January 01, 2014

Implanted pacemakers

Ticking away at progress


For more than 50 years, pacemakers have been used to maintain a steady heart rhythm in hearts that beat too slowly. Just as steadily, progress in pacemaker technology has advanced through the years, as the devices have gotten smaller, more durable and loaded with more helpful features.

In many ways, pacemakers have become such a routine part of medical care that they sometimes seem like yesterday's technology. In fact, pacemakers are incredibly high-tech, and they maintain an important role in prolonging life and improving quality of life.

Can't beat it

A heartbeat starts with an electric signal from the heart's natural pacemaker, the sinoatrial (SA) node. This specialized group of cells acts like a spark plug and is located in the right, upper chamber (atrium) of the heart. The electric signal from the SA node passes through the right and left atria, causing the atria to contract. This squeezes blood into the heart's two lower chambers (ventricles).

After activating the atria, the electrical signals converge at another group of cells called the atrioventricular (AV) node — the heart's junction box. The AV node stalls the electrical signal for a split second, which allows time for the ventricles to fill with blood. It then sends the signal through pathways called bundle branches to the ventricles, causing them to contract and pump blood to the body.

For your heart to function properly, the heart's chambers must work in the coordinated fashion described above. Your heart must also beat at an appropriate rate...