- A pacemaker is a small implanted device that watches the heart’s rhythm and delivers a gentle electrical impulse whenever the rate falls below a set minimum.
- The main reason for implanting one is a heart rate that is too slow to meet the body’s needs. Either the heart’s own natural pacemaker has slowed down, or the signal it sends is being blocked on the way to the pumping chambers.
- There are four broad types. Three of them use thin wires, called leads, to reach the heart. The newest type is a single capsule that sits inside the heart with no wires at all.
- Putting one in is a small procedure. It is done under local anaesthetic with sedation rather than a general anaesthetic, and usually takes 60 to 90 minutes.
- Batteries generally last 8 to 15 years. When one nears the end of its life the generator is replaced and the existing leads are usually kept in place.
- Life with a pacemaker is close to normal for most people. Exercise, travel and household appliances are compatible with the device, with a few straightforward precautions.
Being told that a pacemaker is needed can feel like a significant moment. The idea of a device sitting under the skin, wired to the heart, is not a small one to absorb.
In practice, pacemaker implantation is one of the most established procedures in cardiology, and one of the most reliably effective. For a heart that is beating too slowly, it addresses the problem directly rather than working around it.
A slow heart rate causes tiredness, light-headedness, breathlessness and episodes of fainting. These often improve within days of the device going in.
The change can be striking. A slow rate usually creeps up over months, so the lost energy gets put down to age, or to stress, or to nothing in particular.
How a Pacemaker Works
The two main components
A pacemaker has two parts. The first is a small sealed metal case holding the battery and the electronics, placed under the skin just below the collarbone. It is called the pulse generator, and it is roughly the size of a large coin.
The second part is the leads. These are thin insulated wires that run through a vein into the heart, where their tips are anchored against the inner wall of one or more chambers.
Leadless devices are the exception to this, and are covered further down.
Inside a Dual-Chamber Pacemaker
The pulse generator
A sealed metal case holding the battery and the electronics. It sits under the skin just below the left collarbone and is about the size of a large coin.
The vein under the collarbone
The leads reach the heart through a vein, not through the chest wall. This is why the procedure needs only a small cut and no open surgery.
Lead in the upper chamber
The tip rests against the wall of the upper chamber. It senses the heart’s own signal and paces this chamber if that signal is too slow.
Lead in the lower chamber
The tip sits in the pumping chamber below. This is the chamber that drives blood out to the body, so pacing here is what restores a reliable rate.
A dual-chamber pacemaker on the left side of the chest, which is the usual side. A single-chamber device uses one lead, and a leadless device uses none.
What the device does moment to moment
The pacemaker monitors the heart’s own electrical activity continuously. When the heart beats on its own above the programmed minimum rate, the device simply watches and does nothing.
If the rate drops below that threshold, or a pause is detected, the pacemaker delivers a precisely timed impulse that prompts the heart to beat. This happens within milliseconds. It is painless, and almost nobody can feel it.
A pacemaker sets a floor, not a ceiling. It does not slow a fast heart rhythm down, and it does not take over a rhythm that is working perfectly well on its own.
Smart features
Modern devices are more sophisticated than a simple backup. Rate response programming raises the pacing rate during physical activity, so that the heart rate rises with exertion in the way it naturally would.
Remote monitoring allows the device’s performance and its stored rhythm recordings to be reviewed by the clinical team without a hospital visit. Anything unexpected is flagged automatically between scheduled checks.
Why a Pacemaker Is Recommended
The common thread is a heart rate that is too slow to keep enough blood moving. Two faults account for most cases.
The first is a problem with the sinus node, the small patch of tissue in the upper heart that sets the natural rhythm. It can fire too slowly, pause for a few seconds at a time, or fail to speed up during exercise.
The second is heart block. Here the sinus node works normally, but the signal it sends is slowed or stopped on its way down to the pumping chambers.
A slow pulse in someone with atrial fibrillation is another common reason. A different form of pacing is used in some people with heart failure. There the aim is to get the two pumping chambers working in step again, rather than to lift a slow rate.
Types of Pacemaker
Which device is chosen depends on the underlying rhythm problem, on how much pacing is expected to be needed, and on the individual’s circumstances.
Single-chamber
One lead, placed in a single chamber of the heart. Used where pacing one chamber is enough, such as atrial fibrillation with a pulse that runs too slowly.
Dual-chamber
Two leads, one in an upper chamber and one in a lower chamber. The device times the two to fire in sequence, the way a healthy heart does. The usual choice for heart block.
Biventricular (CRT)
Three leads, pacing both pumping chambers together. Used in heart failure where the two chambers squeeze out of step with each other. Also known as CRT.
