pacemakers – The Student Physiologist

Ethical Implications of Switching Off a Pacemaker

On the 24th of September, the BBC reported the story Nina Adamowicz. Nina, a 72 year old lady with an Implantable Pulse Generator (IPG) who, after having the device for almost 20 years, has requested it be switched off.

After suffering a minor infarct, Adamowicz had said that her continued deteriorating health became too much to bear, said she felt like she was waiting in line to be executed, so she requested her device be switched off. She is reported as stating “It isn’t about ‘I want to die’; I’m dying”.

Her case was referred to her local trust’s ethics committee, who, after careful deliberation decided to proceed in line with the wishes of Mrs Adamowicz.

Before passing away on the same night that her device was switched off, Nina Adamowicz stated that she believed she had the right to decide whether or not she wanted the IPG on or off, and stood by her decision.

This case is thought to be the first of its kind in the UK, but Chicago device specialist Dr Westby Fisher professes to doing this exact thing on a dozen separate occasions. Westby considers the ceased action of an implantable device to removing a feeding tube, or switching off a ventilator.

In particular, in a piece for massdevice.com, Fisher tells of a patient who refused dialysis, saying he’d rather let nature take its course. The patient, who also had an IPG, requested that this was switched off, so Westby agreed, and the next day switched off tachyarrhythmia detection on the device. Fisher says that he feels that both he and his patient did the right thing, together.

I for one, am confused as to the ethical pathway involved in coming to both this decision, and that of the ethics committee associated with Nina Adamowicz.. Assisted suicide is complex, but with respect to these scenarios, is defined as the intentional encouragement or assistance to a patient in ending their own life and it is still illegal under the 1961 Suicide Act of UK law . A medic who administers an overdose of muscle relaxants to a patient whose condition is diagnosed as being terminal, even at the behest of that patient, would be punishable by UK law with manslaughter or murder and potentially serve the maximum terms associated with each.

Why then, is hitting the off switch on a pacemaker not considered to be comparable to the example given previously? Patients with implantable devices often have them to combat life-threatening arrhythmias, so in turning them off, this can effectively issue a death sentence to that patient. I’m not arguing for or against any form of assisted death; I neither understand its intricacies or feel it is my place to denounce or advocate something with which I have had precisely zero experience, I’m simply confused as to why an immediate form of assisted dying is outlawed, and something so similar (on the surface at least), is not. Adamowicz’ clinician has said that other professionals are split in their opinion on his decision, with some feeling it to be “uncomfortably close to euthanasia”.

Is it fair to patients with terminal diagnoses that are forced to travel to countries such as Switzerland, wherein some forms of euthanasia are legal, simply because they do not have an IPG? Does the severity of the condition have any part to play? How similar do individual cases have to be so as to render one illegal and another not so? I have a feeling that this case will spark long debate throughout the medical and legal professions in the UK, and will follow its progress closely.

BBC article

Westby Fisher’s blog

Review: Epicardio Simulation v1.5 (Full Version)

Download for Windows/OSX:

Trial (Free)
Paid (£149-£215)
60% discount for full-time students

Developer: Epicardio.Ltd

After my review of the temporary access trial of Epicardio Simulation (which offered a great deal of praise, I might add) I couldn’t wait to have a look at the full version’s features. I still can’t afford it yet even with the 60% discount offered to full-time students, but thankfully, the good people at Epicardio.Ltd allowed me to access the complete package so that I could review it. As I’ve already covered some of the functions of the program, I won’t re-tread old ground, but you can check out what I thought of the trial version here, and consider this a continuation of those original opinions.

So, what functionality is offered by the full version? Let’s go over it now.

The previously-unavailable tutorial section has some marvellous interactive elements; a view of the electrical action and a live ECG accompany the written tutorial pages, allowing the user to view the very thing they’re reading about in real-time. The procedurally generated ECGs are very accurate (I’ve measured them), but if you want to see a genuine patient-obtained trace recording, then one is included with each arrhythmia, too, which really helps with comparisons to the actual recordings one is likely to find in practice.

Almost everything you can think of is covered in some capacity, both on its own, and linked with other, relevant arrhythmias, so you really get a feel for just how interwoven some conduction and rhythm abnormalities can be.

A marvellous inclusion is the level of interactivity within the tutorials; degradation from VT to VF, for instance, is displayed live on the ECG strip and the defibrillator (that I didn’t really have cause to use in the trial version) can be charged, and a shock administered, altering the rhythm strip as it would a real patient.

The pacing tutorials are easy to use and easy to follow; they walk you through the physics of single and dual chamber, as well as biventricular pacing. In using them to learn the basics of pacing, I can appreciate how effective the arrhythmia sections are and how useful they would have been during the early days of my studies. The interactivity of the aformentioned tutorials remains, too. Placing a pacing wire in different sites allows the user to view live rhythm changes, and sensitivity, HR and pacing rate can be toyed with so as to identify intrinsic rates and pre-pacemaker abnormalities such as 3rd° AV Block on the real-time trace.

