Pacemakers have become quite advanced, very safe and effective, allowing recipients to live active lives.
- A pacemaker is a small, but very advanced, electronic device that is implanted under the skin to help regulate the heartbeat.
Pacemakers are used primarily in people whose hearts are beating slower than normal (bradycardia = less than 60 beats per minute).
They usually end the symptoms caused by bradycardia including:
- dizziness, or loss of consciousness.
How they work:
- Pacemakers do not take over the work of the heart. After you have a pacemaker, your heart still does all its own work. Rather, the pacemaker merely helps to regulate the timing and sequence of your heartbeat.
Pacemakers consist of two major parts: the generator and the leads.
- The generator is like a tiny computer (along with a battery and other electronic components), housed in a hermetically sealed titanium container.
- Most modern pacemaker generators are roughly the size of a 50-cent piece and about three times as thick.
- A lead is a flexible, insulated wire that carries electrical signals back and forth between the pacemaker generator and the heart.
- Most pacemakers today use two leads; one placed in the right atrium and the other in the right ventricle.
- Pacemakers are implanted under local anesthesia.
- The leads are threaded through a nearby vein, advanced to the proper place within the heart, and their ends are plugged into the generator.
The procedure usually takes 30 minutes to an hour.
Once implanted, the pacemaker works by monitoring the heart’s electrical activity, and deciding whether and when to “pace.”
If the heart rate becomes too slow, the device paces by transmitting a tiny electrical signal to the heart muscle, causing it to contract.
- Pacing can be done from the right atrium, the right ventricle, or both.
- The pacemaker decides on a beat-to-beat basis whether it needs to pace, and if so, in which chambers it should pace.
- It makes sure that an appropriate heart rate is always present, and that the work of the cardiac chambers is always coordinated.
Pacemakers are “programmable”
- The specific needed functions can be altered at any time.
- Programming a pacemaker is done by wirelessly transmitting new instructions to the generator, using a special device called a “programmer.” For instance, your doctor can easily reprogram your pacemaker to change the rates at which it will pace your heart.
Today almost all pacemakers have the ability to vary the rate at which they pace, depending on the patient’s immediate needs. These pacemakers are called “rate-responsive pacemakers.”
Rate-responsive pacemakers can use one of the several technologies to find the ideal heart rate, but two, in particular, have proven very useful.
- The activity sensor detects body movement. The more active you are, the faster the pacemaker will pace your heart (within a range of heart rates that set by your doctor).
The other method used to vary the pacing rate is a breathing sensor, which measures your rate of breathing.
- The faster your breathing, the more active you are (presumably), the faster the pacing (again, within a pre-set range).
The rate-responsive pacemakers mimic the normal, moment-to-moment changes in heart rate provided by a normal heart rhythm.
- In most people with pacemakers, the heart’s own electrical system is actually generating most of the heart beats. The pacemaker is there mainly as a “safety valve,” to prevent occasional episodes of inappropriate bradycardia.
- In other people the pacemaker works mainly in the rate-responsive mode, to allow the heart rate to increase appropriately during exercise. While they are at rest, the pacemaker is usually not pacing.
Rate-responsive pacing allows patients to be more active with much less fatigue.
By following a few simple precautions, and your doctor’s instructions for having your device checked periodically, you can plan on leading a life almost free of restrictions by a misbehaving heart.