Congenital Heart Disease in ICU

Quick Answer

Congenital Heart Disease (CHD) encompasses structural abnormalities of the heart and great vessels present at birth, affecting 8-10 per 1,000 live births. CHD represents the most common congenital malformation and a leading cause of infant mortality.

Key Clinical Features:

• Cyanosis (central, not responsive to oxygen in cyanotic CHD)
• Heart failure (tachypnoea, hepatomegaly, poor feeding, failure to thrive)
• Shock (particularly with duct-dependent systemic lesions like coarctation)
• Murmurs (though may be absent in critical lesions)

Emergency Management:

1. Identify duct-dependent lesions - Start PGE1 (alprostadil) 0.01-0.05 mcg/kg/min
2. Stabilize ABC - May require intubation (PGE1 causes apnoea in 10-20%)
3. Urgent echocardiography - Definitive anatomical diagnosis
4. Avoid hyperoxia in duct-dependent pulmonary flow lesions

ICU Mortality: Highly variable by lesion (HLHS Stage 1 Norwood: 10-30%; simple VSD repair: <1%)

Must-Know Facts:

• Duct-dependent lesions require PGE1 to maintain life until surgical correction
• Low cardiac output syndrome peaks 6-18 hours post-cardiopulmonary bypass
• Pulmonary hypertensive crises require iNO, sedation, hyperventilation
• Adult CHD (GUCH) is an increasing ICU population with unique challenges

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CICM Exam Focus

What Examiners Expect

Second Part Written (SAQ):

Common SAQ stems:

• "A 5-day-old neonate presents with sudden cardiovascular collapse and absent femoral pulses. Describe your assessment and management."
• "A 3-day-old infant presents with profound cyanosis unresponsive to oxygen. Outline your approach including the hyperoxia test."
• "A neonate is Day 1 post-Norwood procedure. Describe management of low cardiac output syndrome."
• "Discuss the perioperative management of a child post-Fontan completion with persistent pleural effusions."

Expected depth:

• Understanding of fetal circulation and transition at birth
• Classification of CHD by physiology (shunt direction, obstruction, mixing)
• Duct-dependent lesion recognition and PGE1 management
• Post-operative complications: LCOS, JET, pulmonary hypertensive crisis, chylothorax
• Adult CHD principles including Eisenmenger syndrome

Second Part Hot Case:

Typical presentations:

• "Blue baby"
• cyanotic neonate with cardiac murmur
• Post-operative CHD Day 1-3 with haemodynamic instability
• Adult with unrepaired or palliated CHD in multiorgan failure
• Neonate on PGE1 with apnoea requiring intubation

Examiners assess:

• Systematic A-E examination recognizing cardiac signs
• Interpretation of echocardiography findings
• Understanding of shunt physiology and Qp:Qs
• Post-operative monitoring and complication recognition
• Family communication regarding prognosis

Second Part Viva:

Expected discussion areas:

• Fetal circulation and ductus arteriosus physiology
• PGE1 pharmacology, dosing, and complications
• Post-operative LCOS pathophysiology and management
• Pulmonary hypertension management in CHD
• Staged palliation for single ventricle (Norwood-Glenn-Fontan)
• Indigenous health access to paediatric cardiac surgery

Common Mistakes

• Not considering CHD in a collapsed neonate (attributed to sepsis alone)
• Giving excessive oxygen to cyanotic CHD (may close ductus in duct-dependent pulmonary flow)
• Not recognizing apnoea as a PGE1 side effect requiring airway management
• Failing to understand Qp:Qs and the balance required post-palliative surgery
• Not knowing the staged surgical approach for single ventricle

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Key Points

Must-Know Facts

1. Incidence and Impact: CHD affects 8-10 per 1,000 live births; approximately 25% are critical CHD requiring intervention in the first year of life. [1]

2. Duct-Dependent Lesions Are Medical Emergencies: Recognition and immediate PGE1 initiation is life-saving. Three categories: duct-dependent pulmonary flow, duct-dependent systemic flow, and duct-dependent mixing. [2]

3. PGE1 (Alprostadil) Dosing: Start 0.01-0.05 mcg/kg/min; higher doses (0.1 mcg/kg/min) for reopening a closing ductus. Key side effects: apnoea (10-20%), hypotension, fever, flushing. [3]

4. Hyperoxia Test: PaO2 >150 mmHg on 100% O2 suggests pulmonary disease; PaO2 <100 mmHg despite 100% O2 suggests cyanotic CHD with fixed right-to-left shunt. [4]

5. Low Cardiac Output Syndrome (LCOS): Peaks 6-18 hours post-CPB. Milrinone prophylaxis (PRIMACORP trial) reduces LCOS by 64% with high-dose regimen. [5]

6. Pulmonary Hypertensive Crisis: Management includes 100% FiO2, hyperventilation (alkalosis), sedation/paralysis, iNO 20 ppm, and sildenafil for iNO weaning. [6]

7. Junctional Ectopic Tachycardia (JET): Common post-cardiac surgery arrhythmia. Treat with cooling to 34-35°C, reduce inotropes, amiodarone if persistent. [7]

8. Chylothorax Post-Fontan: Common complication. Manage with MCT diet, NPO/TPN if severe, octreotide, and thoracic duct ligation if refractory. [8]

9. Staged Single Ventricle Palliation: Norwood (neonatal) → Glenn (4-6 months) → Fontan (2-4 years). Each stage has specific physiological considerations. [9]

10. Adult CHD (GUCH): Growing population with unique challenges including arrhythmias, heart failure, pulmonary hypertension. Eisenmenger syndrome has specific anaesthetic and ICU considerations. [10]

Memory Aids

Mnemonic "DUCT PROBLEMS": Duct-Dependent Lesion Recognition

• D: D-TGA (duct-dependent mixing)
• U: Unobstructed TAPVR (may need atrial septostomy)
• C: Coarctation (critical - duct-dependent systemic)
• T: Tricuspid atresia (duct-dependent pulmonary)
• P: Pulmonary atresia (duct-dependent pulmonary)
• R: Right ventricular hypoplasia (duct-dependent pulmonary)
• O: Obstructed TAPVR (surgical emergency)
• B: Bicuspid aortic valve with critical AS (duct-dependent systemic)
• L: Left heart hypoplasia/HLHS (duct-dependent systemic)
• E: Ebstein anomaly (severe - duct-dependent pulmonary)
• M: Mitral atresia (duct-dependent systemic)
• S: Single ventricle physiology (variable duct dependence)

