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

2. 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!

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. CXR of neonate with Pulmonary Atresia

10. 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

11. CXR of neonate with Transposition of the Great Arteries

12. CXR of neonate with Total Anomalous Pulmonary Venous Drainage

13. 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

14. 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

16. 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

18. 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.

19. Infracardiac TAPVD

20. 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

21. 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

23. 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

25. 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

27. 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

28. 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

29. 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

30. 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 bpm
Mostly presents as narrow-complex tachycardia

31. 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

32. 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

33. 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 minutes

35. 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

36. 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

37. “Boot-shaped” heart & Oligaemic CXR

38. “Wall-to-wall” heart

39. Plethoric lung fields

40. 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

41. W-P-W Delta wave

42. Superior axis deviation

43. ST changes (anterolateral)

44. 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

45. 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

46. Treatment of the collapsed cardiac baby (2): Prostaglandin
PGE1 or 2 at 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

47. 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!

48. 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

49. 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

50. 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

51. 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

52. 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 mg decreases systolic infundibular spasm
Emergency surgery:
Correction or Modified BT shunt

53. 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)

54. 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