After aneurysm treatment, the greatest danger is blood leakage around the stent graft (endoleaks), the timely detection of which is critically important but often difficult. To fill this gap and make postoperative care safer, researchers at the Georgia Institute of Technology and Emory University, led by Dr. Woon-Hong Yeo, have developed a revolutionary wireless sensor that is implanted during Endovascular Aneurysm Repair (EVAR). The sensor ensures continuous and non-invasive monitoring of blood leakage.
EVAR is successfully used to treat abdominal aortic aneurysms. However, although this method is less invasive, it does not rule out complications from endoleaks (internal blood leakage), which in turn contributes to subsequent aneurysm growth. Type I endoleaks (caused by incomplete isolation at the stent attachment sites) can be fatal and, accordingly, require rapid response.
Monitoring endoleaks, traditionally carried out by periodic CT and MRI scanning, is suboptimal. Their main disadvantages are radiation exposure, high cost, and infrequent monitoring, due to which blood leakage may be missed.
The Principle of the Sensor’s Operation
To solve this problem, scientists embedded a tiny, flexible, capacitive sensor into the stent graft. This technology detects leakage by measuring changes in electrical signals, which are caused by the accumulation of blood between the stent and the artery wall.
The sensor’s ultra-thin design (5 micrometers) ensures that it does not interfere with the stent’s function or blood flow. Data is transmitted wirelessly via an LC resonant circuit (a circuit that uses an inductor (L) and a capacitor (C) to transmit data to an external reader device without batteries), which is connected to an external reader placed on the patient’s abdomen. This mechanism allows for continuous, real-time monitoring of endoleaks without invasive procedures.
Durability and Practicality
Tests conducted on a pig artery model proved that the sensor detects even small volumes of leakage with the highest accuracy. Additionally, it can simultaneously monitor data such as heart rate and blood flow velocity. The sensor’s amazing durability, even after more than 1,000 cycles of stent expansion and contraction, confirms that it is ready for long-term operation in the high-pressure environment of the aorta.
The main innovation is a specially designed thermal adhesive that securely fixes the sensor to the stent graft fabric. This adhesive material is flexible, biocompatible, and durable, guaranteeing that the sensor remains in place without damaging the blood vessel wall or compromising the stent’s hermetic seal.
Signal transmission is based on powerful inductors embedded in the stent, which ensures that electromagnetic signals penetrate 6 cm deep into the tissue (the depth of the abdominal aorta) and are reliably received by the external device. Since the system does not require batteries or additional implants, it is practical for widespread clinical use.
This flexible sensor technology may be used in the future to monitor other vascular pathologies and to collect detailed physiological information. This is a crucial breakthrough for the safe management of aneurysms and the establishment of a personalized approach to health.
Source: Science
