Tetralogy of Fallot
Tetralogy of Fallot: Excerpt from The 5-Minute Pediatric Consult
Christopher J. Petit, MD
Tetralogy of Fallot - BASICS
Tetralogy of Fallot - description
Anatomic hallmark is anterior malalignment of infundibular septum:
- A large and unrestrictive ventricular septal defect (VSD):
- Various degrees of right ventricular outflow tract obstruction (RVOTO)
- Overriding aorta
- Right ventricular hypertrophy (RVH): Secondary to unrestrictive VSD and RVOTO
Tetralogy of Fallot - epidemiology
Tetralogy of Fallot - prevalence
3.5–8% of all congenital heart disease
Tetralogy of Fallot - risk factors
Tetralogy of Fallot - genetics
- Some cases of tetralogy of Fallot (TOF) are associated with a chromosome 22q11 microdeletion.
- May be associated with other syndromes including Down syndrome, Alagille syndrome, CHARGE syndrome, VACTERL syndrome, fetal alcohol syndrome, and those syndromes involving a variety of limb abnormalities. May also affect infants of diabetic mothers. TOF may also be associated with midline abdominal defects (e.g., omphalocele) as in the pentalogy of Cantrell.
Tetralogy of Fallot - pathophysiology
Severity of clinical signs and symptoms depends on the degree of RVOTO and resulting cyanosis due to right-to-left shunting.
Tetralogy of Fallot - DIAGNOSIS
Tetralogy of Fallot - signs & symptoms
Heart murmur in the newborn period:
- Various degrees of progressive cyanosis
- History of paroxysmal cyanosis, especially when crying or during and after physical exercise
Tetralogy of Fallot - physical exam
Various degrees of cyanosis may be present at birth or may appear later during infancy or childhood as a result of progression of the pulmonary stenosis.
- Normal S1 and single loud S2 secondary to a more anteriorly located aorta
- Systolic ejection murmur at left upper sternal border secondary to RVOTO
Tetralogy of Fallot - tests
Tetralogy of Fallot - imaging
- Electrocardiography: Right axis deviation (+90–180°), RVH
- Chest radiograph: Right aortic arch (30%), decreased pulmonary vascular markings, boot-shaped heart (coeur en sabot) with concave main pulmonary artery (PA) segment
- Echocardiography: Anterior malalignment VSD, infundibular stenosis, overriding aorta, RVH. May also see: Other (muscular) VSDs, valvular pulmonary stenosis and/or branch PA stenosis, abnormal (right-sided) aortic arch anatomy, coronary artery anomalies
- Cardiac catheterization: Generally not indicated unless concern is present regarding branch PA anatomy, coronary anatomy, or multiple additional VSDs that need to be defined before surgery
Tetralogy of Fallot - differencial diagnosis
- TOF should be considered in all infants with heart murmur and/or various degrees of cyanosis, and otherwise acyanotic infants or children with history of hypercyanotic spells.
- Multiple varieties of TOF exist, including TOF with pulmonary atresia (pulmonary blood flow from the ductus arteriosus), TOF with absent pulmonary valve (and severely enlarged main and branch PAS). TOF can also be associated with other cardiac anomalies such as common atrioventricular canal (CAVC).
- Differential diagnosis if cyanotic: Transposition of the great arteries (TGA), tricuspid atresia (TA), total anomalous pulmonary venous return (TAPVR), truncus arteriosus, double-outlet right ventricle (DORV)
- Differential diagnosis if not cyanotic: VSD, DORV, peripheral pulmonic stenosis (PPS), valvular pulmonic stenosis (PS)
Tetralogy of Fallot - TREATMENT
Tetralogy of Fallot - medication
Hypercyanotic spells (aka “tet spells”): Profound cyanosis due to infundibular spasm and decreased pulmonary blood flow.