Leadless
No pocket under the skin and no wires. A capsule the size of a large tablet is passed up through a vein and fixed inside the heart, which removes any problem caused by leads.
Leadless pacemakers are the newest of the four. They suit a particular group rather than everyone, because a single capsule in one chamber cannot time two chambers against each other.
The Implantation Procedure
What happens on the day
A standard pacemaker goes in under local anaesthetic, with sedation to keep the person relaxed. A general anaesthetic is not usually needed. The whole thing normally takes 60 to 90 minutes.
The device is usually placed on the left side of the chest. For a right-handed person that is the non-dominant side, so it interferes less with everyday use of the arm, and the path from the left shoulder down into the heart gives the leads a gentler curve to follow. A right-sided implant is used where there is a reason to prefer it, such as left-handedness, or previous surgery or injury on the left.
A small cut is made below the collarbone to reach a vein. The leads are threaded into position using X-ray pictures to guide them, then tested to check they are picking up the heart’s own signals and pacing reliably.
The generator is connected and settled into a small pocket under the skin. The cut is closed with stitches that dissolve on their own.
A leadless device goes in differently, through a vein in the groin. There is no cut in the chest and no pocket.
Recovery
An overnight stay is usual, with home the next day. The arm on the side of the device is rested for a few weeks. This gives the tips of the leads time to settle firmly into the heart wall.
A wound check and a first reading of the device are normally arranged within the first few weeks. After that, checks every 6 to 12 months continue for the life of the device. Many of these are done remotely, without a visit.
Battery Life and Generator Replacement
Pacemaker batteries generally last between 8 and 15 years. The range is wide because it depends on the type of device, and on how much of the time it is actually pacing. One that is rarely called on lasts far longer than one pacing every beat.
When the battery nears the end of its life, the generator is swapped through the same pocket. The old leads are tested first. If they are working well they are simply reconnected to the new generator rather than replaced. This is a shorter procedure than the original one, and an overnight stay is often not needed.
Battery level is read at every check, and tracked continuously where remote monitoring is set up. There is no sudden cut-off. The replacement is planned months before the battery reaches its limit.
Living With a Pacemaker
Daily life
For most people, life with a pacemaker is essentially unchanged. The device is not felt, does not restrict movement, and is not visible under clothing.
Exercise is safe and encouraged. The device lifts the pacing rate as activity increases, so the heart rate still rises with effort.
Driving restrictions apply for a period afterwards. How long they last, and what they cover, vary by country and by the individual situation, so the implanting team is the right source for that detail.
Flying is safe. Airport security screening does not affect how the device works, although the metal case will usually set off a detector.
Everyone with a pacemaker is given an identification card. It lists the model and the contact details of the clinic that fitted it, which answers most questions quickly in an unfamiliar place.
Appliances and MRI scans
Ordinary household appliances, microwaves included, are compatible with a pacemaker. A distance of around 60cm from an induction hob while it is switched on is a common precaution. Strong industrial electromagnetic fields are the exception and are generally avoided.
Most current models are described as MRI conditional. That means an MRI scan can go ahead as long as certain precautions are taken. The scanning team and the device clinic sort the arrangements out between them beforehand, and the identification card carries the details they need.
What Device Follow-Up Covers
A routine pacemaker check looks at four things: how much battery is left, how well each lead is working, how many beats the device is having to pace, and the rhythm recordings it has stored since the last check.
Those recordings are one of the quieter benefits of having a device. If symptoms come back, what the heart was doing at the time has usually already been captured.
Heart Matters Resource
When in Doubt, Get Checked Out
The return of dizziness, breathlessness or fainting in someone with a pacemaker is worth assessing rather than waiting out. A device check can answer the question quickly, and there is rarely a reason to delay one.
Conclusion
A pacemaker fixes one clear problem, and it fixes it reliably. The technology is well established and the procedure is routine. For a heart that has been beating too slowly, the difference in how a person feels is usually large, and it comes quickly.
The idea is almost always more daunting than the reality. Knowing what the device does, and what the checks are looking for, turns it from something imposed into something understood.
Related Reading
- The Holter Monitor: Catching Arrhythmias in Daily Life
- When a Standard ECG Isn’t Enough: A Guide to Cardiac Rhythm Monitoring
- What Does a Left Bundle Branch Block (LBBB) Mean on an ECG?
- Understanding Palpitations: A Cardiologist’s Approach
- How Atrial Fibrillation Is Treated: From Lifestyle to Ablation
- Understanding Ventricular Tachycardia
