Congenital Heart Defects Flashcards
For the fetus the placenta is
the oxygenator so the lungs do no work
RV & LV contribute equally to
the systemic circulation and pump against similar resistance
Ductus venosus allows
oxygenated blood to bypass the liver
Foramen ovale
R→L atrial level shunt; shunt that bypasses the lungs, It moves blood from the right atrium of the heart to the left atrium
Ductus arteriosus
R→L arterial level shunt;
The ductus arteriosus moves blood from the pulmonary artery to the aorta; it allows most of the blood from the right ventricle to bypass the fetus’s fluid-filled non-functioning lungs
In a right to left shunt, blood __________
(that hasn’t traveled to lungs yet) is shunting across to the left side of the heart
- Oxygen and nutrients from the mother’s blood are transferred across the placenta to the fetus.
- Goal of fetal circulation is to get oxygenated blood to brain
PDA allows blood to go into aorta and into ________
vessels of head and neck (getting blood to brain)
Normal PaO2 in umbilical vein of fetus
30-35 mmHg.
Residue 143
- Single amino acid change of histidine to serine
- Histidine positively charged; Serine neutral
- This change results in LESS binding of 2,3 BPG to fetal Hb which INCREASES fetal oxygen affinity
- Baby has higher affinity for oxygen from moms blood due to single amino acid change
With the first few breaths after baby is born, lungs expand and serve as oxygenator. Placenta is removed from the circuit, systemic pressure _________, pulmonary pressure _________
systemic INCREASES pulmonary DECREASES (so blood can flow to lungs)
- Foramen oval functionally closes
- Ductus arteriosus closes within first 2-3 days
After baby is born, pressure is higher
in L atrium than R atrium, 1 way valve is closed and flow from R to L stops
-shunts close in first 45 seconds of life
Neonates with CHD often rely on _______
a patent ductus arteriosus and/or foramen ovale to sustain life
- The ductus normally closes by 3 days
- The foramen ovale normally closes by 3 months
What function does the PDA provide after birth in a baby with cyanotic congential heart disease?
Provides a source of pulmonary blood flow
In the presence of hypoxia or acidosis (present in ductal-dependent lesions), _____________
the ductus may remain open for a longer period of time
- As a result, these patients can present to the ED as late as the first 2 weeks of life (Sepsis is usually #1 on differential, congenital heart disease is #2
- Start antibiotics and PGE (to keep PDA open)*
S/S of venous congestion
Right side: Hepatomegaly, Ascitis, Pleural effusion, Edema
Left side: *Tachypnea, Retractions, Crepitations
Pulmonary edema
S/S of lower cardiac output
Acutely: Pallor, *Sweating
Cool extremities, increased capillary refill time, Tachycardia
Chronic: *Feeding difficulty, *Fatigue, Poor growth
Neonatal EKG findings
- Highest peak in limb leads (RVH is NORMAL)
- Normal finding bc R vent was dominant when it was inside mom, takes a while for L vent to bulk up and get bigger
- eventually L vent will have stiffer more muscular will and RV will be more compliant chamber
Chromosomal causes of CHD
- Down Syndrome: up to 50% will have defects
- VACTERL, CHARGE Association: 50 - 85% will have defects (involve many body systems)
Maternal illness that causes CHD
-Pre-Gestational Diabetes: 50% increase risk (if diabetes is poorly controlled; vent septal defect, transposition of great arteries, coarctation of aorta)
- Lupus: complete heart block (Abs from mom cross placenta and attack conduction system in baby’s heart; monitor baby heart via EKG)
- Infection (Viral): rubella in 1st 7 wks = Patent Ductus Arteriosus
Maternal substance abuse and CHD
-Severe FAS (EtOH) = 50% have CHD
Down syndrome associations
AV canal and VSD
Turner syndrome associations
Coarctation of aorta
Trisomy 13 (Patau syndrome) and 18 (Edwards syndrome)
VSD and PDA
Fetal alcohol syndrome associations
L–> R shunts and metrology of fallot
CHARGE syndrome
conotruncal lesions (ToF, truncus arteriousus)
Pulse ox on arm and leg and difference in more than 10% saturation= ________
(R upper arm sat 100%; Lower extremities O2 sat is LOWER)
differential cyanosis
- lower limbs are cyanosed but the upper limbs are not
- will see increased precordial activity and displaced PMI
Differential cyanosis is from
PDA with R to L shunt or
CoA with PDA after constriction
S/S of Pulmonary cyanosis
- baby is grunting, struggling to breathe
- tachypnea, distress, retractions with breathing
- cyanosis may improve with crying
- may heart rales, crackles or wheezing in lungs
- normal heart sounds/cardiac silhouette
- CXR shows ground glass, pneumonia, atelectasis, pneumothorax
- normal EKG
- pCO2 increased usually
- PROFOUND response to 100% O2
S/S of Cardiac cyanosis
- baby is blue, but breathing fine (comfortable)
- cyanosis worsens when baby cries
- hear cardiac murmur
- cardiomegaly/abnormal shape or position of heart
- normal lung fields, may see some decreased vascularity or pulmonary vascular congestion
- EKG shows abnormal rhythm
- pCO2 is normal to low
- NO response to 100% O2
Differential pulses, weak in LE, think
CoA