TETRALOGY OF FALLOT

Tetralogy of Fallot

Tetralogy of Fallot

Introduction

Tetralogy of Fallot (TOF) is an innate heart defect, which is classically defined as the four anatomical anomalies (though only three of them are always present). It is the most widespread cyanotic heart flaw, and the most general cause of blue baby syndrome (Neches Ettedgui Park 1998).

It was described in 1672 Niels Stensen, in 1773 Edward Sandifort, and in 1888 a French physician Etienne-Louis Arthur Fallot, for whom it is named (Patel 2007). "Tetralogy" refers to 4 parts of the phenomenon in various fields, including literature, and the name of the four parts of the syndrome implies it is 4 characters. This is not to be confused with the same teratology, in the field of medicine concerned with abnormal development and congenital malformations, which thus includes Fallot in its subject matter.

Thus, by definition, Fallot includes exactly four heart defects, which are together (Neches Ettedgui Park 1998):

Condition

Description

The: Pulmonary stenosis

The narrowing of right ventricular outflow tract and can occur at pulmonary valve (valvular stenosis) or just below pulmonary valve (infundibular stenosis). Infundibular pulmonic stenosis is mostly caused by overgrowth of heart muscle wall (hypertrophy of septoparietal trabeculae), however events leading to formation of overriding aorta are also believed to be the cause. pulmonic stenosis is major cause of malformations, with other associated malformations acting as compensatory mechanisms to pulmonic stenosis. degree of stenosis varies between individuals with TOF, and is primary determinant of symptoms and severity. This malformation is infrequently described as sub-pulmonary stenosis or subpulmonary obstruction.

B: Overriding aorta

An aortic valve with biventricular connection, that is, it is situated above ventricular septal defect and connected to both right and left ventricle. degree to which aorta is attached to right ventricle is referred to as its degree of "override." aortic root can be displaced toward front (interiorly) or directly above septal defect, but it is always abnormally located to right of root of pulmonary artery. degree of override is quite variable, with 5-95% of valve being connected to right ventricle.

C: ventricular sepal defect (VSD)

THE hole between two bottom chambers (ventricles) of heart. defect is centered on most superior aspect of ventricular septum ( outlet septum), and in majority of cases is single and large. In some cases thickening of septum (septal hypertrophy) can narrow margins of defect.

D: Right ventricular hypertrophy

right ventricle is more muscular than normal, causing the characteristic boot-shaped (coeur-en-sabot) appearance as seen by chest X-ray. Due to disarrangement of external ventricular septum, right ventricular wall increases in size to deal with increased obstruction to right outflow tract. This feature is now generally agreed to be the secondary anomaly, as level of hypertrophy generally increases with age.

There is anatomic variation between hearts of individuals with tetralogy of Fallot. Primarily, degree of right ventricular outflow tract obstruction varies between patients and generally determines clinical symptoms and disease progression (Neches Ettedgui Park 1998).

Additional anomalies

In addition, tetralogy of Fallot may present with other anatomical anomalies, including:

stenosis of left pulmonary artery, in 40% of patients

the bicuspid pulmonary valve, ...