Cardiac - Paediatric heart conditions Flashcards
Pathophysiology of heart failure
Heart failure = pathophysiologic state in which the heart fails to pump blood at a rate to meet the demand of the
body, i.e. 2 components:
1) Dysfunction of heart (pump failure) – commonly in adults (e.g. ischemic heart disease, impaired contraction of LV)
2) Cardiac overload (pressure or volume overload with preserved heart function) – more common in children
Imbalanced supply and demand causes S/S of HF
Systemic signs of children with heart failure
Breathlessness (SOB), especially on exertion/feeding
Poor feeding (longer time required to finish milk feed)
Excessive sweating during feeding
Failure to thrive (poor growth)
Recurrent chest infection
Exercise incapacity in older children
Signs of venous congestion
Pulmonary
Tachypnea
Subcostal in-sucking
Wheezing (in infants)
Systemic
Hepatomegaly
Distension of neck veins (not obvious in small children)
Peripheral edema (rare because without cardiac dysfunction
Decompensation:
Low pulse volume
Cool extremities
Prolonged capillary refill
Compensatory mechanism to venous congestion
Tachycardia
Cardiomegaly
Causes of heart failure in neonates
1) Left ventricular outflow tract obstruction
- Coarctation of aorta
- Aortic stenosis
- Aortic atresia/ hypoplastic left heart syndrome
2) Myocardial dysfunction
- Transient myocardial ischemia
- Myocarditis
- Cardiomyopathy
3) Abnormal HR/ rhythm
- Supraventricular tachycardia
- Complete heart block
4) Extra- cardiac causes
- Systemic disturbance causing ventricular dysfunction:
o Sepsis
o Asphyxia
o Hypocalcaemia
- Anaemia (high-output cardiac failure)
Coarctation of aorta in neonate
- Associated syndrome
- Structural abnormalities in heart
- Pathophysiology
- Presentation
Syndrome: Turner’s syndrome with familial clustering (although majority sporadic)
Associations: hypoplasia of transverse aortic arch, VSD, bicuspid aortic valve, berry aneurysms
Pathophysiology: discrete narrowing of descending aorta at insertion of ductus
- RV supplies descending aorta via persistent arterial duct
- impaired flow from proximal to distal part of aorta
- Organs depend on supply from pulmonary artery through PDA to descending aorta»_space; Low perfusion to organs
Presentation
- LV pressure overload with systemic hypertension (duct-independent CoA)
- acute heart failure and renal failure with shock (duct-dependent CoA)
Coarctation of aorta
- Clinical signs for duct-dependant and non-duct dependent CoA
General/ both:
- Compensatory LVH
- Systemic arterial insufficiency»_space; enlargement of intercostal arteries as collaterals with rib notching
- Systolic HTN in UL due to outflow obstruction
Duct-dependent:
- Weak LL pulses
- RV strong impulse
- Soft ESM at LUSB
- Collapse, shock, oliguria after ductal closure
Duct-independent:
- Weak LL pulse with radiofemoral delay*
- LV impulse (heaving apex)
- ESM at LUSB radiating to left interscapular region
- soft continuous murmur throughout chest
Coarctation of aorta
First line investigations and typical finding
□ Bloods: severe metabolic acidosis due to ischaemic colitis and AKI upon duct closure
□ CXR:
→ Cardiomegaly and ↑pulm vascular markings in infants/neonates with HF
→ Cardinal ‘figure of sign at site of coarctation with pre- and post-stenotic dilatation
→ Notching of undersurface of posterior ribs due to erosion by collaterals
□ ECG: RVH if neonatal HF, LVH in others
□ Echo: demonstrate site and severity of coarctation
□ MRI: demonstrates length and severity of coarctation
Critical aortic stenosis in neonate
- Pathophysiology
- Effect
- Signs
Pathophysiology: Critical AS Impedes blood flow from LV to ascending aorta
- Congenital valve defect or rheumatic fever
Effect: LV Pressure overload causes low cardiac output
Signs:
- Low pulses in both upper and lower limbs
- Pulsus parvus et tardus/ anacrotic pulse (slow, notched upstroke with sustained peak)
- LV volume overload: sustained parasternal heave
- Systolic thrill in aortic area
- Ejection systolic murmur at aortic area +/- radiation to bilateral neck
