New type of bionic pacemaker

This looks interesting so I thought I'd share it:

https://www.news-medical.net/news/20191114/New-type-of-bionic-pacemaker.aspx

A new study published in the Journal of Physiology on November 14, 2019, reports the development of a radically different type of cardiac pacemaker which could change the prognosis of patients with heart failure.

This bionic pacemaker follows the natural change in heart rhythm that occurs with breathing, and causes a steep improvement in the efficiency at which the heart supplies blood to the body. The disappearance of this physiological phenomenon in a diseased heart is a predictor of a poor outcome and of sudden death due to a cardiac cause.

Why pacemakers are used

Heart failure affects about 26 million people all over the world, with about 6 million adults in the US and 900 000 people in the UK suffering from this chronic and often crippling condition. The mortality in this illness is about 50% at 5 years from diagnosis. Besides immense health costs and the high death rate, life can be extremely burdensome for such patients. Many of them are fitted with cardiac pacemakers to keep the struggling heart beating at a regular rate, so as to optimize the work it does at the least possible effort.

Cardiac pacemakers are also often used to treat patients who have survived a heart attack. About 1.4 million such survivors live in the UK alone. In the US, there are over a million heart attacks or angina episodes each year. About 86% of these patients survive, while a third may expect to have a recurrence in the future. Pacemakers are used in those who have had a heart attack for several indications. The heart muscle may have been injured badly, and requires an externally generated rhythm because it beats too slowly. Sometimes the nerve pathways that conduct the electrical impulse from the natural pacemaker region are damaged and fail to carry it all over the heart as usual, leading to irregular and uncoordinated contraction. This can quickly lead to heart failure and death.

Heart failure is not a curable condition, but its progress can be slowed considerably by taking medication to strengthen heart contraction, enhance blood vessel function, and prevent fluid buildup in the lungs.

Conventional and bionic pacemakers

The normal heartbeat is a dynamic phenomenon. With every intake of breath, it can be felt to speed up, only to slow down with exhalation – a fascinating change in speed and rhythm called respiratory sinus arrhythmia. There are also several more minor other body processes which modulate the heart rate, causing normal heart rate variability. This became the basis for a new type of pacemaker called a respiratory modulated heart rate pacemaker, which adapts the rate of impulse generation to the breathing, because this allows more blood to be pushed out when more blood is received by the heart during inhalation, and less when the heart is being pushed in by the chest collapse that accompanies exhalation.

Most automatic pacemakers generate a metronome-like rhythm when the patient is at rest, irrespective of the body’s other operations. This doesn’t take advantage of the natural changes that occur in the body. The researchers took note of the poorer prognosis linked to the lack of the natural respiratory sinus arrhythmia to design a new model that would follow this waxing and waning rhythm, and hopefully improve the performance of the heart.

Study findings

To test the new pacemaker the researchers used exquisitely precise echocardiography signals to look at how the heart is pumping before and after pacing for two weeks, in rats that had been induced to develop heart failure. They monitored these heart failure rats with conventional pacemakers as well as the new model, over a period of 2 weeks. They also had a control group of unpaced rats with heart failure.

Researcher O’Callaghan reports, “Within two weeks there was a 20 per cent increase in blood pumped by the heart which was not the case when we used conventional pacemakers.” The cardiac output as well as the stroke volume shot up in the rats who had a pacemaker set to respiratory sinus arrhythmia, compared to those using the other monotonic pacing.

Cardiac output refers to the total volume of blood pumped out from the heart in one minute. The stroke volume refers to the amount of blood pumped from the left ventricle in a single contraction.

The RMH rats also had better ventricular muscle contractility and improved blood flow through the coronary arteries. The mechanism of this improvement was stronger heart muscle contraction, which continued to manifest even after the period of treatment with the pacemaker. This led to the suggestion that the RMH pacing actually reverses undesirable changes in the anatomy of the heart.

Implications

Clinical cardiologists like the Bristol Heart Institute’s Ed Duncan share the researchers’ excitement, commenting, “This approach may represent a novel therapy in addition to those already available for the treatment of heart failure.”

Indeed, the pacemaker may represent a big step forward in designing physiologic pacemakers that can ease the heart’s burden while improving its performance, and thus making life more bearable for patients with cardiac failure. The scientists suggest that providing this more natural form of pacing improves the way the heart functions after an injury by reversing harmful changes in the heart muscle thickness and heart size. This process, called reverse remodeling, not only serves as an estimate of treatment effectiveness but predicts patient outcome.

The researchers now plan to take the design forward into a clinical trial phase in humans, to see if the same outcomes occur when respiratory sinus arrhythmia is used to guide pacemaker stimulation of the heart contractions.

Journal reference:

Enhancing respiratory sinus arrhythmia increases cardiac output in rats with left ventricular dysfunction. Erin L. O'Callaghan, Renata M. Lataro, Eva L. Roloff, Ashok S. Chauhan, Helio C. Salgado, Edward Duncan, Alain Nogaret, and Julian F. R. Paton. Journal of Physiology, 2019. https://doi.org/10.1113/JP277293. https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP277293

11 Comments

Really new?

by crustyg - 2019-11-18 05:06:51

They compared totally fixed rate pacing with pacing that varied with respiration.  Hardly realistic.

