Hypercyanotic (tet) spellMANAGEMENT

PEDIATRIC-SPECIFIC PRESENTATIONS · 12 SECTIONS

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626 items

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Cardiovascular Presentations71▾

Respiratory Presentations52▾

Neurological Presentations83▾

Gastrointestinal Presentations74▾

Genitourinary and Reproductive Presentations48▾

Infectious Disease Presentations148▾

Trauma Presentations89▾

Toxicologic Presentations80▾

Psychiatric Presentations26▾

Musculoskeletal and Rheumatologic Presentations96▾

Dermatology Presentations23▾

Environmental and Exposure Presentations27▾

Hematologic and Oncologic Presentations36▾

Pediatric-Specific Presentations19▾

Bronchiolitis Croup Ductal-dependent congenital heart disease Emergency delivery Febrile seizure Hypercyanotic (tet) spell Inborn error of metabolism Intussusception Kawasaki disease Necrotizing enterocolitis Neonatal jaundice Neonatal resuscitation Nursemaid's elbow Pediatric DKA and cerebral edema Pediatric fever 0 to 28 days Pediatric fever 29 to 60 days Pediatric fever 61 to 90 days Pediatric septic shock Pyloric stenosis

Endocrine and Metabolic Presentations45▾

ENT and Maxillofacial Presentations27▾

Ophthalmologic Presentations19▾

Obstetric Presentations23▾

Systemic and Miscellaneous Presentations17▾

01Approach to the Critical Patient/attcp44

Recognize the hypercyanotic spell

›Abrupt deepening of cyanosis in an infant with known or suspected cyanotic congenital heart disease

›Onset typically on waking, during or after a feed, after prolonged crying, or with straining at stool

›Peak incidence age 2 to 4 months, uncommon before 2 weeks and after 2 years

›May be the first presentation of previously undiagnosed tetralogy of Fallot

›Core clinical triad of an active spell

›Progressive cyanosis moving from blue to a dusky or grey appearance

›Hyperpnea with deep rapid unlaboured breathing rather than retractions or grunting

›Inconsolable irritability that gives way to lethargy as the spell worsens

›Auscultatory clue that separates a spell from baseline

›The right ventricular outflow systolic ejection murmur becomes softer or disappears

›Loss of the murmur reflects near-cessation of flow across the right ventricular outflow tract

›A loud persistent outflow murmur argues against an active spell

›Danger signs of a severe or prolonged spell

›Limpness, pallor, or loss of consciousness

›Convulsion from cerebral hypoxia

›Bradycardia, apnea, or cardiac arrest as terminal events

Immediate stepwise interventions

›Keep the infant with the caregiver and minimise all noxious stimulation

›Defer venipuncture, weighing, and undressing until first-line measures are underway

›Excess handling and crying deepen the spell through catecholamine release

›Knee-to-chest positioning as the first maneuver

›Hold the infant upright against the caregiver chest with hips and knees flexed onto the abdomen

›In an older child allow squatting or place supine with the knees drawn up

›Mechanism is an acute rise in systemic vascular resistance plus increased systemic venous return

›High-concentration oxygen by the least distressing route

›Blow-by or a held mask rather than a tight interface that provokes struggling

›Benefit is limited because the lesion is reduced pulmonary blood flow, not alveolar hypoxia

02History/hx39

Presenting episode and triggers

›Time of onset relative to waking, feeding, crying, bathing, or defecation

›Morning spells on waking are characteristic

›Duration of the episode and whether it self-terminated or required intervention

›Colour change described by the caregiver

›Baseline colour of the lips and nail beds between episodes

›Progression from blue to grey or pale during the episode

›Associated features during the episode

›Fast deep breathing without noisy upper airway sounds

›Limpness, stiffening, eye rolling, or a frank convulsion

›Squatting or knee-drawing in an older child that aborts the episode

›Frequency and trend

›Number of spells over the preceding days to weeks

›Increasing frequency, duration, or severity

›Precipitants in the preceding hours

›Intercurrent febrile illness or gastroenteritis with reduced intake

›Dehydration, hot weather, or a missed beta blocker dose

›Recent immunisation, procedure, or a prolonged crying episode

Cardiac background and general history

›Known congenital heart diagnosis and prior imaging

›Tetralogy of Fallot, double outlet right ventricle with pulmonary stenosis, or other right ventricular outflow obstruction with a ventricular septal defect

›Findings of any prior echocardiogram or cardiac catheterisation

›Prior cardiac interventions

›Previous systemic-to-pulmonary shunt such as a modified Blalock-Taussig-Thomas shunt

›Prior right ventricular outflow tract stent or ductal stent

›Planned date and type of complete repair

›Current cardiac medications

›Oral propranolol dose and timing and any recent change or missed dose

03Physical Exam/exam41

Vital signs and oximetry

›Pulse oximetry on a warm well-perfused extremity

›Spell saturations are often 60 to 80 percent or lower and rise slowly with intervention

›Pre-ductal and post-ductal readings from the right hand and a foot

›A saturation that does not rise with high-concentration oxygen supports intracardiac right-to-left shunting

›Heart rate for age

›Sinus tachycardia is expected during a spell

›Bradycardia is an ominous pre-terminal sign

›Respiratory rate and pattern

›Hyperpnea is deep and rapid without stridor, wheeze, or grunting

›Infant respiratory rate above 60 per minute at rest is abnormal

›Interpret the rate against the child's own baseline and any chronic lung disease or prematurity

›Absence of retractions helps separate a spell from primary airway or lung disease

›Blood pressure and perfusion

›Four-limb blood pressure when a shunt or arch anomaly is possible

›Capillary refill, peripheral temperature, and femoral pulse volume

›Temperature

›Fever raises metabolic demand and lowers systemic vascular resistance and can precipitate a spell

Cardiovascular and general findings

›Precordial auscultation

›Harsh systolic ejection murmur at the left upper sternal border from right ventricular outflow obstruction

›Softening or disappearance of that murmur during an active spell

›Single second heart sound in tetralogy of Fallot

›Palpation

›Right ventricular heave at the left sternal border

›Systolic thrill at the left upper sternal border

›Cyanosis distribution and chronic signs

›Central cyanosis of the lips, tongue, and mucous membranes

04Differential Diagnosis/ddx41

Cyanotic congenital heart disease and its complications

›Hypercyanotic spell in tetralogy of Fallot

›Most common substrate, driven by dynamic infundibular obstruction and a large ventricular septal defect

›Suggested by a known diagnosis, a boot-shaped heart, and a vanishing outflow murmur

›Spell physiology in other right ventricular outflow obstruction lesions

›Double outlet right ventricle with pulmonary stenosis

›Transposition of the great arteries with ventricular septal defect and pulmonary stenosis

›Tricuspid atresia or single ventricle with restrictive pulmonary blood flow

›Shunt or stent failure in a palliated infant

›Acute modified Blalock-Taussig-Thomas shunt thrombosis with sudden profound cyanosis and loss of the continuous shunt murmur

›Right ventricular outflow or ductal stent stenosis or occlusion

›Complications of chronic cyanosis that mimic or accompany a spell

›Cerebral venous or arterial thrombosis from secondary erythrocytosis

›Brain abscess with fever, seizure, or focal deficit in a cyanotic infant

›Iron-deficient erythrocytosis worsening spell frequency

Non-cardiac causes of acute cyanosis or a brief resolved unexplained event

›Sepsis and septic shock

›Fever or hypothermia, poor perfusion, and lactic acidosis

›Can coexist with and precipitate a spell

›Lower airway and parenchymal disease

›Bronchiolitis, pneumonia, or pertussis with hypoxaemia and increased work of breathing

›Retractions, crackles, wheeze, and a saturation that responds to oxygen

›Upper airway obstruction and foreign body aspiration

›Sudden cyanosis with choking, stridor, or focal decreased air entry

›Pulmonary hypertensive crisis

›Cyanosis, low cardiac output, and a loud pulmonary component of the second heart sound

›Methemoglobinemia

›Cyanosis with a normal arterial oxygen tension and chocolate-brown blood

05Laboratory Tests/lt39

Blood gas and acid-base

›Venous or capillary blood gas at presentation and after each intervention

›Metabolic acidosis with a base deficit greater than 5 mmol/l indicates a significant spell

›Lactate above 2 mmol/l reflects anaerobic metabolism from tissue hypoxia

›The trend of base deficit and lactate is the best biochemical marker of response

›A chronically cyanotic infant may run a mild compensated base deficit at baseline, so track the change from that baseline

›Arterial blood gas when the diagnosis is unclear

›An arterial oxygen tension that fails to rise above about 20 mmHg on 100 percent oxygen supports a fixed right-to-left shunt

›A normal arterial oxygen tension with a low measured saturation points to methemoglobinemia

›Co-oximetry

›Direct fractional oxyhaemoglobin and methemoglobin measurement

›Carboxyhaemoglobin if a combustion exposure is possible

›Ionised calcium

›Hypocalcaemia is common in 22q11.2 deletion and can depress myocardial function and provoke seizures

Haematology and iron status

›Complete blood count with haemoglobin and haematocrit

›Chronic cyanosis produces secondary erythrocytosis, so a haemoglobin in the normal range is relatively anaemic

›A haemoglobin below about 150 g/l in a cyanotic infant is inappropriately low and worsens spell risk

›Red cell indices and iron studies

›Microcytosis with a low mean corpuscular volume suggests iron deficiency even when the haemoglobin looks adequate

›Ferritin, serum iron, and transferrin saturation to confirm iron deficiency

›Coagulation screen

›Prothrombin time, activated partial thromboplastin time, and fibrinogen before catheterisation or surgery

›Erythrocytosis is associated with a functional coagulopathy and a spuriously prolonged clotting time from an under-filled citrate tube

›Type and crossmatch

›Prepare packed red cells if transfusion to raise oxygen-carrying capacity is anticipated

