Harvard’s soft robotic sleeve twists and compresses in sync with a beating heart, augmenting cardiovascular functions weakened by heart failure. It does not directly contact blood.
For many patients with congestive heart failure (CHF), walking across the street can be an epic journey. Absent a heart transplant, their condition can be managed with an implanted left ventricular assist device (LVAD), which helps the heart circulate blood. However, the devices have risks, particularly blood clots and bleeding.
But in a recent paper published in Science Translational Medicine, an international group of researchers has demonstrated a potential alternative: a Harvard-designed robotic sleeve that fits over and compresses the heart. The device could be the next evolution in assistive technology, helping manage CHF more safely.
According to the Centers for Disease Control and Prevention, around 5.7 million Americans suffer from heart failure, far more patients than there are donor hearts available. LVADs have been lifesavers, augmenting the damaged hearts’ pumping power, but the device sets up some complicated choices.
“Our concerns with the LVAD are a blood clot forming in the pump and gastrointestinal bleeding,” said Dr. Ajay Srivastava, an advanced heart failure transplant cardiologist at Scripps Health in San Diego. Srivastava did not take part in the study.
To mitigate the clot risk, patients can take aspirin, warfarin or another blood thinner, which in turn increases the possibility of bleeding. In addition, LVADs provide continuous blood flow — without a pulse — which may also increase the risk of bleeding. The robotic heart sleeve could potentially solve these problems.
“The device is extrinsic to the heart,” said Srivastava, “meaning there is no blood going through it and less concern of a clot forming. It’s squeezing and compressing the heart from the outside.”
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The device, which is made from silicon, was modeled on mammalian hearts, conforms to the lower part of the heart and can self-adjust its stiffness. Mechanical actuators mimic cardiac muscles, squeezing and twisting to boost blood flow. To guard against friction and possible inflammation, the team designed a lubricating hydrogel that is placed between the device and the heart.
In the study, the team tested the device in pigs and showed excellent results. There were few signs of inflammation and the robotic sleeve successfully restored blood flow. Still, the device has a long way to go before it can be used in patients. The authors acknowledged that more work needs to be done to assess long-term effects on the heart and other organs.
“We don’t know how the human heart is going to react to this material,” said Srivastava. “Is there a local reaction? Are you going to have inflammation because you have a foreign material wrapping the heart? Will there be a systemic reaction? Will the body see this as a foreign material and generate antibodies?”
However, Srivastava believes these risks can be overcome, as they have with other implantable devices, and the technology is quite promising.
“The thing is, does it increase cardiac output? Can it provide blood flow in a failing heart?” he wondered Srivastava. “They’ve clearly shown this pump can do that.”
Photo: Ellen Rouche/Harvard SEAS
