Most of us are too busy to think about our heart beating. We depend on it to beat regularly 60 to 100 times per minute, keeping our blood flowing and our body functioning.
However, we do notice if our heart beats unusually fast or slow or varies its rhythm. These occurrences are called arrhythmias. Ranging from mild to severe, arrhythmias can cause dizziness, weakness, fainting spells, shortness of breath, chest pain or discomfort. Arrhythmias can even result in death due to sudden cardiac arrest.
Arrhythmias occur most often in older people, but they can also occur in younger people, often related to genetic defects.
Arrhythmias are caused by malfunction of the hearts electrical system. They may be treated with medication, but when medication is not effective, a battery-powered device may be implanted in the chest to keep the heart beating regularly.
The most common device of this type is a pacemaker, which treats slow heart rates. Another type is a defibrillator, which treats slow and fast heart rates. The defibrillator also can provide an electric shock to restart the heart if it stops beating.
In some cases, the devices regulate heart rhythm constantly, while in other cases the devices act only when they detect an abnormality. The physician programs the pacemaker or defibrillator according to the individual patients needs.
About the diameter of a half dollar and ranging in thickness from one-quarter to one-half inch, these devices are surgically implanted under the collarbone at the upper left side of the chest. They are connected to the heart with insulated wires called leads, which are threaded through the veins and attached to the heart muscle.
The implantation is a fairly brief surgery performed while the patient is under sedation. Usually, the patient stays in the hospital only one night. After the incisions heal, the patient feels no discomfort and is unaware of the device and leads in the chest.
Programming the device is done using remote signals, and every three months the physician remotely checks the device to determine whether any changes need to be made. The battery should continue to function for many years, but it is also monitored, and the device is replaced if the battery starts to weaken.
Contrary to some rumors, these devices are not affected by microwave ovens or cellphones. However, MRI scans and airport screening systems should be avoided. Newer models of pacemakers and defibrillators are compatible with MRIs.
Every surgical procedure carries some risks, and with this type of surgery typical risks include infection, perforation of the heart or lungs and malfunction of the leads. Occasionally a device or type of lead is recalled by the manufacturer and has to be replaced.
However, even with these risks, we are fortunate to be able to extend the length and quality of life by implanting these devices, which only became available in the 1990s. Advances in technology over the years have made them smaller and better and proven their safety and effectiveness.