A pacemaker is a small device that helps regulate your heartbeats. It functions by sending an electrical impulse to the heart muscle to maintain a suitable heart rate and rhythm. Doctors classify people with a slow heart rate (bradycardia) or fast heart rate (tachycardia) as arrhythmias.
Tachycardia and bradycardia have categories depending on the place of origin. For example, atrial fibrillation is a rapid heart rate caused by uncoordinated electrical impulses in the atria. Ventricular tachycardia and fibrillation originate in the ventricles.
Understanding the heart
Before elaborating further on a pacemaker, it is helpful to understand how the heart works. An analogy is that the heart is like a house. There are the plumbing and the electrical system. The plumbing consists of pipes of different diameters that move water throughout your home. Similarly, the heart has a piping system in the form of arteries, veins, and capillaries, known as the circulatory or cardiovascular system. This network of vessels acts as a delivery and removal system.
Unlike your home, a power outage doesn’t affect your water supply. It runs without the need for electricity in most cases. The heart, in contrast, requires electricity or electrical impulses to function—no electricity results in no contraction of the various chambers.
The electrical stimulus originates in the sinus node, also known as the sinoatrial node or SA node. The atria are the two upper chambers of the heart. From this location, the impulse travels to the ventricles or two lower chambers. One of the pathways is through the left and right bundles located between the two ventricles. Difficulties arise when a patient has either a left or right bundle branch block. It is uncommon to need a pacemaker for either condition.
Types of pacemakers
Single chamber: The device supplies electrical impulses to either the right atrium or the right ventricle with a single lead (wire).
Dual-chamber: Using two leads, the pacemaker connects to the right atrium and the right ventricle to regulate the contractions of both. This method results in the two chambers contracting and relaxing in rhythm.
Biventricular: This type of pacemaker is also known as cardiac resynchronization therapy (CRT). The operation requires a lead to the right atrium and a wire to both ventricles. Patients with advanced heart failure causing a weak pumping action of the heart muscle may be candidates for this device.
Parts and insertion of the pacemaker
There are two components: the leads or wires and the generator that sends the electrical signal. The pulse generator, which houses the battery and tiny computer, is surgically placed under the skin. First, the physician threads the lead(s) through the veins and implants it in the heart muscle.
A pacemaker is not something that one decides he/she wants. It is a need – precipitated after diagnosis by a cardiologist that you must have a pacemaker to correct a problem with your heart.
The insertion takes place as an outpatient or during your inpatient care if already hospitalized. For an outpatient, the procedure begins with the introduction of the IV line, in the event you need medication. The doctor will connect an ECG (aka EKG) monitor, as well as monitor blood pressure, heart rate, and oxygen level.
Frequently, a sedative is administered for relaxing the patient, before the insertion site receives a local anesthetic. The cardiologist makes a small incision near the left collarbone, before threading the lead through an introducer or sheath inside a large vein to the right side of the heart. The device is placed under the skin, tested, then the incision is sutured, and a sterile dressing applied.
Many patients return home the same day with instructions to call the physician if experiencing any discomfort, such as pressure, swelling, excessive sweating, dizziness, and more.
Unfortunately, pacemakers do not last a lifetime, as the battery in the generator lasts an average of five to ten years. Battery replacement requires the same surgical procedure as the initial insertion, except the leads might remain in place. Medtronic, a medical technology company, manufactures the world’s smallest pacemaker (the Micra) with a battery lasting 8 to 13 years on average. Their vitamin-capsule size device attests to be 93% smaller than other pacemakers are. The self-contained or leadless Micra unit is inserted directly into the heart through a vein in the leg. Therefore, this eliminates the chest incision.
Pacemakers can be lifesavers. They help those with heart problems resume normal physical activities that they may not be able to do without the device. By regulating heart rhythm, the unit allows those who were inactive, to be more active with the assurance that such a small inconspicuous piece of technology can provide. They may not prevent a heart attack or reverse heart disease, but a pacemaker can add life to your years.