What is Tetralogy of Fallot?

1.

Elsevier ClinicalKey Clinical Overview

Terminology Tetralogy of Fallot is a congenital heart condition with the following features: Ventricular septal defect Right ventricular outflow tract obstruction secondary to infundibular and/or pulmonary valvular stenosis Overriding aorta Aorta arises over the ventricular septal defect rather than the left ventricle, allowing blood flow from both ventricles into the aorta Right ventricular hypertrophy

Synopsis Tetralogy of Fallot is a congenital heart condition with the following features: Large ventricular septal defect Right ventricular outflow tract obstruction secondary to infundibular and/or pulmonary valvular stenosis Overriding aorta Right ventricular hypertrophy Exact cause is unknown; however, chromosomal band 22q11.2 deletion is occasionally associated Primary diagnostic tools include history, physical examination, and echocardiography Definitive treatment involves complete surgical repair Patients have excellent survival rate if both the obstruction of the right ventricular outflow tract is corrected and the ventricular septal defect has been closed completely 36-year survival rate after corrective surgical repair is 85% Patients who have undergone repair are at long-term risk for development of arrhythmias and pulmonary regurgitation

2.

Therrien, Judith, Marelli, Ariane J. (2024). In Goldman-Cecil Medicine (pp. 347). DOI: 10.1016/B978-0-323-93038-3.00055-1

Tetralogy of Fallot, the most common cyanotic malformation, is characterized by superior and anterior displacement of the subpulmonary infundibular septum, which causes the tetrad of pulmonary stenosis, VSD, aortic override, and right ventricular hypertrophy. The VSD is perimembranous in 80% of cases. Additional cardiac anomalies include a right-sided aortic arch in up to 25% of patients. An anomalous left anterior descending artery originating from the right coronary cusp and crossing over the right ventricular outflow tract is seen in 10% of cases. Other associated anomalies include ASD, left superior vena cava, defects of the atrioventricular canal, and aortic insufficiency. With pulmonary atresia, pulmonary blood flow occurs through aortic to pulmonary collaterals. Complete surgical repair in childhood consists of patch closure of the VSD and relief of the right ventricular outflow tract obstruction. Adequate pulmonary blood flow is ensured by reconstruction of the distal pulmonary artery bed. Previous palliative shunts are usually taken down. Complete repair in childhood yields a 90 to 95% 10-year survival rate with good functional results, and 30-year survival rates may be as high as 85%. After repair, residual pulmonary stenosis, proximal or distal, can be seen. Some degree of pulmonary insufficiency is common, particularly if a patch has been inserted at the level of the pulmonary valve or if a pulmonary valvotomy has been performed. Residual VSDs can be found in up to 20% of patients. Patients may be asymptomatic or may have symptoms related to long-term complications after surgical repair. Symptoms can reflect residual right ventricular pressure or volume overload or arrhythmias at rest or with exercise. Angina can occur in a young patient if surgical repair has damaged an anomalous left anterior descending artery as it courses across the right ventricular outflow tract. In acyanotic adults, clubbing commonly regresses. On physical examination, a right ventricular impulse is often felt as a result of residual pulmonary insufficiency or stenosis.

3.

Wise-Faberowski L, Asija R, McElhinney DB. Paediatric Anaesthesia. 2019;29(5):475-482. doi:10.1111/pan.13569.

Publish date: May 3, 2019.

Tetralogy of Fallot (TOF) has four anatomic features: right ventricular hypertrophy (RVH), ventriculoseptal defect (VSD), overriding aorta and right ventricular outflow tract obstruction (RVOT) with an occurrence of 3.9 /10,000 births. The pathophysiologic effects in TOF are largely determined by the degree of RVOT and not the VSD. Intra-operative anesthetic management is also dependent on the degree of RVOT obstruction and influenced by the extent of surgical RVOT repair.

4.

Wu, Justina C., Gillam, Linda D., Solomon, Scott D., Bulwer, Illustrated by Bernard (2022). In Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine (pp. 196). DOI: 10.1016/B978-0-323-72219-3.00016-5

The tetralogy of abnormalities consists of an overriding aorta, nonrestrictive subaortic VSD, RVOT obstruction (typically infundibular with variable valvular abnormalities), and secondary RV hypertrophy. Each of these features is readily identifiable with echocardiography (Fig. 16.93).Pentalogy of Fallotrefers to the condition in which an ASD is also present.Surgery for tetralogy consists of patching the VSD and a tailored approach to relieving the RVOT obstruction. Pulmonic regurgitation, sometimes severe, is a frequent finding after surgery for tetralogy of Fallot and may drive the need for repeated surgery. Other problems to remain vigilant for in the years after surgery include residual infundibular (subvalvular) and supravalvular pulmonic stenosis, as well as aneurysmal degeneration of the patch used to open up the infundibulum and/or pulmonary artery.

5.

Valente, Anne Marie, Dorfman, Adam L., Babu-Narayan, Sonya V., Krieger, Eric V. (2022). In Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine (pp. 1541). DOI: 10.1016/B978-0-323-72219-3.00082-7

TOF is the most common cyanotic congenital heart defect, comprising a “tetrad” of overriding aorta, VSD, pulmonary stenosis, and right ventricular hypertrophy (Fig. 82.21). Anterocephalad deviation of the outlet septum together with hypertrophy of the septoparietal trabeculations causes subpulmonary stenosis. The pulmonary valve, main and branch pulmonary arteries may also be narrow. Hypoplasia of the pulmonary arteries has been reported to be as frequent as 50%. Associated anomalies include right aortic arch, present in about 25% of patients, and anomalous course of the coronary arteries, the most common with a left anterior descending artery that originates from the right coronary artery and crosses the RVOT. This may be of surgical importance, sometimes necessitating the use of a RV-to-PA conduit. An ASD, a second muscular inlet VSD, or an AVSD—usually in the setting of Down syndrome—can coexist with TOF. There are important anatomic variations of TOF. TOF with pulmonary atresia with major aortopulmonary collateral arteries (MAPCAs) is an extreme form of TOF present in approximately 15% of all cases. There is absence of any direct connection between the heart and the pulmonary arterial tree, a large VSD and two ventricles. Prior to repair blood reaches the pulmonary bed through the PDA and or MAPCAs. Repair is via unifocalization of MAPCAs, closure of the VSD, and RVOT reconstruction with a conduit. Another anatomic variant is TOF with absent pulmonary valve, in which there is marked stenosis of the pulmonary valve annulus with poorly formed or absent valve leaflets and severely dilated or aneurysmal pulmonary arteries which may produce airway compression at birth. Patients with repaired TOF constitute one of the largest groups of ACHD patients surviving into adulthood.