Skip to textbook content
Doctor’s PassportTextbook
TopicsAll topics

Loading topic navigation…

Textbook navigation
TopicsAll topics

Loading topic navigation…
Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Tetralogy of Fallot and cyanotic congenital heart disease

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
!
Escalate

A hypercyanotic spell, rapidly falling saturation, haemoptysis, syncope or sustained ventricular tachycardia requires immediate ABC care, oxygen when hypoxaemic, correction of precipitants and urgent congenital-cardiology/resuscitation support.

Synopsis

Recognise unrepaired and repaired tetralogy physiology, manage cyanotic emergencies and identify late right-ventricular, pulmonary-valve and arrhythmic complications.

  • Tetralogy comprises VSD, overriding aorta, right-ventricular outflow obstruction and right-ventricular hypertrophy.
  • Severity of RV outflow obstruction determines the degree of right-to-left shunt and cyanosis.
  • Squatting or knee-to-chest positioning raises systemic vascular resistance and can reduce right-to-left shunting during a hypercyanotic spell.
  • Most UK adults are repaired; important late problems include pulmonary regurgitation, RV dilatation/dysfunction, residual RVOT obstruction, atrial arrhythmia and ventricular tachycardia.
  • A right bundle branch block pattern is common after repair; progressive QRS prolongation is a risk marker but never a stand-alone ICD indication.
  • CMR is central for RV volumes, function and pulmonary regurgitant fraction.
  • All repaired tetralogy patients need lifelong expert ACHD follow-up, even when asymptomatic.

Key red flags

Hypercyanotic spell

Sudden deepening cyanosis, tachypnoea, agitation or syncope from increased right-to-left shunting; the RVOT murmur may soften as flow falls.

Late arrhythmia

Palpitations, presyncope or syncope may reflect atrial tachycardia or scar-related monomorphic VT.

Investigation priorities

01
12-lead ECG and ambulatory monitoringFirst step

Assess conduction, QRS duration and atrial/ventricular arrhythmia.

Management branches

FirstAcute cyanotic deterioration

Sudden increased cyanosis, dyspnoea, agitation or collapse.

  1. Call for resuscitation help; assess airway, breathing, circulation, rhythm, saturation and glucose while giving oxygen for hypoxaemia.
  2. Keep the person calm, use knee-to-chest positioning when hypercyanotic physiology is suspected and obtain IV access without delaying stabilisation.
  3. Correct dehydration, anaemia/iron deficiency, infection, acidosis and arrhythmia; avoid abrupt systemic vasodilation.
  4. Transfer urgently to a congenital cardiac centre; use specialist-directed pharmacological or mechanical support if the spell persists.
NextRoutine repaired-tetralogy review

Any adult after tetralogy repair, symptomatic or not.

  1. Reconstruct anatomy and operations, then assess symptoms, rhythm, saturation, examination and ECG trends.
  2. Perform expert echo and periodic CMR, with exercise testing to detect silent functional decline.
  3. Assess pulmonary regurgitation/RVOT obstruction, biventricular function, residual VSD, aortic root and arrhythmia together.
  4. Set an ACHD follow-up interval and provide exercise, pregnancy, endocarditis and emergency advice.
Open full textbook →Answer 2 questionsCardiology check
Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • ESC 2020 adult congenital heart disease guidelineTetralogy surveillance and intervention.
  • NHS England adult congenital heart servicesSpecialist network care.
  • ESC 2022 ventricular arrhythmia and sudden-death guidelineArrhythmic risk and ICD context.
  • Resuscitation Council UK 2025 guidelinesEmergency resuscitation framework.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom