inside-a-pacemaker

Heart Pacemaker – Artificial

Artificial Heart Pacemaker

Heart pacemakerAn artificial heart pacemaker is a small electrical device that is implanted under the skin to help control the heart’s rhythm and rate. It should not be confused with your heart’s natural pacemaker.
In your heart you have a collection of cells called the Sino Atrial Node, it lives in the top right hand corner of your heart and is responsible for controlling your heart rate.  If your heart is beating at 75bpm that is because this bundle of cells is telling it to beat at 75bpm. This property means it is often referred to as the heart’s natural pacemaker. More about your hearts natural pacemaker and how it works can be found in the How the Heart Beats Post.

Artificial Heart Pacemaker

The artificial heart pacemaker we are more familiar with is “something that is implanted into your heart that keeps it going”. These are the words of a friend of mine and is pretty much the understanding of pacemakers to a large portion of the general public. It is this implantable pacemaker that I am going to explain in this post.
Heart PacemakerThe artificial heart pacemaker is used to treat a range of heart conditions by taking control of or assisting with the hearts natural conduction system. It does this by being able to ‘see’ the hearts natural electrical activity and also being able to generate its own and deliver this to the heart.
An artificial heart pacemaker actually consists of a pacemaker box and lead(s). A typical heart is the size of your fist and the pacemaker can range from the size of a large bottle top all the way to a small mobile phone. Essentially the range of pacemaker boxes on the market at the moment are all too large to be placed directly into the heart, so they are connected to the heart using a lead(s). This is shown on this x-ray of a cardiac pacemaker.

Inside an Artificial Heart Pacemaker

Artificial Heart Pacemaker includes…
The Pacemaker Box.
In technical circles this is commonly referred to as ‘the can’ it contains the following: 

Battery: Luckily we all know why this is here very handy so that our pacemaker patients don’t have to be plugged into mains electricity!

Pulse Generator: This is responsible for delivering an electrical pulse down the lead to the heart so is responsible for ‘Paced’ beats.

Sensing Unit: This is the ‘Eyes’ of the pacemaker and amplifies the electrical energy received from the heart which is initially very small.

Microprocessor: This is the pacemakers ‘Brain’, responsible for decisions made by the pacemaker based on how it has been programmed.

Mechanical Features: Some pacemakers have additional mechanical components, two examples are an Accelerometer (A sensor which detects movement of the pacemaker and uses this information to assume a level of exercise) and a Reed Switch (a switch that inhibits certain pacemaker functions when a magnet is placed over the box).

Connection Block: This is simply where the pacing leads plug into.

For those real techies out there…. a naked Heart Pacemaker

What is a Pacemaker

What is a Pacemaker

Credit Unknown
The Pacemaker Lead(s) connect into the connection block and run through a vein and connect directly to the heart (cardiac tissue). They are a bit more than a bit of wire…
One end has the connector that fits into the connection block on the pacemaker can. The other end has a fixation mechanism and one or more electrodes.

The Fixation Mechanism is either Passive or Active, a passive lead has tiny prongs on it that knit tightly into the mesh of cardiac tissue. The active fix leads have a tiny corkscrew which bores into the cardiac tissue and secures itself in that manor.

Heart Pacemaker Leads
The electrodes on the lead have to have the ability to receive electrical energy and send this message back to the pacemaker and delivery a small electrical charge to the heart to make the heart beat when it is going too slowly.
Together the ‘can’ and leads work together to regulate the rate of a person’s heart. Its main purpose is to make the heart beat when it goes too slowly which is very useful indeed in the treatment of a whole host of heart diseases.

Now you know ‘What is a Pacemaker?’ You can now read how a pacemaker is implanted here.

Further explanation around these topics and more is available in the book Pacemakers Made Easy by Carl Robinson.

Time for Lunch!!!! If only I was hungry….
Thank you for reading,
Cardiac Technician

Comments 1

  1. I ‘blew up’ the internet twice .. It would be fascinating to know how the leads are implanted I asked the ‘medical profession’ man this and received a ten word answer and as they are at $500 to $1000 per hour ..

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