Overview of External Pacemaker
An external cardiac pacemaker is a device that helps control the heart’s beat by sending electrical signals to it. This is done through sets of electrodes that can influence how the cells in your heart (myocardiocyte) work together to create the heart’s contractions. Maintaining the right pace of these contractions ensures the heart pumps blood correctly around the body, which is known as having a good heart rate and cardiac output.
When the heart beats too slow, it’s called a bradyarrhythmia. These harmful slow heart rhythms can happen due to different reasons and need to be corrected. One way to treat bradyarrhythmias is by using an external pacemaker, also known as a transcutaneous pacemaker.
However, this pacemaker is meant as a temporary measure to stabilize the heart, while a traveonus pacing device (a type of pacemaker that’s implanted) is arranged for permanent use. This switch is necessary to keep the heart in balance, ensuring it continues beating at the correct speed.
So, the external pacemaker is a vital emergency tool to help save lives by correcting dangerous heart rhythms, but it’s not a long-term solution and needs to be replaced by a permanent version to guarantee ongoing heart health.
Anatomy and Physiology of External Pacemaker
The heart’s electrical system usually starts at the sinoatrial node, located at the top part of the right atrium (one of the heart’s upper chambers). The electricity then spreads through the atrium down to the atrioventricular node (another part of the heart), which is at the bottom of the right atrium. From here, the electrical signal travels down a path known as the His bundle, then the right and left bundle branches, ending up in the ventricles (the lower chambers of the heart) by passing through special fibers called the Purkinje fibers.
In some treatments, like external cardiac pacing, electrical pads are used to stimulate one specific point in the left ventricle (the left lower chamber of the heart). The electricity then spreads from this specific point to the rest of the heart muscle. It’s really hard to directly stimulate the atria (the upper chambers of the heart) using these pads, but sometimes indirect stimulation can be achieved by the electricity moving backward through the atrioventricular node.
Compared to the normal pacing of the heart, transcutaneous cardiac pacing (a procedure where electrical impulses are sent to the heart by pads placed on the skin) is able to produce a higher cardiac output (how much blood the heart pumps) because it can cause strong contractions of the diaphragm and skeletal muscles. Even though it does lower the left ventricular systolic pressure (the pressure your heart generates when it pumps blood out of the left ventricle) and reduce the stroke index (an index showing the amount of blood one heartbeat ejects compared to your body size).
Why do People Need External Pacemaker
External pacing is recommended by the American Heart Association as the quickest method to regulate the heartbeat in cases of slow heart rhythms, called bradycardia. This temporary treatment helps to maintain the heart’s output in situations where the condition is permanent and requires a long-term pacemaker or in reversible cases where a permanent pacemaker is not advised. Simply put, bradycardia is when your heart rate is less than 60 beats per minute, but not all slow heartbeats need pacing. Transcutaneous pacing, a method of external pacing, is only used when the blood pressure is less than 90, the heart rate is less than 40, or if an erratic heartbeat is causing organs to not get enough blood. Prior to starting pacing, a medicine called atropine can be given to try to increase the heart rate. The standard dose is 0.5 milligrams given through an intravenous line, but if the heart rate doesn’t increase, a larger dose can be given.
External pacing is suitable for patients with a condition called Atrioventricular Nodal dysfunction which can be caused by an acute heart attack, trauma to the chest or heart, infections such as Lyme disease or bacterial endocarditis, a blood infection called sepsis, and others. Slow heart rates resulting from electrolyte imbalances, metabolic abnormalities, certain drugs like beta-blockers, or hypothermia also make strong candidates for this type of pacing. It’s important to note that this temporary pacing method is not a substitute for a permanent pacemaker that’s surgically placed in your body. A special kind of heart block called third-degree heart block, which has a shaky rhythm and a high chance of becoming a fast or quivering heart rhythm, is also a case for pacing.
In some cases of a fast heartbeat, known as ventricular tachycardia, such as after surgery or a specific kind called Torsades de Pointes, external pacing can be used if all other options haven’t worked. A study showed that this type of pacing prevented the fast heartbeat from happening again in 14 of 16 patients.
When a Person Should Avoid External Pacemaker
Usually, a treatment known as cardiac pacing isn’t recommended for patients with a slow heart rate, or bradycardia, unless they’re showing symptoms or their health is unstable. Cardiac pacing is a treatment that uses an electrical device to control the beating of the heart.
