CardiologyTier 2Disease (DEADMAN)

Congenital heart disease - tetralogy of Fallot (TOF)

Description

Four features, all from anterior deviation of the infundibular (outlet) septum:
- RVOT obstruction - subpulmonary infundibular stenosis +/- pulmonary atresia
- Unrestrictive malaligned VSD
- Overriding aorta
- RV hypertrophy
Degree of RVOT obstruction determines cyanosis - not the VSD
Essentially every adult you meet is repaired
- The adult disease is the sequelae of repair, not the original lesion

Epidemiology

Commonest cyanotic congenital heart disease
~3-5 per 10,000 live births
22q11.2 deletion (DiGeorge) in ~15%; also Down syndrome
>90% survive to adulthood after repair

Aetiopathogenesis

Embryology

Anterior and cephalad deviation of the outlet septum
- -> subpulmonary infundibular narrowing
- -> malalignment VSD
- -> aorta overrides the septum
- -> RV pressure overload -> RVH

Hypercyanotic ("tet") spells

dec SVR or infundibular spasm
- -> inc right-to-left shunt
- -> acute cyanosis
Squatting inc SVR -> dec shunt -> relief

Diagnosis

Unrepaired - rare in Australian adults

Cyanosis, clubbing, ejection systolic murmur (RVOT), single S2

Repaired adult - what to look for

Absent or diminished radial pulse on the side of a prior Blalock-Taussig shunt
Thoracotomy and sternotomy scars; infraclavicular device
RV heave, raised JVP, S3
Decrescendo diastolic murmur of PR at ULSE - louder on inspiration
AF or other tachyarrhythmia

Investigations

ECG: RBBB near-universal after repair; QRS >180 ms = adverse risk marker
Holter for arrhythmia
CPET - functional capacity, exertional desaturation, arrhythmia
TTE: PR severity, RV function, aortic root
CMR is the key test - RV volumes drive the timing of pulmonary valve replacement

Management

Pulmonary regurgitation - the near-universal residual lesion

Consequence of trans-annular patch repair
Pulmonary valve replacement timed by RV volume and dysfunction, never prophylactically
Surgical, or transcatheter pulmonary valve

Arrhythmia

Atrial arrhythmia common and poorly tolerated - ablation, anticoagulation as indicated
SCD risk - predictors:
- QRS >180 ms
- Non-sustained VT
- LVEDP >12 mmHg
- Extensive RV dilatation, older age at original repair
ICD for secondary prevention; primary prevention individualised

Residual structural lesions

RVOT re-obstruction, branch PA stenosis - stent or surgery
Residual VSD
Aortic root dilatation -> AR; root replacement if large

All patients

Lifelong ACHD follow-up - never discharge
Endocarditis prophylaxis if prosthetic valve/conduit or residual shunt beside patch material
Pregnancy usually tolerated after good repair
Offer 22q11.2 testing and genetic counselling

Associations

22q11.2 deletion (DiGeorge) - hypocalcaemia, immunodeficiency, palatal and learning difficulties
Down syndrome
Right-sided aortic arch (~25%)
Coronary artery anomalies - relevant before any repeat sternotomy
Aortopathy with root dilatation

Natural history & complications

~85% asymptomatic long term after repair, but with objectively reduced exercise capacity
RVOT re-obstruction in 10-15% by 20 years
SCD cumulative incidence 0.5-6% over 30 years
Sequence: PR -> RV dilatation -> TR -> RV failure
Also: atrial and ventricular arrhythmia, LV dysfunction, aortic root dilatation

Monitor

CMR RV volumes - the trigger for valve replacement
QRS duration, Holter
CPET
Aortic root diameter

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