All of the following statements regarding total anomalous pulmonary connection are true except ?

Ans. is 'b' i.e., Always associated with VSD Hemodvnamics of TAPVC o TAPVC results in the pulmonary venous blood reaching the right atrium which also receives the systemic venous blood. o This results in volume overload to right atrium Right atrial enlargement. o Larger volume of blood reaches the right ventricle -f Right ventricle enlargement. o The blood flow to the left atrium is through patent foramen ovale or ASD. o Because there is mixing of unoxygenated blood from systemic circulation and oxygenated blood from pulmonary circulation in the right atrium --> The oxygen saturation of blood in pulmonary aery is higher or identical to that in Aoa. o TAPVC can be divided into : - i) TAPVC with pulmonary venous obstruction Pulmonary venous obstruction results in pulmonary aerial hypeension. Pulmonary obstruction T back pressure -4 T Pulmonary capillary pressure T Pulmonary aery pressure Because of pulmonary venous obstruction oxygenated blood cannot reach hea -4 Cyanosis and CHF during first week of life. ii) TAPVC without obstruction (more common) In TAPVC without obstruction, pulmonary blood flow is high. Patients develops CHF at around 6-8 weeks when the fetal pulmonary resistance falls maximally and pulmonary circulation reaches the maximum. o Infracardiac type of TAPVC is always obstructive whereas cardiac and supracardiac type may be obstructive or nonobstructive.