pulm veins and blood from RA – blood enters LV and then LV pumps pumps blood through aortic valve into aort, majority of output goes to head. Rest of output from LV and RV via ductus arteriosus supplies lower body and fetus, after lower body perfused, deoxygenated blood returned to fetus via umbilical arteries
8
Q
What 2 events occur at birth that change fetus circulation?
A
- umbilical cord is clamped and breathing begins
- this reaction causes sudden increase to resistance of systemic circulation, lungs begin to oxygenate the blood increasing PO2, causing a decrease in pulmonary arterioles constriction and decreasing pulm vascular resistance
- pulm resistance falls below systmic circulation which changes the blood flow across the ductus arteriosus to left to right shunt, this results in closure of foramen ovale and ductus arteriosus
9
Q
What are the 3 main types of atrial septal defects?
A
- opening in atrial septum permitting blood b/t 2 atrias
- 3 major types:
ostium secundum (Most common) - seen in about 10% of CHD
sinus venosus (least common)
ostium primum
10
Q
Clinical presentation of ASD?
A
- most often have no CV sxs
- rarely present with CHF
- heart is usually hyperactive with RV heave felt best at lower L sternal border
- S2 is widely split and fixed at pulmonary area
- crescendo-decrescendo systolic ejection murmur
11
Q
Dx of ASD?
A
- initial testing is usually CXR and EKG
- echo is test of choice!!
12
Q
Tx of ASD?
A
- surgical
- percutaneous transcatheter closure: usually done b/t ages 1-3
this may be done earlier in children with CHF
13
Q
What is VSD?
A
- abnormal opening in ventricular septum which allows blood to flow across right and left ventricles. Single most common reason for infants to see cardiologist!
14
Q
4 types of VSD?
A
- membranous defect (most common)
- subpulmonic or outlet defect
- AV or inlet defect
- muscular defect
15
Q
Clinical presentation of VSD? (small - mod)
A
- small to mod shunts usually have no CV sxs
- small shunts have loud, harsh holosystolic murmur
16
Q
Clinical presentation of VSD large shunts?
A
- frequent respiratory infections
- poor wt gain
- dyspnea and fatigue are common
- CHF develops b/t 1-6 months
- pansystolic murmur
17
Q
Dx of VSD?
A
- initial CXR and EKG
- echo confirms dx, location of lesion and size of shunt
18
Q
Tx of VSD?
A
- small to mod shunts in asx pts don’t require surgery or other intervention
- medical management
- transcatheter closure
- mod to large shunts with LV volume overload and or hx of infectious endocarditis need surgical repair (endocarditis - prophylaxis abx for dental procedures later on in life)
- will need high caloric diet, lasix, ACEI
19
Q
What is PDA?
A
- normal fetal vessel that connects pulm artery to aorta
- accounts for 10% of CHDs
- 2x as common in females than males
- commonly asscd with VSD and coarctation of aorta
- in fetal circulation - higher pressure in pulm artery so blood flowed into aorta but now systemic higher pressure so blood going from aorta into pulmonary arteries - lungs working harder = R side working harder
20
Q
Clinical presentation of PDA?
A
- usually asx unless large, LV failure or pulm HTN can develop
- a continuous rough machinery murmur accentuated late in systole at time of S2, heart at left sternal border at first and second interspaces.
- fast breathing, and poor growth
21
Q
Dx of PDA?
A
- CXR (pulm vascular markings)
- EKG
- echo confirms dx
22
Q
Tx of PDA?
A
- in preterm infants: indomethacin (prostaglandin inhibitor) used to clsoe shunt
- cardiac cath with coils or occluder devices
- large shunts require surgical ligation
23
Q
2 types of cyanotic CHDs?
A
tetralogy of fallot
transposition of great arteries
24
Q
What is tetralogy of fallot?
