 The Mustard procedure was largely replaced in the late 1980s by the Jatene procedure (arterial switch), in which the native arteries were switched back to normal flow, so that the RV (right ventricle) would be connected to the pulmonary artery and the LV (left ventricle) would be connected to the aorta.This surgery had not been possible prior to 1975 because of difficulty with re-implanting coronary arteries which perfuse the actual heart muscle itself (myocardium), and even after it was first performed the excellent results from the Mustard operation meant that it was a long time before the Jatene procedure took over.The Mustard procedure improved an 80% mortality rate in the first year of life to an 80% survival at age 20.