Electrically activated glue used to seal broken blood vessels

Friday, 07 May, 2021

Electrically activated glue used to seal broken blood vessels

A team of researchers led by Nanyang Technological University, Singapore (NTU Singapore) has developed a device that offers a quicker way to seal tears and holes in blood vessels, using an electrically activated glue patch applied via a minimally invasive balloon catheter.

Described in the journal Science Advances, the device could eventually replace the need for open or keyhole surgery to patch up or stitch together internal blood vessel defects.

Patented by NTU and Massachusetts Institute of Technology (MIT) scientists, ‘Voltaglue’ is a new type of adhesive that works in wet environments and hardens when a voltage is applied to it. After inserting a modified catheter into an appropriate blood vessel, an adhesive patch containing Voltaglue can be guided through the body to where the tear is located and then activated using retractable electrodes to glue it shut in a few minutes, all without making a single surgical cut.

The catheter device that deploys Voltaglue was jointly developed by NTU Associate Professor Terry Steele, former NTU PhD student Dr Manisha Singh (now at MIT) and MIT Associate Professor Ellen Roche. The catheter device is the first proof-of-concept application of Voltaglue in a medical setting since it was invented by Assoc Prof Steele in 2015.

“The system that we developed is potentially the answer to the currently unmet medical need for a minimally invasive technique to repair arteriovenous fistulas (an abnormal connection between an artery and a vein) or vascular leaks, without the need for open surgery,” Assoc Prof Steele said. “With Voltaglue and the catheter device, we open up the possibility of not having to make surgical incisions to patch something up inside — we can send a catheter-based device through to do the job.”

The flexible catheter is first inserted and guided through the blood vessel. Once at the site of the break, the balloon is expanded so that the injury is covered by the Voltaglue patch. A small electrical charge is then sent through the catheter’s two wires to activate the patch. The glue’s hardness can be adjusted by changing the amount of voltage applied to it — a process called electrocuring — which allows the patch to adapt to various types of tissue surfaces, from relatively smooth aortic tissue to more irregular, uneven surfaces of synthetic vascular grafts.

The patch starts to set after 20 seconds and fully hardens in 3–5 min. Upon hardening, the patch effectively ‘glues’ the broken vessel together, thereby sealing the two broken ends shut. The wires, deflated balloon and catheter are then withdrawn.

In lab experiments, the device was used to close a 3 mm defect in an explanted pig aorta connected to a mock heart under continuous flow of blood of 10 mL/min. The team left the patch on the pig heart for 1000 physiological stress/strain cycles (heartbeats), which, at 70 beats per minute, was around 15 minutes. When the aorta was examined after the experiment, the patch was found to be still successfully sealing the gap. This showed that the Voltaglue patch can be safely and effectively administered in a variety of situations, including withstanding the high pulsatile pressure of blood in arteries like the aorta.

“Voltaglue is unlike other adhesives in the market as it is voltage-activated, is stable in wet environments and can stick onto soft tissue, making it suitable and effective for repairing blood vessels,” said Dr Singh. “By combining it with existing, commercially available catheters, we have developed a new delivery mechanism that is minimally invasive, yet flexible and adaptable. This system shows promise for a diverse range of medical applications, as the suitability of the patch could be tailored according to the needs of the patient.”

The catheter is designed for use in vessels ranging from 7.5 to 30 mm in size, making it suitable for sealing defects in organs and vessels such as the aorta, intestine and oesophagus. Both Voltaglue and the patch are made with bioresorbable material, are entirely degradable and dissolve after a few weeks.

These properties make the catheter suitable for potential applications such as vascular grafting, a common surgical procedure to redirect blood flow from one area to another, or to seal off blood flow to tumours, in order to kill them off. The researchers also foresee that the catheter device may someday be used to deliver patches to repair birth defects, such as holes in the wall of the heart.

Image caption: Former NTU PhD student Dr Manisha Singh and NTU Associate Professor Terry Steele hold up different patches of Voltaglue. Image credit: NTU Singapore.

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