unbelievable battery life -- 28 years

My first thought was 'Was this a plutonium powered PM?'

by crustyg - 2023-03-22 06:51:28

I'm old enough to recall when it wasn't uncommon for PMs to have a Peltier-effect power source using plutonium as the heat source.  Until relatively recently NASA used these (nicely described in 'The Martian'), so this is real science in action.

The beauty of this approach was that the power supply never needed to be replaced (for a simple PM, perhaps not an ICD) for the lifetime of the patient.

But the general public hysteria over radioactivity (and the inconvenience of disposal at EOL) made them fall out of favour.  And before you shout at me, let me assure you that Chernobyl was *nothing* compared to the long-lasting devastation of Bhopal where a simple chemical killed thousands and has created genetic defects that radiation is often believed (incorrectly) to produce.  People exposed to methyl-isocyanate are having children with birth defects, as methyl-isocyanate is an alkylating agent (we used to use chemicals like that for some cancer treatments) so it changes your DNA.

Power supplies

by piglet22 - 2023-03-24 10:23:29

Interesting comment from crustyg.

That must harp back to days before lithium cells were widely available and components used a lot more power than they do now. A couple of AA cells wouldn't really be suitable for implantation.

In the right situation, it should not be a problem. Plutonium 238 is an alpha emitter and has a halflife of 88 years. Alpha particles certainly would not pass through the casing of the pacemaker and Stamford University quotes the risk as non-existent to patients.

However, disposal is another matter. Toxic and radioactive would be difficult.

Brady

28 years indeed would be possible if you kept the average current used to less than a microamp.

What would become a worry is the actual lifetime physically of the battery/cell and the lifetime of components such as capacitors. It's also a long time to keep the inards dry.

I would also hope that whoever was involved got a face to face checkup more than once in 28 years.

Pacemaker design: little advancement over 28 years?

by brady - 2023-03-24 15:21:47

pitlet22, I believe you are one of the few people who has hands on knowledge of or familiar  with pacemaker circuit design. I sincerely appreciate your help in understanding how to estimate battery life. 

I am in a different situation; my pacemakers are in clinical trial, so I need to understand a lot of pm issues in a short time. The understanding had let me double check if any change in the parameters by the Abbottt engineer was appropriate. For example, at one point my pacing voltage was set to 2.5V when the threshold voltage was only 0.5V. Clearly an unnecessary waste of battery energy.

it seems that over the last 28 years, there is not much advancement on the pacemaker battery capacity and on reducing the power consumption of the pacemaker electronic. 

Regarding battery life, in my view, the fundamental limit is the pacing current (pacing- voltage/impedance), which could be as low as a micro amp or lower. Abbott indicated that in one (or some, or all) of their pacemakers, the current needed to run the pacemaker electronic is 7 micro amp. I assume this amount of current  is the state of the industry. 7 micro amp, for some peoples' pacemakers,  could be many times more than the pacing current. IC is developing 2 nano meter process and I hope that pacemaker manufacturers could invest on IC design and make the electronic consume less power than 7 micro amp.

The pacing current could be greatly reduced by using auto capture, in which the pacing voltage is only 0.25V higher than the threshold voltage.

Pacemaker design: little advancement over 28 years?

by brady - 2023-03-24 15:21:50

pitlet22, I believe you are one of the few people who has hands on knowledge of or familiar  with pacemaker circuit design. I sincerely appreciate your help in understanding how to estimate battery life. 

I am in a different situation; my pacemakers are in clinical trial, so I need to understand a lot of pm issues in a short time. The understanding had let me double check if any change in the parameters by the Abbottt engineer was appropriate. For example, at one point my pacing voltage was set to 2.5V when the threshold voltage was only 0.5V. Clearly an unnecessary waste of battery energy.

it seems that over the last 28 years, there is not much advancement on the pacemaker battery capacity and on reducing the power consumption of the pacemaker electronic. 

Regarding battery life, in my view, the fundamental limit is the pacing current (pacing- voltage/impedance), which could be as low as a micro amp or lower. Ideally, the battery life should be determined by the pacing current needed to make the heart contract and not by the current needed to power the electronic. Abbott indicated that in one (or some, or all) of their pacemakers, the current needed to run the pacemaker electronic is 7 micro amp. I assume this amount of current  is the state of the industry. 7 micro amp, for some peoples' pacemakers,  could be many times more than the pacing current. IC is developing 2 nano meter process and I hope that pacemaker manufacturers could invest on IC design and make the electronic consume less power than 7 micro amp.

The pacing current could be greatly reduced by using auto capture, in which the pacing voltage is only 0.25V higher than the threshold voltage.