Mnemonic "APNOEA": PGE1 Side Effects

• A: Apnoea (10-20%, may need intubation)
• P: Pyrexia (fever, mimics sepsis)
• N: Negative inotropy (hypotension)
• O: Oedema (flushing, vasodilation)
• E: Electrolyte issues (hypokalaemia rare)
• A: Apnoea monitoring mandatory

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Definition & Epidemiology

Definition

Congenital Heart Disease (CHD) encompasses structural abnormalities of the heart or intrathoracic great vessels that are present at birth and are of actual or potential functional significance. [11]

Critical CHD is defined as CHD requiring surgery or catheter-based intervention within the first year of life. Approximately 25% of all CHD is critical. [12]

Classification Systems:

Cyanotic CHD (5 Ts):

1. Tetralogy of Fallot (TOF)
2. Transposition of Great Arteries (TGA)
3. Tricuspid Atresia
4. Total Anomalous Pulmonary Venous Return (TAPVR)
5. Truncus Arteriosus

Acyanotic CHD with Increased Pulmonary Blood Flow:

• Ventricular Septal Defect (VSD)
• Atrial Septal Defect (ASD)
• Patent Ductus Arteriosus (PDA)
• Atrioventricular Septal Defect (AVSD)

Acyanotic CHD with Decreased Systemic Blood Flow (Obstructive):

• Coarctation of Aorta (CoA)
• Aortic Stenosis (AS)
• Hypoplastic Left Heart Syndrome (HLHS)
• Interrupted Aortic Arch (IAA)

Epidemiology

International Data:

• Prevalence: 8-10 per 1,000 live births globally [13]
• Critical CHD requiring neonatal intervention: 2-3 per 1,000 live births [14]
• Leading congenital cause of infant mortality: Responsible for ~3% of infant deaths [15]
• Survival to adulthood: >85% of CHD patients now survive to adulthood due to surgical advances [16]

Australian/NZ Data (ANZPIC, State Cardiac Registries):

• Approximately 3,000 babies born with CHD in Australia annually [17]
• Paediatric cardiac surgery centres: Royal Children's Hospital Melbourne, Sydney Children's Hospital Network (Westmead), Lady Cilento Children's Hospital Brisbane, Princess Margaret Hospital Perth, Women's and Children's Hospital Adelaide [18]
• New Zealand: Starship Children's Hospital Auckland is the sole paediatric cardiac surgery centre [19]

Lesion-Specific Incidence (per 10,000 live births):

Risk Factors:

Maternal Factors:

• Diabetes mellitus (3-5x increased risk, especially TGA, VSD, cardiomyopathy) [20]
• Phenylketonuria (uncontrolled)
• Rubella infection (PDA, pulmonary stenosis)
• Systemic lupus erythematosus (congenital heart block)
• Medications: Lithium (Ebstein anomaly), anticonvulsants, retinoids

Genetic Factors:

• Trisomy 21 (Down syndrome): 40-50% have CHD (AVSD most common) [21]
• Trisomy 18 (Edwards syndrome): 90% have CHD
• Turner syndrome (45,XO): Coarctation, bicuspid aortic valve
• DiGeorge syndrome (22q11 deletion): Truncus arteriosus, interrupted aortic arch, TOF
• Noonan syndrome: Pulmonary stenosis, HCM
• Williams syndrome: Supravalvular aortic stenosis

High-Risk Populations:

• Aboriginal and Torres Strait Islander children: Access disparities to paediatric cardiac surgery; remote communities face significant retrieval challenges [22]
• Māori children: Higher rates of rheumatic heart disease but similar CHD rates [23]
• Rural/remote populations: Delayed diagnosis due to lack of paediatric cardiology expertise

Outcomes by Lesion:

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Applied Basic Sciences

Fetal Circulation

Key Features of Fetal Circulation [24]:

The fetal circulation operates as a parallel circuit with three critical shunts that bypass the non-functioning lungs:

1. Ductus Venosus: Shunts oxygenated blood from the umbilical vein directly to the IVC, bypassing the liver

2. Foramen Ovale: Right-to-left shunt from RA to LA, allowing oxygenated blood from the IVC to reach the systemic circulation

3. Ductus Arteriosus: Shunts blood from the PA to the descending aorta, bypassing the high-resistance pulmonary circulation

Fetal Oxygen Saturations:

• Umbilical vein (from placenta): 80-85%
• Ascending aorta (to brain): 65-70%
• Descending aorta: 55-60%
• Pulmonary artery: 55-60%

Fetal Haemodynamics:

• Pulmonary vascular resistance (PVR): Very high due to hypoxic vasoconstriction and fluid-filled lungs
• Systemic vascular resistance (SVR): Low due to placental circulation
• Pulmonary blood flow: Only 5-10% of combined ventricular output
• Right ventricle dominance: RV contributes ~60% of combined cardiac output

Transition at Birth [25]

The transition from fetal to neonatal circulation involves dramatic physiological changes triggered by:

1. First Breath and Lung Expansion:

   • Lung aeration replaces fluid with air
   • PaO2 rises from 25-30 mmHg to 70-100 mmHg
   • PVR drops dramatically (by 80%) within minutes
   • Pulmonary blood flow increases 8-10 fold

2. Cord Clamping:

   • Removal of low-resistance placental circuit
   • SVR increases abruptly
   • Loss of placenta eliminates prostaglandin source

3. Foramen Ovale Closure:

   • Increased pulmonary venous return raises LA pressure
   • Decreased IVC flow reduces RA pressure
   • When LA pressure > RA pressure, septum primum opposes septum secundum
   • Functional closure within minutes; anatomical fusion over months

4. Ductus Arteriosus Closure:

   • Rising PaO2 inhibits voltage-gated K+ channels in ductal smooth muscle
   • Ca2+ influx causes ductal constriction
   • Falling prostaglandin E2 levels remove dilatory stimulus
   • Functional closure: 12-72 hours in term infants
   • Anatomical closure: 2-3 weeks (ligamentum arteriosum)

Implications for Critical CHD:

• Infants dependent on ductal patency will deteriorate as the ductus closes
• This typically occurs between Day 2-14 of life
• Presentation depends on which circulation is duct-dependent

Shunt Physiology

Qp:Qs Ratio [26]:

The ratio of pulmonary blood flow (Qp) to systemic blood flow (Qs) is fundamental to understanding CHD haemodynamics.

