Diaphragmatic Pacing – Twitching After a Pacemaker/ICD Implant
What is Diaphragmatic Pacing?
What is the Phrenic Nerve?
Why is it more common in Biventricular Pacemakers?
We can often resolve this issue by reprogramming the pacemaker (adjusting the settings)
How can this be stopped with Reprogramming the Pacemaker?
If you have an RV Lead in this will make the heart beat – the LV Lead is there to help the heart beat more efficiently (read my posts on Biventricular Pacemakers).
Therefore, if worst comes to the worst and the LV Lead does not stimulate the heart at you will have a return of Heart Failure symptoms and not Asystole (NO HEART BEAT). On return of these symptoms you can seek help and the pacemaker team and your Cardiologist will re-evaluate your case.
Until now we have just discussed pacemakers delivering a charge down a lead, in actual fact part of the heart makes the circuit through which the electrical current passes.
The fact electricity requires a circuit is a concept you are probably familiar with..
- Birds do not get electrocuted when they land on power lines
- Taser guns have two electrical prongs that the electricity passes between.
This is the same with a pacemaker, some of your tissue (mostly Cardiac) is involved in the circuit. It is the electricity passing around this circuit that captures the tissue and makes your heart beat.
In its simplest form we can change most modern pacemakers from ‘Bipolar’ to ‘Unipolar’ and vice versa. We are changing the circuit used by the pacemaker and therefore the Cardiac tissue involved.
Cast your eyes left and in the top picture you can see the pacemaker and lead. This is what we call a BIPOLAR lead because it has two exposed ‘electrodes’. I realise you may have to squint to see these I have drawn them in pink!
When set ‘Unipolar’ the pacemaker uses itself, ONE of these electrodes and some of your flesh and blood to make the circuit (Middle Picture).
When set BIPOLAR, the pacemaker uses the TWO available electrodes and some of your tissue to complete the circuit (bottom picture of the three).
You can quite clearly see that the circuit involves different areas of soft tissue.
In a Biventricular Device we have a few different configurations that we can set the circuit to – but the priniciple is the same. By altering the circuit you are selecting and discriminating the soft tissue involved in the circuit. If a person Phrenic Nerve is being included in the electrical circuit then you may have Diaphragmatic pacing – you could then change the configuration (polarity) to descriminate/eliminate the Phrenic nerve from the circuit.
In the image below I have shown a few polarity options we have in a Biventricular Pacemaker – each involves different areas of soft tissue.
If altering the energy delivered and/or altering the ‘polarity’ of the device are unable to ‘cure’ the Diaphragmatic Pacing then surgery may be required to re position the lead somewhere further form the Phrenic Nerve.
Further explanation around these topics and more is available in the book Pacemakers Made Easy by Carl Robinson.
Sometimes Diaphragmatic Pacing can be intermittent and this is because the Phrenic Nerve is only occasionally being ‘irritated’ by the pacemaker lead. One common trigger is the patient laying on their left hand side – where the lead is pushed together with the Phrenic nerve. Another is when a person sneezes or coughs – this changes the pressures within the chest and again brings the lead and the nerve closer together. If you were to draw two dots on either side of a balloon, when inflated these dots will be quite far apart, when you deflate the balloon however the dots will come very close together – this is the same principle – a sudden exhalation can bring everything in the chest cavity closer together, bringing the Phrenic Nerve closer to the pacemaker lead tip.
I hope this has shed some light as I know a lot of my readers have experienced some Diaphragmatic Pacing in the past!
Time to e-mail my mate Neville in Australia ..
Thank you for reading
In my next post I interview somebody who experienced quite bizarre Diaphragmatic Pacing!