›Request irradiated cytomegalovirus-safe product when 22q11.2 deletion is known or suspected

06Diagnostic Tests/dt53

Scoring Systems

›No validated severity score exists for the acute hypercyanotic spell

›Management is driven by the clinical trajectory and the base deficit trend, not a score

›Document a structured description of colour, breathing, tone, saturation, and murmur instead

›Related risk frameworks used in the disease rather than the spell

›The Nakata index and the McGoon ratio describe pulmonary artery size for surgical planning

›A Pediatric Early Warning Score can flag ward deterioration but is not spell-specific

›Arterial oxygen saturation as a pragmatic severity marker

›A saturation that stays below about 70 percent despite first-line therapy defines a severe spell

›A rising saturation with a falling respiratory rate defines response

MRI

›Cardiac magnetic resonance imaging has no role in the acute spell

›It is not obtainable at the bedside and needs sedation that is hazardous mid-spell

›Sedation for imaging can itself precipitate or deepen a spell

›Elective cardiac magnetic resonance imaging after stabilisation

›Quantifies right ventricular volume and function and pulmonary regurgitant fraction

›Defines branch pulmonary artery anatomy and aortopulmonary collaterals before repair

›Brain magnetic resonance imaging when neurologic signs persist

›Diffusion-weighted imaging for hypoxic or embolic infarction

›Contrast-enhanced imaging for suspected brain abscess in a cyanotic child

›Non-contrast head computed tomography for an acute focal deficit, prolonged coma, or seizure

›Identifies haemorrhage, large infarction, and mass effect from abscess

›Faster and more accessible than magnetic resonance imaging in an unstable infant

›Electrocardiogram-gated cardiac computed tomography angiography after stabilisation

›Delineates the right ventricular outflow tract, pulmonary arteries, coronary origins, and any shunt

›An anomalous coronary artery crossing the outflow tract changes the surgical approach

›Computed tomography pulmonary angiography only if pulmonary embolism is genuinely suspected

›Rare in infants and reserved for a compelling thrombotic history

Ultrasound

›Transthoracic echocardiography is the definitive diagnostic test

›Confirms a large malaligned ventricular septal defect, an overriding aorta, and right ventricular outflow obstruction

›Localises obstruction to the infundibulum, the pulmonary valve, or the branch pulmonary arteries

›Estimates the outflow gradient and shunt direction and excludes an anomalous coronary artery

›Focused echocardiography during a refractory spell

›Demonstrates near-obliteration of the infundibulum and a torrential right-to-left shunt

›Assesses biventricular filling and function to guide fluid versus vasoconstrictor

›Shunt and stent interrogation in a palliated infant

›Colour and spectral Doppler for flow through a modified Blalock-Taussig-Thomas shunt or a stent

›Absent flow signals acute thrombosis and the need for emergency intervention

›Point-of-care ultrasound adjuncts

›Inferior vena cava calibre and lung profile to gauge volume status

›Cranial ultrasound through the fontanelle for intraventricular haemorrhage in a young infant

Electrocardiogram and chest radiograph

›Twelve-lead electrocardiogram

›Right axis deviation and right ventricular hypertrophy are expected in tetralogy of Fallot

›New ST segment depression or T wave inversion indicates subendocardial ischaemia during the spell

›Excludes supraventricular tachycardia as an alternative cause of the acute deterioration

›Electrocardiographic monitoring where therapy shifts electrolytes

›Sodium bicarbonate can lower ionised calcium and potassium, so watch for QT prolongation and T wave change

›Beta blockade can unmask sinus node dysfunction or atrioventricular block

›Continuous cardiorespiratory and saturation monitoring

›Watch for bradycardia and arrhythmia as the spell deepens

›Portable chest radiograph

›Boot-shaped cardiac silhouette with an uplifted apex and a concave main pulmonary artery segment

›Decreased pulmonary vascular markings during reduced pulmonary blood flow

›Right-sided aortic arch in about a quarter of tetralogy of Fallot

›Identifies pneumonia, pneumothorax, hyperinflation, or a foreign body as an alternative explanation

07Disposition/dispo33

Admission and level of care

›Admit every infant with a genuine hypercyanotic spell

›No infant with a true spell is safe for discharge from the emergency department

›A brief self-terminated spell still warrants admission and inpatient cardiology assessment

›Pediatric intensive care admission

›Any spell that needed more than positioning and oxygen

›Any infant who received an opioid, a vasoconstrictor, bicarbonate, or a beta blocker

›Persisting acidosis, altered mental status, or recurrent spells

›Monitored ward admission only under defined conditions

›A single brief spell, full recovery, a normal blood gas, with cardiology agreement and continuous monitoring

›A written escalation plan and bedside knee-to-chest coaching completed

›Inpatient measures

›Continuous pulse oximetry and cardiorespiratory monitoring

›Isotonic maintenance hydration and prompt treatment of fever

›Start or optimise oral propranolol 1 to 4 mg per kg per day divided every 6 hours and start iron replacement

