Artificial Cardiac Pacemaker

 

A pacemaker is a small, battery-operated device. This device senses when your heart is beating irregularly or too slowly. It sends a signal to your heart that makes your heart beat at the correct pace.

Modern pacemakers have two parts. One part, called the pulse generator, contains the battery and the electronics that control your heartbeat. The other part is one or more leads to send electrical signals to your heart. Leads are small wires that run from the pulse generator to your heart.Some people need a special type of pacemaker called a biventricular pacemaker, or bivent. You may need a bivent if you have severe heart failure. A bivent makes the two sides of the heart beat in sync. This is known as cardiac re-synchronization therapy (CRT).

Pacemakers generally treat two types of arrhythmia:

• tachycardia, a heartbeat that’s too fast
• bradycardia, a heartbeat that’s too slow

Not all pacemakers are permanent. Temporary pacemakers can control certain types of problems. You may need a temporary pacemaker after a heart attack or heart surgery. You may also need one if a medication overdose temporarily slowed your heart.Your doctor or cardiologist will test you to see if you’re a good candidate for a pacemaker.

Complications

Complications from having surgery to implant a pacemaker are uncommon (each 1-3 % approximately), but could include: infection where the pacemaker is implanted or in the bloodstream; allergic reaction to the dye or anesthesia used during the procedure; swelling, bruising or bleeding at the generator site, or around the heart, especially if the patient is taking blood thinners, elderly, of thin frame or otherwise on chronic steroids use. A possible complication of dual-chamber artificial pacemakers is 'pacemaker-mediated tachycardia' (PMT), a form of reentrant tachycardia. In PMT, the artificial pacemaker forms the anterograde (atrium to ventricle) limb of the circuit and the atrioventricular (AV) node forms the retrograde limb (ventricle to atrium) of the circuit.Treatment of PMT typically involves reprogramming the pacemaker.

Another possible complication is "pacemaker-tracked tachycardia," where a supraventricular tachycardia such as atrial fibrillation or atrial flutter is tracked by the pacemaker and produces beats from a ventricular lead. This is becoming exceedingly rare as newer devices are often programmed to recognize supraventricular tachycardias and switch to non-tracking modes.Sometimes the leads, which are small diameter wires, from the pacemaker to the implantation site in the heart muscle will need to be removed. The most common reason for lead removal is infection, however over time leads can degrade due to a number of reasons such as lead flexing.^[ Changes to programming of the pacemaker may overcome lead degradation to some extent. However, a patient who has several pacemaker replacements over a decade or two in which the leads were reused may require a lead replacement surgery.Lead replacement may be done in one of two ways. Insert a new set of leads without removing the current leads (not recommended as it provides additional obstruction to blood flow and heart valve function) or remove the current leads and then insert replacements. The lead removal technique will vary depending on the surgeon's estimation of the probability that simple traction will suffice to more complex procedures. Leads can normally be disconnected from the pacemaker easily which is why device replacement usually entails simple surgery to access the device and replace it by simply unhooking the leads from the device to replace and hooking the leads to the new device. The possible complications, such as perforation of the heart wall, come from removing the lead{s} from the patient's body.The other end of a pacemaker lead is actually implanted into the heart muscle with a miniature screw or anchored with small plastic hooks called tines. In addition, the longer the leads have been implanted starting from a year or two, the more likely that they will have attachments to the patient's body at various places in the pathway from device to heart muscle, since the human body tends to incorporate foreign devices into tissue. In some cases, for a lead that has been inserted for a short amount of time, removal may involve simple traction to pull the lead from the body. Removal in other cases is typically done with a laser or cutting device which threads like a cannula with a cutting edge over the lead and is moved down the lead to remove any organic attachments with tiny cutting lasers or similar device.Pacemaker lead malposition in various locations has been described in the literature. Depending on the location of the pacer lead and symptoms treatment varies.Another possible complication called twiddler's syndrome occurs when a patient manipulates the pacemaker and causes the leads to be removed from their intended location and causes possible stimulation of other nerves.