Evaluation of Merci Retriever by experimental modeling

Area of Science:

• Neurology
• Biomedical Engineering
• Medical Devices

Background:

• Cerebral ischemia, often caused by embolisms, presents a critical challenge in stroke treatment.
• Mechanical thrombectomy devices aim to restore blood flow by removing obstructive clots.
• The Merci Retriever was developed as an early-generation device for mechanical embolus removal.

Purpose of the Study:

• To evaluate the efficacy and limitations of the Merci Retriever in experimental models of cerebral ischemia.
• To assess the device's performance in clot capture, retrieval, and aspiration under controlled conditions.

Main Methods:

• Three experimental stroke models were utilized: a silicone embolism model with a flow system, a pig embolism model, and a silicone-pig tortuous artery model.
• Coagulated blood clots simulated embolic material in carotid or middle cerebral artery models.
• The Merci Retriever's extraction procedures were examined under flow control.

Main Results:

• Successful clot retrieval varied significantly across models: 1/6 in the carotid artery silicone model, 2/4 in the middle cerebral artery model, 5/5 in the pig model, and 3/5 in the tortuous artery model.
• The device's helical tip sometimes failed to retain the embolism, and the helix could distort in challenging lumens.
• Aspiration success rates were also variable, indicating limitations in clot removal.

Conclusions:

• The Merci Retriever demonstrates potential for mechanical embolus removal but exhibits inconsistent performance in clot retention and device integrity.
• Its effectiveness is limited by factors such as clot dislodgement and helical tip distortion in complex vascular anatomies.
• Further device development is warranted to improve reliability and success rates in treating embolic stroke.