›Contact and droplet precautions when a viral respiratory illness is the trigger

›Consultations to obtain

›Pediatric cardiology for bedside echocardiography and timing of intervention

›Pediatric cardiac surgery and interventional cardiology for repair, shunt, or outflow tract stent

›Pediatric critical care and anaesthesia for airway control and extracorporeal support

›Clinical genetics and haematology for 22q11.2 deletion evaluation and management of erythrocytosis and iron deficiency

Transfer to a pediatric cardiac centre

›Transfer any infant with a spell who is not at a centre with pediatric cardiology and cardiac surgery

›A first spell is an indication to bring forward complete repair or a palliative procedure

›Recurrent or refractory spells require transfer without delay

›Stabilise before and during transport

›Positioning, oxygen, an opioid, a fluid bolus, and correction of acidosis before departure

›Secure intravenous access and have phenylephrine and a beta blocker immediately available

08Treatment/t188

Positioning and calming measures

›Knee-to-chest position immediately

›The caregiver holds the infant upright against the chest with the hips and knees fully flexed

›An older child squats or is placed supine with the knees pulled to the chest

›Raises systemic vascular resistance and augments systemic venous return, cutting the right-to-left shunt

›Minimise agitation

›Keep the infant with the caregiver in a quiet dim space

›Cluster care and defer painful procedures until first-line measures are in place

›Consider intranasal or buccal analgesia to avoid the crying provoked by intravenous cannulation

›Treat reversible aggravators

›Antipyresis for fever with acetaminophen 15 mg per kg per dose enterally no more often than every 6 hours and no more than 4 doses in 24 hours

›Warm the hypothermic infant and correct hypoglycaemia

›Relieve a full bladder or constipation if straining triggered the spell

Oxygen

›High-concentration oxygen from the outset

›Deliver by blow-by, a held mask, or a non-rebreather as tolerated without forcing an interface

›Target a rising trend rather than an absolute number during the spell

›Understand and communicate the limited effect

›The rate-limiting problem is pulmonary blood flow across a near-closed outflow tract, not alveolar oxygen

›Failure of the saturation to improve with oxygen is expected and is not by itself a reason to intubate for oxygenation

›Saturation targets and their exceptions

›Accept the infant's known cyanotic baseline, often 75 to 85 percent, rather than chasing 94 percent during a spell

›In a palliated single-ventricle infant a saturation of 75 to 85 percent is the goal and higher values may signal pulmonary overcirculation

›After complete repair aim for a normal saturation above 94 percent

›In coexisting chronic lung disease or pulmonary hypertension titrate to the documented baseline rather than a fixed number

Analgesia and sedation

›Morphine as the first-line agent to interrupt hyperpnea

›Morphine 0.1 to 0.2 mg per kg subcutaneously or intramuscularly when there is no intravenous access

›The same 0.1 to 0.2 mg per kg intravenously, given slowly over 3 to 5 minutes

›Repeat once after 15 to 20 minutes if hyperpnea persists and perfusion allows

›Reduce the dose and slow the rate when hypotension or apnea is a concern

›Maximum single dose 15 mg

›Verify against current pediatric guideline before use

›Mechanism is central suppression of hyperpnea with sedation and reduced catecholamine drive

›Monitor respiratory rate and oxygen saturation and keep naloxone and airway equipment at the bedside

›Intranasal fentanyl when no line is present and rapid effect is wanted

›Fentanyl 1.5 to 2 micrograms per kg intranasally, split between the nostrils

›May repeat once at 10 minutes, maximum single dose 100 micrograms

›Verify against current pediatric guideline before use

›Avoids the crying and catecholamine surge of intravenous access

›Ketamine when sedation plus support of systemic vascular resistance is desirable

›Ketamine 0.5 to 1 mg per kg intravenously over 1 to 2 minutes

›Ketamine 3 to 4 mg per kg intramuscularly if there is no intravenous access

›Titrate further 0.25 to 0.5 mg per kg intravenous increments to effect

›Preserves airway reflexes and raises systemic vascular resistance, which reduces the shunt

›Maximum initial intravenous dose about 2 mg per kg

›Verify against current pediatric guideline before use

›Accept that any associated tachycardia can modestly worsen dynamic obstruction and combine with a beta blocker if needed

›Dexmedetomidine as a calming adjunct where available

›Dexmedetomidine 0.5 to 1 microgram per kg intravenously over 10 minutes then 0.2 to 0.7 micrograms per kg per hour

›Provides calm without respiratory depression and modestly slows the heart rate

›Pause the loading dose if bradycardia or hypotension develops

›Verify against current pediatric guideline before use

›Avoid sedatives that lower systemic vascular resistance without treating the spell

›Propofol 1 to 2 mg per kg intravenously drops systemic vascular resistance and can abruptly worsen the shunt

›If propofol is unavoidable for induction, pre-load with volume and start phenylephrine and use a reduced dose

Volume expansion and anaemia correction

›Isotonic crystalloid bolus to fill the right ventricular outflow tract

›Balanced crystalloid or 0.9 percent sodium chloride 10 to 20 mL per kg intravenously over 10 to 20 minutes

