B4.048 Congenital Heart Disease Flashcards
definition of CHD
abnormalities of the heart and great vessels present from birth
may be symptomatic at birth, infancy and childhood, or become apparent only later in life
may be isolated or part of a syndrome (downs, diGeorge)
may be major or minor
incidence of CHD
1% of all newborns
among most prevalent birth defects
most common type of pediatric heart disease
main known causes of CHD
single gene mutations
small chromosomal deletions
additions/deletions of whole chromosomes (trisomies and monosomies)
environmental causes
most common genetic cause of CHD
trisomy 21
40% have heart defects
most likely cause of CHD
combination of multifactorial effects of several genes, maternal, and environmental factors
greatest risk factor for CHD
CHD in parent or sibling
why might mutations in any one of several genes produce similar defects?
many of the transcription factors interact in large protein complexes
non syndromic genes associated with CHD
NKX2-5
GATA-4
TBX-20
all function as transcription factors
CHD associated with NKX205
ASD, VSD, conduction defects
CHD associated with GATA-4
ASD, VSD
CHD associated with TBX-20
ASD, VSD, valve abnormalities
syndromic genes associated with CHD
TBX5 - transcription factor
TBX1- transcription factor
JAG1, NOTCH2- notch signaling
fibrillin- structural protein, TGFB signaling
CHD and syndrome associated with TBX5
holt-oram
ASD, VSD, conduction defects
CHD and syndrome associated with TBX1
diGeorge
cardiac outflow tract defects
CHD and syndrome associated with JAG1, NOTCH2
alagille
pulm artery stenosis, ToF
CHD and syndrome associated with fibrillin
marfan
aortic aneurysm
valve abnormalities
which 12 disorders make up 85% of all CHDs
VSD (40%) ASD (10%) pulm stenosis PDA (7%) ToF (5%) coarctation of the aorta (5%) AV septal defect aortic stenosis transposition of great vessels truncus arteriosus total PV connection tricuspid atresia
which of the 12 disorders exhibit cyanosis
ToF transposition of great vessels truncus arteriosus total PV connection tricuspid atresia
3 major pathophys categories of CHD
left to right shunt
right to left shunt
obstruction
why do right to left shunts cause cyanosis
pulmonary circulation is bypassed and poorly oxygenated blood shunts directly into systemic arterial supply
what is Eisenmenger syndrome
when a left to right shunt becomes a right to left shunt
this happens because pulm blood flow and pressure is increased by shunt leading to hypertrophy and constriction by pulmonary arteries as well as RV hypertrophy
eventually, pulm vascular resistance approaches systemic levels and the shunt switches to become a right to left shunt that introduces poorly oxygenated blood into the systemic circulation
what happens once irreversible pulmonary hypertension occurs in Eisenmenger syndrome?
structural defects of CHD are considered irreparable
subsequent right HF leads to patient’s death
characterize VSDs
incomplete closure of the ventricular septum
may be isolated or part of a complex
muscular or membranous (90%) part of the septum
solitary or multiple
large in membranous, small in muscle usually
50% of small defects close spontaneously
what % of VSDs are isolated
only 20-30%
if first detected in an adult, probably isolated
what is the eventual fate of patients with large, unclosed VSDs
irreversible pulm vascular disease > shunt reversal > cyanosis > death
why is surgical/catheter based closure of an asymptomatic VSD delayed?
hopes of spontaneous closure
when do babies need early correction?
when they have large defects present
classification of ASDs
ASD secundum type (90%) - defect of fossa ovalis
ASD primum type - adjacent to AV valves, associated with cleft anterior mitral leaflet
ASD of sinus venosus- near entrance of superior vena cava
define ASD
abnormal, fixed openings in the atrial septum caused by incomplete tissue formation that allows communication of blood between left and right atria
usually asymptomatic until adulthood
characterize an ASD
murmur due to excessive flow through the pulmonary valve (turbulence)
usually asymptomatic until age 30
irreversible pulm hypertension unusual
surgical closure prevents serious complications
discuss mortality associated with ASDs
low mortality
long term survival comparable to normal population
clinical features of ASDs
mild L > R shunt, acyanotic
pulm blood flow 2-8x normal
pulmonary valve murmur often present
which type of ASD is associated with other anomalies
septum primum type
may be associated with mitral and tricuspid anomalies
characterize a PDA defect
usually DA closes functionally within 10-15 hrs, anatomically 2-3 days after birth
PDA normal in premature babies
indomethacin may induce closure
clinical features of PDA
left to right shunt
continuous, harsh machinery murmur
clinical impact depends on diameter and cardiovascular status of individual
what can ultimately happen with large PDAs
additional volume and pressure overloads pulm circulation leading to a shunt reversal (from L > R to R > L) causing cyanosis and clubbing of toes
why do toes club with PDA but not fingers?
hypoxemic blood is shunted into descending aorta
what are 3 features associated with coarctation of the aorta
- hypertension in upper parts of the body, hypotension or normal in lower parts
- anastomoses develop between subclavian artery and aorta through intercostal arteries
- notching of ribs due to dilated intercostal arteries
what other defect frequently accompanies coarctation of the aorta?
50% of the time is accompanies by a bicuspid aortic valve
may be associated with aortic stenosis, ASD, VSD, mitral regurg, or berry aneurysms of the circle of willis
what are the 2 classic forms of coarctation of the aorta?
- infantile form- often symptomatic in early childhood with tubular hypoplasia of aortic arch proximal to PDA
- adult form with discrete, ridge-like infolding of the aorta, just opposite closed DA
which form is less severe?
coarctation WITHOUT pda, uless constriction is severe
usually asymptomatic well into adult life
what is particularly characteristic of coarctation of the aorta
collateral circulation between the pre-coarctation and post-coarctation arteries through enlarged intercostal and internal mammary arteries
produce visible erosions of the ribs
murmur associated with coarctation of the aorta
when significant
murmurs present throughout systole
sometimes a vibratory thrill present
resolution of uncomplicated coarctation of the aorta
surgical resection and end to end anastomosis
OR
replacement of the affected aortic segment by a prosthetic graft
what is a simian crease?
single crease in hand associated with downs syndrome
ophthalmic exam results common in downs
Brushfield spots- speckled rings at the periphery of the irides
what type of murmur will a VSD produce??
pansystolic murmur with peak intensity in mid-systole
murmur associated with aortic stenosis
early systolic murmur transmitted to the carotid arteries
murmur associated with PDA
machinery like murmur heard throughout systole and diastole
murmur associated with mitral valve prolapse
mid systolic click
murmur associated with pulm regurg
pandiastolic murmur diminishing in intensity from early to late diastole
EKG findings in ASD
incomplete bundle branch block
slight RAD
CXR findings in ASD
cardiomegaly
prominent pulm artery segment (due to increased flow)
and prominent pulm vasculature
cardiac cath findings in ASD
elevated pulm wedge pressure, pulm artery pressure, RV pressure
elevated RV and RA O2 sat
how are ASDs repaired in many cases?
placing a patch into heart through a catheter
patch placed across the ASD
