Embryology + Congenital + Inherited Flashcards
what is the function of the placenta
Fetal homeostasis Gas exchange Acid base balance Nutrient transport to fetus Waste product transport from fetus Hormone production Transport of IgG produces PGE2 (prostaglandin E2)
describe the lungs in utero
fluid filled and unexpanded
what is the role of the pulmonary circulation in utero
to supply the lungs with what it needs to grow and develop
what is the role of the liver and gut
liver little role in nutrition and waste management
gut not in use
where does the foetal heart pump blood to
the placenta via the umbilical arteries
from what arteries do the umbilical arteries arise from
illiac arteries
where does blood from the placenta travel to
to the foetus via the umbilical vein
where does the oxygenated blood from the placenta return to in the heart and what is its role
right side of the heart, to be distributed around the heart to the growing foetus
why is the pulmonary resistance in utero so high
as lungs collapsed
what are shunts and why are they needed
as pulmonary circulation very high resistance the vessels cant deal with all the blood, shunts are passage ways that allow most of the blood supply to bypass the lungs
what are the 3 shunts in foetal circulation
ductus venosus,
foramen ovale,
ductus arteriosus,
what is the role of the ductus venosus
connects the umbilical vein to the vena cava, allowing the blood from the placenta to bypass the liver
what is the foramen ovale and what is its role
opening in atrial septum connecting RA to LA allowing passage of blood between sides of the circulation
what is the role of the ductus arteriosus
connects pulmonary bifurcation to the descending aorta
what is the name of the liver circulation and what is it bypassed by, and why
portal circulation
bypassed by ductus venosus
as nutrients from placenta don’t need further processing in liver
why is the mixing of blood facilitated by the foramen ovale so important
as allows the best oxygenated blood to enter left atrium then on to LV where it goes to ascending aorta and carotids, supplying the development of the foetus
on which side is the membrane flap of the foramen ovale on
left atrium side
how is foetal circulation opposite to adult circulation
pressure in right atrium and pulmonary circulation much higher than left side- (because of collapsed lungs) allows blood to flow through foramen ovale
how much of RV output goes to lungs and why
7% as pressure do high, rest taken by ductus arteriosus to descending aorta
how is the patency of the ductus arteriosus maintained
by circulating prostagladin E2
what happens to the lungs in the first few minutes following birth
baby initially low sats (60%)
baby inflates lungs by crying (lung fluid goes into amniotic fluid)
baby goes from blue to pink
what happens to the Pulmonary vascular resistance after birth and how
lungs expand, increase in circulating oxygen-
relaxes smooth muscles of lungs = resistance decreases= cardiac output to lungs increases
what happens to systemic vascular resistance after birth
cord clamped and cut, placenta gone, resistance to flow in systemic system rises
what do the changes in circulation following birth lead to
closure of the foramen ovale and constriction and closure of the ductus arteriosus
what causes the foramen ovale to close
fall in P(ulmonary) VR and rise in SVR= increases the LA pressure, making it exceed to RA pressure pushing the membrane flap shut
what causes duct constriction
increased pO2 (only place in body that O2 causes vasoconstriction) decreased blood flow (decrease pulmonary vascular resistance) decreased prostaglandins (placenta removed)
when does the ductus arteriosus close and what does it form
functional closure first hours/days
anatomical closure 7-10 days
forms the fibrous ligament- ligamentum arteriosum
what can a patent ductus arteriosus lead to in peterm infants
excessive blood in ling circulation and not enough blood in brain and gut
what are the treatment options for a patent ductus arteriosus
‘wait and see’, NSAIDs (inhibit prostaglandin production to help constrict the duct),
surgery
what is the treatment for a duct dependant circulation
IV prostaglandin E2 can keep duct open until an alternative shunt established/ definitive surgery carried out
when does pulmonary resistance reach a normal level
drops after birth until 2-3 months
in what conditions is persistent pulmonary hypertension more common in newborns
sepsis, hypoxic ischaemic insult, meconium aspiration syndrome, cold stress, anatomical abnormality (e.g. congenital diaphragmatic hernia)
what physiological failures can cause persistence of pulmonary hypertension in a newborn
patent foramen ovale or ductus arteriolus
what are the symptoms of persistent pulmonary hypertension in newborns
blue baby, large difference between pre and post ductal oxygen saturation
how is PPHN treated
ventilation, oxygenation, high systemic blood pressure, inhaled nitric oxide (will drop vasculature pressure), ECLS (extracorporeal membrane oxygenation (ECMO))
where is pre and post ductal saturation measured
pre hands (80%), post feet (60%)
what is congenital heart disease
abnormality of the structure of the heart (doesnt include cardiomyopathy or arrhythmias that present later)
“a gross structural abnormality of the heart or intrathoracic great vessels that is actually or potentially of functional significance.”
