All of the following are components/features of Tetralogy of Fallot, EXCEPT
(B) Left ventricular hypertrophy # TETRALOGY OF FALLOT (TOF) is a congenital heart defect which classically has four anatomical components.> It is the most common cyanotic heart defect and the most common cause of blue baby syndrome.> As classically described tetralogy of Fallot involves four heart malformations:> Ventricular septal defect (VSD): a hole between the two bottom chambers (ventricles) of the heart.> Pulmonic stenosis: Right ventricular outflow tract obstruction, a narrowing at or just below the pulmonary valve.> Degree of stenosis varies between individuals with TOF & it is the primary cause of symptoms.> Overriding aorta: The aorta is positioned over the VSD instead of in the left ventricle.> Right ventricular hypertrophy (RVH): The right ventricle is more muscular than normal and may also be dilated. This causes a characteristic coeur-en-sabot (boot-shaped) appearance as seen by chest X-ray.> Pathophysiology:> TOF generally results in low oxygenation of blood due to mixing of oxygenated and deoxygenated blood in the left ventricle and preferential flow of blood from the ventricles to the aorta because of obstruction to flow through the pulmonary valve.> This is known as a right-to-left shunt. It is often evidenced by a bluish tint to the baby's skin (cyanosis).> However there are 'pink tests' in which the degree of obstruction in the right ventricular outflow tract is low.> Blood flows preferentially from the ventricles to the lungs and only minimal desaturation occurs in the systemic circulation beca use of mixing of saturated and desaturated blood in the ventricles.> This degree of desaturation may be undetectable to the eye and requires a pulse oximeter to identify it.> Even children who are generally not too deeply cyanosed (blue) may develop acute severe cyanosis or hypoxic 'tet spells> The precise mechanism of spelling is in doubt but certainly, this is a dangerous event and presumably results from an increas e in resistance to blood flow to the lungs with the increased preferential flow of desaturated blood to the body.> Untreated TOF, over the long term, results in progressive right ventricular hypertrophy and dilatation due to the increased resists nee on the right ventricle.> This progresses to right heart failure and death.
RV outlet obstruction
Left ventricular hypertrophy
Aorta over riding VSD
Malaligned VSD
Miscellaneous