Aortic atresia/ hypoplastic left heart syndrome in neonates
- Pathophysiology
- Associated syndrome
- Effect
- Pulse
Pathophysiology
No left heart function: Complete atresia of aortic valve, mitral valve atresia and left ventricular hypoplasia
Blood returning to lungs then to LA is channeled through patent foramen ovale/ atrial communication into right atrium and right ventricle
From RV through pulmonary trunk, supply lungs and aorta through persistent ductus arteriosus
A/w Turner’s syndrome
Effect:
Right heart supports both pulmonary circulation and systemic circulation
Pulse:
Lower pulse in both upper and lower limbs
Myocardial dysfunction in neonate
- Causes
Transient myocardial ischaemia (due to perinatal asphyxia and hypoxemia»_space; transient disturbance of ventricular contraction»_space; metabolic acidosis)
Myocarditis (uncommon; acquired infection from mother)
Cardiomyopathy (usually in older children)
Abnormal heart rate/ arrhythmia in neonates
Causes
Supraventricular tachycardia (more common): Associated with accessory pathways like in Wolff-Parkinson-White
Complete heart block: Maternal SLE with anti-Ro and anti-La destroys fetal heart conduction tissue
Extra-cardiac causes of neonatal heart failure
Systemic disturbance causing ventricular dysfunction:
o Sepsis
o Asphyxia
o Hypocalcaemia
Anaemia (high-output cardiac failure)
Causes of heart failure in infants
Due to large left-to-right shunts
- Ventricular septal defect (VSD)
- Atrioventricular septal defect (AVSD)
- Persistent arterial duct (patent ductus arteriosus, PDA)
- Atrial septal defect (less common)
Ventricular septal defect (VSD) in infants
- Pathophysiology
- Clinical signs
- Associated syndrome
Pathophysiology:
Defect in ventricular septum - severe Left to right shunt
High pulmonary flow - pulmonary hypertension
Increased pulmonary venous return - LV volume overload
Clinical signs:
- Pansystolic murmur at tricuspid area, widely radiating with thrills
- Pulmonary arterial congestion»_space; respiratory distress
- ± RV pressure overload (parasternal heave) at LATE stage
- LV volume overload (displaced, thrusting apex)
- Pulmonary hypertension (loud P2 or single S2)
Syndromes:
DiGeorge
Down
Eisenmenger
Atrioventricular septal defect (AVSD) in infants
Pathophysiology
Most commonly associated syndrome
Clinical signs
Pathophysiology:
AV septum devoid of partition due to valve formation defect
Blood flows from LA to RA and LV to RV
Particularly common in Down syndrome
Clinical signs:
- Pulmonary arterial congestion»_space; respiratory distress
- Volume overload of LA»_space; Parasternal heave
- LV dilatation»_space; Displaced apex, strong LV impulse
Persistent arterial duct (patent ductus arteriosus, PDA) in infants
Pathophysiology
- Clinical signs
Pathophysiology
Ductus arteriosus connects aorta to pulmonary artery
Aortic pressure is much greater than pulmonary artery pressure
L to R shunt of blood from aorta to pulmonary artery
Clinical signs:
- Differential clubbing (toes only)
- Collapsing pulse/ Corrigan’s sign
- Continuous murmur at L infraclav/LUSB
- LV volume overload (displaced thrusting apex)
- Pulmonary arterial congestion»_space; respiratory distress
- Volume overload of LA»_space; Parasternal heave
- RV dilatation
ASD in infants
- Pathophysiology
- Effect
- Signs
Pathophysiology:
- Atrial septum formed by Septum primum with foramina primum and secundum, and Septum secundum with foramen ovale
- At birth, High pulmonary venous return increases LA pressure
→ septum primum pressed against foramen ovale for closure + gradual fusion
- Failure to close foramen secundum → secundum ASD
- Failure to close foramen primum → primum ASD
Effect:
- chronic L-to-R shunt
- RV volume overload (cf other L-to-R shunt usu a/w LV overload)
Signs: RV volume overload (parasternal heave) Wide, fixed splitting of S2 (characteristic) ESM at LUSB due to ↑PV flow MDM at LLSB due to ↑TV flow
Causes of heart failure in older children
1) Myocardial disease (acquired):
Myocarditis (usually viral)
Cardiomyopathy (primary/ secondary) (mutation of sarcomeric proteins, e.g. actin, myosin, troponin, etc.)