when do congenital heart diseases present
at birth
what is the incidence of congenital heart disease
between 1-13 per 1000 live births
what is the spectrum of severity of congenital heart diseases
mild, moderate, severe and major
describe mild heart disease
asymptomatic- may resolve spontaneously or may progress to moderate of severe in adulthood
describe moderate congenital heart disease
require specialist intervention and monitoring in cardiac centre
describe severe congenital heart disease
present severely ill/ die in newborn period or early infancy
describe major congenital heart disease
requires surgery within the first year of life
give examples of mild Congenital HD and how they can progress
Small VSD, PFO / small ASD, small PDA. Bicuspid aortic valve may progress in adulthood to severe AS or AR and need surgery
give examples of moderate congenital HD
mild or moderate AS, PS. larger or complex ASD, VSD
give examples of severe congenital heart disease
cyanotic lesions, all duct dependant lesions, truncus
how does congenital heart disease present
screening: antenatal, newborn baby check
well baby with clinical signs- murmur
unwell baby with- cyanosis, shock, cardiac failure due to low CO
what signs are seen in congenital heart disease when presenting soon after birth
cyanosis
what signs are seen in congenital heart disease when presenting at the day 1-2 baby check
murmurs, abnormal pulses, cyanosis
what signs are seen in congenital heart disease when presenting 3-7 days after birth
sudden circulatory collapse, shock, cyanosis, sudden death
what signs are seen in congenital heart disease when presenting at 4-6 weeks
what signs are seen in congenital heart disease when presenting soon after birth
what signs are seen in congenital heart disease when presenting at 6-8 weeks
incidental finding of murmurs
why causes blue baby/ cyanosis
any condition that causes deoxygenated blood to bypass the lungs and enter the systemic circulation /
mixed oxygenated and deoxygenated blood enters the systemic circulation from the heart
what are the differential diagnosis’ of cyanosis in newborns
cardiac disease, respiratory disease, persistent pulmonary hypertension
what is the most common cyanotic condition
transposition of great arteries
why does transposition of the great arteries cause acidosis
as babies unable to perform anaerobic metabolism and builds up lactic acod
what happens when a duct closes in a baby who has duct dependent circulation
collapse, severe cyanosis or pallor, tachypnoea, distress, grunting, rapid deterioration, death
what are the clinical signs of duct closure
pallor, prolonged CRT, poor or absent pulses, hepatomegaly, crepitations, increased work of breathing, profoundly acidotic
how is duct closure treated
ABC, prostaglandin E2 to reopen duct, surgery
what are the two types of duct dependent conditions
duct dependent systemic circulation (physical obstruction to blood getting to left side of the heart)
duct dependent pulmonary circulation (right side of heart)
what can cause duct dependent systemic circulation (left side of the heart)
hypoplastic left heart,
critical aortic stenosis,
interrupted aortic arch,
critical coarctation of aorta
what can cause duct dependent pulmonary circulation (right side)
tricuspid atresia,
pulmonary atresia
(complete blockage)
describe hypoplastic left heart syndrome
underdeveloped left heart- very small LV< mitral valve and ascending aorta= mixed blood in right side, PA and AO. no palpable pulse and increasingly acidotic
what does pulmonary atresia result in
retrograde filling of PA via ductus arteriosus. No VR output, associated with VSD, circulation to lungs via aorta
what can cause a presentation of heart failure
large right to left shunts (increased pulmonary load) e.g large VSD
when does cardiac failure present in neonates
after a few weeks as pulmonary pressure drops
what are the clinical signs of heart failure in babies
Failure to thrive Slow / reduced feeding Breathlessness (especially when feeding) Sweatiness Hepatomegaly Crepitations
when does a VSD murmur develop
as pulmonary pressure drops over first weeks
why does VSD lead to congestive heart failure
as increases pulmonary circulation and work load in right ventricle
how is CCF treated in babies
diuretics and high calorie formula to help baby grow before surgery
what is the long term management for major congenital heart disease
surgery, further interventions for developmental problems, hypoxia, further surgery, emotional/ social issues
what is a patent ductus arteriosus repaired
catheter procedure, in through femoral vein to the heart
how is a hypoplastic left heart treated
3 stage complex surgery, RV will fail over time, need transplant
what mutations can cause inherited cardiac problems
on genes that encode cardiac muscle or ion channels of the heart
what are the two forms of arrhythmogenic inherited cardiac conditions
channelopathies (arrhythmogenesis is related to an ion current imbalance) and cardiomyopathies (arrhythmogenesis related to scar/ electrical barrier formation and subsequent re entry)
name two inherited channelopathies
congenital long QT syndrome, brugada syndrome, short QT syndrome
