Artificial muscles to keep 64 million hearts pumping
The need
Heart failure affects more than and researchers expect the incidence to rise as populations age. Heart transplants are not always an option, and the cardiac assistive devices designed to help the heart pump blood as an alternative to a transplant can be bulky, noisy and vulnerable to infection and clotting.
The solution
A new, soft robotic device designed by Dr Thanh Nho Do and his team surrounds the heart in a woven net of artificial muscle filaments, providing safe, simple and effective hydraulic compression that mimics the heart’s natural movement.
If you asked someone to imagine what a device to help pump blood through a failing heart might look like, it’s unlikely they would conjure up an image of the heart sleeve designed by Dr Thanh Nho Do and his team of biomedical engineers in the ʹڲƱ Medical Robotics Lab.
The robotic device resembles an open-weave basket. Made of two long soft artificial muscle filaments, it’s designed to surround a weakening heart, expanding and contracting to actively assist the weakened organ to pump blood around the body.
The ‘basket’ has two layers. The horizontal filament provides a compression force on the heart, while the vertical filament is slanted to follow the shape of the heart’s fibres, inducing a predefined twist when activated.
It’s an elegant and simple solution to a complex issue.
“There’s a huge clinical need for a simple and effective cardiac assist device,” says Do, a Scientia Senior Lecturer at the ʹڲƱ School of Biomedical Engineering and the principal investigator and director of the ʹڲƱ Medical Robotics Lab.
“More than 64 million people worldwide have heart failure, but there aren’t enough donor hearts for everyone who needs a transplant. We want to build a low-cost device, using commercially available components, that can help a failing heart to work better.”
The heavy burden of heart failure
‘Heart failure’ occurs when the heart muscle becomes too weak or too stiff to pump blood around the body effectively. Heart attack, coronary disease and advanced age are the main causes of heart failure, but high blood pressure, diabetes and diseases of the heart muscle (cardiomyopathy) also take a toll.
In Australia, about . The condition causes , with every three hours, according to the Heart Foundation website.
A cardiac assistive device can help patients with advanced heart failure regain some quality of life. It can also be used to keep a patient alive until a heart transplant is available.
We want to build a low-cost device, using commercially available components, that can help a failing heart to work better.
Current cardiac assistive devices have limitations
The devices currently available to patients with advanced heart failure are effective at helping weakened hearts pump blood, .
Some employ a number of rigid components that come into direct contact with blood in the heart chambers, increasing the potential for infection, bleeding, and blood coagulating into a thrombosis. Others use air inflation to compress the heart, but , requiring noisy pneumatic sources to drive them, and .
The hydraulic heart sleeve designed by Do and his team uses fluid rather than air to activate the artificial muscles, making it less bulky; and the weave is arranged in a way that mimics the heart’s natural turning and twisting motions, so it’s less likely to impede the natural beat of a patient’s heart. The sleeve also features an artificial pericardium that sits between the synthetic muscle filaments and the heart to distribute force more evenly on the heart surface. In addition, the device will provide real-time pressure sensing so that clinicians can monitor heart–device interactions.
Scope for further development
Do’s research team has attained proof-of-concept for their device, successfully . The next step is to conduct pre-clinical trials in live animals, to test the safety and effectiveness of the device.
The team is keen to explore the abundant possibilities for customisation of the sleeve. including using artificial muscle filaments of larger diameters, varying the stiffness of the weave for the left and right ventricles, or using more filaments and a denser weave to deliver compression to the heart faster.
They are also investigating the potential to utilise soft artificial muscles across a range of clinical treatments and devices. Current investigations include using and smart fabrics to create for physical rehabilitation, and the development of that would allow a surgeon to get feedback through touch when performing remote surgery. A for minimally invasive surgery is also being developed.
“One of the main things is that any of the technology we develop should be low cost,” says Do. “A device should be available to all patients, including patients in developing countries.
“My vision for this research now – although I need to attract the funding first – is to translate this strategy to the market, to the hospital. We want to bring this research to the patient, so they can use it.”