The heart is a hollow muscular pump that propels blood to the different parts of the body and is controlled by electrical signals generated within the heart itself. A number of heart conditions such as bradycardia (slow heart rhythm), supraventricular tachycardia (very fast heart rhythm), fainting (syncope) and heart failure are associated with an abnormal heart beat, which may be too slow, too fast or irregular and can lead to fatigue, shortness of breath and fainting.
A pacemaker is a small device that is implanted under the skin of the chest or abdomen to regularize an abnormal heart rhythm by transmitting regular electrical impulses to the heart muscle. Therefore, a pacemaker helps to relieve symptoms due to an abnormal cardiac rhythm and enables the patient to resume an active lifestyle.
The pacemaker apparatus consists of a small battery operated pulse generator and a battery. It is connected to the heart through wires and electrodes that are inserted through the veins connecting to the heart. A pacemaker battery usually lasts for about 8 to 10 years. The pulse generator recognizes an abnormal heart rhythm and responds by sending electrical pulses to control the heart rhythm. Once the rhythm is normalized it may stop sending signals and allow the normal heart rhythm to take over. The pulse generator is programmed after implantation of the pacemaker, according to the individual needs of a patient.
The pacemaker can be implanted either by an endocardial (transvenous) approach or epicardial (surface of the heart) approach.
Endocardial (transvenous) approach: This is the most widely used approach. A small incision is made over the left shoulder at the front, under general anaesthesia. The lead of the pacemaker is then inserted through the incision into a cardiac vein, guided by intra-operative xray, and the lead is positioned into the heart muscle within the right ventricle. A second lead may be positioned in the right atrium to allow coordinated pacing of the topa and bottom chambers of the heart. The leads are then tested by electronically interrogating them and transmitting a small amount of energy to the heart to control the heart rhythm. After having successfully tested the leads, the ends of the leads are then connected to the pacemaker generator. The pacemaker is then placed in a small pocket under the skin of the chest.
Epicardial approach: This is a less common approach. It is used more often in children and patients undergoing heart surgery at the same time. This procedure is performed under general anaesthesia. The lead of the pacemaker is attached to the surface of the heart using sutures. Once the leads are tested, the other end is connected to the pacemaker that is placed in a pocket created under the skin of the abdomen.
Irrespective of the approach, a technician makes the final adjustments to the pacemaker settings, using an external device 12-24 hours after device implantation. The settings are determined by your doctor and depend on the individual’s underlying heart rhythm, indication for requiring a pacemaker and other factors.
Your cardiac surgeon will determine the best approach for pacemaker implantation depending on your age, size, the underlying heart condition and other associated conditions.
Pacemaker implantation is generally a very safe procedure but may be associated with a few risks that include:
- Pacemaker infection: Pacemaker infection is associated with symptoms of high temperature and/ or pain, swelling and redness at the site of pacemaker implantation.
- Pacemaker malfunction: Symptoms of a pacemaker malfunction may include abnormal heart beat, dizziness, hiccups or fainting.
- Lead dislodgement: this can be a cause of pacemaker malfunction and occurs when the position of the lead changes in the heart
- Bleeding and air leak from the lung are other potential complications
Contact Dr Orr immediately if you experience any of the above mentioned symptoms, after an implant surgery. Treatment of pacemaker infection mostly involves antibiotics and surgery to remove and replace the pacemaker. Pacemaker malfunction may require lead repositioning or alteration of the device settings depending on the underlying problem.