Heart defibrillators come in a variety of kinds: external, implanted, monophasic and biphasic, to name a few. All of them have the same purpose: helping the heart return to its normal heart beat. The human heart is a true marvel of creation. Anyone who doesn't believe that, just look at man's efforts at creating a replacement. Size of the original model: about the same as a person's fist. Size of the replacement – including at the necessary external "accoutrements": massive. The real one's power source and "control center": a small cluster of cells known as the sinus node. The matching components on the artificial one: big and bulky.

Now, normally the heart's natural pacemaker fires a series of small electrical pulses through the cardiac muscle, which keeps it beating at a steady pace. And, as the poets say: "Every beat separates a man from eternity." Yet, with age, injury and/or disease, that rhythm can become irregular. As a result, the heart is rendered unable to contract. It's a condition called: ventricular fibrillation (VF). Decades ago, medical researchers discovered that the best way to "jump start" the heart and get its normal rhythm – defibrillation – restored was with a mild electrical jolt delivered right to the surface of the organ. Of course, outside of a hospital's operating room, that's not always possible. More often than not, some sort of external defibrillator must be used.

Between network television shows, both dramas and comedies, and various medical programs, we have all seen a person having a heart attack get zapped with the little paddles as a doctor yells: "Clear!" Heart disease claims nearly a quarter of a million people a year, and that is just in the United States. From the moment someone's heart goes into VF, the first five minutes is critical. That's where some type of defibrillator comes into play. External devices are applied to the chest, internal ones are implanted as part of a surgical procedure, usually in conjunction with an artificial pacemaker. Also, often times the internal models will have some kind of telemetry component that records the patient's heart activity and then download it to the doctor's office, thus enabling him/her to monitor the patient's progress.

So, while the heart can usually take care of itself, it's a great comfort to know that modern medical science has reached a point where some kind of heart defibrillator is available to help it, when needed. And most people hope they never require that kind of assistance.