In an infographic for Stanford Magazine, we illustrate a non-simultaneous extended altruistic donor (NEAD) chain for kidney exchange. In paired kidney donation, where a patient with a willing but incompatible donor is able to receive a kidney from another donor in a similar situation (and vice versa), the surgeries are done simultaneously to prevent donors from backing out. But when an “altruistic donor” makes a non-directed donation — that is, to anyone in need — he or she can set in motion a chain of non-simultaneous transplant surgeries that could, theoretically, go on indefinitely. (The longest NEAD chain to date involved kidney swaps among 60 individuals in 11 states.) See how algorithm meets altruism in the NEAD chain diagrammed below.