Using graphene patches to treat arrhythmias

The Problem

There aren’t many options when your heart gets out of rhythm.

Your heart is made up of individual cells that are all connected. An electrical pulse is sent to these cells and causes each one to contract and your heart to beat. This happens in a nice, consistent way when the cells contract at the same time.

But when they don’t? Problems start.

This is called a cardiac arrhythmia. Irregular heartbeats can happen for a lot of reasons and can be mild or deadly. For example, AFib is a common type, but arrhythmias can also be the result of heart attacks or other heart conditions.

The effects of arrhythmias range from temporarily irregular heartbeats that fix themselves, to death. Serious arrhythmias are treated with pacemakers or implanted defibrillators to keep your heart beating. These devices both sense and treat arrhythmias.

These cardiac implants help your cells contract together by sending electrical pulses when your heart isn’t beating properly. While pacemakers work well and keep many people alive, they could be better.

Traditional pacemakers are made of rigid metals. While they stay together well, they don’t exactly mold themselves to the heart. Have you ever tried to mold a stiff piece of metal to your skin? It doesn’t make for a good fit. This lack of flexibility can lead to complications.

Scientists are turning to new types of materials to address these problems. The one this week’s authors turned to is graphene.

The Solution

Graphene is an atomically thin layer of carbon arranged into hexagonal sheets. If you’ve ever used a mechanical pencil, you’ve used a close cousin to graphene: graphite. Graphite is made up of many layers of graphene stacked on top of each other.

Fun fact: graphene was first produced by taking scotch tape and peeling off layers of graphite. Learn how to make your own here.

Graphene has some remarkable properties that make it a great choice for a cardiac implant:

1. Super strong.

   By weight, it’s 200x stronger than steel. No need to worry about it breaking.

2. Flexible.

   Since it’s so thin, graphene is still flexible and stretchable despite being so strong. This lets it mold to the heart, provide a better signal, and stay attached more effectively.

3. Conductive.

   It needs to be conductive to measure a heart rate. Or more specifically, to measure the electrical signal that causes the heart cells to contract.

The heart’s electrical signals are carried out largely by little calcium ions that enter the cells and cause them to contract. Optical mapping is a technique used to study heartbeats with high accuracy in both space and time.

This lets scientists measure important functions related to how the heart works both in health and disease. However, it doesn’t work with normal metal cardiac implants because they’re not transparent. Since optical mapping is a light-based technique, device transparency is key.

Being transparent, the graphene patches work well for optical mapping while the normal metal devices don’t.

The authors went on to show the graphene patch’s potential to treat arrhythmias.

Atrioventricular block (AV Block) is a common type of arrhythmia where the heart’s electrical conduction is interrupted. Without stimulation, the heart beats irregularly and weakly. You can see this in the “No Stimulation” panels below.

Activating the graphene patch restores a normal rhythm to the heartbeat. This is shown in the middle part of the graph below. This demonstrates the patch’s ability to sense and correct abnormal heartbeats in real-time.

The graphene patch withstood ~30,000 heartbeats during this test without getting dislodged.

Overall, graphene patches are a flexible, effective method for cardiac monitoring and stimulation. Unlike traditional pacemakers, they can mold directly to the heart without being dislodged during use.

See you next week for more science,

Neil

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