Congenital Heart Disease 1, 2, 3 Flashcards
structural anomalies of the heart present though not necessarily manifest at birth
congenital heart disease
How does pulmonary edema due to CHD differ from pulmonary edema in adults?
interstitial vs alveolar
How does CHD contribute to pneumonia risk in infants?
increased pulmonary flow manifests as dilation of pulmonary arteries –> bronchiolar compression –> poor movement in bronchioles –> infection
What constitutes pulmonary vascular disease due to CHD?
high pressure in pulmonary arteries leads to scarring AKA Eisenmenger reaction–> rate of development is dependent on pressure and o2 sat
How does ventricular failure manifest in CHD?
exercise/feeding intolerance, growth failure, elevation of venous pressures (pulmonary edema, hepatomegaly)
What are the consequences of cyanosis?
low o2/rbc –> metabolic acidosis
- can compensate by polycythemia but this can lead to hyperviscosity (too many RBCs) which has risk of clotting and exercise intolerance
- if can’t compensate due to iron-def anemia –> can have the clinical issues without looking cyanotic
T/F high pulmonary blood flow can accelerate pulmonary vascular disease
T –> especially if cyanotic
2 categories of acyanotic CHD
left to right shunts, obstructive disease
How does resistance factor into the determination of flow through a large VSD?
pulmonary flow depends on the ratio of pulmonary to systemic resistance
*the pressures are the same with a big VSD so pressure difference absolutely cannot determine the flow
Normally, pulmonary vascular resistance rises/falls over the first week of life
falls –> smooth muscle in lungs has to relax to allow blood flow
W/a large VSD, what happens to pulmonary vascular resistance over the first weeks of life?
falls slowly for several weeks then rises up (as smooth muscle hypertrophy, scarring increases a la eisenmenger, resistance increases again)
W/a large ASD, what happens to pulmonary vascular resistance over the first weeks of life?
nothing –> blood in atrium doesnt affect what happens in lungs –> AV and semilunar valves are never open simultaneously
Why is flow normal early in a VSD?
both resistance and pressure is high –> despite big hole, blood doesn’t want to flow L to R b/c of high resistance –> flow through the hole is minimal (no murmur in 1st week of life)
What happens to flow later in a VSD?
to compensate for VSD, pulmonary arteries dilate and blood volume increases –> by the time resistance is reduced in lungs, flow increases to compensate for high pressure
hi pressure = hi flow * nl resistance
As the eisenmenger reaction sets in due to VSD what happens to the heart?
after initial compensation, lung scarring occurs –> increase lung resistance –> flow decrease –> volume handling is reduced to normal and heart starts shrinking–> pulmonary resistance exceeds systemic resistance and shunt reversal occurs –> deox blood mixes with ox blood on systemic side –> cyanosis
Why are there multiple murmurs in a large VSD?
- holosystolic murmur through VSD
- middiastolic murmur (sounds like mitral stenosis) through mitral valve b/c of large volume of pulmonary return passing from atrium to ventricle
Signs of Eisenmenger complex
murmur goes away –> rely on a loud single second heart sound + right ventricular hypertrophy on EKG
EKG findings in the course of acyanotic CHD
initially normal –> after drop in pulmonary resistance, left sided hypertrophy –> as pulmonary resistance increases, biventricular hypertrophy (heart shrinks generally as volume reduces) –> right ventricular hypertrophy
Which way does flow go across ASD? newborn
no flow –> right ventricle and left ventricle have similar compliance as they have shared load in utero
Which way does flow go across ASD? toddler
RV compliance increases b/c it is thinner –> flow goes from left to right in atria –> RV has to handle extra work hence hypertrophy/RA dilates –> flow across pulmonary valve = murmur (sounds like pulmonary stenosis)
Difference between VSD and PDA shunting?
VSD can only shunt when valves are open whereas PDA shunting occurs all the time as there is no valve –> even a small PDA can have a lot of flow
*continuous murmur –> systolic murmur that continues past S2
How can fetal coarctation lead to hypertension?
aortic obstruction like a bicuspid valve reduces flow in aorta towards brain –> retrograde flow up aorta from ductus arteriosus compensates by splitting –> shelf creates at the split point –> when ductus closes, the shelf point remains and creates a discrete coarctation/narrowing of aortic lumen –> collaterals form to ensure blood flow however kidneys lose pulsatile flow and pump out renin leading to upper extremity hypertension
What is a fetal hypoplastic arch?
if instead of late-presenting (i.e. in late fetal life) aortic obstruction occurs, can cope. however, if have a VSD (or other structural defect) that forms before the formation of the aortic arch, the aortic arch will not develop to its full width –> loss of lower extremity flow after closure of DA –> shock in early infancy
Disease manifestations of left heart obstructive lesions
- left atrial htn
- ventricular hypertrophy
- ductal dependence (shock when ductus closed)
Complications of left heart obstructive lesions
CHF, acidosis, circulatory collapse, sudden death, endocarditis
What are the two types of cyanotic CHD?
- PBF dependent (cyanosis depends on PBF) - tetralogy of fallot
- PBF independent -transposition
How does pulmonary blood flow determine cyanosis in cyanotic CHD?
PBF proportional to systemic resistance/pulmonary resistance –> as PBF increases, cyanosis decreases
*usually have decreased PBF –> unlimited systemic-pulmonic mixing leads to cyanosis
Tetralogy of Fallot
- VSD
- narrowed pulmonary outflow tract + conal septal shift
- RVH (due to VSD not /bc of the pulmonary stenosis)
- overriding aorta
Transposition of the great arteries
2 separate circulations: aorta comes off RV and PA comes off LV –> PFO permits limited mixing –> cyanosis not proportional to PBF (in fact have increased PBF)
What determines mixing with an ASD (as in when trying to repair a transposition)
- size of ASD
- ventricular compliance (as PR falls, left ventricular compliance improves –> when blood comes back to the atria, it will store in LV until pulmonary valve is closed at which point the right side of the heart will get a boost of blood)
Complications of cyanotic CHD
- polycythemia
- stroke
- brain abscess
- growth failure
- bilirubin gall stones