Calculating Qp:Qs:

Qp:Qs = (SaO2 - SvO2) / (PvO2 - PaO2)

Where:
- SaO2 = Systemic arterial O2 saturation
- SvO2 = Mixed venous O2 saturation
- PvO2 = Pulmonary venous O2 saturation (assumed 100% if lungs normal)
- PaO2 = Pulmonary arterial O2 saturation

Interpretation:

Left-to-Right Shunts (VSD, ASD, PDA, AVSD):

• Blood flows from high-pressure left heart to low-pressure right heart
• Results in pulmonary overcirculation
• Symptoms: Heart failure, failure to thrive, recurrent respiratory infections
• Longstanding uncorrected → pulmonary vascular disease → Eisenmenger syndrome

Right-to-Left Shunts (TOF, Pulmonary atresia, Tricuspid atresia):

• Deoxygenated blood enters systemic circulation
• Results in cyanosis
• Dependent on adequate pulmonary blood flow through alternative pathway (PDA, collaterals)

Mixing Lesions (TGA, Single ventricle, Truncus arteriosus):

• Complete mixing of oxygenated and deoxygenated blood
• Systemic saturation depends on degree of mixing
• May be duct-dependent for adequate mixing

Duct-Dependent Lesions

Classification by Duct Dependence [27]:

Prostaglandin E1 (Alprostadil) [28]:

Critical Pearl: Apnoea is the most significant side effect. Have intubation equipment at bedside and lower threshold for elective intubation before retrieval.

Pharmacology

Milrinone [29]:

Inhaled Nitric Oxide (iNO) [30]:

Sildenafil [31]:

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Clinical Presentation

ICU Admission Scenarios

Scenario 1: Cyanotic Neonate ("Blue Baby") [32]

• History: Term neonate, Day 2-3 of life, feeding difficulties, noted to be "dusky"
• Examination: Central cyanosis, SpO2 75-85% on room air, minimal respiratory distress, soft systolic murmur or no murmur
• Differential: TGA (most common), TOF, Tricuspid atresia, TAPVR, Truncus arteriosus, PPHN
• Key Feature: Cyanosis out of proportion to respiratory distress

Scenario 2: Collapsed Neonate with Shock [33]

• History: Well at birth, Day 5-10 of life, sudden deterioration with poor feeding, mottled, lethargic
• Examination: Grey, mottled, poor perfusion, absent femoral pulses, upper > lower BP difference, hepatomegaly
• Differential: Critical coarctation, HLHS, Interrupted aortic arch, Critical AS
• Key Feature: Shock coincides with ductal closure; easily mistaken for sepsis

Scenario 3: Infant with Heart Failure

• History: 4-6 week old, failure to thrive, sweating with feeds, tachypnoea
• Examination: Tachypnoea, hepatomegaly, loud pansystolic murmur, bounding pulses
• Differential: Large VSD, PDA, AVSD, Truncus arteriosus
• Key Feature: Left-to-right shunt causing pulmonary overcirculation

Scenario 4: Post-Operative CHD Repair

• History: Day 1-3 post-cardiac surgery, progressive haemodynamic instability
• Examination: Low cardiac output signs (cool peripheries, oliguria, rising lactate)
• Issues: LCOS, JET, pulmonary hypertensive crisis, residual lesion, bleeding
• Key Feature: LCOS peaks 6-18 hours post-CPB; JET common after VSD, TOF repair

Symptoms & Signs

A - Airway:

• Usually patent unless severe heart failure with upper airway oedema
• May have associated syndromes affecting airway (22q11 deletion, Down syndrome)

B - Breathing:

• Cyanotic CHD: Cyanosis without significant respiratory distress ("happy blue baby")
• Acyanotic CHD with L→R shunt: Tachypnoea, increased work of breathing, pulmonary oedema
• Critical obstruction: Pulmonary oedema (LV failure), may be minimal if duct-dependent

C - Circulation:

D - Disability:

• Usually normal GCS unless severe hypoxia or cardiogenic shock
• Irritability may indicate hypoxia or pain

E - Exposure:

• Dysmorphic features: Suggest syndromic association (Down, DiGeorge, Noonan)
• Midline sternotomy scar: Previous cardiac surgery
• BT shunt murmur: Continuous murmur in infraclavicular area

Specific Presentations

Hypercyanotic Spell (Tet Spell) in TOF [34]:

A hypercyanotic spell is a paroxysmal increase in cyanosis due to acute increase in right-to-left shunting across the VSD.

Mechanism:

1. Infundibular spasm (dynamic RVOT obstruction) → reduced pulmonary blood flow
2. Decreased SVR (crying, straining, dehydration) → increased R→L shunt
3. Hypoxia → acidosis → further infundibular spasm → vicious cycle

Clinical Features:

• Paroxysmal cyanosis with irritability
• Hyperpnoea (rapid, deep breathing)
• Limpness, syncope, seizures in severe cases
• May occur on waking, with crying, feeding, fever

Immediate Management:

1. Calm the child, knee-chest position (increases SVR)
2. Oxygen (though limited benefit if fixed shunt)
3. IV access, fluid bolus (10-20 mL/kg)
4. Morphine 0.1-0.2 mg/kg IV (reduces catecholamines, sedation)
5. Phenylephrine 2-10 mcg/kg bolus (alpha-1 agonist, increases SVR)
6. Beta-blocker (Esmolol 100-500 mcg/kg bolus, or Propranolol 0.1 mg/kg IV) - reduces infundibular spasm
7. Ketamine 1-2 mg/kg (increases SVR, sedation)
8. Sodium bicarbonate for acidosis
9. Urgent surgical repair if spells recurrent

Differential Diagnosis

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Investigations

Laboratory Investigations

Arterial Blood Gas [35]:

• Cyanotic CHD: PaO2 <100 mmHg despite 100% FiO2 (positive hyperoxia test)
• LCOS post-surgery: Metabolic acidosis, elevated lactate, low SvO2
• Pulmonary overcirculation: May have mild respiratory alkalosis initially

Hyperoxia Test Protocol:

1. Obtain pre-ductal (right radial) ABG on room air
2. Administer 100% FiO2 for 10-15 minutes via headbox or ETT
3. Repeat ABG

Caution: In duct-dependent pulmonary flow lesions, prolonged high FiO2 may accelerate ductal closure.

