Pacemaker for the slowly beating heart<\/p>\n
A. Fauzi Yahya, Contributor, Jakarta<\/p>\n
Worldwide, there are about three million people with pacemakers,
\na small smart device used to regulate heart rhythm, and every
\nyear, 600,000 pacemakers are implanted.<\/p>\n
Although most people who receive pacemakers aged 60 years or
\nolder, people of any age -- even children -- may need pacemakers.<\/p>\n
Most are implanted to prevent the heart from beating too
\nslowly. Some new types of pacemaker may be helpful in certain
\npatients with congestive heart failure. Pacemakers have become a
\nreliable means of helping people live longer and improve their
\nlifestyles despite having a slow heart rhythm.<\/p>\n
* Heart's electrical system<\/p>\n
The heart, like any mechanical pump, needs an electrical
\nsource to drive it. It has its own natural electrical system
\n(cardiac conduction system) which is called the sinoatrial (SA)
\nnode or sinus node. It's a small mass of specialized cells in the
\ntop of the upper right chamber (right atria). It makes the
\nelectrical impulses that cause the heart to beat. A chamber of
\nthe heart contracts when an electrical impulse moves across it.<\/p>\n
For the heart to beat properly, the signal must travel down a
\nspecific path to reach the ventricles -- the heart's lower
\nchambers. It causes the ventricles to contract and squeeze blood
\nout to the body and lungs. At rest, the normal SA node fires at
\nan average rate of 60-80 beats per minute. The SA node can
\nincrease the frequency of the signal 2- to 3- fold, such as
\nduring stress or exercise, to speed up the heart rate in order to
\nmeet the body's increased metabolic demands. Each signal that
\npasses through the conduction system results in one heartbeat.<\/p>\n
Why might someone need a pacemaker?<\/p>\n
Any interruption in the normal flow of the electrical signal
\nthrough the cardiac conduction system can cause an abnormality in
\nthe heart's rhythm.<\/p>\n
The SA node can \"slow down\" as the result of the normal aging
\nprocess. This can cause the heart to beat too slowly or fail to
\naccelerate the heart rate with normal activity or exercise. This
\ncondition is called sick sinus syndrome which is the most common
\nreason for pacemaker implantation.<\/p>\n
The other leading cause for pacemaker implantation is a
\n\"block\" somewhere in the electrical pathway which does not allow
\nthe electrical activity to spread to all of the necessary
\nportions of the heart muscle. The underlying cause of this may be
\nscar tissue, most frequently from previous heart attacks.<\/p>\n
The slowly beating heart does not circulate enough blood to
\nmeet the metabolic needs of the body and resultantly can cause
\nshortness of breath, fatigue, activity intolerance, a loss of
\nconsciousness (syncope), or even death. In other cases, people
\nmay have no symptoms but are at high risk for dangerously slow
\nheart rates because of disturbances of the electrical system of
\nthe heart. A pacemaker may be recommended for these people before
\nsymptoms occur.<\/p>\n
* Pulse generator and wires<\/p>\n
The artificial pacemaker implanted by physicians corrects both
\ncauses of slow heart beating by providing electrical signals to
\ntell the heart to beat at the proper rates and by delivering the
\nsignal to the appropriate chambers of the heart.<\/p>\n
The pacemaker system includes the pulse generator and wires
\n(leads) that connect the pacemaker to the heart. The generator
\nunit is slightly larger than a man's wristwatch and contains a
\nlithium battery (generally lasting from six to 10 years) and
\ncomputer circuits (Photo left).<\/p>\n
The computer circuits continuously monitor the heart's natural
\nrhythm and delivers an electrical signal to cause the heart to
\nbeat at the desired rate. The electrical signal that is sent from
\nthe pacemaker is strong enough to stimulate the heart to beat but
\nnot strong enough for you to feel.<\/p>\n
Many pacemakers implanted today also may have rate
\nresponsiveness features that allow temporary pacing of the heart
\nat a faster rate during periods of exercise. Single-chamber
\npacemakers have only one wire connected to the heart and dual
\nchambers pacemakers have wires to both the top and bottom
\nchambers of the heart. Your cardiologist will recommend which
\ntype of pacemaker needed.<\/p>\n
So, how is the pacemaker implanted?<\/p>\n
The pacemaker is implanted by a minor surgical procedure
\nperformed under local anesthesia. A small incision (2-3 inches)
\nis made under the collarbone either on the right or left side of
\nthe chest.<\/p>\n
The wires are placed through a blood vessel beneath the collar
\nbone and threaded down to the inside of the heart under a special
\ntype of x-ray (fluoroscope). The wires are then attached to the
\ninner surface of the heart muscle (Photo right). Once the wires
\nare positioned inside the heart muscle, the physician will create
\n\"a small pocket\" to fit the pulse generator under the skin of the
\nchest. The wires are then plugged in to the pulse generator and
\nfirmly tightened in place. The pulse generator is then placed in
\nto the pocket and the skin is sutured back together.<\/p>\n
The procedure usually takes about one or two hours and the
\nrisk of procedure complications is about 1 to 2 percent.<\/p>\n
Other than restrictions on heavy lifting and extreme motion of
\nthe arm on the side of the pacemaker for several weeks, recovery
\nfrom the procedure is minimal. Most patients return to normal
\nactivities within a few days.<\/p>\n
It is recommended that patients carry an identification card
\nthat provides specific information on the type of leads and
\npacemaker implanted. Such a card can be shown to healthcare
\nprofessionals during medical evaluations and to security
\npersonnel at airports.<\/p>\n
The writer is a cardiovascular fellow at Cardiology Department
\nof Medical School University of Indonesia\/National Cardiovascular
\nCenter Harapan Kita, West Jakarta.<\/p>",
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"sponsor_url": "https:\/\/okusiassociates.com"
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