The test area throws generated ECGs at the student, and offers multiple answers from which to choose. Much like any degree-worthy multiple choice test, they range from incredibly easy to downright tricky, but a review section allows you to view the areas that might require further learning before each future run-through. As with the main bulk of the software, measurement calipers are useable during the test, allowing for some precise questions to be given. Importantly, this software allows and encourages repetition; fundamental to successful learning. It may seem obvious, but I noticed that my understanding of unfamiliar areas increased the more I explored them. What won’t be obvious, is just how quickly this occurred. With the addition of the test function, the user can consolidate what they have learned at their own pace, and not have to exit the program find a different testing app.

My time with the trial version of Epicardio only threw up a couple of minor issues. Whilst these are still present, they detract from the simulator even less than before, due to the myriad of extra content present in the full release. My only new problem came in the single chamber pacing tutorial, wherein I was instructed to reduce the pacing rate to 45bpm, yet I couldn’t lower it past 50bpm. This made it impossible to view the intrinsic rhythm of the digital patient (the point of the page in question’s existence), but only in this instance. It’s worth pointing out that regular updates exist to iron out glitches such as this, so errors needn’t remain for long.

If, like me, your learing speed is increased by doing, as oppose to just reading or seeing, then you’ll find this tool invaluable. To be able to safely induce life-threatening ventricular rhythm is, understandably, an uncommon occurrence, so a method to facilitate this, and things like it, is always going to be welcome for students. In Epicardio, however, you get so much more than that. Pacing of all types is covered in depth, real and digitally created ECGs, and an effective test facility really do set this above any of the other programs that I’ve used. It’s also incredibly simple to get the hang of, too. The things it does well far outweigh its minor issues, so I can wholeheartedly recommend this program to everyone who wants learn about cardiac arrhythmia and interventions. Whilst the implementation of a 60% student discount brings the price down to the £59-£89 mark, it is still expensive, but you really do get what you pay for.

New Art!

I’ve added some new work to the online store. Head over there and you can find work inspired by Torsades de Pointes, an anatomical representation of a pacemaker in situ and an illustrated (and truncated) chronology of pacemakers (I’ve been doing some pacing).

As with those already up, these designs are available on mugs, books and smartphone cases, as well as clothing.

Remember, every penny made via sales goes straight back into this website.

Thanks!

Introduction to Pacing

Exams are over, coursework is in, and I’ve FINALLY got some time to devote to TSP, so I’ll endeavour to post updates with the same level of regularity as I did a few moths ago. It’s been a while since I added anything other than study pages, so it’s proving difficult to get back into the swing of reflective writing. I shall try to be clear, however.

The first week of my 15 week placement has been an interesting and challenging one. I’ve been in pacing clinics (the third of which allowed me to have some hands-on experience), tape clinics and have analysed my first full 24 hour ECG recording, so the amount of information I’ve absorbed has been of a high volume in a short space of time.

I’m not going to comment on tape analysis or clinics just yet, as I’m yet to have my completed work assessed, so I’ll wait until I’ve gained some feedback on my current performance. Pacing, however, is extracurricular, so I’ll glady share my experience.

Pacing checks were very fun; during eight or so hours of lingering/observation, I was gradually allowed to do a bit more with regards to clinical practice; analysing lead outputs and EGM readings, setting up programming equipment and learning my way around each box-specific bit of software, etc.

The majority of patients that came into the clinic were annual follow-ups, and six week post-insertion assessments, wherein the overestimated pacing parameters are altered so as to preserve battery life, and due to their nature, each was simply a case of checking each value and adjusting accordingly, meaning each 15 or 20 minute consult went off without a hitch, and I got a feel for the regular procedure and could have some of the physics explained to me. It also allowed my tutors to ask me questions and test me a bit.

The third and final clinic, however, allowed me to assume the role of primary (under strict supervision, of course) and perform threshold tests on my patient. It’s amazing how quickly it’s possible to forget everything you’ve spent the last few days learning, when it comes to actually doing it; the sudden pressure of being thrown into practical learning caused my mind to go completely blank, but with a bit of time, I settled into the role and things started to make sense as I was doing them. There’s a really overwhelming feeling of resposibility when you’re charged with manually increasing or decreasing your patient’s heart rate during threshold tests, and in addition, spotting the loss of atrial capture is, in most cases, far more difficult that that of ventricular capture. It was an exillerating experience, though, and I really felt like I had accomlished something at the end of the clinic. In three days I felt like I could quantify my progression, so the first week has left me feeling excited for the rest of the placement block.

Until this week, I’d never considered pacing as a future specialism – I was focussed on echo – but getting some real exposure has shown me how much I could enjoy a future in the discipline. I can’t wait to do more.

I’ll write more about my own research into pacing as I do it, so keep an eye out for that.

Thanks!

