5.6.1 Haemodynamic effects
Tetralogy of Fallot is a severe defect with significant haemodynamic effects. RV outflow obstruction results in increased RV pressure and this is the cause of the hypertrophy. Infundibular hypertrophy may itself result in an element of outflow obstruction. The presence of a VSD means that there is a communication between the RV and the LV so that deoxygenated blood can pass into the systemic circulation. High RV pressure allows blood to flow into the LV. The presence of the overriding aorta means that some of this blood is ejected directly into the aorta.