From the Guidelines
Tetralogy of Fallot is a congenital heart defect characterized by four specific abnormalities: a ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta, which can lead to serious complications if left untreated, including heart failure, stroke, and life-threatening arrhythmias 1.
Definition and Components
Tetralogy of Fallot consists of four key components:
- A ventricular septal defect (a hole between the heart's lower chambers)
- Pulmonary stenosis (narrowing of the pulmonary valve and outflow tract)
- Right ventricular hypertrophy (thickening of the right ventricle's muscle)
- An overriding aorta (the aorta is shifted over the right ventricle and septal defect instead of coming completely from the left ventricle) This condition causes oxygen-poor blood to flow into the body, resulting in cyanosis (a bluish discoloration of the skin) and other symptoms like difficulty feeding, poor weight gain, and developmental delays in infants.
Treatment and Management
Tetralogy of Fallot requires surgical correction, typically performed in the first year of life, to repair the defects and restore normal blood flow 1. The main pathologic basis is antero-cephalad deviation of the developing conal septum, which causes a malalignment type ventricular septal defect (VSD), resulting in an “overriding aorta” and right ventricular (RV) outflow tract (RVOT) obstruction, ultimately leading to RV hypertrophy.
Complications and Risks
Without treatment, Tetralogy of Fallot can lead to serious complications, including:
- Heart failure
- Stroke
- Delayed growth and development
- Potentially life-threatening arrhythmias The exact cause is unknown, but genetic factors may play a role, and it sometimes occurs as part of genetic syndromes like DiGeorge syndrome or Down syndrome 1.
Follow-up and Monitoring
Patients with repaired Tetralogy of Fallot should have at least annual follow-up with a cardiologist who has expertise in ACHD, and echocardiographic examinations and/or MRIs performed by staff with expertise in ACHD 1. Screening for heritable causes of their condition (e.g., 22q11 deletion) should be offered to all patients with Tetralogy of Fallot 1.
From the Research
Definition of Tetralogy of Fallot
Tetralogy of Fallot (TOF) is a congenital cardiac malformation that consists of:
- An interventricular communication, also known as a ventricular septal defect
- Obstruction of the right ventricular outflow tract
- Override of the ventricular septum by the aortic root
- Right ventricular hypertrophy 2, 3, 4, 5
Characteristics of Tetralogy of Fallot
The clinical spectrum and course of TOF are greatly heterogeneous, with characteristic features including:
- Subaortic ventricular septal defect
- Overriding aorta
- Right ventricular hypertrophy
- Pulmonary stenosis 2
- Cyanosis, which develops in the first year of life if not already present at birth 3
Diagnosis and Treatment of Tetralogy of Fallot
Useful diagnostic tests for TOF include:
- Chest radiograph
- Electrocardiogram
- Echocardiogram, which establishes the definitive diagnosis and usually provides sufficient information for planning of treatment 5 Treatment for TOF is surgical, with initial intervention possibly being palliative, such as surgical creation of a systemic-to-pulmonary arterial shunt, but the trend is increasingly towards neonatal complete repair 5
Complications and Long-term Management of Tetralogy of Fallot
Chronic issues that face adults with TOF include: