Cardiac Holters, Loops and Memos!
|Patient wearing a Holter Monitor
Holter Monitors and Loop Recorders are devices that a patient wears to record their heart rhythm. The data they collect is a simple ECG or ‘Rhythm Strip’ that can be interpreted by a trained healthcare professional.
They are very helpful in recording the hearts RHYTHM and therefore the diagnosis of ‘Palpitations’ and Very Slow
/Fast Heart Rates
Usually attached to the patient by some ‘electrodes’ (stickers) and leads, there are a variety of makes and models that differ slightly but all function in a similar way to record a persons heart activity over a sustained duration. These tend to be warn for 1 Day to 1 Week.
They are less helpful in the detection of structural or plumbing issues of the heart because they are not as comprehensive as a 12 Lead ECG.
How is a 12 Lead ECG More Comprehensive??
If you think of the heart as a 3D Structure (which it is) we need to be viewing it from all sides to see what is truly going on. Imagine looking at a Dice if you only looked at the front of it you may think that it had a single dot on all 6 sides. You would need to view the dice from all angles to build a complete picture of it.
On a 12 Lead ECG we have 12 ‘views’ of the heart to build up the complete picture.
On Holter monitors and Loop Recorders we usually have between 1 and 3 ‘views’. A single view of the heart is often called a ‘rhythm strip’ as its main use is to interpret the hearts rhythm!
So although useful for somethings, Holter Monitors and Loop Recorders are not totally comprehensive.
“A rhythm strip is a little like reading the blurb on the back of a book where as the 12 Lead ECG is like reading the book cover to cover. “
12 Lead ECG:
Single View Rhythm Strip:
Why do we use Holter Monitors and Loop Recorders?
The major advantage over a 12 Lead ECG is that they are AMBULATORY (can be taken away from the hospital) and worn for a long period of time. Very often heart problems come and go and can last for just a few seconds a week or even a year. Holter and Loop Monitors give us a better chance of ‘catching’ a heart problem in the act!
Some common reasons why people are requested to wear a Holter Monitor include:-
- Unexplained Fainting/Dizziness
- Unexplained Stroke
- Other known Heart Conditions
- Family History of Arrhythmia
- The ‘Burden’ of Arrhythmia – How often somebodies heart is misbehaving.
- Assess the affect of medication/treatments on an already diagnosed problem.
What is the Difference between Loop Recorders and Holter Monitors:-
The main difference between the two is that a Holter Monitor records everything for whereas a Loop Recorder will only store periods of heart rhythm that it has ‘recognised’ as irregular.
A similar principle is at work in some road traffic accident hot spots. There are cameras that sit on top of traffic lights where many accidents occur. The constantly record and delete a rolling 1 minute long video clip of the road. If the camera ‘hears’ a car accident (it is programmed to the range of sounds a car accident produces) then it stores the minute it has just recorded and 5 Minutes after. That way the police can review the car accident footage. this means that the camera does not need huge MEMORY to record constantly like a CCTV Camera.
A loop recorder does the same – it is constantly recording and deleting your heart rhythm strip. It only saves the interesting stuff! When it recognises an irregular rhythm. This also means that the results are quicker to review for the healthcare professional…. wahoo!
|Image Courtesy of www.rbain.org.uk
What is a Cardiac Memo?
Quite often people describe palpitations that come and last a few minutes or more. If this is the case then a Cardiac Memo can be suitable! Essentially it looks like a pager with four metal pads on it. If you have symptoms then you activate it (press a button) and press it to your chest – it will record a short blast of your hearts rhythm. These can be given to patients for up to two months making them very useful for patients with symptoms that occur very infrequently!
Implantable Loop Recorders
Implantable loop recorders are exactly what they sound like. A loop recorder that is implanted under the skin (a minor medical procedure) and left in a person recording away for up to 3 years. These are particularly useful if somebodies symptoms are particularly sparse. Once every year or so for example…
They did look like the picture on the left!
|Medtronic Reveal Linq
However Medtronic have introduced the new Reveal LINQ which will revolutionise Implantable Loop Recorders. I will feature the Medtronic LINQ in my next post but for now have a picture!
So that is that, I hope this has helped explain the difference between the Cardiac monitor that most hospitals are currently using
Thanks for Reading,
Time to return to my Prison Break box set!