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Treating Congestive Heart Failure
This article will look into the question of the so-called Pacemaker Syndrome and explore what it is. A companion article addresses the question of how a pacemaker works and what it is used for.
A pacemaker is used in congestive heart failure to treat three specific conditions which result in arrhythmia: (a) heart failure; (b) an abnormally slow heartbeat; (c) an abnormally fast heart beat.
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A pacemaker is an electronic device which (if fitted permanently) is usually implanted in the patient’s chest or abdomen. One (or up to three) wires extend from the device and are connected to the heart, such that the electrical signal can be transmitted to the heart muscle. When arrhythmia is detected, the computer causes the generator to send an impulse to the heart to correct the condition. The electrical signal generated by the heart’s sinus node passes from the top of the heart downwards causing the heart muscle to contract, and pump blood, as it does so; the pacemaker replicates this action.
Pacemaker syndrome is a condition where the atrioventricular synchronicity is lost. It was first identified in 1969 as a complication of right ventricular pacing (i.e. the pacemaker is used to stimulate the right side of the heart). The symptoms associated with pacemaker syndrome are due to reduction of cardiac output since the heart is no longer beating efficiently. When the first chamber of the heart (the atrium) is primed with blood, the second chamber (the ventricle) will be relaxed. As the atrium starts to contract, blood is forced into the ventricle, starting to fill it; when the ventricle starts to contract, blood is pumped out of the heart and around the body. Any disturbance to the synchronicity of the chambers of the heart will reduce the efficiency with which blood is circulated. The symptoms associated with pacemaker syndrome (& congestive heart failure) include dyspnea (the technical term for shortness of breath), particularly during exertion; paroxysmal dyspnea (shortness of breath during sleeping that wakes the sufferer up); abnormally low blood pressure (hypotension); feeling faint or fainting (syncope); easily becoming tired; headaches and general malaise – all of these symptoms are associated with congestive heart failure, of course.
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Treating Pacemaker Syndrome
Since pacemaker syndrome is due to the failure of the device to stimulate the heart as intended, it can be treated by adjusting the pacemaker itself, or through connecting it to a different part of the heart. Where the pacemaker was connected to the ventricle by a single lead, a second arterial lead may need to be connected; once atrioventricular pacing is established, the problem is usually resolved.
Where the pacemaker is already connected by an arterial lead, data that the pacemaker records may need to be evaluated and the device adjusted to recover atrioventricular synchrony.
In a few instances, the symptoms can be alleviated by increasing the threshold before the pacemaker starts to work. For instance, the rate may be dropped to initiate pacing only after the heartbeat falls below 50 beats per minute; then the pacemaker is initiated and set to cause the heart to beat at 60 beats per minute (this technique is referred to as hysteresis). Since the pacemaker is used less frequently, the condition can be alleviated (in these cases; the exact circumstances responsible for congestive heart failure in the patient need to be considered).
In some circumstances, the pacemaker may need to replaced and a more suitable device substituted in its place.
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- British Heart Foundation: http://www.bhf.org.uk/living_with_a_heart_condition/treatment/pacemakers-1.aspx
- National Institutes of Health, Pacemakers: http://www.nhlbi.nih.gov/health/dci/Diseases/pace/pace_whatis.html
- PubMed NIH: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1502063/
- Pacemaker Syndrome: Treatment and Medication: http://emedicine.medscape.com/article/159706-treatment