<prompt> Vein used to bypass the coronary aeryLong saphenous veinSho saphenous veinSoleal veinTibial vein  <response>: Varicose veins are due to the touosity of the long saphenous vein and occur mostly due to prolonged standing.The long saphenous vein is used to bypass the coronary aery after inveing the vein.Ref: Chaurasia; Volume 2; 6th edition; Page no: 135 