The Collapsed Cardiac Baby

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The Collapsed Cardiac Baby

• Peter Davis
• Paediatric Intensive Care Unit
• Bristol Royal Hospital for Children

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The Context

• Congenital heart disease occurs in approximately
  0.8 of all live births
• Despite antenatal screening newborn checks many
  infants with cardiac abnormalities go
  unrecognised until collapse
• Differentiation of cardiac disease from other
  causes of collapse (e.g. sepsis, metabolic
  conditions) should not necessarily need a
  cardiologist!

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The foetal circulation (1)

• Foetal circulation
• Oxygenated blood from placenta shunts through
  Foramen Ovale
• Left heart supplies head upper body
• Lower body supply also via ductus arteriosus
• Only 5-10 of cardiac output goes to lungs

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The foetal circulation (2)

• Foetal circulation
• PaO2 in mmHg
• Higher PaO2 supplied to head upper body
• SVC supplies Right Atrium Right Ventricle
• IVC supplies Left Atrium across Foramen Ovale

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The adult circulation

• ? Pulmonary Vascular Resistance with 1st breath
• ? return via pulmonary veins ? ? Left Atrial
  Pressure
• ? return from placenta ? ? Right Atrial Pressure
• ? Closure of Foramen Ovale
• Ductus Arteriosus closes with ?Systemic Vascular
  Resistance / flow reverse
• ? PaO2

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Presentations of cardiac disease in infants

• Wide variation in presentation incidental murmur
  to acute cardiorespiratory collapse
• Collapse can present with
• Cyanosis (/or)
• Shock (/or)
• Congestive heart failure
• Hypercyanotic episodes

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Cyanosis The blue baby

• Respiratory causes
• Pneumonia Bronchiolitis Sepsis or neurological
  depression causing hypoventilation
• Cardiac causes
• Transposition of the Great Arteries
• Right-to-left shunting due to right ventricular
  outflow tract obstruction
• Pulmonary atresia or stenosis
• Tricuspid atresia

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Approach to the cyanosed neonatecardiac vs.
respiratory disease

• Is the infant in respiratory distress?
• YES ? respiratory or severe cardiac failure
• NO ? cardiac
• Are the lung fields oligaemic on CXR?
• YES ? Right-sided outflow obstruction

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CXR of neonate withPulmonary Atresia
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Approach to the cyanosed neonatecardiac vs.
respiratory disease

• Is the infant in respiratory distress?
• YES ? respiratory or severe cardiac failure
• NO ? cardiac
• Are the lung fields oligaemic on CXR?
• YES ? Right-sided outflow obstruction
• NO ? respiratory or TGA / obstructed TAPVD

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CXR of neonate with Transposition of the Great
Arteries
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CXR of neonate with Total Anomalous Pulmonary
Venous Drainage
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Approach to the cyanosed neonatecardiac vs.
respiratory disease

• Is the infant in respiratory distress?
• YES ? respiratory or severe cardiac failure
• NO ? cardiac
• Are the lung fields oligaemic on CXR?
• YES ? Right-sided outflow obstruction
• NO ? respiratory or TGA / obstructed TAPVD
• Does oxygenation improve in 100 O2?
• YES ? respiratory (PaO2 gt 15kPa)
• NO ? cardiac (e.g. TGA) or PPHN

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Transposition of the Great Arteries (TGA)

• Commonest cyanotic congenital cardiac condition
• 5 of all congenital heart disease
• ? Incidence of 1 in 3000 live births
• Marked male preponderance
• Extracardiac malformations or chromosome
  abnormalities uncommon
• 2/3 of affected infants have no other cardiac
  malformation i.e. simple TGA

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Pulmonary Atresia (with intact septum)

• 3 of neonates with congenital heart disease (3rd
  most common cyanotic condition)
• Usually associated with some degree of right
  ventricular hypoplasia
• May be associated coronary artery abnormalities

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Total Anomalous Pulmonary Venous Drainage (TAPVD)

• 1-3 of congenital heart disease
• Site of connection
• Supracardiac 40-59
• Cardiac 25-30
• Infracardiac 10-20
• Mixed 6-8
• Obstructed a true neonatal cardiac surgical
  emergency usually infracardiac, male
  preponderance present cyanosed.