2) Unoperated structural heart defects
3) Certain repaired/ palliated congenital heart defects (ventricular dysfunction +/- valvular insufficiencies)
General management options for paediatric heart failure
1) Identify the cause and precipitating factors, e.g.
Surgical intervention (e.g. VSD, large ASD)
Catheter intervention (e.g. large ASD)
Tackle precipitating factors (infection, metabolic disturbance…)
2) Supportive treatment (optimize nutrition)
3) Medical therapy
4) Mechanical circulatory support:
a) Extracorporeal membrane oxygenation:
b) Ventricular assist device
5) Heart transplantation (e.g. terminal dilated cardiomyopathy)
Medical therapy options for paediatric heart failure
Medical therapy of heart failure:
Diuretics (corrects preload because HF activates RAAS for fluid retention)
ACEI (symptoms)
Carvedilol (= beta blockers for dilated cardiomyopathies)
Digoxin
Indications for Mechanical circulatory support in paediatric heart failure
Extracorporeal membrane oxygenation:
- Viral myocarditis
- Terminal dilated cardiomyopathy (bridge to heart transplant)
Ventricular assist device
- Bridge to heart transplant
Treatment for duct-dependent systemic circulation in infants e.g. coarctation of aorta, interrupted aortic arch, PDA
1) Initial stabilization by prostaglandin E1/ E2
- maintain ductal patency/ open stenosed arterial ducts to ensure adequate blood flow to systemic circulation
2) Corrective surgery/ catheter intervention (balloon dilation)
Treatment of paediatric heart conditions with severe left to right shunts
Surgical closure of septum defects:
VSD (patch repair/ catheter delivery to occlude the defect)
Large PDA (ductal ligation (main choice)/ device closure)
ASD (device closure)
Cyanosis in children
- Hb level for visible cyanosis
- Confirmatory Ix of low Hb
Apparent in infants and children with 3-5 g/dL of reduced haemoglobin (note the confounding influence of anaemia/ polycythaemia)
Confirm cyanosis with pulse oximetry, oxygen saturation
Causes of central cyanosis in children
a) Cyanotic congenital heart disease
b) Respiratory tract disease:
Airway obstruction
Pulmonary parenchymal disease (congenital pneumonia, meconium aspiration syndrome, diaphragmatic hernia)
c) Central nervous system damage:
Hypoventilation
Brain damage
Drug effect (from mother)
d) Congenital methaemoglobinaemia
e) ‘Traumatic’ cyanosis (difficult labor: venous congestion may mimic central cyanosis)
How to differentiate cardiac or respiratory cyanosis?
