Arrhythmias - what can your pacemaker do to help?

Self Test

by Penguin - 2024-05-27 15:35:40

My wishlist includes a self test that doesn’t trigger arrhythmia or which, at the very least, can be re-programmed so that it happens at a programmable time of day which suits the patient and doesn’t disturb precious sleep. 

Research into sleep shows that good quality sleep really matters in brain health / vascular health as disturbed sleep affects the work of the ‘glymphatic system’ (the brain’s independent cleansing system).  An arrhythmic event in the middle of the night certainly disturbs sleep! 

It is probably already possible to arrange the test so that it occurs at a different time of day when this important cleansing process isn’t active.  However, reported experiences on this forum suggest that most people resolve the issue by having the test turned off altogether. 

Pacemaker and arrhythmia

by AgentX86 - 2024-05-27 15:42:37

Sure, Bradycardia is technically an arrhythmia, as is tachycardia, but they're nothing like the others, in that they' aren't a-rhythmic.  They're just abnormal.

As you know, a pacemaker can only make the heart go faster.  Flutter, for instance, is usually 240bpm to 360bpm and can go even higher. It wouldn't be a good idea to make that "go faster". Pacemakers can try to outpace SVTs and PVCs to try to let the heart regain control.  They can't do it for long because the real problem is tachycaria, not the arrhythmia itself. It's a case of the (even potential - not assured) cure being worse than the disease.

A device that could stop arrhythmias would be an entirely different thing.  The errant signals are within the heart itself, coming from just about anywhere. Not even an ablation works 100% of the time because they rely on burning a fire line around the source of the arrhythmia.  That part of the heart no can no longer send, or receive, pacing signals (including normal heart function). If there is another forrest fire, or the fire line isn't complete around the area (a bridge heals), the signal can get out, causing the problem to resurface.

An external (to the heart) device is going to have a hard time monitoring every part of the heart, then isolating troubling areas. It could be a defibrillator and do a cardioversion, but that's a rather violent and dangerous thing to do just to stop a benign heart rhythm.

Self-test: I was reading through the manual for my PM.  IIRC (I'm not at that computer), self-test can only be scheduled for "OFF", 12:OOAM or 1:00AM.  I have it turned off.  My EP siad that it was more problem than it was worth.  Just increase the capture margin a bit and be done with it.

(Anyone notice that cut an paste no longer work? I used it as a spell-checker.  <cntl>-C <cntl>-V still works but no spell checker.)

Agent - Self Test

by Penguin - 2024-05-27 17:01:17

I get what you're saying, but my self test is programmed to guard against an issue connected to a safety alert which was issued for my device and the possibility of moisture ingress.  I don't think that increasing the capture margin would cut it (?) so I have to run the gauntlet of arrhythmia or entertain the (small) but possible risk.   That's why I asked. 

AgentX86 and Penguin

by Gemita - 2024-05-27 17:54:46

AgentX86, you make some excellent points and clearly I need to be careful what I wish for.  I accept that a fast atrial tachy arrhythmia like Atrial Fibrillation or Flutter could quickly get out of hand if we tried to outpace it, unless the patient had a defibrillator, but then that would carry its own risks. 

I am thinking here mainly about my atrial/ventricular ectopic beats that are apparently coming in fast and triggering my disturbances.  I have strong evidence to confirm this now, so if I can better control the ectopics, I might just help fix the AF/non sustained VT runs.   I know there are already settings currently being used for PVCs (but not PACs on my pacemaker).  There is a PVC response algorithm for retrograde conduction following a PVC.  Retrograde (backwards) conduction can disrupt AV synchrony and adversely affect pacing mode timing.  For tracking modes (DDDR and DDD) for example, retrograde conduction following a PVC can initiate a pacemaker-mediated tachycardia, so the PVC response algorithm is important but it is far from perfect. There is no PAC Response algorithm.  In fact, PAC runs are not recorded on my pacemaker and my clinic had no real answer when I asked why?  I hope that any future pacemaker will have more in the way of algorithms to help with ectopics, like more effective rate smoothing/stabilising algorithms.  Surely this wouldn't be asking too much?

Penguin, I hear what you are saying and totally agree.  What arrhythmia is being triggered and is it the same arrhythmia each time and at what speed?  That is a heavy price to pay for being monitored nightly.  I think reprogramming is needed.  Have you actually asked for monitoring at a time that suits you better?

Ah to sleep.  A good night's sleep keeps my immune system healthy and I know how much it can do for my heart and brain.  If I don’t get enough of it, I cannot function and my mood/memory is awful.

I am currently off my beta blocker in preparation for my stress echo.  My ectopics were particularly bad last night, triggering AF in the early hours

Ectopics

by piglet22 - 2024-05-28 06:48:06

Gemita 

You know which PM I have (Medtronic Ensura DDDR) and also that it's not good at dealing with ectopics.

I personally don't understand why there isn't an algorithmic solution to distinguish between in sequence and out of sequence pulses.

I have an electronic wireless system that counts pulses, actually the electricity meter.

Occasionally, it misses a transmission which clearly shows as a gap in the numbers. It was easy to fix in software by looking at the pattern before the missing pulse, do some sums, and correct it, all done in microseconds.

It's a type of pattern recognition and should be capable of of adapting.

I can see that there could be consequences if it went wrong that doesn't matter with a utility meter.

Piglet

by Gemita - 2024-05-28 12:33:31

I like your statement:  I personally don't understand why there isn't an algorithmic solution to distinguish between in sequence and out of sequence pulses.   You make it sound so simple Piglet and so easy to solve, so why haven't they?  Our doctors know only too well that the "effective output" from an ectopic beat will be significantly less than from a normal heart beat, so we may not benefit from it at all.  Furthermore the pacemaker will accurately sense these ineffective beats and withhold pacing which is why we can feel as though our heart rate is much lower during prolonged ectopics.  

Yes, I know with the same pacemaker we have the same struggle with ectopic beats.  We certainly don’t have any appropriately set algorithms to help smooth these out just yet, do we, although rate stabilisation/rate smoothing algorithms are available in many pacemakers.   With a device change we may just see some improvements in the future.  

Although PVCs are common, some patients with frequent PVCs or frequent PACs will go on to develop premature contraction induced cardiomyopathy which is reversible after elimination of the ectopics.

Some of my pacing algorithms that maximize native conduction and minimize ventricular pacing can allow relatively long ventricular pauses, so this might increase the risk of ventricular arrhythmias like PVCs, non sustained VT.

Ventricular/atrial arrhythmias are often preceded by abrupt changes in ventricular/atrial cycle lengths (ie, the interval between successive beats), referred to as short-long-short sequences.  My AF always follows periods of atrial ectopics

Pattern recognition

by AgentX86 - 2024-05-30 14:33:44

Assuming a pacemaker can detect arrhythmias (they can), what's to be done about  them?  The heartbeat can't be held steady because it's already started when the detection occurs.  It only sees the impulse as it gets to the pacemaker probe.  By then, it's a done deal. If it's a slow ectopic, like PVCs normally are, the pacemaker can be set to a higher rate so the PVCs are effectivly burried,

My pacemaker is set to insert a pace when it detects an ectopic, not to stop anything, rather to make sure the ectopic completes the depolarization of the ventrical before the next pace starts.  The next pace knows exactly the state of the heart, so it can provide the next pace relative to the PVC, not the original pace. This can reduce VT because the heart doesn't get a beat when it's repolarizing, which can cause VT or Vfib.

There are already some therapies for arrhythmias but by the very nature of the arrhythmias there isn't a lot that can be done by a device that can only "go faster", when the answer is "go slower".