Similarly, no strong reasons exist against the use of a technique called external pacing when needed. External pacing is a temporary method to restore normal heart rat, commonly used in emergency situations.
However, there have been a few cases where negative side effects occurred due to a process called cardioversion, which is used to correct abnormal heart rhythms. Some issues that were reported include the failure of small devices (known as leads) implanted in the heart chambers to control rhythm. These complications have been rare, but considering they happened after cardioversion, the same risks might potentially apply to external pacing as well.
Preparing for External Pacemaker
Wherever possible, it’s important to get the skin ready before applying the pacer pads, which are special pads that help control your heart rhythm. If you have a lot of body hair, it should be taken off but not fully shaved. This is because shaving can increase your risk of getting an infection. Dirt, sweat, or any other substances on the skin should also be cleaned off, ideally using an alcohol wipe. This clean surface will allow the pacer pads to work as effectively as possible, as it improves the connection between the pads and your skin.
How is External Pacemaker performed
In a procedure involving the heart, special pads are placed on the patient’s chest. These pads can be arranged in different ways – either on the front and side of the chest or on the front and back. A few specific arrangements can include having one pad on the left side of the breastbone with the other in the right shoulder blade area, one pad on the left side of the breastbone (a bone running down the middle of your chest) with the other pad in the left shoulder blade area, or one pad at the lower tip of the heart or the region of lead V3 with another pad in the right side of the breastbone. It’s important that the pad placed in the lower tip of the heart or front is negatively charged. The exact placement is not crucial as long as this condition is met.
The electric stimulation that will be given to your heart is paced to imitate your heartbeat, ideally at a rate of 60 to 90 beats per minute. This stimulation starts low and is slowly increased until a spike in heart rhythm is seen in the heart monitor, indicating that your heart is being electrically stimulated. The stimulation is further increased until your heart produces a normal heartbeat after each spike, indicating successful electrical stimulation.
To make sure the heart is actually contracting and pumping blood, the medical staff would feel for a pulse. This confirmation can also be obtained by using ultrasound technology that lets them see if the heart is contracting. If the patient is awake, they may experience some discomfort during the procedure. Some sedation can be given to help them feel more comfortable.
Possible Complications of External Pacemaker
Placing a pacemaker, a small device that helps control your heartbeats, can majorly lessen the amount of blood the heart pumps in people with a healthy left chamber of the heart (also known as ventricle). This effect is also seen in patients with heart failure – a condition where the heart doesn’t pump blood as well as it should. Whether the pacemaker control is external or internal, it can lead to a decreased percentage of blood that leaves the heart each time it contracts, a measure known as ejection fraction. However, increasing the pace at which the heart beats can help to maintain an approximately normal amount of blood flow from the heart.
There can be some side effects of transcutaneous pacing, which is a temporary way to control heartbeats by attaching electrodes to the skin. These can include skin burns and muscle contractions. Superficial injuries caused by the electrodes may look like mild skin inflammation around hair follicles, known as folliculitis. There’s no denying that the muscle contractions can be quite painful and could even require painkillers or sedatives. But despite the discomfort, there’s no evidence of damage to the skeletal or heart muscle even after 30 minutes of pacing at specific electrical currents with rates a bit above the normal resting heart rate. Mostly, the burns caused by pacing pads are minor. However, there have been some reports of severe burns, particularly in newborns, children, and older people after cardiac pacing. The risk of burns seems to increase when the pacing pads are not used as instructed by the manufacturer and are reused several times.
Research is currently being undertaken to find new non-invasive methods to set the heart’s pace, hoping it could decrease the side effects of transcutaneous pacing. The first method being studied uses high-intensity frequency ultrasound to stimulate pacing. The second method involves injecting tiny iron particles into the bloodstream and then using a generated magnetic field. This new approach is known as mechano-electrical feedback.
What Else Should I Know About External Pacemaker?
External pacing is a fast and simple method to treat various heart rhythm issues. It can help manage conditions ranging from a slow heartbeat (bradycardia) to a fast, serious condition known as ventricular tachycardia. The method serves as a temporary solution until a more permanent treatment can be given.
This type of pacing can be useful in many scenarios. For instance, when medication causes alterations in heart rhythm or when a heart attack hinders the system that controls your heartbeats. It can be used in hospitals, but it’s also used by emergency healthcare workers when transporting very sick patients. This is key to ensure that the heart pumps enough blood for the proper functioning of your body’s organs.