Many folk here will have some sort of Rate Response enabled, so they are already receiving variable rate pacing.  Getting a PM to reliably detect respiration (as Minute Ventilation - Resp_rate * Resp_depth) isn't easy - there's a lot of noise in the signal, but it can be done.

Pardon me for being very sceptical.

But it does remind me of the very best flyleaf inscription that I've read on a PhD:

"All scientific truths go through three stages: Firstly people say that it conflicts with the Bible, Secondly they say that it's been discovered before and Finally they say that they've believed it all along."

Really new?

by AgentX86 - 2019-11-18 08:51:44

This reads like a marketing blurb from the manufacturer. There is precious little real information here, so it's really hard to figure out which of the three categories it falls into. For sure, it's from the marketing or stockholder relations departments.

another miracle...praise be

by ROBO Pop - 2019-11-19 11:45:57

You'll forgive me if I don't hold my breath waiting for your miracle cure.

Apologies, I checked your bio after posting. Now I realize you are a marketing weenie, how could I ever have doubted...

Why so much hate and now name calling?

by MarkFranklin99 - 2019-11-19 16:02:15

Friends 

I simply posted this article because it is a genuine piece of research. I am not connected to any of it. I thought people might find it interesting. If you don't, move on.

Now I find myself attacked for no reason at all. I guess this is the first and last time I am going to share on this forum.

Sad to see so many people who have so little vision. I suppose the first pacemaker in the world was greeted with equal scepticism but now these devices are keeping some of the same luddites alive today.

Mark

by IAN MC - 2019-11-20 15:14:13

I was amazed to read all the negativity and cynicism directed to you after your post.

I found the study which you quoted to be interesting and I am encouraged that research is continuing to produce pacemakers which are more physiological in their action.

This is potentially a further improvement of the Boston Scientific Minute Ventilation system of pacing and I am amazed that your responders dismissed it .   Ignorance is bliss I guess !

Ian

Thanks, Ian MC

by MarkFranklin99 - 2019-11-20 15:51:40

Thanks for that, Ian. 

R&D is one of those fascinating fields where, yes, often it leads nowhere but sometimes the outcomes are nothing short of spectacular. 

That's how I feel about the little box in my chest. I wish I didn't need it but I count myself lucky to live in our time now and not in 1970, when they were the size of a cigarette box and the battery lasted a year.

Given that kind of progress, can you imagine what they will look like in another 50 years? My specialist tech mentioned that in the not too distant future there will be no box but only two little pods right inside your heart. 

My unit has been in me now for three years and the battery is still predicting 11 years. Given my Apple Watch (another marvel I love) sometimes struggles to make it through the day I think this is incredible.

May the world continue to produce clever people who can invent life saving devices and pair them up with entrepreneurs willing to take risks and bring them to market.

Cheers, Mark

Dismissal

by AgentX86 - 2019-11-20 22:53:30

I dismissed it because it had all the superlatives a marketing or stockholders relations department could give it.  It was not a research article.  These things are unmistakable. University research departments are great for this sort of trash.

Dismissal / Closed mind ?

by IAN MC - 2019-11-21 05:20:00

Having been  a research chemist in the pharmaceutical industry, I am  very well aware of what is a research article and what isn't  !

The post by Mark clearly stated that it was a report from " News-Medical " an online organiisation which attempts to disseminate scientific information in an easy-to-understand way, It may sometimes become over-enthusiastic  in its journalistic style but that shouldn't negate the underlying news.

The sourse of the information was clearly stated to be the Journal of Physiology which is a reputable peer-reviewed scientific publication.

To dismiss it as " this sort of trash" really is evidence of an  incredibly closed mind.

Ian

Bull

by AgentX86 - 2019-11-21 08:43:42

By your admission it was written by a know nothing for know nothings.it was full of superlatives completely void of content. Much like the reports of cold nuclear fusion a couple of decades back.

Not bull

by atiras - 2019-11-25 10:38:26

"Clinical cardiologists like the Bristol Heart Institute’s Ed Duncan share the researchers’ excitement, commenting, “This approach may represent a novel therapy in addition to those already available for the treatment of heart failure.”"

Ed Duncan is my cardiologist, and isn't prone to jump on bandwagons.

Admittedly, I read the journal article referred to and not the pop digest, but it sounds intereresting -- arguing that varying the heart rate with respiration AT REST might be beneficial for those with heart failure (which is not what Rate Response does).

Bionic PM

by gaman - 2022-11-28 21:44:35

Talked with my EP today about the bionic pacemaker. They supposedly are starting human trials this year or in 2023. If, and keyword is if, it can pace the natural variability of heart, he agreed that is a good thing regarding heart health. I'm not getting my hopes up till there is hard clinical evidence but I will follow-up on results of trials when available.

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