Ankle brachial index is the ratio between blood pressures at the ankle and arm, an important measure in assessment of peripheral vascular disease (PVD).
Breath holding spell has a precipitating factor (does not occur abruptly) which causes the child to cry incessantly and this is followed by breath holding.
Classic Blalock Taussig shunt (BT shunt) is done on opposite side of aortic arch so that brachiocephalic trunk prevents kinking of the subclavian artery.