Blood Tests:

• FBC: Polycythaemia (chronic cyanosis), anaemia (dilutional in L→R shunts)
• UEC: Renal function (may be impaired in shock, post-CPB)
• LFT: Hepatic congestion in right heart failure
• Coagulation: Post-CPB coagulopathy, anticoagulation monitoring
• Lactate: Serial measurements for LCOS monitoring
• BNP/NT-proBNP: Elevated in heart failure, useful for monitoring
• Troponin: May be elevated post-surgery, useful in LCOS assessment

Imaging

Chest X-Ray [36]:

Pulmonary Vascularity on CXR:

• Increased: L→R shunts (VSD, PDA, AVSD)
• Decreased: R→L shunts with reduced pulmonary flow (TOF, pulmonary atresia)
• Normal to Decreased with Pulmonary Oedema: TAPVR with obstruction, critical mitral stenosis

Echocardiography [37]:

The GOLD STANDARD for CHD diagnosis

CT Angiography:

• Useful for extracardiac anatomy: Aortic arch anomalies, pulmonary artery anatomy, collateral vessels
• Pre-operative planning for complex repairs

Cardiac MRI:

• Gold standard for quantification of shunts, ventricular volumes, valve regurgitation
• Assessment of post-operative RVOT anatomy (TOF repair follow-up)
• Limited in unstable ICU patients

ECG Patterns

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ICU Management

Pre-Operative Stabilization

Goals [38]:

1. Maintain ductal patency (PGE1 if duct-dependent)
2. Optimize oxygen delivery while avoiding excessive pulmonary blood flow
3. Maintain acid-base balance
4. Prevent end-organ injury
5. Achieve adequate sedation/analgesia for transport

PGE1 Management:

Starting Dose: 0.01-0.05 mcg/kg/min
- Lower doses often effective once duct open
- Higher doses (0.1 mcg/kg/min) for reopening closing duct

Monitoring:
- Continuous SpO2 and respiratory monitoring (apnoea)
- Regular blood pressure (hypotension)
- Temperature (fever common)
- Ductal patency confirmation on echo

Airway Preparation:
- Intubation equipment at bedside at all times
- Low threshold for elective intubation before retrieval
- Consider intubation if: >2 apnoeas, FiO2 requirement >0.6, shock

Oxygen Strategy:

Fluid and Inotrope Support:

• Cautious fluid resuscitation (10 mL/kg boluses)
• Avoid aggressive fluid loading in duct-dependent systemic lesions (worsens pulmonary overcirculation)
• Consider low-dose inotrope (dopamine 3-5 mcg/kg/min) if perfusion poor

Post-Operative ICU Management

Initial Post-CPB Period [39]:

A - Airway:

• Remain intubated until haemodynamically stable
• ETT position confirmed (post-sternotomy CXR)

B - Breathing:

• Lung-protective ventilation: Vt 6-8 mL/kg, PEEP 5-8 cmH2O
• Target normoxia and normocarbia (unless PHT management)
• Avoid high FiO2 in single ventricle physiology (balanced circulation)

C - Circulation:

Anticipate Low Cardiac Output Syndrome (LCOS) [40]:

LCOS peaks 6-18 hours post-CPB due to:

• Myocardial oedema from CPB
• Inflammatory response (systemic inflammatory response to bypass)
• Reperfusion injury
• Myocardial stunning
• Temperature and electrolyte fluctuations

LCOS Recognition:

• Rising lactate (>2 mmol/L or increasing trend)
• Decreasing mixed venous saturation (<60%)
• Oliguria (<1 mL/kg/hr)
• Poor peripheral perfusion (cool extremities, prolonged CRT)
• Widening core-peripheral temperature gap (>2°C)
• Metabolic acidosis
• Hypotension (late sign)

LCOS Management:

1. Optimise Preload:
   - Maintain appropriate filling (guided by LA/RA pressures)
   - Volume resuscitation if hypovolaemic
   - Consider pacing if bradycardic

2. Reduce Afterload:
   - Milrinone (first-line inodilator)
   - Sodium nitroprusside
   - Target MAP appropriate for age

3. Inotropic Support:
   - Milrinone 0.25-0.75 mcg/kg/min (PRIMACORP prophylaxis)
   - Adrenaline 0.01-0.1 mcg/kg/min
   - Dopamine 5-10 mcg/kg/min (limited role)

4. Consider Mechanical Support:
   - ECMO (VA-ECMO) for refractory LCOS
   - Early escalation if poor response to maximal therapy

Specific Surgical Considerations:

Stage 1 Norwood Procedure (HLHS) [41]:

Glenn Procedure (Stage 2) [42]:

• Superior vena cava to pulmonary artery anastomosis
• Passive pulmonary blood flow (no subpulmonary pump)
• PVR must be low for adequate oxygenation
• Target: SpO2 75-85%, low PEEP, early extubation beneficial
• Head position neutral/elevated (SVC drainage)

Fontan Procedure (Stage 3) [43]:

• Total cavopulmonary connection
• Systemic venous return flows passively to lungs
• Critically dependent on low PVR, good ventricular function, low CVP
• Common complications: Prolonged pleural effusions, chylothorax
• Target: Early extubation, spontaneous breathing preferred, low PEEP

Arrhythmia Management

Junctional Ectopic Tachycardia (JET) [44]:

JET is the most common arrhythmia after paediatric cardiac surgery, especially repairs involving the conduction system (VSD, TOF, AVSD).

