IntroductionSome people can periodically experience an abnormally low heart rate and can lose consciousness during critical life style moments such as physical activity, driving an automobile, or just walking up a flight of stairs.
The cardiac pacemaker demonstrates the tremendous intersection of a significant medical problem with several key engineering specialties and is a great example of a Biomedical Engineering solution. Briefly, electrical and computer engineering skills are used to design the electronics and programming logic which drive the device - all pacemakers are based on fully functioning microprocessors. The pacemaker is implanted inside the human body (a particularly hostile environment) and therefore must be impervious to the biological fluids and must also not cause a rejection reaction.
Thus the biocompatibility issues and the subsequent solution with engineered biomaterials were crucial to the long term success of the pacemaker. Additionally, the wires connecting the device with the heart tissue must be flexible but resilient enough to withstand the repetitive motion produced by a beating heart. Further, the wires cannot dislodge from stable sites within the heart under these same conditions. The subsequent mechanical design of the pacemaker wires has solved this problem.
The battery energy source which powers the pacemaker was originally a set of ordinary mercury cells but the need to increase energy density lead to the development of the lithium battery technology increasing the life span of the device from 12 - 18 months to 8 - 10 years. The lithium battery technology is now common place in a wide range of consumer and industrial products. Of significant note is the fact that the National Academy of Engineering has established an award for major engineering contributions which have significantly impacted society and has contributed to the advancement of the human condition - The Russ Prize. The first Russ Prize was awarded in 2001 to two Biomedical Engineers credited with inventing the cardiac pacemaker: Earl Bakken and Wilson Greatbatch. More than 400,000 pacemakers are implanted annually around the world!