›Reassess after each aliquot and repeat to a total of 40 to 60 mL per kg while the liver stays small and work of breathing does not worsen

›Slow or stop if the liver edge descends or respiratory distress increases

›Increased preload widens the infundibulum and improves diastolic filling across the obstruction

›Verify against current pediatric guideline before use

›Isotonic maintenance fluid after the acute phase to prevent the dehydration that precipitates further spells

›Resume frequent small enteral feeds once the infant is stable

›Red cell transfusion to raise oxygen-carrying capacity

›Packed red blood cells 10 to 15 mL per kg intravenously over 3 to 4 hours when the haemoglobin is below about 150 g/l in a cyanotic infant

›Give 5 mL per kg aliquots with reassessment when heart failure or pulmonary overcirculation is a concern

›Correcting relative anaemia reduces spell frequency and severity

›Verify against current pediatric guideline before use

›Oral iron for iron deficiency once stable, ferrous sulfate providing 3 to 6 mg per kg per day of elemental iron divided once or twice daily

›Recheck haemoglobin and reticulocytes and continue iron for at least 3 months

Correction of acidosis

›Sodium bicarbonate for a significant metabolic acidosis that is sustaining the hyperpneic cycle

›Sodium bicarbonate 1 to 2 mmol per kg intravenously over 10 to 30 minutes for a base deficit greater than 5 mmol/l or a pH below 7.2

›Recheck the blood gas 15 to 20 minutes after the dose and repeat guided by the base deficit

›Ensure effective ventilation first because bicarbonate generates carbon dioxide that must be exhaled

›Give as a dilute solution through a secure line and avoid extravasation

›Do not co-infuse with calcium-containing fluids

›Verify against current pediatric guideline before use

›Correcting acidaemia restores systemic vascular resistance responsiveness and reduces the central drive to hyperpnea

›Address the cause of the acidosis in parallel

›The definitive correction is restoring pulmonary blood flow, not repeated bicarbonate

›A persistent or worsening base deficit despite therapy signals a refractory spell that needs rescue

Systemic vascular resistance support

›Phenylephrine as the preferred vasoconstrictor

›Phenylephrine 5 to 10 micrograms per kg by intravenous bolus for an acute severe spell

›Follow with an infusion 0.1 to 0.5 micrograms per kg per minute titrated to saturation and perfusion

›Titrate up by 0.1 micrograms per kg per minute every 5 to 10 minutes to effect

›Step down in 0.1 micrograms per kg per minute decrements once the saturation stabilises to avoid rebound hypertension

›Usual maximum infusion about 3 to 5 micrograms per kg per minute

›Verify against current pediatric guideline before use

›Pharmacologic class is a selective alpha-1 agonist that raises systemic vascular resistance and reduces right-to-left shunting, with reflex slowing of the heart rate that also helps

›Norepinephrine as an alternative when one agent for both resistance and output is preferred

›Norepinephrine 0.05 to 0.1 micrograms per kg per minute intravenously, titrated to 0.5 micrograms per kg per minute

›Predominant alpha effect raises systemic vascular resistance with modest inotropy

›Verify against current pediatric guideline before use

›Do not use agents that lower systemic vascular resistance

›Dihydropyridine calcium channel blockers such as nicardipine and clevidipine are arterial vasodilators and are contraindicated in a spell

›Angiotensin converting enzyme inhibitors, hydralazine, and nitroprusside all deepen the shunt

Beta blockade for infundibular spasm

›Esmolol when a titratable intravenous agent is wanted

›Esmolol 500 micrograms per kg intravenously over 1 minute

›Followed by an infusion 50 micrograms per kg per minute

›Titrate by 25 to 50 micrograms per kg per minute every 5 to 10 minutes toward relief of the spell

›Move to smaller increments as the heart rate falls toward the low-normal range for age to avoid excessive negative inotropy

›Maximum 300 micrograms per kg per minute

›Omit the bolus and start the infusion at 25 to 50 micrograms per kg per minute if perfusion is borderline

›Verify against current pediatric guideline before use

›Relaxes the hypercontractile infundibulum and slows the heart rate to improve diastolic filling across the obstruction

›Propranolol when esmolol is unavailable

›Propranolol 0.01 to 0.1 mg per kg by slow intravenous injection over 5 to 10 minutes

›Start at 0.01 mg per kg and titrate upward, maximum single dose 1 mg in an infant and 3 mg in a child

›Repeat no more often than every 6 to 8 hours acutely

›Watch for bradycardia, hypotension, bronchospasm, and hypoglycaemia

›Verify against current pediatric guideline before use

›Oral propranolol 1 to 4 mg per kg per day divided every 6 hours as a bridge to repair once the acute spell settles

›Cautions common to beta blockade in a spell

›Avoid in overt cardiogenic shock or high-grade atrioventricular block

›Reserve for the spell not responding to positioning, oxygen, an opioid, volume, and phenylephrine