A
- condition of several related congenital defects that occur
- 4 components:
VSD
pulm obstruction (narrowing of pulm valve)
overriding aorta (valve sits above defect) - shifting to the right of aorta, so it overrides the R ventricle and is in communication with septal defect
RVH - this is most common cyanotic CHD
- assoc with cleft palate, hypospadias, skeletal malformations
25
Clinical presentation of TOF?
- cyanotic
- fatigability and dyspnea on exertion
- tet spells: when baby cries or has BM - increase blood flow to periphery and arteries dilate, decreasing resistance in systemic circulation, and allows right to left flow so child turns cyanotic so to decrease sxs have to raise L sided pressure and peripheral vascular resistance this is done by squatting - this raises L pressure of heart.
- harsh systolic ejection murmur
26
Dx of TOF?
CXR: boot legged heart b/c of RVH
- EKF
- echo
- cardiac cath: see how bad defect is
27
Tx of TOF?
- immediate: prostaglandins: keep ductus arteriosus open
- surgical: temp placement of blalock taussig shunt: shunt back to pulm artery (act like PDA)
- total repair
28
What is transposition of the Great Arteries?
- division of truncus arteriosus which aorta comes off R ventricle and pulm artery comes of LV
- 2nd most common cyanotic CHD
- more common in males 3:1
- also known as blue baby syndrome
29
Clinical presentation of TGA?
cyanotic
poor feeders
fatigue
30
Dx of TGA?
- CXR: egg on a string appearance
- EKG: little help
- echo: usually dx
- cardiac cath: rashkind balloon
31
Tx of TGA?
- prostaglandins to keep ductus open
- atrial septostomy: rashkind balloon
- arterial switch operation usually at 4-7 days after birth
32
What are the obstructive CHDs?
- pulmonic valve stenosis
- coarction of aorta
- congenital aortic stenosis
33
What is pulmonic valve stenosis?
obstruction of blood flow from RV to pulmonary artery
- obstruction usually caused by narrowing
- areas of narrowing:
thickened muscle below pulmonary valve, stenosis of valve itself (most common), stenosis of pulmonary artery above the valve
- valve stenosis: valve leaflets are thickened and fuse together
34
Clinical presentation of PVS?
- usually asx
- newborn: cyanotic
- older child usually dx by
rough ejection systolic murmur and ejection click
- could have RV failure: working so hard to get blood through pulmonary valve
35
Dx of PVS?
- echo
| - cardiac cath
36
Tx of PVS?
- mild stenosis rarely needs intervention
- moderate to severe: require tx with balloon valvuloplasty
- surgery reqd for more complex valves
37
What is coarctation of the aorta?
- narrowing of aorta most commonly at juctaductual aorta
- occurs in about 6% of CHD
- 3x as many males as females
- assoc with Turners sydrome
38
clinical presentation of COA?
- usually presents at age 4-10 days
- cardinal finding is decrease or absence of femoral pulses
- can have blowing systolic murmur heard in left axilla and left back that is pathognomonic
- bounding pulses in arms and carotids compared to weak or delayed pulses in legs.
39
Dx of COA?
- CXR: notching of ribs (high pressure in upper body, bounding arteries - notches, around age 5)
- EKG
- echo
40
Tx of COA?
- prostaglandins (want to keep ductus arteriosus open)
- primary balloon aortoplasty
- rurgery to repair defect
41
What is congenital aortic stenosis?
- obstruction of blood outflow b/t LV and aorta
3 types:
valvular aortic stenosis (most common), subvalvular aortic stenosis, supravalvular aortic stenosis
42
Clinical presentation of AVS?
- usually asx until severe
- usually do well until 3-5th decades of life
- mild exercise intolerance and fatigue
- systolic ejection murmur
- maybe an older child will complain about light headedness, fainting, assocd with exertion
43
Dx of AVS?
- CXR and EKG: may show LVH
| - echo: most dx
44
Tx of AVS?
- cardiac cath
- surgical repair or replacement:
ross procedure - take pulm valve and attach to aorta and take pulm valve graph from donor
