Pacemaker

The heart is a muscular organ that pumps blood throughout the body. The rhythmic beating of the heart is triggered by electrical signals generated within the heart. A change or interruption in these signals can cause a change in the rhythm of the heart, affecting normal heart function. A pacemaker is a small device placed under the skin of the chest or abdomen that conveys electrical impulses to the heart muscle to help maintain a proper heart rate and rhythm.

Indications

Abnormal heart rhythm and symptoms associated with it is the main indication for pacemaker implantation. A number of heart conditions such as bradycardia, supraventricular tachycardia, syncope, heart failure, and hypertrophic cardiomyopathy can disrupt normal heart signals and cause an abnormal heartbeat, which may be too slow, fast or irregular and can lead to symptoms such as palpitations, fatigue, shortness of breath, sweating, and fainting.

Working Mechanism of a Pacemaker

The pacemaker apparatus consists of a small battery-operated pulse generator. It is connected to the heart through wires and electrodes. 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 correct it. Once the rhythm is normalized, it stops sending signals. The pulse generator is programmed after implantation of the pacemaker, according to the individual needs of the patient.

Types of Pacemaker

Based on your heart condition, your physician may recommend one of the following pacemaker types:

• Single chamber pacemaker: This type of pacemaker is used when the electric impulses from the right atrium to the right ventricle slow down, which in turn slows down the heart rate. The pacemaker has a single lead wire placed in either the right atrium or the right ventricle.
• Dual chamber pacemaker: This type of pacemaker has two lead wires, one in the right atrium and the other in the right ventricle. It regulates the heart rhythm continuously and maximizes the pumping ability of the heart.
• Biventricular pacemaker: This type of pacemaker is used to synchronize the contractions of the left ventricle with the right ventricle to improve the ejection fraction in patients with heart failure.  Ejection fraction is a measure of blood that is pumped out by the left ventricle of the heart.  A patient with heart failure has a low ejection fraction hampering the blood supply to various parts of the body.

Preparation

Preoperative preparation for pacemaker implantation surgery may involve the following:

• A review of your medical history and a thorough physical examination
• Routine blood work, imaging, and other tests specific to your condition
• Informing your doctor of any allergies to medications, anesthesia, or latex
• A review of your medications and the need to refrain from medications such as blood thinners, aspirin, or NSAIDs for a specific period
• Refraining from solids or liquids at least 8 hours prior to surgery
• Signing a consent form after the risks and benefits of the surgery have been explained

Surgical procedure

The pacemaker can be implanted either by an endocardial (transvenous) approach or epicardial approach.

Endocardial Approach: This is the most widely used approach. In this approach, a small incision is made over the chest, under local anesthesia and sedation. The leads of the pacemaker are then inserted through the incision into a cardiac vein, guided by intra-operative fluoroscopy, and then lodged into the heart tissue. The leads are then tested by transmitting a small amount of energy to contract the heart. After having successfully tested the leads, the other ends are connected to the pacemaker. In this approach, the pacemaker is 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 anesthesia. The leads of the pacemaker are attached to the epicardium, the outer layer of the wall of the heart. Once the leads are tested, the other ends are connected to the pacemaker that is placed in a pocket created under the skin of the abdomen. This approach takes a longer operative and recovery time than the endocardial approach. This can be significantly reduced with the use of minimally invasive techniques.

Irrespective of the approach, the final adjustments of the pacemaker are made by the doctor after pacemaker implantation by using an external device. The settings of the pacemaker depend on the individual requirement of electrical energy to stimulate normal heart rhythm.

Your cardiac surgeon will determine the best approach depending on your age and other associated conditions.

Postoperative care

Postoperative care instructions following a pacemaker implantation may involve the following:

• You will be transferred to the recovery area where your nurse will monitor your vital signs, including heart rate and rhythm.
• A chest X-ray is obtained on the morning after surgery to confirm the pacemaker and leads are in the correct position.
• You will have pain, soreness, and bruising around the incision site. Medicines will be provided as needed to address these.
• Instructions on incision site care and bathing will be provided.
• Avoid strenuous activities and lifting weights heavier than 10 pounds.
• You may return to work within a couple of weeks, as well as resume your normal daily activities within a few days, but with certain activity restrictions.

Risks and Complications

Pacemaker implantation is a relatively safe procedure; however, as with any surgery some risks and complications may occur such as:

• Infection
• Bleeding
• Scarring
• Damage to nerves or blood vessels
• Pacemaker malfunction
• Punctured lung or heart in rare circumstances

Summary

A pacemaker is a small, battery-operated device that is usually implanted on the left side of the chest just below your collarbone to regularize an abnormal heart rhythm by transmitting electrical impulses to the heart muscle. Hence, a pacemaker helps to relieve the symptoms associated with abnormal cardiac rhythm and enables the patient to resume an active lifestyle.