›Have atropine and a chronotropic backup available for excessive bradycardia

Refractory spell rescue

›Induction of general anaesthesia with a definitive airway

›Abolishes the catecholamine surge driving infundibular spasm and hyperpnea

›Preferred induction is ketamine 1 to 2 mg per kg with rocuronium 1 mg per kg for paralysis

›Etomidate 0.2 to 0.3 mg per kg is an alternative that better preserves systemic vascular resistance

›Pre-load with crystalloid and start phenylephrine before induction to blunt the fall in systemic vascular resistance

›Verify against current pediatric guideline before use

›Ventilate with a low mean airway pressure and 100 percent oxygen and avoid high positive end-expiratory pressure that impedes pulmonary blood flow

›Emergency catheterisation or surgery

›Balloon dilation or stenting of the right ventricular outflow tract or the duct to secure pulmonary blood flow

›Emergency systemic-to-pulmonary shunt or primary complete repair depending on anatomy and centre practice

›Extracorporeal membrane oxygenation

›Veno-arterial support as a bridge when spells recur despite maximal medical therapy or after arrest

›Manual and pharmacologic adjuncts while arranging rescue

›Manual abdominal compression or repositioning to further augment systemic vascular resistance

›Continue phenylephrine, beta blockade, volume, and bicarbonate titrated to the base deficit

Troubleshooting the spell that is not improving

›Re-examine the diagnosis

›Reconsider sepsis, supraventricular tachycardia, tension pneumothorax, foreign body aspiration, and methemoglobinemia

›Obtain focused echocardiography to confirm dynamic infundibular obstruction and exclude shunt or stent thrombosis

›Audit the interventions already delivered

›Confirm the infant is genuinely knee-to-chest and is not being over-handled

›Confirm a therapeutic opioid dose and an adequate cumulative fluid volume have been given

›Confirm the phenylephrine infusion is patent, connected, and reaching the patient

›Recheck and correct physiology

›Repeat blood gas, glucose, ionised calcium, haemoglobin, and lactate

›Treat glucose below 2.6 mmol/l with 10 percent dextrose 2 mL per kg intravenously

›Verify against current pediatric guideline before use

›Treat fever, correct a base deficit greater than 5 mmol/l, and transfuse if relatively anaemic

›Treat a precipitating infection

›Obtain blood culture then give empiric antibiotics when sepsis is the suspected trigger

›Neonate under 28 days: ampicillin 50 to 100 mg per kg per dose intravenously plus gentamicin 4 to 5 mg per kg intravenously, or ampicillin plus cefotaxime 50 mg per kg per dose

›Ampicillin monotherapy is inadequate at this age and a second agent for gram-negative and Listeria cover is required

›Avoid ceftriaxone in the neonate because it displaces bilirubin and precipitates with calcium

›Dosing interval varies with postnatal age and gestation, so confirm against a neonatal reference

›Infant 1 to 3 months: ceftriaxone 50 mg per kg per dose intravenously, with ampicillin added when Listeria is a concern

›Use meningitic dosing if a central nervous system source cannot be excluded

›Monitoring cadence during titrated therapy

›Continuous pulse oximetry and electrocardiogram with blood pressure every 3 to 5 minutes during active titration

›Blood gas every 15 to 20 minutes until the base deficit is clearly improving

›Reassess liver size and lung examination after every fluid aliquot

›Escalate on defined triggers

›No improvement within 15 to 30 minutes of full medical therapy

›A falling heart rate, a rising base deficit, or deteriorating mental status at any point

Iatrogenic harms to anticipate and avoid

›Intubation and positive pressure ventilation

›Induction agents and raised intrathoracic pressure drop systemic vascular resistance and pulmonary blood flow and can precipitate arrest

›Reserve for the refractory spell, pre-treat with volume and phenylephrine, and ventilate at a low mean airway pressure

›Sedation choices

›Propofol 1 to 2 mg per kg and high-dose benzodiazepine lower systemic vascular resistance and worsen the shunt

›Prefer ketamine, which supports systemic vascular resistance

›Fluid loading errors

›Under-resuscitation leaves the infundibulum empty and the spell unbroken

›Over-transfusion in a shunted infant with pulmonary overcirculation causes heart failure, so give in 5 mL per kg aliquots and reassess the liver

›Oxygen expectations

›Oxygen helps but will not correct the saturation, and chasing a normal number drives unnecessary escalation

›Inotropes and chronotropes are contraindicated during an active spell

›Dopamine, dobutamine, adrenaline, isoprenaline, and digoxin increase infundibular contractility and worsen dynamic outflow obstruction

›When a vasopressor is required use phenylephrine for its pure alpha-1 effect

›Adrenaline 0.01 mg per kg, which is 0.1 mL per kg of the 1 in 10000 concentration, intravenously is reserved for cardiac arrest only

›Verify against current pediatric guideline before use

›Vasodilators and afterload reduction

›Angiotensin converting enzyme inhibitors, hydralazine, nitroprusside, and dihydropyridine calcium channel blockers are contraindicated because lowering systemic vascular resistance increases right-to-left shunting