Recognition:

• Narrow complex tachycardia (150-250 bpm)
• AV dissociation (P waves "march through" QRS)
• Rates exceed the child's normal sinus rate
• Warm peripheries, bounding pulses (high output state initially)

Management Algorithm:

Step 1: Reduce Triggers
- Decrease catecholamines (wean/stop dopamine, adrenaline)
- Correct electrolytes (K+ 4.0-4.5, Mg 1.0-1.2, iCa normal)
- Treat fever aggressively
- Optimise sedation

Step 2: Active Cooling
- Target 34-35°C core temperature
- Surface cooling initially
- Avoid shivering (ensure adequate sedation/paralysis)

Step 3: Pharmacological
- Amiodarone 5 mg/kg IV over 1 hour, then 5-10 mcg/kg/min
- Procainamide (alternative)

Step 4: Atrial Pacing
- If atrial pacing wires present
- Overdrive pace the atrium faster than JET rate
- Restores AV synchrony and improves cardiac output

Pulmonary Hypertensive Crisis

Pulmonary Hypertensive Crisis Management [45]:

A pulmonary hypertensive crisis occurs when pulmonary artery pressure acutely exceeds systemic pressure, causing right ventricular failure and cardiovascular collapse.

Risk Factors:

• Post-operative (AVSD, VSD with pre-operative PHT, TAPVR)
• Pre-existing pulmonary vascular disease
• Triggers: Suctioning, pain, hypoxia, hypercarbia, acidosis

Recognition:

• Sudden desaturation
• Systemic hypotension
• Rising CVP/RA pressure
• Decreasing LA pressure
• Bradycardia (preterminal)

Immediate Management Protocol:

1. 100% FiO2 (potent pulmonary vasodilator)

2. Hand Ventilation (if intubated)
   - Increase minute ventilation
   - Target hyperventilation (PaCO2 30-35 mmHg, pH 7.45-7.55)

3. Deepen Sedation
   - Fentanyl/midazolam boluses
   - Neuromuscular blockade

4. Inhaled Nitric Oxide
   - Start 20 ppm immediately
   - Can increase to 40 ppm if needed

5. Correct Precipitants
   - Suction briefly if secretions
   - Treat acidosis (NaHCO3)
   - Correct hypoglycaemia, hypothermia

6. Inotropic Support for RV
   - Adrenaline (inotrope)
   - Milrinone (reduces PVR)
   - Avoid systemic vasodilators initially

7. If Refractory
   - IV sildenafil
   - ECMO (VA-ECMO)

Prevention:

• Adequate sedation and analgesia
• Avoid suctioning in high-risk period
• Preoxygenate before any airway intervention
• Wean iNO slowly (add sildenafil before weaning)

Chylothorax Management

Chylothorax After Cardiac Surgery [46]:

Chylothorax occurs due to thoracic duct injury, especially in Fontan patients (high CVP impairs lymphatic drainage).

Diagnosis:

• Milky pleural effusion (if enteral feeds)
• Pleural fluid: Triglycerides >1.1 mmol/L, lymphocyte predominant
• May be serous if NPO

Step-wise Management:

Step 1: Conservative (2-4 weeks)
- NPO with TPN
- OR MCT-only diet (bypasses lymphatics)
- Chest drain for symptomatic effusions
- Monitor immunoglobulin levels (lymphocyte loss → immunodeficiency)

Step 2: Pharmacological
- Octreotide 1-4 mcg/kg/hr IV or SC
  (reduces splanchnic blood flow and lymph production)
- Monitor glucose (hyperglycaemia), thyroid function

Step 3: Interventional (if refractory 2-4 weeks)
- Thoracic duct ligation (surgical)
- Thoracic duct embolization (interventional radiology)
- Chemical pleurodesis (povidone-iodine)

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Adult Congenital Heart Disease (ACHD/GUCH)

Overview [47]

Grown-Up Congenital Heart Disease (GUCH) represents a rapidly expanding patient population due to improved surgical outcomes.

Key Considerations:

• More adults with CHD than children in developed countries
• Complex physiology often not understood by general ICU staff
• Require specialist ACHD centre involvement

Eisenmenger Syndrome

Definition: Reversal of an initially left-to-right shunt to right-to-left due to pulmonary vascular disease, resulting in cyanosis.

Pathophysiology:

1. Large unrepaired L→R shunt (VSD, PDA, AVSD)
2. Chronic pulmonary overcirculation
3. Pulmonary vascular remodelling (medial hypertrophy, intimal fibrosis)
4. PVR eventually exceeds SVR
5. Shunt reverses → R→L → cyanosis

Clinical Features:

• Chronic cyanosis, clubbing
• Polycythaemia (Hct 55-75%)
• Haemoptysis
• Paradoxical emboli (stroke, brain abscess)
• Right heart failure
• Arrhythmias

ICU Considerations:

1. Maintain SVR (avoid vasodilators, anaesthetic hypotension)
2. Avoid pulmonary vasoconstrictors (hypoxia, hypercarbia, acidosis)
3. Aggressive hydration (polycythaemia increases viscosity)
4. VTE prophylaxis controversial (risk of haemorrhage vs thrombosis)
5. Air embolism precautions (meticulous IV line care)
6. Pregnancy: 30-50% maternal mortality (contraindicated)
7. Do NOT attempt to repair at this stage (irreversible PVD)

Pregnancy in CHD

High-Risk Lesions (WHO Class III-IV, pregnancy discouraged or contraindicated) [48]:

• Eisenmenger syndrome (maternal mortality 30-50%)
• Severe pulmonary hypertension
• Severe systemic ventricular dysfunction (EF <30%)
• Fontan circulation with complications
• Severe aortic coarctation
• Severe symptomatic aortic stenosis
• Marfan syndrome with aortic root >45mm

Management Principles:

• Multidisciplinary team (Obstetrics, Cardiology, Anaesthesia, ICU)
• Tertiary centre with ACHD expertise
• Planned delivery with careful haemodynamic monitoring
• Regional anaesthesia preferred if tolerated (avoid sudden SVR drop)

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Prognosis & Outcome Measures

Mortality by Lesion

Prognostic Factors

Good Prognostic Factors:

• Simple lesion with complete repair
• Early surgical correction before complications
• Good ventricular function
• No pulmonary vascular disease
• High-volume surgical centre
• No associated syndromes

Poor Prognostic Factors:

• Single ventricle physiology
• Delayed diagnosis with end-organ injury
• Pre-operative shock or acidosis
• Low birth weight (<2.5 kg)
• Prematurity
• Associated genetic syndromes
• Low surgical centre volume
• Pulmonary vascular disease
• Post-operative ECMO requirement

Australian CHD Surgical Centres

Paediatric Cardiac Surgery Centres in Australia [49]:

• Royal Children's Hospital Melbourne
• Sydney Children's Hospital Network (Westmead)
• Queensland Children's Hospital (Lady Cilento) Brisbane
• Perth Children's Hospital
• Women's and Children's Hospital Adelaide

New Zealand:

• Starship Children's Hospital Auckland (sole centre)

Retrieval Considerations:

• State-based retrieval services coordinate transfer (NETS NSW, PIPER Victoria, RSQ Queensland)
• RFDS for remote areas
• PGE1 must be maintained during transport
• Consider intubation before retrieval if apnoea or unstable

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Children [50]:

• Similar CHD incidence but higher prevalence of acquired heart disease (rheumatic)
• Significant barriers to accessing tertiary cardiac surgery centres
• Remote communities may have delayed diagnosis
• Cultural considerations for family involvement in decision-making
• Aboriginal Health Workers (AHWs) and Aboriginal Liaison Officers (ALOs) involvement essential
• Language barriers may require interpreter services
• Extended family involvement in care decisions

Māori Children (New Zealand):

• Similar access challenges for those outside Auckland
• Higher rates of rheumatic heart disease
• Whānau (family) involvement in care decisions
• Māori Health Workers should be involved

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SAQ Practice

SAQ 1: Neonate with Coarctation

Time Allocation: 10 minutes
Total Marks: 20

Stem: A 7-day-old term neonate presents to the Emergency Department with sudden deterioration. The parents report poor feeding and irritability for 24 hours. The infant was well at birth with no concerns noted at the newborn examination.

Observations on arrival:

• HR: 180 bpm
• BP (right arm): 65/40 mmHg
• RR: 60/min
• SpO2: 88% (room air)
• Temperature: 35.8°C

Examination:

• Mottled, grey, lethargic infant
• Weak femoral pulses bilaterally
• Brachial pulses palpable but weak
• Hepatomegaly 3cm below costal margin
• Gallop rhythm on auscultation
• Cool peripheries, capillary refill 5 seconds

ABG (room air):

• pH: 7.18
• PaCO2: 32 mmHg
• PaO2: 58 mmHg
• HCO3: 12 mmol/L
• Lactate: 9.2 mmol/L

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Question 1.1 (8 marks)

What is the most likely diagnosis and outline your immediate resuscitation in the first 60 minutes.

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Question 1.2 (6 marks)

Describe the pathophysiology of this condition and explain why the infant was well at birth.

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Question 1.3 (6 marks)

Discuss the specific management of Prostaglandin E1 in this infant, including dosing, monitoring, and potential complications.

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Model Answer SAQ 1

Question 1.1 (8 marks total)

Most Likely Diagnosis (2 marks):

• Critical coarctation of the aorta (or duct-dependent systemic circulation lesion)
• Differential includes HLHS, interrupted aortic arch, critical aortic stenosis

Immediate Resuscitation (6 marks):

A - Airway (1 mark):

• Prepare for intubation (PGE1 causes apnoea)
• Lower threshold for early intubation given shock state

B - Breathing (1 mark):

• High-flow oxygen initially
• Intubate and ventilate if deteriorating or requiring PGE1
• Avoid hyperventilation (may worsen pulmonary overcirculation)

C - Circulation (3 marks):

• IV/IO access immediately
• PGE1 0.05-0.1 mcg/kg/min - to reopen ductus arteriosus (life-saving)
• Fluid resuscitation: 10 mL/kg crystalloid bolus (cautious - avoid pulmonary oedema)
• Inotropic support: Dopamine 5-10 mcg/kg/min or Adrenaline 0.05-0.1 mcg/kg/min
• Correct acidosis: Consider sodium bicarbonate 1-2 mmol/kg if pH <7.1

D - Disability (0.5 marks):

• Blood glucose check and correction

E - Everything Else (0.5 marks):

• Temperature management (warm)
• Urgent echocardiography
• Notify paediatric cardiac surgery centre for retrieval

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Question 1.2 (6 marks total)

Pathophysiology of Critical Coarctation (4 marks):

Critical coarctation is a severe narrowing of the aortic isthmus (typically opposite the ductus arteriosus) causing obstruction to systemic blood flow.

Why well at birth (2 marks):

1. In utero, the ductus arteriosus was patent, allowing blood from the pulmonary artery to bypass the coarctation and perfuse the descending aorta
2. The lower body received adequate blood flow via right-to-left ductal flow
3. As the ductus begins to close postnatally (typically Day 2-10), systemic perfusion to the lower body is compromised
4. The left ventricle faces acute pressure overload trying to push blood through the coarctation
5. LV failure ensues → pulmonary oedema → cardiogenic shock

The timing of presentation coincides with ductal closure.

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Question 1.3 (6 marks total)

PGE1 (Alprostadil) Management (6 marks):

Dosing (2 marks):

• Initial dose: 0.05-0.1 mcg/kg/min (higher dose for reopening closing ductus)
• Once ductus open and stable: Titrate to lowest effective dose (0.01-0.02 mcg/kg/min)
• Continuous IV infusion via dedicated line

Monitoring (2 marks):

• Continuous respiratory monitoring for apnoea
• Continuous SpO2 and BP
• Temperature monitoring (fever common)
• Echocardiography to confirm ductal patency
• Serial lactate and acid-base status

Complications (2 marks):

• Apnoea: 10-20% of neonates; higher with higher doses and younger gestational age
  • "Management: Be prepared to intubate; consider elective intubation before retrieval"
• Hypotension: Due to systemic vasodilation
  • "Management: Cautious fluid bolus, inotrope support"
• Fever/Flushing: Common; must differentiate from sepsis
• Seizures: Rare
• Long-term use complications: Cortical hyperostosis, gastric outlet obstruction (antral hyperplasia) if used for weeks

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SAQ 2: Post-Norwood Management

Time Allocation: 10 minutes
Total Marks: 20

Stem: A 5-day-old infant with hypoplastic left heart syndrome (HLHS) is Day 1 post-Stage 1 Norwood procedure with a Sano shunt. The surgery was uncomplicated with cardiopulmonary bypass time of 180 minutes.

