"How do pacemakers affect the heart?" -Shabana Hameed Senior Manager Clinical QA at Boston Scientific
"Home" - http://www.innerbody.com/image/card01.html
"How does the heart work?" - http://www.heartfailurematters.org/en_GB/Understanding-heart-failure/How-does-the-normal-heart-work
"How do the heart and lungs work together?" http://www.healthcentral.com/copd/c/52325/169890/heart-lungs-work/