Heartbeat treat.

It's not just eats that have extra lives--meet a dog that does, too!

"If Sunshine was a eat with nine lives," laughs John Wren, owner of the nine-year-old German shepherd, "she would have been through four of them!"

Sunshine earned her fourth life recently when she received a pacemaker, a small electrical unit that keeps her heart beating. (See "Your Contraction Action," page 9.) And this pacemaker came to Sunshine from its last owner, a human!

This isn't Sunshine's first narrow escape. She was first adopted by John years ago when her previous owner was hauled off to jail by the police.

Sunshine settled in, but developed heart trouble. The electrical impulse that makes the upper and lower heart contract in order was being blocked. The lower chambers would beat on their own, keeping her alive--barely.

So Sunshine got a pacemaker. It worked fine until she started having trouble again. "Whenever she was exercising or putting her body under a load, that heart rate wasn't coming back up," John said. When the body works harder, the heart is supposed to beat faster to provide more blood.

The pacemaker's battery was running low. Luckily a replacement turned up when an elderly woman passed away after telling her family she wanted her pacemaker to be reused. So Sunshine got lucky again.

John is happy they've been able to help Sunshine. "I'm glad we were in a position where we could do something for her; she's been a great pet," he said.

Ed. Note: To read more about Sunshine, visit her 144b site at www.jcwren.com/sunshine/.

Your Contraction Action

Muscles squeeze, or contract, when they receive a small jolt of electricity passed to them from the brain. Your heart is a muscle, and it needs the juice, too. Here's how it works:

* The brain's electrical beat message travels from the brain down to the heart.

* It hits the sinoatrial (sigh-no-A-tree-ull) node, which fires like a sparkplug. (The SA node is the heart's natural pacemaker.)

* That small electrical burst goes through the upper and lower chambers of the heart, causing them to contract and squeeze blood out to the rest of the body.

Sometimes the electrical burst is blocked because of disease or damage to the heart muscle. That's when an artificial pacemaker can provide the jolt, keeping the heart beating.