name two inherited cardiomyopathies
hypertrophic cardiomyopathies, arrhythmogenic right ventricular cardiomyopathy (dilated right ventricle that causes arrhythmia), dilated cardiomyopathy
how do inherited cardiac conditions present
can have no symptoms, heart rhythm, palpitations, fast heart rate, fainting, breathlessness, chest pain, swollen legs, weakness, sudden death
how are inherited cardiac conditions diagnosed
clinical testing, genetic tests
how are the risks of inherited cardiac conditions managed
risk management, lifestyle, pharmacological and non pharmacological intervention
what electrical activity is mainly affected in a channelopathies
depolarisation
when should inherited cardiac conditions be considered in patients
young people with AF
what channel is mostly affected in long QT syndrome
potassium channel
what does congenital long QT syndrome look like on an ECG
polymorphic VT (torsades de pointes)
what triggers the polymorphic VT seen in LQTS
adrenergic stimulation
is LQTS autosomal dominant or recessive
can be both- 13 subtypes
what is the mechanism behind LQTS
less repolarising current and more depolarising current prolongs AP depolarisation
what can trigger LQTS
exercise, emotional stress, sleep, sudden auditory stimuli, QT prolonging conditions (medications, hypokalaemia)
what is the primary presenting complaint of LQTS
syncope, sudden cardiac death
how is congenital LQTS managed
avoidance of stimuli (swimming, breath holding, loud sudden noises), correction of electrolyte adnormalities, avoidance of QT prolonging drugs
what creates risk of SCD in LQTS
age dependent, gender (pre-teen boys, adult females), increasing QT duration, prior syncope
what can be shown on an ECG in brugada syndrome
risk of polymorphic VT, VF, AF common, ST elevation, RBBB in V1-3
how does brugadas commonly present
in young men who go to sleep and dont wake up
what types of inheritance pattern does brugadas have
autosomal dominant
what can trigger VF in brugada
rest or sleep, fever, excessive alcohol, large meals
what drugs should be avoided in brugada
anti-arrhythmic, psycotropics (used in schizophrenia), analgesics, anaesthetics
what is catecholaminergic polymorphic ventricular tachycardia
channelopathy
describe CPVT
Adrenergic induced bidirectional and polymorphic VT, SVTs, triggered by emotional stress, physical activity
normal ECG and echo
both autosomal dominant and recessive
how is risk managed in CPVT
avoidance of strenuous activity, stressful environments
beta blockers and ICD implantation (sometimes flecainide)
what are the clinical presentations of hypertrophic cardiomyopathies
sudden death, heart failure, angina, atrial fibrillation, asymptomatic
how is heart failure in HOCM treated
beta blockers, ACE I, diuretics, consider transplantation
how is AF or atrial flutter treated
oral anticoagulant, antithrombotic, amiodarone to restore sinus rhythm and b blockers, verapamil and diliazem to maintain / catheter ablation
what is lamin A/C
gene where mutations associated with DCM
What is SAD
syncope angina dyspnoea
what are after depolarisations
abnormal depolarisations if cardiac myocytes that interrupt phase 2, 3 or 4 of the cardiac AP in the cardiac conduction system of the heart
can lead to triggered activity
what are early depolarisations
) occur with abnormal depolarization during phase 2 or phase 3, and are caused by an increase in the frequency of abortive action potentials before normal repolarization is completed
can result in Torsades de Pointes
what is a treatment for DCM
ICD- implantable cardiac defibrillator
what causes arrhythmogenic right ventricular cardiomyopathy
fibro-fatty replacement of cardiomyocytes
what adds to the risk of SCD
Family history of premature SCD Severity of RV and LV function Frequent non-sustained VT ECG : QRS prolongation VT induction on EPS Male gender Age of presentation
what can help prevent SCD in pre symptomatic patients
life style changes, beta blockers, ICDs
describe embryonic folding
when embryo folds laterally and longitudinally, making the two initial heart tubes fuse, moving them into the midline, and making them start to beat
happens at 18 days
what happens when the two primitive heart tubes fuse together
form single primordial heart tube situated in the midline of the embryo
what is the trunctus arteriosus and what does it form
cranial segment of embryonic heart which forms pulmonary and aortic trunks
what is heart tube looping
when tubular heart forms a c then an s shape which resembles adult heart
describe sepation of the heart
the formation of atria and ventricles in the embryonic heart from endocardial cushions
what is the role of cardinal veins
return poorly oxygenated blood from the body if the embryo
what is the role of the foramen ovale
allows blood to travel from the right to the left atrium (shunt)
what is the role of the ductus venosus
allows blood from the umbilical vein to bypass the liver into the IVC
what is the role of the ductus arteriosus
allows blood to pass from the pulmonary trunk into the aorta (blood can bypass the lungs, liver and kidneys whose functions are performed by the placenta)
what germ layer is the heart formed from
mesoderm
