OT: Artificial heart that seems to work

[Bill Sloman]

IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side of the spinning rotor feeds the lungs and the other the rest of the body - and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

--
Bill Sloman, Sydney

 

[Martin Riddle]

On Wed, 28 Aug 2019 18:23:49 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side of the spinning rotor feeds the lungs and the other the rest of the body - and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

There was already a constant flow heart pump developed, about 15 years
ago. Might be the same company.

Cheers

 

[Mike Coon]

In article <eb3d14bb-2a6b-43de-a877-089f806373da@googlegroups.com>,
bill.sloman@ieee.org says...

Probably not compatible with magnetic resonance scans.

Before I had an MRI scan I was sent back to my car in the car-park to
fetch the details of my passive heart valve repair re-inforcement so it
could be verified as not problematic...

Mike.

 

[Tom Gardner]

On 29/08/19 02:23, Bill Sloman wrote:

IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side
of the spinning rotor feeds the lungs and the other the rest of the body -
and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

Many things aren't!

ISTR - decades ago - that the constant velocity pumps were
believed to cause problems due to the lack of a pulse.

The article doesn't mention varying the RPM to simulate
the pulse to any degree.

 

[boB]

On Thu, 29 Aug 2019 07:56:46 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

On 29/08/19 02:23, Bill Sloman wrote:
IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side
of the spinning rotor feeds the lungs and the other the rest of the body -
and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

Many things aren't!

ISTR - decades ago - that the constant velocity pumps were
believed to cause problems due to the lack of a pulse.

The article doesn't mention varying the RPM to simulate
the pulse to any degree.

I am curious as to what designers have to do to actually make some of
these newer electronic implantable devices MRI compatible.

 

[Clive Arthur]

On 29/08/2019 02:23, Bill Sloman wrote:

IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side of the spinning rotor feeds the lungs and the other the rest of the body - and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

Precession could be awkward - try to roll over in bed and end up sitting
upright.

Cheers
--
Clive

 

[Winfield Hill]

Clive Arthur wrote...

Precession could be awkward - try to roll over
in bed and end up sitting upright.

One could, with practice, devise a new quick
easy way to get out of bed.


--
Thanks,
- Win

 

[Bob Engelhardt]

In the early days of artificial hearts a huge problem was the mechanical
damage done to blood cells. IIRC, that was the motivation to go to
membrane style pumps - they were gentler. Now we have a 2000 rpm
centrifugal pump? I guess that I'm missing something.

 

[Clive Arthur]

On 29/08/2019 14:12, Bob Engelhardt wrote:

In the early days of artificial hearts a huge problem was the mechanical
damage done to blood cells.  IIRC, that was the motivation to go to
membrane style pumps - they were gentler.  Now we have a 2000 rpm
centrifugal pump?  I guess that I'm missing something.

They do explain that in the article. I hope they make the battery packs
compatible with USB power banks and PSUs.

Cheers
--
Clive

 

[Bob Engelhardt]

On 8/29/2019 9:59 AM, Clive Arthur wrote:

On 29/08/2019 14:12, Bob Engelhardt wrote:
In the early days of artificial hearts a huge problem was the
mechanical damage done to blood cells.  IIRC, that was the motivation
to go to membrane style pumps - they were gentler.  Now we have a 2000
rpm centrifugal pump?  I guess that I'm missing something.

They do explain that in the article.  I hope they make the battery packs
compatible with USB power banks and PSUs.

Cheers

My bad - I didn't read the whole article. I'll have to go back to it.
Thanks.

 

[Bill Sloman]

On Thursday, August 29, 2019 at 11:13:01 PM UTC+10, Bob Engelhardt wrote:

In the early days of artificial hearts a huge problem was the mechanical
damage done to blood cells. IIRC, that was the motivation to go to
membrane style pumps - they were gentler. Now we have a 2000 rpm
centrifugal pump? I guess that I'm missing something.

The article asserts that the spinning disk doesn't create large enough shear forces to damage red and while blood cells.

The actual shear forces aren't predictable just from the speed of rotation. You'd need the actual speed of the disk, and it's spacing from the static supporting structure. Note that the disk is magnetically levitated, so you haven't got any tight clearances.

--
Bill Sloman, Sydney

 

[Bob Engelhardt]

On 8/29/2019 9:12 AM, Bob Engelhardt wrote:

In the early days of artificial hearts a huge problem was the mechanical
damage done to blood cells.  IIRC, that was the motivation to go to
membrane style pumps - they were gentler.  Now we have a 2000 rpm
centrifugal pump?  I guess that I'm missing something.

I went back to the article, and to their website. Part of my problem
was assuming that their "centrifugal pump" was like all the others that
I've seen. In name only - the impeller is radical:
https://imgur.com/4Arx1Qt

 

[Robert Baer]

Bill Sloman wrote:

IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side of the spinning rotor feeds the lungs and the other the rest of the body - and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

....adjust the resonance frequency to the pump spin rate..

 

[Bill Sloman]

On Friday, August 30, 2019 at 2:53:03 PM UTC+10, Robert Baer wrote:

Bill Sloman wrote:
IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side of the spinning rotor feeds the lungs and the other the rest of the body - and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

...adjust the resonance frequency to the pump spin rate..

That's not the problem. There are permanent magnets in the rotor disc, and the large magnetic field inside a magnetic resonance scanner is going to influence them in ways which may not be compatible with the job the rotor is designed to do.

--
Bill Sloman, Sydney

 

On Thu, 29 Aug 2019 00:47:17 -0700, boB <boB@K7IQ.com> wrote:

On Thu, 29 Aug 2019 07:56:46 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 29/08/19 02:23, Bill Sloman wrote:
IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side
of the spinning rotor feeds the lungs and the other the rest of the body -
and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

Many things aren't!

