TETRALOGY OF FALLOT

Introduction

▪ Tetralogy of Fallot (TOF) is one of the most common congenital heart disorders (CHDs). ▪ This condition is classified as a cyanotic heart disorder,

because tetralogy of Fallot results in an inadequate flow of blood to the lungs for oxygenation (right-to-left shunt)▪ Patients with tetralogy of Fallot initially present with

cyanosis shortly after birth, thereby attracting early medical attention.▪ Louis Arthur Fallot, after whom the name tetralogy of

Fallot is derived

Components

1. Pulmonary stenosis2. Overriding Aorta 3. Ventricular septal defect4. Right ventricular hypertrophy

Haemodynamics

▪ Acyanotic Fallot : - Obstruction to pulmonary flow is minimal - Pink Fallot

▪ Cyanotic Fallot : - Pulmonary resistance is high - Increased shunting right-to-left side aggravating the central cyanosis

Aetiology

▪ The embryological causes is abnormal development of bulbar septum that separates the ascending aorta from the pulmonary artery▪ It normally aligns and fuses with the outflow part of

intraventricular septum ▪ Prenatal factors associated with a higher incidence of

tetralogy of Fallot (TOF) include maternal rubella (or other viral illnesses) during pregnancy, poor prenatal nutrition, maternal alcohol use, maternal age older than 40 years, maternal phenylketonuria (PKU) birth defects, and diabetes. Children with Down syndrome also have a higher incidence of tetralogy of Fallot, as do infants with fetal hydantoin syndrome or fetal carbamazepine syndrome. ▪ The defect occurs in about 1 in 2000 births

Clinical features

▪ Most infants with tetralogy of Fallot have difficulty with feeding, and failure to thrive (FTT) is commonly observed▪ At birth, some infants with tetralogy of Fallot do not

show signs of cyanosis, but they may later develop episodes of bluish pale skin during crying or feeding and may become apnoeic and unconscious – Fallot’s spells▪ In older children, Fallot’s spells are uncommon but

cyanosis becomes increasingly apparent, stunting of growth, digital clubbing ,polycythemia, chest pain ,headache and tachyponea ▪ Some children characteristically obtain relief by

squatting after exertion, which increases the afterload of left heart and reduces the right-to-left shunt - Fallot’s sign

▪On examination :▪ Combination of cyanosis with a loud ejection systolic

murmur in the pulmonary area▪ However, cyanosis may be absent in the newborn or in

patients with only mild right ventricular flow obstruction

Differential diagnosis

▪ TGA with pulmonary stenosis ▪ VSD with pulmonary stenosis ▪ TGA with VSD with pulmonary stenosis▪ VSD with pulmonary atresia ▪ Tricuspid atresia ▪ Eisenmenger’s syndrome

Investigations

▪ ECG shows right ventricular hypertrophy

▪ X-ray shows an abnormally small pulmonary artery and a ‘boot-shaped’ heart

▪ ECHO is diagnostic and demonstrates that aorta is not continuous with ventricular septum

▪ Colour Doppler Study▪ Right and left ventriculography ▪ Aortography▪ Cardiac catheterization

Management

▪Medical line :oTreatment of cyanotic spells oTreatment of polycythemiaoPrevention of complications

Surgical line

▪ Palliative shunt operations - recurrent spells, children who cannot tolerate total correction, anatomical abnormality, infants with early symptoms Types :Blalock–Taussig shunt subclavian artery & pulmonary artery anastomosis1. Modified Blalock – Taussig shunt Gore-Tex interposition 2. Waterson shunt Ascending aorta to right pulmonary artery 3. Potts-Smith shunt Descending aorta to left pulmonary

artery 4. Glenn’s shunt Superior vena cava to right pulmonary

artery

Right pulmonary artery

Left pulmonary artery

▪ Total correction• Brock’s procedure : The infundibulum is resected and

patch closure of VSD is done.• Rastelli’s operation : In cases with severe hypoplasia or

atresia of right ventricular outflow usually done after 5 yrs . Pulmonary artery is divided from left ventricle and cardiac end is overseen. An intracardiac tunnel is placed between large VSD and aorta. The right ventricle is connected to divided pulmonary artery by an aortic homograft.

▪ Rastelli procedure

▪ The prognosis after total correction is good, especially if the operation performed in childhood▪ Follow up is needed to identify residual shunting, recurrent

pulmonary stenosis and arrhythmias ▪ An implantable defibrillator is sometimes recommended in

adulthood

Thank you

A PPT BY : Vinaykumar.S.Appannavar