Using morphine consumption data from a retrospective study we conducted in evaluating the total opiate consumption in the first 24 hours following LVHR surgery, in order to detect a reduction of morphine consumption by 50% in the first 24 hours post-operatively with alpha of 0.05 and power of 0.9, 43 patients are required in each group. We will aim for 48 patients in each arm anticipating for possible drop outs.