Overview of Pacemaker Indications
Pacemakers are medical devices that help regulate your heartbeat by sending electrical signals. They can help keep the heart beating normally, or jumpstart it if it pauses or slows down. The first pacemaker was introduced by Zoll in 1952. It was an external device that could only be used for a short period of time. It worked by sending electrical pulses through the skin to the heart.
In 1957, doctors found a way to directly attach electrodes to the heart to treat a condition called ‘complete heart block’. This opened people’s eyes to the idea that electrical problems in the heart could be managed. Based on this idea, Chardack, Gage, and Greatbatch invented a pacemaker that could be completely inserted into the body.
Pacemakers have come a long way since then. The modern pacemaker is a small device placed under the skin. There are three types of pacemakers:
1. Implantable pulse generators with electrodes inside the heart or on its surface.
2. External, miniaturized, portable pacemakers powered by batteries. These come with electrodes that can be temporarily placed inside the heart or on its surface.
3. Console-based pacemakers or heart monitors powered by batteries or electricity. These send high- or low-current electrical signals either through the skin or electrodes placed in the heart or on its surface. They can be set to work automatically, or be started manually.
Every pacemaker consists of two parts: a pulse generator that makes the electrical signal, and one or more electrodes or wires, which carry the electrical signal from the generator to the heart tissue. The remainder of this discussion will focus on why and when a pacemaker should be placed.
Why do People Need Pacemaker Indications
The main reasons doctors may suggest a patient get a pacemaker permanently are issues with the sinus node (the area of your heart that sets its pace) and serious issues with the atrioventricular (AV) block, which affects the timing between when the upper and lower parts of the heart contract. Establishing when cardiac pacemakers are appropriate is guided by task groups created by The American College of Cardiology (ACC), the American Heart Association (AHA), and the Heart Rhythm Society (HRS) in the US and the European Society of Cardiology in Europe.
These guidelines consider three different scenarios. In Class I situations, having a pacemaker is both beneficial and necessary with the benefits greatly outweighing the risks. Class II covers circumstances where it might be useful to have a pacemaker, but there is a mixture of evidence and opinions. Within Class II, Class IIa suggests the benefits are likely to be greater than the risks and class IIb suggests the benefits could be equal to the risks. Class III covers conditions where it is not recommended to have a pacemaker and could potentially be harmful as risks exceed the benefits.
There are several situations covered by these guidelines where placing a pacemaker is suggested. We will focus on Class I and II recommendations.
These situations include:
Sinus node issues (Class I and II)
AV block issues (Class I and II)
Persistent issues with the bundle of His, part of your heart’s electrical system (Class I and II)
Following the acute phase of a heart attack (myocardial infarction) (Class I and II)
Neurocardiogenic syncope and hypersensitive carotid sinus syndrome, issues related to a sudden drop in heart rate or blood pressure that can lead to fainting (Class I and II)
After a heart transplant (Class I and II)
Hypertrophic cardiomyopathy, a condition where your heart muscle becomes abnormally thick (Class I and II)
Pacing to detect and stop a very fast heart rate (tachycardia) (Class I and II)
Cardiac resynchronization therapy for patients with severe heart failure where the heart is unable to pump an adequate amount of blood to the rest of your body (Class I and II)
Patients with congenital (from birth) heart diseases (Class I and II)
More specifically, patients showing symptoms such as slow heart rate (sinus bradycardia) that are linked to their conditions or that affect their medication, may need a pacemaker. As well as those who during tests show an inability to increase their heart rate to the level appropriate for their age.
When a Person Should Avoid Pacemaker Indications
Just like any other medical procedure, putting a pacemaker into someone’s body must be done thoughtfully, considering their specific health situation. Sometimes, a pacemaker might not be the best option, or it may not have enough evidence to prove it’s beneficial. Medical professionals sometimes refer to these as class III indications in ACC/AHA/HRS guidelines or European Society of Cardiology guidelines.