Pacemaker Re-Use For The Developing World

To some of my experienced readers, the fact that pacemaker charities that recycle pacemakers exist may not be news at all, however if, like me, you had no idea, then hopefully this post will make for some heart-warming (sorry) reading.

I was interested in what happened to pacemakers when the user passed away, and after a quick internet search, I found that they were almost invariably stockpiled when cremation was requested, or buried with the deceased. Considering that there are over 34,000 pacing procedures performed in the UK alone, this seemed somewhat wasteful. Knowing that the average life of a standard pacemaker is currently anywhere between 6-10 years, I found it hard to believe that there would not be remaining battery life in the devices when they were no longer required.

Pacemaker research is advancing all the time; Medtronic released their “Micra” (pictured right), which is lead-less and no bigger than a large multivitamin tablet, so with more advances, the price of a standard pacemaker is dropping. The current prices are still out of reach for the people who need them in many developing countries and that’s before the cost of the procedure and hospitals accommodation/ follow up care are considered.

A study at the Hospital of the University of Pennsylvania, led by Dr Payman Zamani discovered that of 27 pacemakers taken from a mortuary stockpile, 8 had a remaining battery life of at least 4 years. This is obviously 8×4 years of alleviated symptoms that are going to waste in this one mortuary alone, and it was estimated in 2011 that more than 1 million people from the developing world died as a result of not having access to pacemakers, so health organisations began looking at ways to reduce this waste.

Companies such as Heartbeat International and Heart to Heart have been recycling pacemakers since as far back as 1994, but in 2013, Pace4Life, a UK company run by Chemistry graduate Balasundaram Lavan began a partnership with the NHS and other healthcare organisations, and morgues to recycle as many viable pacing devices as possible. It’s against EU legislation for recycled pacemakers to be used domestically, but it is well within the confines of European guidelines for them to be taken from consenting individuals and used outside of its boundaries

Pace4Life only accept devices with >70% battery life remaining and during the refurbishing process, all former patient data is erased, so confidentiality is in no way compromised. Their website at http://www.pace4life.org contains a list of studies and guidelines with which they work as well as patient, next of kin and mortuary donation documents to enable people to help the less fortunate gain access to potentially life-saving medical equipment.

I’ll let Lavan himself explain a bit more:

Thanks!

Are Athletes At Greater Risk Of Pacing In Later Life?

If so, what is the cause?

The Athletic Heart Syndrome isn’t indicative of any pathology in athletes, and although it is theorised that the changes the heart undergoes as a result of training, there exists no evidence of long-term effects. The athletic heart often has a resting rate much slower than that of an individual of a less active nature. This is not uncommon in physical athletes, as it has been reported that Sir Chris Hoy has a resting HR of 30bpm and fellow cyclist Miguel Indurain one of just 28..!

The cause of this is a very active vagal tone, resulting in bradycardia. As I’m certain many of you are aware, this is a condition that would almost certainly (correct me if I’m wrong) require pacemaker intervention in elderly patients, but in the case of athletes, this bradycardia is due to an increased stroke volume which means the required workload of the heart is decreased. All well and good whilst one is in training, but what if this lower HR did not ‘reset’ to within the normal parameters once training had ceased? I don’t think I’m incorrect in assuming that this would lead to the same treatment a non-athlete, former or otherwise, would receive anyway, regardless of any prior level of fitness.

There is in fact a 2007 study by Baldesberger et al, that suggests this is indeed the case.

Published in the European Heart Journal and found in full here: http://eurheartj.oxfordjournals.org/content/29/1/71 it is shown that there is a statistically significant increase of sinus node disease in the tested former cyclists when compared to the control group, in this case golfers.

Interestingly, I have stumbled across a British Heart Foundation- funded study run in part by the University of Manchester, that they feel suggests the increased presence of arrhythmias in athletes is due to molecular changes as oppose to increased activity in the autonomic nervous system.

The study in rodents showed a decrease in HCN4, a protein found in the mammalian SA node. In humans, a mutation in the HCN4 gene is sometimes found in patients exhibiting sick sinus syndrome and in those who display bradycardia, so the teams behind this study believe that if they can replicate the rodent’s results in humans, it will help us understand arrhythmias that endurance athletes often suffer in later life.

The published study can be found here: http://www.nature.com/ncomms/2014/140513/ncomms4775/full/ncomms4775.html

I’ll answer my second question, “if so, what is the cause?” with an obligatory “je ne sais pas”, but it’s clear that we are edging ever- closer to an answer. Of course, whether that answer is due to molecular changes, or nervous ones remains to be seen.

Either way, it is stated by the team at the University of Manchester that although endurance training can have harmful effects on the heart, these effects are more than outweighed by the benefits.

As an added bonus, here is a short video by Sarah Pratt showing some common differences in an athlete’s ECG (in this case the featured athlete is the NHL’s Tobi Rieder *!*) compared with that of the rest of us. Enjoy!

As ever, if I’ve missed anything, or am just plain wrong about any part of this piece, sound off in the comments below and I’ll do my best to rectify this.

Thanks!