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Detailed information of TETRALOGY OF FALLOT (ToF)
TETRALOGY OF FALLOT (ToF)
DEFINITION:
A cyanotic congenital heart disease characterized by right
ventricular hypertrophy, pulmonary stenosis, ventricular septal
defect (VSD), and dextroposition of the aorta.
EPIDEMIOLOGY:
- incidence: 5-7% of all congenital cardiac lesions most common
cyanotic congenital cardiac anomaly
- age of first detection:
- risk factors:
- deletion 10q, CHARGE association, VATER association, FAVS,
TAR
TYPES:
- ASD (Pentalogy of Fallot)
- Dextrocardia
- Endocardial Cushion Defects
- Patent Ductus Arteriosus
2. Acyanotic or Atypical ToF
- patients with lesser degrees of pulmonary stenosis producing
a balanced interventricular shunt or L -> R shunt
PATHOGENESIS:
- first description of Tetralogy
1888 - Fallot
- reported on a series of patients with ToF
- described the 4 components of ToF
1945 - Blalock and Taussig
- anastomosed the subclavian artery to the pulmonary artery
1955 - Lillehei
- first to use open heart surgury for a total correction of
a ToF
CLINICAL FEATURES:
- variable from severe (birth) -> milder (1-2 years)
- central (lips & mouth), peripheral (fingers & toes)
2. Dyspnea on Exertion
- assume squatting position
3. Paroxysmal Hypercyanotic Attacks (Blue Spells)
- problem in first 2 years
- characterized by SOB, restlessness, cyanosis, gasping,
syncope
- most frequently in the morning but can be spontaneous and
unpredictable
- lasts minutes to hours:
- short spells - followed by generalized weakness/sleep
- severe spells - may progress to loss of consciousness,
seizures, hemiparesis
- mechanism:
- transient increased ratio of pulmonary vascular/systemic
vascular resistence -> increased R->L shunt
- treatment:
- place in knee-chest position
- administer oxygen, morphine, propranolol
4. Growth and Development
- delayed -> failure to thrive
2. Signs
- cyanosis, clubbing, congestive heart failure
2. Palpation
- normal pulse
- systolic thrill @ mLSB (3-4 parasternal space)
- RVH - substernal thrust @ LLSB
3. Auscultation
- S2 - single (loss of pulmonary valve)
2. Murmurs
- due to turbulence over RV outflow tract
- mild/mod - long & loud SEM at mLSB
- severe - murmur shorter & softer
2. Diastolic
- infrequently heard on any part of chest
- produced by enlargened bronchial vessels secondary to
PA
INVESTIGATIONS:
- boot-shaped (coeur en sabot)
- concavity of L cardiac border (no PA)
- normal heart size
- RVH -> elevation of apical shadow
- diminished pulmonary vascularity
- aortic arch to R in 20%
2. ECG
MANAGEMENT:
- 3 years of age or 25 lbs or sooner if:
- clinical - CHF, failure to thrive, frequent Tet spells,
recurrent respiratory infections
- oxygen content <15 (urgent if <10)
2. Types:
- anastomosis of the subclavian artery to the pulmonary
artery
2. Modified Blalock-Taussig Operation
- interposition of a tubular graft between the
subclavian and pulmonary arteries
2. Corrective - Intracardiac
- performed under cardiopulmonary bypass
- children < 2 years
- closure of the VSD (Dacron patch)
- resection of the RV outflow obstruction
3. Complications:
- congestive heart failure
- cerebral vascular accident
- early occlusion of shunt
- hemothorax
- phrenic nerve injury
- pleural effusion
2. Late
- congestive heart failure
- stenosis of PA at site of anastomosis
- pulmonary hypertension
3. Death
2. Corrective
- pulmonary edema
- heart block
- hemorrhage (pericardial tamponade, hemothorax,
persistent drainage from chest tubes)
2. Late
- RV outflow obstruction
- pulmonary valve regurgitation
- residual VSD
- arrhythmias - i.e., PVC
3. Death
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Pediatric Database - TETRALOGY OF FALLOT (ToF)
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