Current Status:

• Ventilated via oral ETT
• Sedated with fentanyl and midazolam infusions
• Arterial line in place showing BP 55/35 mmHg, MAP 42 mmHg
• LA line pressure: 8 mmHg
• RA line pressure: 10 mmHg
• SpO2: 82%

Observations:

• HR: 170 bpm (AV sequential pacing at 150, sensing native rhythm at 170)
• Current SpO2: 82%
• Temperature: 36.8°C
• Urine output last 4 hours: 0.3 mL/kg/hr

ABG (FiO2 0.30):

• pH: 7.28
• PaCO2: 42 mmHg
• PaO2: 45 mmHg
• HCO3: 19 mmol/L
• Lactate: 4.8 mmol/L (was 2.1 at end of surgery)
• SvO2: 52%

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Question 2.1 (8 marks)

Describe the expected physiology post-Norwood with a Sano shunt and identify the concerns with this infant's current status.

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Question 2.2 (6 marks)

Outline your management approach for this infant over the next 6 hours.

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Question 2.3 (6 marks)

If the infant continues to deteriorate despite maximal medical management, discuss the indications for and principles of ECMO in this setting.

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Model Answer SAQ 2

Question 2.1 (8 marks total)

Post-Norwood Physiology with Sano Shunt (4 marks):

The Stage 1 Norwood creates:

1. Neo-aorta: Right ventricle → neo-aorta → systemic circulation (RV is the systemic ventricle)
2. Atrial septectomy: Unobstructed pulmonary venous return to the single ventricle
3. Sano shunt: RV-to-PA conduit providing pulmonary blood flow (alternative: BT shunt)

Expected Physiology:

• Single ventricle parallel circulation
• Pulmonary and systemic circulations in parallel (not series)
• Target Qp:Qs = 1:1 (balanced circulation)
• Target SpO2: 75-85% (indicates balanced Qp:Qs)
• SvO2 should be 55-65% in balanced state

Current Concerns (4 marks):

Interpretation: This infant has Low Cardiac Output Syndrome (LCOS)

• Rising lactate with falling SvO2 indicates inadequate systemic oxygen delivery
• This is occurring at the expected LCOS peak (6-18 hours post-CPB)
• Relatively "good" SpO2 (82%) with low SvO2 suggests Qp:Qs may be too high (pulmonary overcirculation at expense of systemic flow)

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Question 2.2 (6 marks total)

Management Approach (6 marks):

Optimize Preload (1 mark):

• LA pressure 8, RA pressure 10 mmHg suggests adequate filling
• Small volume challenge (5 mL/kg) if concerned about hypovolaemia
• Avoid volume overload

Reduce Afterload / Inotropic Support (2 marks):

• Milrinone: Increase infusion to 0.5-0.75 mcg/kg/min (reduces SVR and PVR, improves contractility)
• Consider adding low-dose adrenaline (0.03-0.05 mcg/kg/min) if BP remains low

Optimize Qp:Qs Balance (2 marks): The SpO2 is 82% (high end) but SvO2 is low → suggests pulmonary overcirculation stealing from systemic flow

• Increase FiO2 cautiously - DO NOT increase; current FiO2 0.30 is appropriate
• Allow permissive hypercarbia (PaCO2 45-50) to increase PVR and reduce pulmonary blood flow
• Consider reducing PEEP if high (increases intrathoracic pressure, reduces venous return)

Address Acidosis (0.5 marks):

• Sodium bicarbonate if pH <7.20 and worsening

Investigate for Complications (0.5 marks):

• Echocardiography: Assess ventricular function, shunt patency, neo-aortic arch obstruction
• Consider bleeding, tamponade, residual lesion

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Question 2.3 (6 marks total)

ECMO Indications Post-Norwood (3 marks):

Indications for ECMO:

• Refractory LCOS despite maximal medical management
• Cardiac arrest (E-CPR)
• Persistent lactataemia with end-organ dysfunction
• Hypotension unresponsive to inotropes and afterload reduction
• Inability to wean from CPB in OR

Specific criteria often include:

• Lactate >6-8 mmol/L and rising despite intervention
• SvO2 <40% despite optimization
• Vasopressor requirement: Adrenaline >0.2 mcg/kg/min equivalent
• pH <7.15 refractory to treatment

Principles of ECMO in Norwood (3 marks):

Mode: VA-ECMO (veno-arterial) - provides cardiac and respiratory support

Cannulation:

• Central cannulation (via sternotomy if chest still open)
• Arterial: Ascending aorta or neo-aorta
• Venous: Right atrial appendage

Specific Considerations:

• Target flows 100-150 mL/kg/min initially
• Maintain low SVR (milrinone continues)
• Ensure Sano shunt patency (pulmonary blood flow still needed)
• May need to control shunt flow to avoid pulmonary overcirculation
• Anticoagulation: Heparin (higher ACT targets post-CPB with coagulopathy)
• Monitor for LV distension (may need atrial septostomy or LA venting)
• Bridge to recovery (majority) or transplant listing (rare)

Outcomes:

• ECMO after Norwood has survival to discharge of approximately 40-50%
• Lower survival than ECMO for other cardiac surgery

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Viva Scenarios

Viva Scenario 1: PGE1 Complications

Stem: "You are the ICU registrar. A 3-day-old neonate with suspected critical congenital heart disease has been commenced on Prostaglandin E1 (alprostadil) at 0.05 mcg/kg/min in the Emergency Department 2 hours ago. The infant is now en route to your tertiary ICU for echocardiography and further management. The retrieval team calls to report the infant has had 3 apnoeic episodes in the last 30 minutes."

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Opening Question: "What are your immediate concerns and how would you advise the retrieval team?"

