Pacemaker Implantation
A pacemaker provides treatment for a dangerously slow heart rate. Without treatment, a slow heart rate can lead to weakness, confusion, dizziness, fainting, shortness of breath, and death. A slow heart rate can be the result of metabolic abnormalities or can occur as a result of blocked arteries to the heart's conduction system. In some instances, these conditions can be treated and a normal heart rate will resume. A slow heart rate can also be a side effect of medications. In such cases discontinuation of the medicine or a reduction in its dose may correct the problem. In some cases, the conduction system of the heart becomes irreversibly damaged for any one of a number of reasons. Additionally, some patients require medications that cause slow heart rate as a side effect in order to prevent other serious problems. Because there is no medication that one can take on a long term basis to increase the heart rate, a pacemaker is often the only solution. Fortunately, having a pacemaker implanted is a relatively minor surgical procedure. This is not open-heart surgery. After a pacemaker is implanted, most people resume their previous lifestyle with little or no limitation.
The procedure is performed with sedation and local anesthesia. General anesthesia is indicated only rarely. A 2-inch incision is made parallel to and just below a collarbone. Pacemaker electrical wires or “leads” are then inserted into a vein that lies just under the collarbone and advanced through that vein under fluoroscopic guidance into the heart. Depending on clinical circumstances, either one or two pacing leads are implanted. One end of the pacing leads is connected to a "generator" that is implanted under the skin beneath the collarbone. The generator is typically about half an inch deep and one and a half inches wide. The skin is then sutured closed and the patient leaves the hospital the following day. Incisional pain is mild and transient and usually responds to Tylenol. It is possible to feel the pacer generator under the skin, and a slight deformity of the skin may be evident.
Patients must keep the incision dry for 7 to 10 days following implantation and should avoid excessively exerting the arm on the side in which the pacer was placed for about three weeks. Subsequently the patient may resume a normal lifestyle without limitation. Household appliances do not interfere with modern day pacemakers. Cell phones should be kept 12 inches away from the pacemaker when in use, preferably at the ear on the side opposite from the pacemaker. Patients with pacemakers should avoid powerful electromagnetic fields, which may reprogram the pacemaker. MRI (magnetic resonance imaging) scans cannot be performed on patients with pacemakers for this reason.
The pacemaker generator is a small computer powered by a lithium battery. The generator can communicate with an external device placed on the skin overlying the pacemaker. Through this device, a physician can change the programming of the pacemaker to best suit the individual needs and investigate the status of the pacemaker. Some pacemakers also report on the performance of the patient's heart.
Pacemakers can be checked also over the telephone. The patient places a device and a magnet over the pacemaker and the pacemaker transmits a signal over a telephone line to be analyzed in the physician’s office. Pacemaker batteries give off warning signals when they are running low on power many months before they actually fail. This can be detected either by a telephone check or by a formal interrogation with an external device. Pacemakers are generally checked at least every 3 months to facilitate advance warning to replace the generator when the battery is running low on power. Changing the generator entails a minor procedure in which the original incision is opten, the old generator is removed, and the existing wires are attached to a new generator. The patient goes home the same day. Most batteries last at least 5 years. Pacemakers sense every heartbeat the patient has and only pace the heart when the patient's heart rate falls below a programmed limit. Patients are usually completely unaware of when the pacer is pacing their heart. In some patients, the pacemaker only needs to fire very rarely because the slow heartbeat only occurs intermittently. In other patients, the heartbeat is always too slow and the pacemaker has to pace the heart all of the time. Such patients are said to be “pacemaker dependent”.
Another use of pacemakers is for a disease called hypertrophic obstructive cardiomyopathy. This is a disease in which overgrown heart muscle blocks the egress of blood out of the heart. By altering the electrical activation pattern of the heart muscle, pacemakers can alleviate this problem in selected patients.
