We'll talk today about athletes and cardiac pacemakers. I was reminded by a reader over the weekend that rhythm problems in athletes sometimes necessitate the implantation of a pacemaker. I'll follow-up on today's article with another on athletes and internal cardioverter-defibrillators (ICDs) since I also mentioned these devices a couple weeks ago here at the blog.
The Heart's Electrical System
The heart has a very elaborate electrical system that is designed to initiate and carry electrical impulses throughout the heart, causing the heart muscle to contract (in just the right way) and pump the blood that it holds.
The electrical impulses start in an area in (or near) the top of the right atrium called the sinus node. These impulses are generated automatically and, for most people, have a rate of 60-100 beats per minute. The electrical impulses then spread out over the left and right atria and travel to a way station called the atrioventricular (AV) node. The AV node builds in a slight delay and then the impulses travel to the lower, or pumping, chambers of the heart--the ventricles. As the electrical impulses travel through the ventricles, the pumping chambers contract, ejecting the blood that they hold.
Common Problems That Are Treated With a Pacemaker
There are many disorders of the electrical system of the heart--far too many to discuss here in this article. Indeed, entire textbooks have been written about these problems. For affected athletes who are reading here, it would be wise to discuss your PERSONAL situation with your doctor so that you understand the PARTICULAR electrical problem that you have. Today, we'll focus on just 2 common problems that are sometimes treated with a pacemaker: a slow heart rate (bradycardia) and heart block (the situation where there is undue delay getting the electrical impulses throughout the heart).
Bradycardia is defined as a heartrate less than 60 beats per minute. Sometimes the heartrate can become so slow that affected individuals have problems such as light-headedness--or even black out. We call that symptomatic bracycardia.
Individuals with heart block may have electrical impulses that start at 80 beats per minute at the sinus node, but because of the block, these electrical impulses are delayed (or lost entirely) and the ventricles might beat at only 30 beats per minute--far too slow to manage the necessary pumping function of the heart.
In both of these situations, a pacemaker may be the appropriate treatment.
What Is a Pacemaker?
A pacemaker is an implanted medical device that corrects for a problem with the heart's electrical system. The pacemaker usually consists of 2 parts: 1) a battery (or "generator") that is implanted beneath the skin of the upper chest and 2) a set of wires that are threaded through a vein and fastened to the lining of the heart.
With the most modern pacemakers, the generator is about the size of a stack of 3 half dollars. The battery lasts for several years and will then need to be replaced. The wires (or "leads) are designed to remain in place for a long time--many years, or potentially, forever. The generator and leads are placed during a operative procedure that usually lasts less than an hour and can be done with either local anesthesia and sedation or with general anesthesia.
In the most typical configuration, one lead is placed into the right atrium and another is placed into the right ventricle. These leads are designed to sense the heart's own electrical activity. This information is gathered by the computer that is part of the generator, and then the computer uses those same 2 leads to deliver electrical impulses, as needed, to speed up the heart (in the case of bradycardia) or to provide missing electrical impulses (in the case of heart block).
For patients with pacemakers, the pacemaker can be checked periodically using a hand-held computer device directly over the pacemaker. This device gathers information about the functioning of the pacemaker and about the battery's lifespan and this information can be transmitted either directly or by telephone to the patient's doctor for review. Sometimes adjustments must be made to the settings of the pacemaker to guarantee the most appropriate functioning of the pacemaker.
Issues for Athletes
The first important issue for athletes with pacemakers is the healing time after the pacemaker implantation procedure. Like for any surgical procedure, some time is needed for the body to heal after the operation. For pacemakers, it also takes time for the heart to heal at the location where the leads have been implanted. Until this healing process is complete, the leads can become dislodged inadvertently with vigorous activity. It's common for implanting physicians to recommend no arm activity (on the side of the implant) and no vigorous activity, in general, for a period of several weeks after the pacemaker procedure. After that time, most implanting physicians will allow a gradual return to pre-implantation activities.
In the long term, there continues to be a small risk of lead dislodgement and some physicians recommend that patients avoid athletic activities that place a patient at risk of severe body blows. Many athletes, though, can return to their sports after implantation of a pacemaker, but it's important to have a detailed discussion with their physician about this issue.
The second major issue for athletes relates to the settings for the pacemaker. Each pacemaker system contains a microprocessor that can be programmed to work optimally for an individual patient. One important setting for athletes is the maximal rate setting. As an example, let's consider an athlete with heart block. She exercises vigorously and her sinus rate rises to 180 beats per minute. Ideally, the pacemaker would stimulate her ventricles at the same rate of 180 beats per minute. If the maximal rate setting were only 140, she would have the feeling of "not enough oomph" from her heart to continue the exercise. This is just one example. Athletes will need to have ongoing discussions with their physician about the settings for their pacemaker....and it may take some trial and error to set things up satisfactorily.
For More Information
There are probably many web-based information sources that are useful to athletes who have--or are considering--a pacemaker. After a quick look around, a couple that I like are:
http://www.pacemakerclub.com/ This is a free online "club" designed as a support group for patients with a pacemaker or ICD and their families. There are topical-oriented forums where members can network with people with similar problems and concerns.
http://www.americanheart.org/presenter.jhtml?identifier=4676 This link is to the American Heart Association (AHA) page that deals with pacemakers. At this page, there are additional links for more detailed information on a variety of topics.
http://www.medtronic.com/your-health/bradycardia/index.htm This link is to a page at the Medtronic (a company that manufactures pacemakers) site that deals with bradycardia and pacemakers. There are also additional links to information about related topics.
I'll be back next with an article on Athletes and ICD's.