- Knee-chest position:
- Oxygen
- Morphine sulfate (0.1 mg/kg IV or IM)
- IV fluid bolus and/or NaHCOBeta-blocker (esmolol infusion for immediate therapy, propranolol for long-term prophylaxis)
- Phenylephrine (0.02 mg/kg IV)
- Presurgical management:
- Polycythemia: Oral iron supplement for iron deficiency to avoid microcytosis
- Beta-blocker for “tet spell” prophylaxis
- Subacute bacterial endocarditis (SBE) prophylaxis
Tetralogy of Fallot - surgery
- Palliative surgery: Blalock–Taussig systemic-pulmonary shunt
- Corrective surgery: VSD patch closure and right ventricular outflow tract reconstruction (either an RV-to-PA conduit or a patched reconstruction of the MPA segment)
Tetralogy of Fallot - FOLLOW UP
Tetralogy of Fallot - prognosis
Generally good if condition treated surgically in a timely manner:
- >90% of children with TOF are expected to survive to adulthood.
- Surgical mortality is low in most centers: 5-year survival >95%, 20-year survival ~94%
- Long-term quality of life in adulthood is comparable with that of the general population.
- Young patients with TOF have a greater risk of requiring additional help in school.
- Residual hemodynamic abnormalities are quite common
- Pulmonary insufficiency (PI) is common with transannular patch repair:
- Residual RVOTO may occur.
- Right ventricular dysfunction +/− ventricular arrhythmias in adulthood from right ventricular volume overload secondary to PI
- In the setting of severe RV dysfunction and dilatation due to severe PI, some patients require surgical revision of the right ventricular outflow tract in adolescence or adulthood
- Left PA stenosis
- Residual VSD occurs rarely
- Conduction abnormalities (e.g., complete heart block, right bundle branch block [RBBB])
- Supraventricular and ventricular arrhythmias
Tetralogy of Fallot - complications
Preoperatively:
- Paroxysmal hypoxic spells (i.e., hypercyanotic spells, “tet spell”)
- Bacterial endocarditis
- Cerebrovascular accident (CVA) secondary to cyanosis, polycythemia, and microcytic anemia
Postoperatively:
- Right ventricular dysfunction and ventricular arrhythmia
- Postoperative sudden death (ventricular arrhythmias and/or complete heart block)
- Exercise intolerance and dyspnea due to severe RV dilatation/dysfunction in the setting of PI
Tetralogy of Fallot - bibliography
- Cobanoglu A, Schultz JM. Total correction of tetralogy of Fallot in the first year of life: Late results. Ann Thorac Surg. 2005;74:133–138.
- Nollert G, Fischlein T, Bouterwek S, et al. Long-term survival in patients with repair of tetralogy of Fallot: 36-year follow-up of 490 survivors of the first year after surgical repair. J Am Coll Cardiol. 1997;30:1374–1383.
Siwik ES. Moss and Adams Heart Diseases in Infants, Children and Adolescents. 5th ed. Baltimore: Williams & Wilkins; 2001:880–902.- Walker WT, Temple IK, Gnanapragasam JP, et al. Quality of life after repair of tetralogy of Fallot. Cardiol Young. 2002;12:549–553.
Tetralogy of Fallot - CODES
Tetralogy of Fallot - icd9
745.2 Tetralogy of Fallot
Tetralogy of Fallot - FAQ
- Q: What is the etiology of the “tet spell”?
- A: There is an increased impedance to flow through the RVOT and/or pulmonary vascular bed that leads to a dramatic decrease in pulmonary blood flow and an increased right-to-left shunt at the level of the VSD. Therefore, treatment should be aimed at increasing pulmonary blood flow either by decreasing pulmonary vascular resistance (e.g., OQ: When is an optimal time for surgical repair of TOF?
- A: At The Children’s Hospital of Philadelphia, we recommend elective repair of “typical” TOF in early infancy (3–6 months). Progressive hypoxemia or recurrent “tet spell” indicates a need for earlier surgical intervention. Patients with TOF with pulmonary atresia or TOF with absent pulmonary valve are treated on a patient-by-patient basis.
Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
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