What Are Pacemaker Cells

Did you know that your heart has its natural pacemaker? This pacemaker is made up of cells called sinoatrial (SA) nodes. The SA node is responsible for setting the rhythm of your heart. If something happens to the SA node or not working correctly, a pacemaker may be needed to help keep your heart rhythm stable. Pacemakers are electronic devices that are implanted under the skin of your chest. They send electrical impulses to your heart to help keep it beating at a steady pace.

Let’s Talk About Pacemaker Cells

The cells that make up the SA node are called pacemaker cells. These cells have proteins, called ion channels, in their cell membranes. Ions are atoms with an electrical charge due to the gain or loss of electrons. For example, one type of ion is sodium (Na). Positively charged sodium ions enter your pacemaker cells through tiny channels on the cell membrane. As more sodium enters your SA node, more electrical impulses are released. This causes your heart to contract or beat.

The Cycle

This cycle starts when your SA node sends an electrical impulse down your heart’s conduction system. Your heart is made up of four chambers: the right and left atria and the right and left ventricles. First, the impulse passes through a small group of specialized cells called the atrioventricular (AV) node, located in the center of your heart. The impulse then goes to the ventricles through a bundle of fibers called the bundle of His, which forms part of the conduction system.

The Heart’s Conduction

The heart’s conduction system comprises muscle cells, fibers, and special cells. It’s in charge of sending electrical impulses throughout your heart. The system works much like the electric grid in your town: power is supplied to your home, and you get the correct amount of energy needed to run your appliances. In this case, the SA node produces and delivers electrical impulses to your heart’s conduction system, which distributes the electrical energy throughout your heart.

Failure of the SA Node

Most people with a failing SA node have fatigue, dizziness, or fainting symptoms. The most common cause of failure of the SA node is damaged due to aging. Smoking, alcoholism, and high blood pressure can also damage the SA node over time. Damage to the SA node can lead to the heart’s conduction system taking over its electrical impulses. This can cause an irregular heartbeat or arrhythmia. When this happens, you may need a pacemaker.

Cells

The cells that make up the SA node are called pacemaker cells. These cells have proteins, called ion channels, in their cell membranes. Ions are atoms with an electrical charge due to the gain or loss of electrons. For example, one type of ion is sodium (Na). Positively charged sodium ions enter your pacemaker cells through tiny channels on the cell membrane. As more sodium enters your SA node, more electrical impulses are released. This causes your heart to contract or beat.

 Molecular Mechanisms In Pacemaker Cells

 

1. The inward rectifier potassium channel: This type of ion channel allows positively charged ions to flow through the cell membrane in one direction only. In the heart, this channel allows positively charged ions to flow into the cell from outside of the SA node during diastole (the time between the two heartbeats). This creates a negative electrical charge inside the SA node, which is required to produce another electrical impulse.

2. The L-type calcium channel: This ion channel allows positively charged ions such as calcium (Ca) to flow through the cell membrane during systole. The more calcium flows into the cell, and the more electrical impulses are produced.

3. ATP/ADP: The potassium and calcium ion channels discussed above require a supply of the molecule adenosine triphosphate (ATP) to work. During times of stress, your body uses up your stores of ATP. This decreases the number of potassium and calcium ions that can enter the cell and an irregular heartbeat. A pacemaker supplies your heart with an electric current that stimulates the production of ATP and keeps these ion channels working correctly.

Electrical Signals

When it comes to the heart, electrical signals can make or break you. Think of your heart as a well-oiled machine, pumping blood throughout your body to deliver oxygen and nutrients. Like any machine, your heart requires fuel to work. However, instead of diesel or gasoline, your heart runs on electricity. Neurons, or nerve cells, use electrical impulses to communicate with other cells, tissues, and organs. Without electricity, there would be no life.

Trouble in Paradise

Without a heart, there is no life. A healthy heart is responsible for pumping blood throughout your body, which exchanges oxygen and nutrients with the cells in your body. Every beat of your heart is the result of timed electrical impulses. Pacemaker cells, which are found in your heart’s natural pacemaker (the sinoatrial node), generate these electrical impulses that control your heartbeat. However, bradycardia is a condition that refers to a heart rate of fewer than 60 beats per minute (BPM). The American Heart Association reports that 2.7 million Americans suffer from this condition.

Pacing the Panic Attack

Keeping your heart beating at a steady pace is the job of these pacemaker cells. These cells have proteins, called ion channels, in their cell membranes. Ions are atoms with an electrical charge due to the gain or loss of electrons. For example, one type of ion is sodium (Na). Positively charged sodium ions enter your pacemaker cells through tiny channels on the cell membrane. This causes your heart to contract or beat.

What happens when the electrical signals of the pacemaker cells start to fluctuate?

That’s when something called “heart block” occurs. Heart block is a severe condition in which your heart rate slows to an irregular beat. This change in rhythm can cause cardiac arrhythmias, which refers to any problem with the rate or rhythm of your heartbeat. Without proper heart function, your body cannot receive the oxygen and nutrients it needs.

Pacemakers To The Rescue

Once upon a time, if you experienced heart block, your options were limited. However, technological advances have led to the creation of external pacemakers. An external pacemaker is a small device about the size of a deck of cards implanted under your skin on the left side of your chest. 

When does Temporary Pacemaker Need?

Some people who have heart block may only need a pacemaker temporarily. For example, if you experience a heart block after a heart attack, your doctor may recommend implanting an external device for about three to six months until your heart heals. However, if you have chronic heart block, meaning that your condition doesn’t improve after three to six months of treatment, your doctor may recommend the permanent implantation of a pacemaker.

When you have an external device, doctors can check the pacemaker’s function by performing a “capture test.” The captured test involves placing an ECG electrode on your chest to measure the electrical activity of your heart. If the pacemaker is working correctly, your ECG should show electrical signals after a premature beat (an atrial or ventricular contraction that occurs before the next expected impulse).

Wireless Pacing

You May All Be Winners Today, technology has advanced to some external pacemakers programmed wirelessly. They can be activated to deliver an electrical impulse if your heart rate is too slow or deactivated if your heart rate becomes too fast. This means that you can go about your average, everyday activities without worrying about a wire attached to your chest—something called “wireless pacing.”

What Is Rate Response?

Rate response technology can detect specific changes in your heart rate and change the rate of your pacemaker to keep it within a normal range. For example, if your heart rate is dangerously low, the rate response feature may activate the pacemaker to increase your heart rate.

In addition, some wireless pacemakers can adjust themselves based on the amount of physical activity they do throughout the day. Your heart needs more energy (and therefore beats faster) when you’re active. By using sensors that monitor your movements, it adjusts the rate of your pacemaker to increase or decrease your heart rate.

What happens when destination therapy is not available?

If you or someone you love suffers from heart block, you may benefit from a transvenous pacemaker. As opposed to an external device placed under the skin of your chest, a transvenous device travels through a vein to the right side of your heart, where it “hides” in one of the heart’s chambers.

Bottom Line

Doctors have performed successful transvenous pacemaker implantation on patients with heart block who participate in very active,

Strenuous activities—from bicycling to parachuting. You may be wondering why anyone would choose an external device over a transvenous device. It’s because many people don’t want to go through an invasive procedure that requires surgery to implant a device in their chest. It’s important to note that with the advancements in technology. External devices are becoming less and less invasive as time goes on. Find out how long does a pacemaker last and essential details about a temporary pacemaker.