Pacemakers

Pacemaker

A pacemaker is a medical device that generates electrical impulses delivered by electrodes to contract the heart muscles and regulate the electrical conduction system of the heart. The primary purpose of a pacemaker is to maintain an adequate heart rate, either because the heart's natural 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.

History

The development of the pacemaker has involved many innovations over the years. The first external pacemaker was developed in 1950 by Canadian electrical engineer John Hopps, based on research by Wilfred Bigelow and John Callaghan. The first implantable pacemaker was introduced in 1958 by Arne Larsson and was implanted by surgeon Åke Senning in Stockholm, Sweden. This device was powered by a nickel-cadmium rechargeable battery, which was a significant advancement at the time.

Types

Pacemakers can be classified based on their functionality:

• Single-chamber pacemakers stimulate either the right atrium or the right ventricle.
• Dual-chamber pacemakers stimulate both the right atrium and the right ventricle, coordinating the timing between the two chambers.
• Biventricular pacemakers, also known as Cardiac Resynchronization Therapy (CRT) devices, are used for the treatment of heart failure by coordinating the contractions of the left and right ventricles.

Indications

Pacemakers are indicated for various conditions, including:

• Bradycardia - a slower than normal heart rate
• Heart block - a delay or complete block of the heart's electrical impulse from reaching the ventricles
• Atrial fibrillation with slow ventricular response - a common type of irregular heartbeat
• Heart failure - particularly when associated with abnormal electrical conduction

Procedure

The pacemaker implantation procedure is typically performed under local anesthesia. It involves making a small incision near the collarbone, through which the pacemaker leads (wires) are inserted into a vein and guided to the heart with the help of fluoroscopy. The leads are then attached to the heart muscle, while the other end is connected to the pacemaker device, which is placed under the skin in the chest.

Risks and Complications

While pacemaker implantation is generally safe, there are risks and potential complications, including:

• Infection at the implantation site
• Swelling, bruising, or bleeding
• Damage to the blood vessels or nerves near the implantation site
• Pneumothorax (collapsed lung)
• Lead displacement

Living with a Pacemaker

Patients with pacemakers can lead normal lives but are advised to take certain precautions:

• Avoiding close or prolonged exposure to electrical or magnetic fields
• Informing all healthcare providers about their pacemaker
• Carrying a pacemaker identification card at all times
• Regular follow-ups with the cardiologist for pacemaker checks

Future Directions

Advancements in pacemaker technology continue to evolve, focusing on increasing the longevity of the device, minimizing complications, and enhancing patient comfort and quality of life. Leadless pacemakers and biologic pacemakers are areas of active research.