Commonest pa of subclan aery to be affected by stenosis is

<p> Subclan steal syndrome:- Obstruction of first pa of subclan aery. Veebral aery provides collateral circulation to arm by reversing its blood flow. This causes cerebral ischemia with syncopal attacks , visual disturbances, dimnished BP in affected limb. More common on left side. Radial pulses on both sides become assymmetrical. Blood pressure on the diseased side will be 20 mm Hg less compared to normal side. Javid test- compression of carotid aery makes ipsilateral radial pulse feeble. {Reference: SRB&;s manual of surgery, 5th edition , page no. 189}