[HN Gopher] Smallest Pacemaker Is the Size of a Rice Grain
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Smallest Pacemaker Is the Size of a Rice Grain
Author : lnyan
Score : 91 points
Date : 2025-04-04 18:10 UTC (4 days ago)
(HTM) web link (www.sciencealert.com)
(TXT) w3m dump (www.sciencealert.com)
| echoangle wrote:
| Does anyone know how something like this is injected? It has to
| be close to the heart so it's probably not going into the
| bloodstream. And you can't really inject something precisely into
| the heart itself while it is pumping, right? And do you just aim
| by hand or is there some apparatus that does the alignment so you
| hit a specific location and depth?
| mathieuh wrote:
| I know basically nothing about this area so take all this with
| a large grain of salt (or rice), but my understanding is they
| can go through the femoral or brachial vein to inject things
| directly into the heart.
|
| https://en.wikipedia.org/wiki/Peripherally_inserted_central_...
| throwup238 wrote:
| I don't know how exactly this one will be done specifically but
| I have a (much larger) passive implant that was inserted via a
| catheter in a vein in my leg and guided up to my atrium, with
| an endoscope down my throat to see it as it was positioned. My
| atrial septal defect occluder was not only precisely positioned
| inside my heart but unwrapped from a shape that can fit down a
| vein to a stacked flat disc shape that clamps on two side of
| the heart wall to hold itself in place.
|
| This technique is being expanded to robotic catheters that can
| carry out the precise surgery automatically and there are the
| simpler "deployable stabilization devices" that are used to
| stabilize the heart muscle. If this is really small enough to
| be injected, it should work with either of those methods rather
| noninvasively.
| gadders wrote:
| Mine was done under sedation and inserted under my pec (for
| protection as I lift a lot) with the wires fed into my heart (I
| assume).
| fluidcruft wrote:
| They mention the use case of temporary pacing after surgery
| (specifically children where the desolving of the device is a
| great feature that leaves less abandoned litter behind as the
| grow).
|
| I imagine if it's useful for adults, something that small will
| probably be put in using a catheter (similar to how stents
| often are placed).
| _qua wrote:
| A cardiac electrophysiologist advances a catheter into the
| right ventricle and then deploys this directly onto the heart
| muscle. This is only a little bit smaller than existing
| leadless pacemakers which are in wide use.
| userbinator wrote:
| _It has also been designed to dissolve into the body when no
| longer needed, sparing patients invasive surgery._
|
| More likely, it will just remain a (hopefully) inert embedded
| implant. If it has active electronics, and thus semiconductors, I
| doubt e.g. silicon will dissolve.
|
| Edit: care to refute?
| tatjam wrote:
| I've access to the article, this snippet explains it (taken
| directly from the article, but formatted for HN).
|
| "The device exploits a self-powered mechanism, where the
| battery electrodes are the pacing electrodes. Specifically, an
| active, bioresorbable magnesium (Mg) alloy AZ31(Mg 96 Al 3 Zn
| 1) foil or a zinc (Zn) composite (1.6 mm x 1.6 mm) serves as
| the anode, and a more electropositive bioresorbable molybdenum
| trioxide (MoO3) composite (1.6 mm x 1.6 mm) serves as the
| cathode 18-20.
|
| The cardiac tissue and associated biofluids act as the
| electrolyte to form a galvanic cell/battery (Mg-MoO3 or Zn-MoO
| 3). As a demonstration, the pacemaker utilizes the Mg-MoO3 pair
| if not otherwise specified. The two electrodes electrically
| interconnect through a silicon (Si) bipolar junction
| phototransistor (Supplementary Figs. 1 and 2), designed to
| respond at tissue-penetrating wavelengths in the near-infrared
| (NIR) range. This component provides an optical mechanism to
| control the operation of the device with an external light
| source. In particular, the anode and cathode connect to the
| emitter and the collector terminals of the phototransistor,
| respectively, using a biodegradable conductive paste
| (Candelilla wax/tungsten (W) powder)21. A bioresorbable
| formulation of polyanhydride 22 or wax 21 encapsulates the
| entire structure, leaving regions of the electrodes exposed to
| the interface with the cardiac tissue. These unusual materials,
| components, and operating mechanisms serve as the basis for the
| pacing technology"
|
| Indeed there's no comment about the "bioresorbability" of
| silicon, possibly it's such an small quantity it doesn't
| matter.
| fluidcruft wrote:
| I think the pacing/logic part is in the patch worn on the skin
| surface. From what I understand the rice grain part converts an
| optical signal it sends into an evoked potential.
| jamesgasek wrote:
| To be fair, that's a pretty huge grain of rice.
| rokkamokka wrote:
| Does this grain of rice make me look fat?
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(page generated 2025-04-08 23:02 UTC)