These situations can include when someone has very slow heartbeats but doesn’t experience any symptoms, or someone has a heart condition that is likely to get better on its own. This could be due to factors such as drug poisoning, Lyme disease, or a temporary increase in activity of the vagus nerve which helps control heart rate.
People who have symptoms of slow heartbeat even without actually showing a slow heart rate on tests are also not usually recommended to have a pacemaker. Those who have an irregular heartbeat pattern known as second-degree Mobitz type-I block but show no symptoms also fall in the same category.
A pacemaker may also not be necessary if someone experiences long heart rate pauses due to conditions like atrial fibrillation but does not show any symptoms. Furthermore, it’s not usually suitable for those who have overly responsive hearts to the stimulation of the carotid sinus (a area in your neck that helps control your heart rate) if they don’t show any symptoms or only have vague symptoms such as feeling dizzy or lightheaded.
A pacemaker might not be suitable when someone has slow heart rate only during sleep. It’s also not typically used for people whose overall wellness isn’t mostly limited by heart-related conditions, those with a certain type of abnormal heart rhythm without any symptoms, or those with long QT syndrome due to reversible causes.
Lastly, a pacemaker may not be beneficial for those who possess an extra passageway for electrical impulses in their heart that could potentially speed up their heartbeats, or patients with certain heart failure symptoms and an abnormal heart rhythm pattern with a certain duration of electrical QRS waves in the heart.
Possible Complications of Pacemaker Indications
Procedures called pacing and CRT, both of which help manage heartbeat, can sometimes cause issues. Most of these issues will happen in the hospital or within the first six months after the procedure. The main reason some patients need the procedure redone is problems with the lead, which is the wire that sends electrical signals from the device to the heart.
There might also be other complications including infections or the formation of a hematoma, which is a swelling filled with blood. Some patients could encounter a condition called pericardial effusion or tamponade, where fluid builds up around the heart. Pneumothorax is another risk, which is when air gets into the space between the chest wall and the lungs. Lastly, in rare cases, the procedure can also cause a dissection or perforation in the coronary sinus, a vein that collects blood from the heart muscle.
Another thing to note is that older pacemakers might not be safe to use with MRI machines, which use strong magnets to create images of the inside of the body. This means that if a patient with an older pacemaker needs an MRI, extra precautions may be necessary.
What Else Should I Know About Pacemaker Indications?
A pacemaker is a device placed in the chest to help control abnormal heart rhythms. Studies have shown that getting a pacemaker can actually help reduce the risk of death in certain heart conditions. There’s a large study called the CARE-HF trial, which focused on people with a certain type of heart rhythm problem. It found out that therapy involving pacemakers led to a significant 36% drop in deaths compared to just treating the patients using the usual medications. This therapy is referred to as “resynchronization therapy”.
There have also been many other studies, showing that this resynchronization therapy can lead to improvements in everyday tasks and reduce the risk of other heart complications. However, in clinical trials, it hasn’t shown to be as helpful for those with a mild type of heart failure.
Our guidelines from 2012 took a good look at a variety of conditions, including hypertrophic cardiomyopathy (a condition where the heart muscle becomes abnormally thick), genetic arrhythmia syndrome (a group of conditions causing abnormal heart rhythms), and more. The guidelines didn’t really change for these conditions compared to the 2008 version of the guidelines. But there was a pretty significant change when it came to the circumstances in which a pacemaker could be recommended.
The new guidelines now suggest that we should consider a pacemaker for patients with a QRS duration (part of the heart’s electrical cycle) greater than or equal to 150 milliseconds. This is a change from the previous guideline, which suggested it for those with a QRS duration greater than or equal to 120 milliseconds. The European guidelines for these heart conditions are very similar to ours, but there are a few differences. An important difference is that the European guidelines suggest considering pacemakers for patients with heart failure and abnormal heart rhythm who have a QRS duration of less than or equal to 120 milliseconds, whereas our guidelines do not.