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Infracardiac TAPVD
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The Shocked baby

• Left heart obstruction
• Critical Aortic Valve Stenosis
• Hypoplastic Left Heart Syndrome
• Coarctation of the Aorta
• Myocardial failure
• Anomalous Left Coronary Artery arising from
  Pulmonary Artery (ALCAPA)
• Dilated Cardiomyopathy
• Tachyarrhythmias

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Critical Aortic Valve Stenosis

• 60-75 of LVOTOs occur at valve level
• 4 times more common in males
• Some evidence of inheritance
• Commonly associated lesions of coarctation
  patent ductus arteriosus
• Critical AS presents as ductus closes common
  differential diagnosis is overwhelming sepsis

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Hypoplastic Left Heart Syndrome (HLHS)

• 4th most common congenital cardiac condition
  presenting in 1st year of life
• Continuum of congenital anomalies
  underdevelopment of aorta, aortic valve, left
  ventricle, mitral valve left atrium
• 21 Male preponderance
• May present with shock as ductus closes at few
  days of age
• Without surgery almost all die within neonatal
  period

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Coarctation of the Aorta

• Usually occurs in sporadic fashion but
  particularly associated with Turners syndrome
  (45XO)
• Most individuals with coarctation asymptomatic
• Typically juxtaductal, so in some cases may
  present with shock as ductus closes in first week
  of life

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Anomalous Left Coronary Artery from Pulmonary
Artery (ALCAPA)

• Pulmonary artery supplies desaturated blood at
  low pressures to left ventricle
• Further steal to pulmonary arteries from
  collaterals from right coronary artery
• Resistance falls in left coronary arteries
  leading to myocardial ischaemia
• 90 present in infancy
• May cause shock sudden death, particularly
  after exertion

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Dilated Cardiomyopathy

• Often presents as congestive heart failure, but
  may present shocked, especially if superimposed
  infectious illness
• Huge range of causes, although many idiopathic
  presenting in infancy
• Infectious myocarditis, particularly viral
• Familial hereditary e.g. Barths syndrome
• Deficiencies e.g. Carnitine, Selenium
• Mitochondrial disorders

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Tachyarrhythmias

• Paroxysmal supraventricular tachycardia (SVT)
  most common significant arrhythmia
• Describes group of arrhythmias with similar ECG
  manifestations but different mechanisms, e.g.
• AV re-entry tachycardia 2o to accessory pathway
  (AVRT)
• Atrioventricular nodal reentrant tachycardia
  (AVNRT)
• Primary atrial tachycardia

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Supraventricular tachycardia

• Estimated incidence of 1 in 250 to 1000
• Most commonly occurs in males aged lt 4 months
• Predisposing factors include
• Infection/fever
• Wolff-Parkinson-White syndrome
• Congenital heart disease e.g. VSD, Ebsteins
• Rate usually ranges from 220-320 bpm
• Mostly presents as narrow-complex tachycardia

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Congestive Heart Failure

• Symptoms include respiratory distress, poor
  feeding, sweating, hepatomegaly, gallop rhythm
• If unrecognised may present with shock
• Causes vary with age
• 1st week of life HLHS, TAPVD, tachyarrhythmias,
  tricuspid regurgitation, critical aortic or
  pulmonary stenosis
• 1 week to 3 months coarctation, left-to-right
  shunts (VSD, PDA, AVSD), tachyarrhythmias,
  ALCAPA, cardiomyopathy

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Hypercyanotic episodes

• Occur secondary to dynamic obstruction of
  muscular right ventricular outflow tract
• Hyper-reactive to stimuli
• May be acutely life-threatening with resultant
  right-to-left shunting
• Inadequate pulmonary blood flow causes marked
  cyanosis may lead to death
• Particularly occurs in Tetralogy of Fallot

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Tetralogy of Fallot

• 3rd most common presenting congenital cardiac
  condition in infancy
• 20-30 have an abnormality of Chromosome 22
• Usually degree of cyanosis by 3 months
• Hypercyanotic Spells
• may occur without warning or with activity
• more common in morning, during summer months
  with intercurrent illness
• usually self-limiting of between 15-30 minutes

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Investigation of the collapsed cardiac baby (1)

• History
• Attempt to elicit history of particular symptoms
  and where possible relate to age of child
• Examination
• Cyanosis unresponsive to oxygen
• Reduced or absent femoral pulses
• Marked tachycardia
• Murmur/gallop rhythm
• Hepatomegaly

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Investigation of the collapsed cardiac baby (2)

• Chest X-ray
• Heart-shape
• Boot-Shaped / raised apex ? right ventricular
  hypertrophy e.g. Fallots tetralogy
• Heart-size
• Very large e.g., dilated cardiomyopathy,
  Ebsteins tricuspid valve anomaly
• Lung fields
• Oligaemic ? RVOTO e.g. pulmonary atresia
• Plethoric ? Left-to-right shunt e.g. TAPVD,
  PDA, VSD, AVSD

