[216B] Congenital Heart Defects Flashcards
What’s an echocardiogram?
Ultrasound of the heart.
What are 3 anatomical structures present in fetal circulation that should not be present after birth?
- Ductus venosus.
- Foramen ovale.
- Ductus arteriosus.
Why do fetuses have increased pulmonary resistance?
They still have fluid in their lungs.
What physiological changes would we expect to see with the heart muscle after the transition to postnatal circulation? Why?
RV hypertrophy: must overcome pressure to pump blood into the lungs.
Which notable genetic condition is associated with CHD?
Trisomy 21 (Down Syndrome).
What is the size of the ASD determined by?
Volume of shunting
What are the 3 types of ASDs and their locations?
- Sinus venosus (junction of the SVC + RA)
- Secundum (mid septum)
- Primum (low septum at the “crux”)
What’s the average adult’s CO?
4900 mL/min.
What is the tx for HF & FTT?
- Fluid restriction
- Diuretics
- ACE inhibitors
- O2
- Optimize nutrition (hypercaloric tube feeds)
- Coil occlude in catheter (NOT for sinus venosus)
- Surgical closure
What range would we expect an infant’s SV to fall into?
5-13 mL/beat.
Would we expect an infant to have a higher or lower HR compared to an adult?
Higher.
If there is a left to right shunt, that means there’s an increased ____ blood flow from re-circulation of ____ blood
pulmonary, oxygenated
What’s the equation for cardiac output?
CO= SV x HR
List 5 factors that affect CO (besides the ones in the equation).
- Body size/body surface area (BSA).
- Metabolic needs of tissues.
- Preload.
- Afterload.
- Contractility.
Would you be concerned if you heard 2 S2 heart sounds? Why might we see this?
It can be normal: the pulmonic valve may close slower than the aortic valve.
Can systolic or diastolic murmurs be benign? When would we classify them as such?
Only systolic - when the murmur disappears with position/respirations.
Diastolic murmurs are always concerning!
Patent ductus arteriosus (PDA) occurs in 2 phases:
- Functional closure (continuous contraction of the smooth muscle wall in the first 12h after birth).
- Cessation of PGE2 in the fetal period.
What is the tx if the ASD is restrictive?
None
Average CO for an infant?
~600 mL/min
Which 2 anatomical structures does a PDA allow blood to flow between?
Aorta > pulmonary arteries.
In a PDA, there is a ____ to ____ shunt.
Left to right.
List 3 factors that affect the amount of shunting in a PDA.
- PDA size & length.
- Pressure gradients between aorta (higher) and pulmonary arteries (lower).
- Changing vascular resistance from the transition to postnatal period (increasing SVR, decreasing PVR).
A PDA increases the _____ ______ [heart chamber] preload & output.
left ventricle.
List 6 s&s of a PDA.
- Pulmonary HTN.
- CHF.
- Increased work of breathing.
- Continuous murmur.
- Palpable thrill in LUSB (left upper sternal border) - d/t high LV output.
- Apneas in premature infants - d/t immature myelination.
List 4 tx for PDAs.
- NSAIDs PO (ex: Indomethacin) - inhib prostaglandin synthesis causing muscle contraction.
- Prostaglandins IV (ex: Alprostadil) - life-saving in some defects until they can be repaired.
- Device/coils closure.
- Surgical ligation.
What are 3 indications to close a VSD for infants?
- Large shunt
- CHF
- FTT
What is an indication to close a VSD for children + adolescents?
- Reversible pulmonary vascular resistance
- Qp:Qs > 2:1
- Aortic valve involvement
Define a ventricular septal defect (VSD)
Direct communication between the left + right ventricles
During what age is spontaneous closure of VSD most common?
First year
Is there a genetic link for VSDs?
No
What should be the tx for an adolescent with a VSD + Eisenmenger’s syndrome?
Heart-lung transplant
Define an atrioventricular septal defect (AVSD)
Lesion that affects septum + AV valves
40-50% of children with ____ Syndrome are affected by AVSD
Down’s
What are 3 physical exam findings of AVSDs?
- Increased pulmonary blood flow (ie. tachypnea, bad g&d)
- Systolic ejection murmur in LUSB or holosystolic ejection murmur in MV
- Pulmonary HTN
What are 2 objectives of a partial AVSD repair?
- Close ASD
- Restoration of MV cleft
What are 3 objectives of a complete AVSD repair?
- Close interatrial + intraventricular holes
- Construct 2 separate AV valves
- Repair valve clefts
What is the preferred technique for complete AVSD repairs?
Two-patch
What are 3 drug classes for tx of AVSDs? Explain why
- Diuretics (decrease pulmonary edema)
- ACE-I (decrease BP + fluid)
- PDE5 + O2 (stop pulmonary HTN)
What are the 4 structural lesions of the Tetralogy of Fallot (TOF)?
- Large unrestrictive VSD
- Overriding aorta
- RV outflow tract obstruction
(RVOT) PS (Pulmonary Stenosis) - RV hypertrophy
What are 4 physical exam findings of TOF?
- Cyanosis
- Pink tet
- Loud systolic ejection murmur
- Single S2 sound (no pulm. valve)
Describe how tet spells (hypercyanotic) occur
Increased activity or irritability –> increased O2 demand –> SOB –> cyanosis
What are the 7 tx for TOF? Explain them
- Comfort kid + knees to chest (decrease PVR)
- IV bolus of colloid (increase vasc volume)
- IV morphine (relieve pain)
- Esmolol/propanol (BB to decrease HR)
- Pheylephrine (vasoconstrict PV)
- Sodium bicarb (acidosis)
- Intubation