Expected Answer (2-3 minutes):

Immediate concerns:

1. Apnoea is a known side effect of PGE1 - occurs in 10-20% of neonates, more common at higher doses and younger gestational age
2. The infant is at significant risk of further apnoea and potential respiratory arrest during transport
3. The PGE1 cannot be stopped as the infant is duct-dependent (stopping will cause deterioration)

Advice to retrieval team:

1. Recommend intubation before continuing transport
   • This provides airway protection and controlled ventilation
   • Allows safe continuation of PGE1
2. If intubation not possible immediately:
   • Ensure bag-mask ventilation equipment ready
   • Continuous monitoring
   • Consider reducing PGE1 dose to 0.02-0.03 mcg/kg/min (but not stopping)
3. Ensure adequate IV access for PGE1 (cannot be interrupted)
4. Continue transport once airway secured

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Follow-up Question 1: "The retrieval team elects to intubate. What are your considerations for RSI in this neonate?"

Expected Answer:

Pre-oxygenation:

• Difficult in neonates (small FRC, high O2 consumption)
• 100% FiO2 via face mask or bag-mask (avoid positive pressure until ready)

Induction agents:

• Propofol: Avoid or use minimal dose (profound hypotension in sick neonate)
• Ketamine 2 mg/kg IV: Preferred - maintains SVR and BP
• Fentanyl 2-5 mcg/kg IV: For analgesia, blunts intubation response

Muscle relaxant:

• Rocuronium 1 mg/kg IV: Preferred in neonates
• Suxamethonium relatively contraindicated (hyperkalaemia risk, bradycardia)

Atropine:

• 20 mcg/kg IV pretreatment (vagolytic - prevents reflex bradycardia)

Post-intubation:

• Confirm placement (auscultation, CO2 detection, CXR)
• Low ventilator settings (Vt 5-7 mL/kg, PEEP 4-5)
• Avoid hyperoxia in duct-dependent pulmonary flow lesions

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Follow-up Question 2: "The infant has a fever of 38.2°C. How do you interpret this and what would you do?"

Expected Answer:

Fever on PGE1:

• PGE1 commonly causes fever (affects hypothalamic temperature set point)
• This is a well-recognized side effect
• However, must also consider sepsis (sick neonate)

Approach:

1. Don't stop PGE1 for fever alone
2. Clinical assessment for other signs of sepsis (perfusion, WCC, CRP)
3. Blood cultures (if not already taken)
4. Broad-spectrum antibiotics (ceftriaxone or ampicillin + gentamicin) - empiric treatment if any suspicion
5. External cooling for comfort if temperature very high

Key Point: The differential between PGE1-induced fever and sepsis can be challenging. In a sick neonate, sepsis screen and empiric antibiotics are appropriate while continuing PGE1.

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Viva Scenario 2: Pulmonary Hypertensive Crisis

Stem: "A 4-month-old infant is Day 1 post-complete AVSD repair. The infant had pre-operative pulmonary hypertension with PA pressures estimated at 60% systemic. During routine tracheal suctioning, the infant suddenly desaturates from SpO2 92% to 50%, becomes bradycardic to 60 bpm, and the arterial line shows BP falling from 65/40 to 35/20 mmHg."

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Opening Question: "What is the most likely diagnosis and what are your immediate actions?"

Expected Answer (2-3 minutes):

Most Likely Diagnosis: Pulmonary Hypertensive Crisis

Precipitated by tracheal suctioning in a patient with pre-existing pulmonary hypertension.

Immediate Actions (in order):

1. STOP SUCTIONING immediately

2. 100% FiO2 - maximize oxygen delivery, pulmonary vasodilation

3. Hand ventilate with 100% O2

   • Assess bilateral air entry
   • Hyperventilate gently to induce respiratory alkalosis (pH 7.45-7.55)
   • Target PaCO2 30-35 mmHg

4. Call for help - senior assistance, prepare drugs

5. Deepen sedation

   • Fentanyl bolus 2-5 mcg/kg
   • Midazolam bolus 0.1 mg/kg
   • Consider neuromuscular blockade (rocuronium)

6. Inhaled Nitric Oxide

   • Start 20 ppm immediately
   • Selective pulmonary vasodilator

7. Inotropic support

   • Adrenaline bolus 1-2 mcg/kg if bradycardia/peri-arrest
   • Start or increase adrenaline infusion

8. Correct metabolic acidosis

   • Sodium bicarbonate 1-2 mmol/kg if severe acidosis

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Follow-up Question 1: "The infant responds to 100% O2, hyperventilation, sedation, and iNO 20 ppm. SpO2 improves to 88% and BP to 55/35. What are your ongoing management priorities?"

Expected Answer:

Ongoing Management:

1. Prevention of further episodes:

   • Maintain deep sedation (possibly paralysis for 24-48 hours)
   • Minimize stimulation (cluster care)
   • Preoxygenate before any airway intervention
   • Use closed suction system

2. iNO management:

   • Continue at 20 ppm
   • Wean slowly when stable (reduce by 5 ppm increments)
   • Sildenafil should be started before attempting iNO wean (prevents rebound PHT)

3. Optimize oxygenation and ventilation:

   • Maintain SpO2 >90%
   • Mild hyperventilation (PaCO2 35-40 mmHg)
   • Avoid atelectasis (adequate PEEP)

4. Haemodynamic support:

   • Milrinone (reduces PVR)
   • Adrenaline if needed for RV support
   • Maintain adequate preload

5. Monitor for residual lesion:

   • Echocardiography to assess AVSD repair, PA pressures, ventricular function
   • Residual shunt may contribute to ongoing PHT

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Follow-up Question 2: "Why is this infant at high risk of pulmonary hypertensive crises?"

Expected Answer:

Risk Factors in this Patient:

1. Pre-operative pulmonary hypertension:

   • PA pressure 60% systemic pre-op indicates established pulmonary vascular disease
   • Even after successful repair, the pulmonary vasculature remains hyperreactive

2. AVSD physiology:

   • Large left-to-right shunt with pulmonary overcirculation
   • Months of high pulmonary blood flow causes vascular remodelling
   • The younger the patient at repair, the more reversible the PHT

3. Post-cardiopulmonary bypass inflammation:

   • CPB triggers systemic inflammatory response
   • Endothelial dysfunction and pulmonary vascular reactivity

4. Triggers in ICU:

   • Pain, agitation
   • Suctioning, airway manipulation
   • Hypoxia, hypercarbia, acidosis
   • Hypothermia

5. Down syndrome association:

   • AVSD commonly associated with Trisomy 21
   • Down syndrome infants have more reactive pulmonary vasculature
   • Higher risk of PHT crises post-repair