›Pulmonary vasodilators

›Inhaled nitric oxide and inhaled prostacyclin do not relieve a fixed or dynamic anatomic right ventricular outflow obstruction and waste time

›Prostaglandin E1 is not a spell treatment

›It has no role in a classic tetralogy spell that has antegrade pulmonary blood flow

›Alprostadil 0.01 to 0.05 micrograms per kg per minute intravenously is appropriate only for a duct-dependent lesion such as pulmonary atresia in a neonate

›Verify against current pediatric guideline before use

›Analgesia omission

›Leaving a distressed infant crying perpetuates the catecholamine-driven spell, so give opioid analgesia early

›Anticoagulation and fibrinolysis

›Not part of spell treatment, but systemic heparin or catheter-directed therapy is indicated for acute modified Blalock-Taussig-Thomas shunt thrombosis

›Weigh the bleeding risk from the erythrocytosis-associated coagulopathy

›Mechanical circulatory support

›An intra-aortic balloon pump has no role because diastolic augmentation does not address right ventricular outflow obstruction

›Veno-arterial extracorporeal membrane oxygenation is the correct mechanical support when it is needed

09Special Populations/sp47

Pregnancy

›Unrepaired or palliated right ventricular outflow obstruction in a pregnant patient

›The physiologic fall in systemic vascular resistance in pregnancy increases right-to-left shunting and can produce adult hypercyanotic episodes

›Hypovolaemia from haemorrhage, vomiting, or aortocaval compression is a common trigger

›Acute management mirrors the pediatric ladder

›Left lateral tilt to relieve aortocaval compression, high-flow oxygen, and a rapid crystalloid bolus 500 to 1000 mL

›Phenylephrine 50 to 100 micrograms intravenous bolus then an infusion titrated to restore systemic vascular resistance, the vasopressor of choice in obstetric practice

›Opioid analgesia to reduce hyperpnea and catecholamine drive

›Beta blockade with a titratable agent such as esmolol or labetalol for refractory infundibular spasm, accepting a small risk of fetal bradycardia and growth restriction

›Multidisciplinary care and monitoring

›Cardio-obstetrics, cardiac anaesthesia, and maternal-fetal medicine involvement

›Continuous fetal monitoring once viable and endocarditis prophylaxis per lesion

›Plan delivery mode and location around maternal haemodynamics, favouring assisted vaginal delivery with slowly titrated regional analgesia

›Preconception and antenatal considerations

›Repair before pregnancy where feasible

›Fetal echocardiography given an approximately 3 percent recurrence of congenital heart disease, higher with 22q11.2 deletion

Geriatric

›The hypercyanotic spell is a disease of infancy and is essentially not seen in older adults

›Almost all patients have undergone complete repair or a palliative shunt in childhood

›Unoperated tetralogy of Fallot surviving beyond middle age is rare, with historical unoperated survival to age 40 in only a small minority

›Late problems in the repaired adult are different and are not spells

›Severe pulmonary regurgitation with progressive right ventricular dilation and failure

›Atrial and ventricular tachyarrhythmia and a risk of sudden cardiac death

›Residual outflow obstruction or branch pulmonary artery stenosis

›If an older unrepaired or palliated adult presents with a cyanotic episode

›Apply the same principles of raising systemic vascular resistance, restoring volume, opioid analgesia, and beta blockade

›Account for coexisting coronary disease, so avoid profound bradycardia and watch for demand ischaemia

›Manage secondary erythrocytosis and hyperviscosity and the associated bleeding and thrombotic tendency

10Background/b46

Epidemiology

›Tetralogy of Fallot is the most common cyanotic congenital heart lesion

›Prevalence about 3 to 5 per 10000 live births, roughly 7 to 10 percent of all congenital heart disease

›A slight male predominance

›Frequency of hypercyanotic spells

›Historically spells occurred in about 20 to 70 percent of infants with unrepaired tetralogy of Fallot before the era of early repair

›Now less common because most infants undergo elective repair by 3 to 6 months of age

›The peak age for spells is 2 to 4 months

›Outcome

›An untreated severe prolonged spell can be fatal from hypoxic cardiac arrest or cerebral injury

›With prompt stepwise treatment the great majority of spells resolve

›Contemporary complete repair carries an operative mortality below about 2 percent with excellent long-term survival

›Associations

›22q11.2 deletion in about 15 percent of tetralogy of Fallot, higher with pulmonary atresia or an absent pulmonary valve

›Trisomy 21, trisomy 18, CHARGE association, and Alagille syndrome

›Maternal diabetes, maternal phenylketonuria, and prenatal retinoic acid exposure

Pathophysiology

›Underlying anatomy

›Anterior and cephalad deviation of the outlet septum produces subpulmonary infundibular stenosis, a large malalignment ventricular septal defect, an overriding aorta, and right ventricular hypertrophy

›Obstruction may be infundibular, valvar, supravalvar, or at the branch pulmonary arteries, and is often multilevel

›The shunt is set by competing resistances

›Flow across the ventricular septal defect follows the ratio of right ventricular outflow resistance to systemic vascular resistance