1) Find predisposing factors to respiratory disease:
- Maternal infections associated with congenital pneumonia
- Meconium-stained liquor
2) Respiratory distress signs
3) Chest radiography
4) Hyperoxic test/ nitrogen washout test: give high concentration oxygen to observe rise in PaO2
Radiological features of congenital respiratory vs cardiac central cyanosis
Respiratory conditions: usually abnormality of pulmonary parenchyma
Cyanotic congenital heart conditions:
R-to-L shunts: lung usually dark (oligaemic with reduced pulmonary blood flow)
Transposition of great vessels, truncus arteriosus: high pulmonary blood flow
Ddx cardiac causes of central cyanosis in neonates
Systemic venous blood bypassing the lung:
a) Right-to-left shunts with RV outflow obstruction
- Tetralogy of Fallot
- Tetralogy of Fallot with pulmonary atresia (aka pulmonary atresia with VSD)
- Pulmonary atresia with intact ventricular septum (PAIVS)
b) Transposition haemodynamics/ transposition of the great arteries
c) Ebstein anomaly
Common-mixing conditions
a) Arterial levels – truncus arteriosus
b) Ventricular level – univentricular heart
c) Atrial level – total anomalous pulmonary venous return
Tetralogy of fallot
- Structural defects
- Pathogenesis
Defects: □ Pulmonary stenosis: usually infundibular stenosis □ RV hypertrophy □ Overriding aorta □ Ventricular septal defect
Pathogenesis:
□ Bulbar septum normally grows spirally to septate the outflow tract into pulmonary trunk and aorta → grows proximally to fuse with IV septum
□ Bulbar septum malformation → Unequal division of outflow tract with failure to fuse with IV septum, forming Overiding aorta and VSD
□ Main haemodynamic determinant is RVOT obstruction
Tetralogy of fallot
- Presentation
1) Hypercyanotic (Tet, Fallot) spells: transient spells of near-occlusion of RVOT with profound cyanosis
Usually related to spasm of muscles guarding right ventricular
outflow
less blood to lungs and more deoxygenated blood to aorta causes intense oxygen desaturation
Baby may lose consciousness and have convulsions
2) Heart failure
Tetralogy of fallot
Signs
Cyanosis, clubbing, failure to thrive
RV impulse ± systolic thrill
Single S2 due to soft inaudible P2
ESM at LUSB radiating posteriorly
VSD-like in those with mild RVOT obstruction
Tetralogy of Fallot
- Radiological features
CXR: ‘boot-shaped’ heart (‘coeur-en-sabot’) with low pulmonary vascularity (oligemic lung fields)
- RVH → uptilting of cardiac apex
- Small PA → concavity of left upper cardiac border
± right-sided aortic arch (20%) → exaggerates concavity
Echo: aorta not continuous with IV septum
- Presence of associated anomalies, eg. right aortic arch, coronary artery anomalies, ASD (pentalogy)
Tetralogy of Fallot
Immediate and definitive management options
Immediate:
Hold + calm baby in knee-chest position (↑SVR)
O2 supplementation
Stepwise rescue:
- IV fluid + morphine (improve RV filling and pulmonary flow)
- IV β-blocker (esmolol, propranolol → relaxation of RVOT obstruction)
- IV vasoconstrictor (phenylephrine → ↑SVR)
Definitive:
- IV PGE1 with early shunting
- Palliative procedure before definitive repair: Modified Blalock-Taussig shunt (mBTS)
- Complete repair (usually at 6-12mo): Repair of VSD by patch closure, Enlargement of RVOT by resecting infundibular and
subinfundibular muscle bundles
Tetralogy of Fallot with pulmonary atresia (aka pulmonary atresia with VSD)
- Structural defects
- Effect
Defects:
- Large VSD
- RV outflow narrowing (complete atresia)
- RV hypertrophy
- Overriding aorta
Effect:
- No blood from RV to pulmonary arteries»_space; pulmonary arteries only
supplied by persistent ductus arteriosus
- With closure of ductus arteriosus, baby will become more
cyanotic because of further reduction of blood flow to lungs
Tetralogy of Fallot with pulmonary atresia (aka pulmonary atresia with VSD)
Treatment
- ‘Ductal-dependent pulmonary circulation’ - prostaglandin E1/ E2
