Download Artificial Pacemakers

Q: Characterize the different types of pacemaker. Explain the
various steps of pacing?
 Pacemaker is define as a medical device which uses electrical impulses,
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delivered by electrodes contacting the heart muscles, to regulate the beating
of the heart.
There are three basic types of permanent pacemakers, classified according to the
number of chambers involved and their basic operating mechanism:
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Single-chamber pacemaker. In this type, only one pacing lead is placed
into a chamber of the heart, either the atrium or the ventricle.
Dual-chamber pacemaker. Here, wires are placed in two chambers of the
heart. One lead paces the atrium and one paces the ventricle. This type
more closely resembles the natural pacing of the heart by assisting the
heart in coordinating the function between the atria and ventricles.
Rate-responsive pacemaker. This pacemaker has sensors that detect
changes in the patient's physical activity and automatically adjust the
pacing rate to fulfill the body's metabolic needs.
 Various steps of pacing or insertion of a pacemaker:
 A pacemaker is typically inserted into the patient through a simple
surgery using either local anaesthetic or a general anesthetic.
 The patient may be given a drug for relaxation before the surgery as well.
An antibiotic is typically administered to prevent infection.
 In most cases the pacemaker is inserted in the left shoulder area where an
incision is made below the collar bone creating a small pocket where the
pacemaker is actually housed in the patient's body.
 The lead or leads (the number of leads varies depending on the type of
pacemaker) are fed into the heart through a large vein using a fluoroscope
to monitor the progress of lead insertion.
 A temporary drain may be installed and removed the following day. The
actual surgery may take about an hour.
 Following surgery the patient should exercise reasonable care about the
wound as it heals.
 There is a follow up session during which the pacemaker is checked
using a "programmer" that can communicate with the device and allows a
health care professional to evaluate the system's integrity and determine
the settings such as pacing voltage output.
 The patient may want to consider some basic preparation before the
surgery. The most basic preparation is that people who have body hair on
the chest may want to remove the hair by shaving or using a depilatory
agent as the surgery will involve bandages and monitoring equipment to
be affixed to the body.
 Since a pacemaker uses batteries, the device itself will need replacement
as the batteries lose power. Device replacement is usually a simpler
procedure than the original insertion as it does not normally require leads
to be implanted.
 The typical replacement requires a surgery in which an incision is made
to remove the existing device, the leads are removed from the existing
device, the leads are attached to the new device, and the new device is
inserted into the patient's body replacing the previous device.
Thus the following steps are taken into consideration while pacing a
pacemaker.
Q: Describe the working of pacemaker, suggest the safety
precautions to be taken after inserting a pacemaker?
 A pacemaker is a medical device which uses electrical impulses, delivered
by electrodes contacting the heart muscles, to regulate the beating of the
heart.
 The primary purpose of a pacemaker is to maintain an adequate heart rate,
either because the heart's native pacemaker is not fast enough, or there is a
block in the heart's electrical conduction system.
 Modern pacemakers are externally programmable and allow the cardiologist
to select the optimum pacing modes for individual patients. Some combine a
pacemaker and defibrillator in a single implantable device.
 Others have multiple electrodes stimulating differing positions within the
heart to improve synchronisation of the lower chambers of the heart.
Working of a pacemaker:
 The conduction system includes several components.
 The first part of the conduction system is the sinoatrial (SA) node,
located in the myocardium at the top of the right atrium.
 Without any neural stimulation, the sinoatrial node rhythmically
initiates electrical impulses 70 to 80 times per minute.
 Because it establishes the basic rhythm of the heartbeat, it is called
the heart's natural pacemaker.
 Each electrical impulse from the SA node travels through the muscle
fibers of the atria and ventricles, causing them to contract.
 Other parts of the conduction system include the atrioventricular (AV)
node, atrioventricular bundle, bundle branches, and conduction
myofibers.
 All these components coordinate the contraction and relaxation of the
heart chambers. Although the SA node sends electrical impulses at a
certain rate, your heart rate may still change depending on physical
demands, stress, or hormonal factors.
 Basic function
 The most basic form monitors the heart's native electrical rhythm.
 When the pacemaker fails to sense a heartbeat within a normal beat-tobeat time period, it will stimulate the ventricle of the heart with a short
low voltage pulse.
 This sensing and stimulating activity continues on a beat by beat basis .
Safety precautions to be taken after pacing a pacemaker:
 A patient's lifestyle is usually not modified to any great degree after
insertion of a pacemaker.
 There are a few activities that are unwise such as full contact sports and
activities that involve intense magnetic fields.
 The pacemaker patient may find that some types of everyday actions need
to be modified. For instance, the shoulder harness of a vehicle seatbelt
may be uncomfortable if the harness should fall across the pacemaker
insertion site.
 Any kind of an activity that involves intense magnetic fields should be
avoided. This includes activities such as arc welding possibly, with
certain types of equipment or maintaining heavy equipment that may
generate intense magnetic fields (such as an MRI (Magnetic Resonance
Imaging Machine)
 A 2008 U.S. study has found that the magnets in some portable music
players, when placed within an inch of pacemakers, may cause
interference.
 Some medical procedures may require the use of antibiotics to be
administered before the procedure.
 The patient should inform all medical personnel that they have a
pacemaker. Some standard medical procedures such as the use of
Magnetic resonance imaging (MRI) may be ruled out by the patient
having a pacemaker.
 In addition, according to the American Heart Association, some home
devices have a remote potential to cause interference by occasionally
inhibiting a single beat. Cellphones available in the United States (less
than 3 watts) do not seem to damage pulse generators or affect how the
pacemaker works.
Thus life is not modified to a great extent only certain
precautionary measures are required to be taken care of after
inserting a pacemaker.