Congenital heart abnormalities Flashcards
what are congenital cardiac abnormalities associated with?
chromosomal abnormalities
what causes congenital cardiac defects?
chromosomal abnormalities
teratogens
mostly multi-factorial complex interplay between genetic and environmental factors
maternal disease - such as diabetes
embryological origin of heart
heart tubes from lateral plate mesoderm
when do heart tubes begin to form?
4th week of development
single primitive heart tube forms and then week 5-8 it septates
when does the heart begin to beat?
day 22 of development
when does blood begin to circulate?
day 24 of development
what causes vascular abnormalities?
failure of remodelling
right sided aortic arch
due to involution of left aortic arch and failure of involution of right aortic arch
persistence of both primitive aortic arches
results in vascular ring encircling the oesophagus and trachea, potentially constricting these and causes breathing difficulties or dysphagia
foramen ovale
between atria in fetal heart
ductus arteriosus
between pulmonary circulation and aorta in fetal heart
what forms the outflow tract of ventricles?
conus cordis
abnormalities of lateralisation
reversal of direction of heart tube folding
what are abnormalities of lateralisation?
dextrocardia
situs inversus
levocardia
dextrocardia
heart on right but abdominal contents are normally positioned (situs solitus) discordance between viscera and so there are often cardiac abnormalities, such as atrioventricular discordance, septal defects, single ventricle, transposition of great arteries, anomalous pulmonary venous return
situs inversus
reversal of laterality of thoracic and abdominal organs
- concordance between reversal of laterality can mean patients are asymptomatic
- patients with situs inversus not particularly at increased risk of cardiac defects but increased chance of pulmonary disease
Kartagener’s syndrome
disorder of ciliary motility: chronic sinusitis nasal polyposis bronchiectasis risk in situs inversus
levocardia
normal thoracic viscera positioning
reversed abdominal contents positioning
rarer
discordance means there are congenital defects in 95% of patients
what forms the vena cava?
sinus venosus
becomes incorporated into right atrium
what forms the pulmonary veins?
left atrium
crista terminalis
border between trabeculated and smooth walled part of right atrium
left atrial appendage
primitive left atrium
when does atrial septation occur?
week 4 and onwards
what divides the common primitive atria?
septum primum and septum secondum
how is the foramen ovale formed?
opening left by septum secondum
what is the foramen ovale?
shunt from right to left atrium
fossa ovalis
closure of foramen ovale
can be seen on medial wall of right ventricle
what causes an ASD?
failure of formation of atrial septa
what causes a patent foramen ovale?
failure of fusion of septum primum and secondum = PFO
ASD prevalence
10% of congenital cardiac defects
ASD
continuous left to right shunting of blood
impacts right side of heart
risk of paradoxical embolus
Paradoxical embolus in PFO
thrombus passing between venous and arterial circulation
indication for closure of PFO
PFO
common
present in 20-30% of population
often asymptomatic
risks of PFO
paradoxical embolus if right atrial pressure exceeds left side in pulmonary disease
atrioventricular canal defect
failure of formation of endocardial cushions
affects all chambers of heart
can be associated with chromosomal abnormalities, specifically trisomy 21
atrioventricular canal defect
frequent communication between sides of the heart
increased right sided heart pressure
pulmonary hypertension
heart failure
can cause recurrent respiratory tract infections
when is the ventricular septum formed?
end of week 4
formation of interventricular septum
involves neural crest cells
trabeculated part of right ventricle
bulbus cordis
trabeculated part of left ventricle
common primitive ventricle
what causes VSD?
failure of formation of ventricular septum
most common congenital cardiac abnormality in children and 2nd most common in adults
which part is most commonly affected in VSD?
membranous part of ventricular septum
VSD symptoms
vary depending on severity and size
can be asymptomatic if there is minimal shunting or can show symptoms of heart failure
what are the symptoms of heart failure?
hepatomegaly failure to thrive exertional dyspnoea raised JVP peripheral oedema
mitral valve
anterior and posterior cusps
tricuspid valve
anterior, posterior and septal cusps
what forms the aortic and pulmonary trunks?
truncus arteriosus
neural crest cells
influence development of cardiac septa and outflow tracts
failure of formation of conotruncal septa
results in persistent truncus arteriosus
persistent truncus arteriosus
single blood vessel carrying blood from heart to systemic, pulmonary and coronary circulations
always associated with VSD
how does persistent truncus arteriosus present?
congestive heart failure
cyanosis
what causes transposition of great vessels?
failure of correct formation of conotruncal septa
transposition of great vessels
aorta arises from right ventricle and pulmonary outflow tract arises from left ventricle
transposition of great vessels presentation
within 24 hours
cyanosis
tetralogy of fallot
pulmonary infundibular stenosis, VSD, overriding aorta and right ventricular hypertrophy (develops after birth)
tetralogy of fallot presentation
cyanosis
right to left shunting of blood
transition to post-natal circulation
at birth pulmonary vascular resistance falls and blood circulates through lungs
patent ductus arteriosus and foramen ovale close forming ligamentum arteriosum and fossa ovalis
failure of closure of foramen ovale
PFO
failure of closure of ductus arteriosus
= patent ductus arteriosus, in some circumstances can be necessary to preserve life where there is structural heart disease, e.g. tetralogy of fallot
- patent ductus arteriosus symptoms vary depending on size
presentaation of patent ductus arteriosus
if large can present within 1 year of birth
failure to thrive
breathing difficulties
small one may not present until adulthood
uncorrected patent ductus arteriosus
can lead to pulmonary hypertension and right sided heart failure