ISTR - decades ago - that the constant velocity pumps were
believed to cause problems due to the lack of a pulse.

The article doesn't mention varying the RPM to simulate
the pulse to any degree.


I am curious as to what designers have to do to actually make some of
these newer electronic implantable devices MRI compatible.

Primarily the lack of magnetic materials in the device and lead(s) and
a means to disable feedback (shuts off sensing and enters an open-loop
mode with default operation). The device is signaled to go into this
"safe mode" by placing a rare earth magnet over the device (opens a
reed switch).

 

[boB]

On Sun, 01 Sep 2019 22:39:27 -0400, krw@notreal.com wrote:

On Thu, 29 Aug 2019 00:47:17 -0700, boB <boB@K7IQ.com> wrote:

On Thu, 29 Aug 2019 07:56:46 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 29/08/19 02:23, Bill Sloman wrote:
IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side
of the spinning rotor feeds the lungs and the other the rest of the body -
and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

Many things aren't!

ISTR - decades ago - that the constant velocity pumps were
believed to cause problems due to the lack of a pulse.

The article doesn't mention varying the RPM to simulate
the pulse to any degree.


I am curious as to what designers have to do to actually make some of
these newer electronic implantable devices MRI compatible.

Primarily the lack of magnetic materials in the device and lead(s) and
a means to disable feedback (shuts off sensing and enters an open-loop
mode with default operation). The device is signaled to go into this
"safe mode" by placing a rare earth magnet over the device (opens a
reed switch).

Makes sense. My girlfriend's pacemaker turns off with the magnet.

 

[Winfield Hill]

boB wrote...

My girlfriend's pacemaker turns off with the magnet.

Hopefully she doesn't also turn off.

Brings a whole new meaning to the phrase,
"That's a real turn off".


--
Thanks,
- Win

 

On Sun, 01 Sep 2019 20:47:48 -0700, boB <boB@K7IQ.com> wrote:

On Sun, 01 Sep 2019 22:39:27 -0400, krw@notreal.com wrote:

On Thu, 29 Aug 2019 00:47:17 -0700, boB <boB@K7IQ.com> wrote:

On Thu, 29 Aug 2019 07:56:46 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 29/08/19 02:23, Bill Sloman wrote:
IEEE Spectrum has thrown up an interesting project

https://spectrum.ieee.org/biomedical/devices/this-maglev-heart-could-keep-cardiac-patients-alive

It's a purely centrifugal pump - or perhaps a pair of pumps , since one side
of the spinning rotor feeds the lungs and the other the rest of the body -
and seems to work fine in cows.

Probably not compatible with magnetic resonance scans.

Many things aren't!

ISTR - decades ago - that the constant velocity pumps were
believed to cause problems due to the lack of a pulse.

The article doesn't mention varying the RPM to simulate
the pulse to any degree.


I am curious as to what designers have to do to actually make some of
these newer electronic implantable devices MRI compatible.

Primarily the lack of magnetic materials in the device and lead(s) and
a means to disable feedback (shuts off sensing and enters an open-loop
mode with default operation). The device is signaled to go into this
"safe mode" by placing a rare earth magnet over the device (opens a
reed switch).


Makes sense. My girlfriend's pacemaker turns off with the magnet.

The magnet doesn't turn it off, rather puts it in a known, hardware
defined, state (60bpm, AOO or, less often, VOO mode). Turning off a
pacemaker isn't usually a wise move. The response to the magnet isn't
programmed. It's a hardware function. The point is to bring the
pacemaker down to its most basic operation.

The unit is downloaded before the procedure and completely
reprogrammed after, in case the MRI upset the firmware.

 

[Mike Coon]

In article <prvomedk1or32a3b8q3jlnte0m4o78umvr@4ax.com>, krw@notreal.com
says...

Primarily the lack of magnetic materials in the device and lead(s) and
a means to disable feedback (shuts off sensing and enters an open-loop
mode with default operation). The device is signaled to go into this
"safe mode" by placing a rare earth magnet over the device (opens a
reed switch).

Interestingly (to me, at any rate!) the model name of my pacemaker
includes "MRI" suggesting they are proud of its compatibilty. On the
other hand, no-one suggested not putting a magnet over it...

Mike.

 

On Mon, 2 Sep 2019 19:34:23 +0100, Mike Coon <gravity@mjcoon.plus.com>
wrote:

In article <prvomedk1or32a3b8q3jlnte0m4o78umvr@4ax.com>, krw@notreal.com
says...

Primarily the lack of magnetic materials in the device and lead(s) and
a means to disable feedback (shuts off sensing and enters an open-loop
mode with default operation). The device is signaled to go into this
"safe mode" by placing a rare earth magnet over the device (opens a
reed switch).

Interestingly (to me, at any rate!) the model name of my pacemaker
includes "MRI" suggesting they are proud of its compatibilty. On the
other hand, no-one suggested not putting a magnet over it...

That's malpractice by your hospital/cardiologist/electrophysiologist
and staff. I can't count the number of times I was warned, and that
was _before_ I left the hospital. It does take a strong magnet,
placed very close to the device but the magnets in high-end headphones
are enough to do it. They're not likely to cause a problem, in use,
because of the distance from your ear to chest but hanging them around
your neck can cause problems. I also was warned to not put my cell
phone in my shirt pocket. In addition to the transmitter being very
close to the device, the magnet in the speaker is pretty strong (to
make it small). Or, as one of the tech suggested, a spouse listening
to music while resting their head on my chest may be enough. Well,
that's not likely to happen for a few reasons. ;-)

Magnetic fields in general are badness but not only because it might
trigger the safe mode. Large AC magnetic fields can confuse sensing
causing abnormal and unpredictable device operation (really not
goodness).