- Surgical palliation:
a) Systemic-pulmonary arterial shunt (e.g. modified Blalock-Taussig shunt)
b) Unifocalization of aortopulmonary collaterals - Total surgical repair in infancy to early childhood
1) Implant artificial valve conduit between RV and pulmonary arteries
2) Close VSD
Pulmonary atresia with intact ventricular septum (PAIVS)
Structural defects
Effect
Pulmonary valve atresia/ muscular atresia (complete obliteration):
No flow from RV to pulmonary arteries
Blood from right side of circulation can only go through patent foramen ovale (or ASD) into left atrium, then through mitral valve into LV, then through aortic valve into ascending aorta
oxygen relies on patency of arterial duct: With closure of ductus arteriosus, baby will become more cyanotic
Pulmonary atresia with intact ventricular septum (PAIVS)
Treatment options
- Initial stabilization with PGE1/ E2 to maintain duct-dependent pulmonary circulation
- Surgical palliation: systemic-to- pulmonary arterial shunt
- Catheter/ surgical opening of atretic pulmonary outflow:
Radiofrequency-assisted pulmonary valvotomy
Transposition haemodynamics/ transposition of the great arteries in neonates
- Structural defect
- Effect
Defects:
Aorta from RV, Pulmonary artery from LV - results in parallel systemic and pulmonary circulation
Effect:
- Increasing oxygenation of pulmonary circulation
- Decreasing oxygenation of aortic circulation
“The poor gets poorer, the rich gets richer” - heart stops working
Transposition of great arteries
- Management options
Maintain and augment the potential sites for mixing of oxygenated and deoxygenated blood:
- Arterial duct (patent ductus arteriosus) – PGE1/ E2 to stabilize babies
- Atrial septal defect (patent foramen ovale at birth) – balloon atrial septostomy to enlarge the atrial communication
Surgical treatment:
- Arterial switch operation for anatomic correction (current choice)
- Venous switch operation (Mustard/ Senning operations) for physiological correction (now obsolete)
Ebstein anomaly
Structural defect
Effect
S/S
Radiological sign
Defect:
- Downward displacement of tricuspid valve causes severe tricuspid regurgitation from RV to RA:
- Atrializaton of RV (part of RV becomes RA with thinning of myocardial wall)
- Associated with ASD
Effect:
High pressure TR causes blood flow from RV to RA, then through ASD to left heart circulation
S/S: Cyanosis
Radiological: X-ray: giant right atrium due to severe TR and atrialization of RV
truncus arteriosus
Structural defect
Effect
Defect:
- In normal development: common trunk from ventricular mass divides to form aorta and pulmonary artery
- In persistent truncus arteriosus:
No division of common trunk into aorta and pulmonary artery
Usually associated with VSD
Effect:
- Deoxygenated blood in pulmonary artery directly flows into aorta, causes cyanosis
- Pulmonary arterial congestion causes ventricular volume overload and heart failure
Univentricular heart
Structural defect
Effect
Treatment option
Defect:
- Single large functional ventricle supports both aorta and pulmonary artery/ single aorta with pulmonary atresia
Effect:
Mixing of oxygenated and deoxygenated blood causes cyanosis
Tx:
- Shunt insertion for severe pulmonary outflow obstruction
- Fontan-type operation:
i. Channel all the blood from IVC via extra cardiac conduit to
pulmonary artery
ii. Anastomose blood from SVC to pulmonary artery bypassing
the heart
total anomalous pulmonary venous return
Structural defects
Effect
Pulmonary vein insertion defects:
- Supracardiac: Drain through ascending blood vessels to join innominate vein and SVC
- cardiac Drain directly to RA
- infracardiac: Join to form a descending vein to liver portal circulation to arrive at RA
Effect:
Pulmonary venous blood empties back into RA
No blood emptying to LA: only source of blood to LV is from atrial communication (ASD, patent foramen ovale)
