Here’s what I know. The thump-thump of a heartbeat is the sound made by the four valves closing. If you’re an adult, your heart is about the same size as two fists. A human heart beats about 100,000 times in one day. It never stops. Like skin, a damaged heart scars. Scarred hearts don’t heal. But over time, scars can change. They can become smoother, softer and sometimes they just fade away. Lately, after nearly 17 years of scar ownership, I see mine differently. It never really bothered me all that much, even when it was fresh in 2001 after open-heart surgery to remove a benign cardiac tumor. Often hidden…