›Anything that raises outflow resistance or lowers systemic vascular resistance increases right-to-left shunting and cyanosis

›The spell as a vicious cycle

›A trigger such as crying or catecholamine release causes dynamic infundibular muscular spasm and a fall in systemic vascular resistance

›Right-to-left shunting increases, the arterial oxygen tension falls, and carbon dioxide and hydrogen ion rise

›Hypoxaemia, hypercapnia, and acidaemia stimulate the respiratory centre and produce hyperpnea

›Hyperpnea increases systemic venous return and the work of breathing, raises catecholamines further, and lowers systemic vascular resistance, closing the loop

11Patient Discharge Instructions/pdi36

When these instructions apply

›These instructions are for the family of an infant who has had a hypercyanotic spell

›They are given at hospital discharge after admission and cardiology assessment, not from the emergency department

›Every infant with a true spell is admitted first

›Reinforce the plan already made with cardiology

›The confirmed diagnosis, the date and type of planned surgery, and the current medication list

›Who to call at any hour and which hospital to attend

copy discharge instructions

›Your child had a blue spell, also called a hypercyanotic or tet spell, caused by their heart condition

›During a spell the blood flow to the lungs briefly drops, so less oxygen reaches the body and the lips, tongue, and skin turn blue or grey

›Spells can be set off by crying, waking, feeding, straining to pass stool, fever, and not drinking enough

›What to do the moment a spell starts

›Stay calm and keep your baby calm, because crying makes a spell worse

›Straight away bring your baby's knees up firmly against the chest and hold them there, or hold your baby against your chest with the knees tucked up tightly

›For an older child, help them squat or lie down and pull their knees to their chest

›Hold the position and comfort your child, and give any rescue medicine exactly as you were shown

›Call an ambulance now if

›The blue colour or the fast heavy breathing lasts more than 15 minutes despite the knee-to-chest position

›Your child becomes floppy, very hard to wake, or unresponsive

›Your child has a seizure or stops breathing at any point

›Your child looks much bluer than their normal colour even at rest

›Medicines

›Give propranolol exactly as prescribed, usually 1 to 4 mg per kg per day split into doses every 6 hours, and do not skip doses or stop it suddenly

›If your child vomits within 30 minutes of a dose or a dose is missed, call the cardiology team for advice rather than doubling up

›Give the iron supplement, ferrous sulfate providing 3 to 6 mg per kg per day of elemental iron, every day as prescribed, with a citrus drink if possible, and expect darker stools

›For fever, give acetaminophen 15 mg for each kilogram of your child's weight per dose, no more often than every 6 hours and no more than 4 doses in 24 hours

›If your child is older than 6 months you may instead give ibuprofen 10 mg per kg per dose every 6 to 8 hours with food

›Do not give over-the-counter cough, cold, or decongestant medicines, and check any new medicine with the cardiology team first

12References/r19

Guidelines and society statements

›Adult congenital heart disease management guidelines

›Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA/ACC Guideline for the Management of Adults With Congenital Heart Disease. American Heart Association and American College of Cardiology. Circulation 2019

›Baumgartner H, De Backer J, Babu-Narayan SV, et al. 2020 ESC Guidelines for the management of adult congenital heart disease. European Society of Cardiology. European Heart Journal 2021

›Pediatric resuscitation guidance

›Topjian AA, Raymond TT, Atkins D, et al. Part 4: Pediatric Basic and Advanced Life Support. 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation 2020

›American Heart Association. Pediatric Advanced Life Support Provider Manual. American Heart Association 2020

›Pulmonary artery size assessment for repair planning

›Nakata S, Imai Y, Takanashi Y, et al. A new method for the quantitative standardization of cross-sectional areas of the pulmonary arteries in congenital heart disease. Journal of Thoracic and Cardiovascular Surgery 1984

›Kirklin JW, Barratt-Boyes BG. Tetralogy of Fallot with pulmonary stenosis. In: Cardiac Surgery. Elsevier

Landmark studies and reviews

›Origin of systemic-to-pulmonary shunt palliation

›Blalock A, Taussig HB. The surgical treatment of malformations of the heart in which there is pulmonary stenosis or pulmonary atresia. JAMA 1945

›Taussig HB. Congenital Malformations of the Heart. Commonwealth Fund 1947

›Contemporary clinical reviews of tetralogy of Fallot

›Apitz C, Webb GD, Redington AN. Tetralogy of Fallot. Lancet 2009

›Bailliard F, Anderson RH. Tetralogy of Fallot. Orphanet Journal of Rare Diseases 2009

›Villafane J, Feinstein JA, Jenkins KJ, et al. Hot topics in tetralogy of Fallot. Journal of the American College of Cardiology 2013

›Reference texts for acute spell management

›Park MK, Salamat M. Park's Pediatric Cardiology for Practitioners. Elsevier, 7th edition 2021

›Nichols DG, Shaffner DH, editors. Rogers' Textbook of Pediatric Intensive Care. Wolters Kluwer, 5th edition 2016

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed September 13, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.