Devi Shetty is obsessed with making heart surgery affordable for millions of Indians. On his office desk are photographs of two of his heroes: Mother Teresa and Mahatma Gandhi. Shetty is not a public health official motivated by charity. He’s a heart surgeon turned businessman who has started a chain of 21 medical centers around India. By trimming costs with such measures as buying cheaper scrubs and spurning air-conditioning, he has cut the price of artery-clearing coronary bypass surgery to...