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Boot-shaped heart Oligaemic CXR
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Wall-to-wall heart
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Plethoric lung fields
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Investigation of the collapsed cardiac baby (3)

• ECG
• Rate
• gt200 bpm ? tachyarrhythmia
• ( Delta wave ? WPW)
• Axis deviation
• Left axis deviation ? right ventricular
  hypoplasia
• Superior axis deviation ? AVSD
• Ventricular hypertrophy right or left
• ST segment changes
• Ischaemic changes ? ALCAPA

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W-P-W Delta wave
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Superior axis deviation
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ST changes (anterolateral)
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Investigation of the collapsed cardiac baby (4)

• Bloods
• Arterial gas incl. lactate
• FBC film
• UEs, LFTs, Calcium Magnesium
• Glucose
• Blood Cultures
• Echocardiogram liaise with paediatric
  cardiologists

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Treatment of the collapsed cardiac baby (1)

• Resuscitate as per ABC, including antibiotics,
  but
• Limit oxygen to minimum for cyanosed infants as
  oxygen may unbalance circulation
• Treat shock with fluid with some caution, as
  excessive preload may cause overdistension
• For cyanosed or shocked neonates with suspected
  left heart obstruction start prostaglandin

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Treatment of the collapsed cardiac baby (2)
Prostaglandin

• PGE1 or 2 at 10-50 nanograms/kg/min to maintain
  PDA or relax juxtaductal tissue
• Use minimum dose to achieve effect
• Side effects
• apnoea some dose dependence
• fever
• vasodilatation /- hypotension (rare)
• seizures
• vomiting

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Rationale for starting prostaglandin infusion

• Risk of withholding prostaglandin dependent on
  clinical condition i.e. the threshold for
  starting is lower, if sicker
• More likely prostaglandin sensitive lesion
• in cyanosed infant, if murmur heard
• in non-cyanosed infant, abnormal pulses
• If in doubt, start it anyway ventilate!

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Inotropic support for the collapsed cardiac baby

• Use catecholamines to improve myocardial
  contractility and cardiac output
• Act on cardiac b-adrenergic receptors
• Increase intracellular cyclic AMP
• Results in increased intracellular calcium
  concentration during systole
• Usually start with dopamine or dobutamine
  titrate to effect
• Higher doses of dopamine will cause
  vasoconstriction via a-adrenergic receptors

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Treatment of Supraventricular Tachycardia

• Vagal manoeuvres e.g. ice to face
• Adenosine iv 50mg/kg bolus, repeat increase by
  50mg/kg every 2 minutes to a maximum of 300mg/kg
• Amiodarone iv 25mg/kg/min for 4 hours, then 5-15
  mg/kg/min
• If shocked, cardioversion 0.5-1J/kg

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Treatment of congestive heart failure

• ABC resuscitation, including ventilation and use
  of inotropic support
• Keep fluid boluses to a minimum only to maintain
  adequate preload
• Diurese cautiously
• Usually furosemide iv 0.5-1mg/kg doses
• Beware hypovolaemia
• Beware hypokalaemia risk of arrhythmias

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Treatment of hypercyanotic spells (1)

• Aim of initial management is to increase systemic
  vascular resistance (SVR) decrease pulmonary
  vascular resistance (PVR)
• Increase SVR
• Increase preload by placing in knee-to-chest
  position (equivalent of squatting)
• Correct hypovolaemia with iv fluids
• Vasoconstrictors e.g. phenylephrine iv 10-20mg/kg
  or metaraminol 10mg/kg

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Treatment of hypercyanotic spells (2)

• Decrease PVR
• Administer 100 oxygen
• Correct any acidosis e.g. intubate
  hyperventilate
• Give iv opiate e.g. fentanyl iv 5-10mg/kg
• Propanolol iv 10-100mg decreases systolic
  infundibular spasm
• Emergency surgery
• Correction or Modified BT shunt

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Referral to Paediatric Cardiology

• Once cardiac disease suspected do not delay
  referral
• Have results of CXR ECG available if possible
  to help confirm diagnosis
• Neonates with cyanosis may require emergency
  intervention e.g. Balloon Atrial Septostomy
  (Rashkind) for TGA
• Neonates with cyanosis or LVOTO may require
  urgent surgery e.g. correction or palliation
  (modified Blalock-Taussig shunt)

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Summary

• Cardiac disease remains in differential for all
  previously undiagnosed collapsed infants
• Recognition of potential modes of presentation
  and findings of investigations of collapsed
  cardiac baby essential to guide appropriate
  treatment referral
• ED practitioners must remain cogniscent of the
  risk of worsening the condition of cardiac
  infants through injudicious management