The Collapsed Cardiac Baby Peter Davis Paediatric Intensive Care Unit Bristol Royal Hospital for Children

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!

The foetal circulation (1) 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

The foetal circulation (2) PaO2 in mmHg Higher PaO2 supplied to head & upper body SVC supplies Right Atrium & Right Ventricle IVC supplies Left Atrium across Foramen Ovale

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

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

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

Approach to the cyanosed neonate: cardiac 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

CXR of neonate with Pulmonary Atresia

Approach to the cyanosed neonate: cardiac 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

CXR of neonate with Transposition of the Great Arteries

CXR of neonate with Total Anomalous Pulmonary Venous Drainage

Approach to the cyanosed neonate: cardiac 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 > 15kPa) NO  cardiac (e.g. TGA) or PPHN

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

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

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.

Infracardiac TAPVD

The “Shocked” baby Left heart obstruction: Myocardial failure: 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

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

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 2:1 Male preponderance May present with shock as ductus closes at few days of age Without surgery almost all die within neonatal period

Coarctation of the Aorta Usually occurs in sporadic fashion but particularly associated with Turner’s 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

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

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. Barth’s syndrome Deficiencies e.g. Carnitine, Selenium Mitochondrial disorders

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

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

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

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

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

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

Investigation of the collapsed cardiac baby (2) Chest X-ray: Heart-shape “Boot-Shaped” / raised apex  right ventricular hypertrophy e.g. Fallot’s tetralogy Heart-size Very large e.g., dilated cardiomyopathy, Ebstein’s tricuspid valve anomaly Lung fields Oligaemic  RVOTO e.g. pulmonary atresia Plethoric  “Left-to-right” shunt e.g. TAPVD, PDA, VSD, AVSD

“Boot-shaped” heart & Oligaemic CXR

“Wall-to-wall” heart

Plethoric lung fields

Investigation of the collapsed cardiac baby (3) ECG: Rate >200 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

W-P-W Delta wave

Superior axis deviation

ST changes (anterolateral)

Investigation of the collapsed cardiac baby (4) Bloods: Arterial gas incl. lactate FBC & film U&Es, LFTs, Calcium & Magnesium Glucose Blood Cultures Echocardiogram – liaise with paediatric cardiologists

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

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

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!

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

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

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

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

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

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)

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