Pacemaker Insertion

Pacemaker Insertion is the implantation of a small electronic device in the chest to help regulate the beating of the heart.

Some facts about Pacemaker Insertion:

• The electrical impulses, delivered by electrodes can be used by the pacemaker contracting the heart muscles, to regulate the beating of the heart.
• An adequate heart rate can be maintained by using a pacemaker when the natural PM of heart is not fast enough, or there is a block in the electrical conduction system of heart.
• Pacemakers can be programmable and the optimum pacing modes for individual patients can be selected by the cardiologist.
• A Pacemakers and defibrillator is combined in a single implantable device in some cases.
• Pacemakers can be either temporary or permanent.
• Short term heart problems, such as a slow heartbeat caused by either a heart surgery, heart attack or an overdose of medications can be treated by using a temporary pacemaker where as problems of long term heart rhythm can be controlled by using a permanent pacemaker.
• Some arrhythmia symptoms, such as fatigue and fainting can be relieved by a pacemaker.
• A person who has abnormal HRs can resume a more active lifestyle by the help of a pacemaker.
• The size of an artificial cardiac pacemakers is approximately equal to a matchbox and has a weight of 20 to 50gm.
• Intrinsic heart rhythm can be sensed by the pacemaker and electrical impulses can be transmitted to stimulate the heart and replace the defective natural PM and the sinus node.
• Temporary pacemaker can be used for short term heart problems, such as arrhythmias caused by myocardial infraction. These can also be used in emergencies.
• Permanent are used for chronic cardiac rhythm dysfunction.

Procedure of Implantation:

• A pacemaker consists of a pulse generator, a battery, one or more leads and an electrode on each lead.
• A pulse generator contains electronic circuitry with a small computer and a battery. The impulses sent to the heart is regulated by it. It sense the intrinsic cardiac electric potentials by the the computerized information it contains and stimulate cardiac contraction.
• Leads are insulated wires with electrodes at their tips which connect the heart to the generator and transfer all the data between them. One end of lead is connected to the pulse generator and the other end is placed inside one of the chambers of heart. The electrode touches the heart wall on the end of a lead.
• The electrical impulses are delivered by the lead to the heart. It also senses the electrical activity of heart and relays this information back to the pulse generator. The leads of a pacemaker can be placed in the atrium or ventricle or both, depending on the medical condition.
• An electrical impulse is sent through the lead to the electrode and causes the heart to beat at a faster rate if the rate of heart is slower than the programmed limit.
• The pacemaker generally monitors the heart rate and will not pace when the heart beats at a rate faster than the programmed limit.
• Electrical impulses will not be sent to the heart unless the natural heart rate falls below the lower limit of pacemaker.
• Sometimes, the two ventricles do not pump in a normal manner in in heart failure. Biventricular pacemaker is a newer type of pacemaker that can help increase the amount of blood pumped by the heart by pacing both ventricles at the same time.
• It is called cardiac resynchronization therapy or CRT when the treatment is done by using Biventricular pacemaker.
• Implantation of permanent pacemaker is considered to be a minimally invasive procedure and is performed in a cardiac catheterization laboratory under local anesthesia.
• The preferable technique is transvenous access to the heart chambers which can be done through a percutaneous approach of the subclavian vein, the cephalic vein or the cut down technique. It is rarely done through the axillary vein, the internal jugular vein or the femoral vein.
• Both subclavian vein and cephalic vein are punctured in some cases.
• An initial intravenous contrast injection called venography is administred in the peripheral arm vein if the vein is blindly punctured.
• A small incision of 3.8 to 5.1 cm is made in the infraclavicular area and a pocket is created to implant the generator after the puncture.
• A guide wire is advanced and placed on the right atrium or the vena caval area under fluoroscopy after successful vein access.
• A second guide wire can also be positioned, if necessary. It can be positioned through the same route by a second puncture. A double wire technique can also be used to position the second wire in which two guide wires are inserted through the first sheath.  
• A sheath and dilator are advanced. The guide wire and the dilator are retracted when sheath is set in the right place.
• The lead is then inserted into the sheath and advanced under fluoroscopy to the appropriate heart chamber.
• The ventricular lead is the first to be placed when implanting a DDD.
• The sheath is removed when leads are securely placed.
• Specifics tests for sensing and pacing are done to avoid stimulation of the diaphragm, and the pacing is set at 10 V.
• A nonabsorbable suture is used to sew the lead to the underlying tissue and afterwards. The generator is placed in to the pocket and is connected to the lead.
• Finally, the incision is closed with absorbable sutures and an arm immobilizer is applied for 12 to 24 hours.
• Extensive skin and muscle dissection is required to visualize the vein in the cut down technique of the cephalic vein.
• A pacemaker can be surgically implanted through a thoracotomy and the generator is placed in the abdominal area.
• Antibiotic prophylaxis is must for device implantation.
• Cefazolin 1 g i.v. one  hour prior to the procedure, or alternatively 1 g vancomycin i.v. in case of allergy to penicillin and cephalosporins should be given routinely.
• A chest radiograph in standing position anteroposterior and lateral is performed, to confirm lead position and exclude the complication of pneumothorax, the day following the implantation.
• Regularly scheduled appointments should be made to ensure the pacemaker is functioning properly after the insertion of pacemaker.
• A programmer is used by the doctor to review the activity of pacemaker and adjust the settings when needed.

Risks of Implantation:

Bleeding from the incision or catheter insertion site, damage to the vessel at the catheter insertion site, infection of the incision or catheter site and pneumothorax are some of the possible of pacemaker.