The first two conditions are necessary because, to lower the chances of rejection, the patient's immune system must be deliberately weakened; infections or cancers could then quickly spread.
「絕對條件」的前兩項，都是由於換心手術後要長期服用抗排斥藥物，而排斥與免疫（抵抗力）是一體兩面，抑制排斥也就是減低人體免疫力，這時若體內原已有發炎或癌症，很快就會蔓延開來，不可收拾。