Embolization Particles: MedSun Small Sample Survey Summary
MedSun: Newsletter #77, October 2012

Survey Topic: Embolization Particles - Summary of Responses
Year Conducted: 2012

Embolization Particles are devices used to obstruct or reduce blood flow to hypervascularized tumors or arteriovenous malformations. They are designed for use under fluoroscopic guidance through compatible delivery microcatheters and are classified by the FDA as Class II medical devices.

FDA wants to learn more about experience with clinical use of these devices. This survey effort addresses the current use of embolization particles and will provide FDA with a better understanding of the clinical use of embolization particles and related issues.

Survey respondents are nine Interventional Radiologists (IRs) from hospitals and group practices on the west coast, east coast, mid-west, south, and southeast. The information that follows is a summary of their responses.

The approximate number of embolization procedures performed by the nine Interventional Radiologists (IR) ranges from 50-1000 procedures per year; an average of 150 to 3,000 procedures over the last three years. All nine respondents perform multiple types of embolization procedures at the time of this survey, including procedures to treat uterine fibroids, hepatic neoplasms, abnormal arteriovenous connections, aneurysms, bronchial arteries, and gonadal veins, and also procedures for trauma-related hemorrhage involving the gastrointestinal system- liver, kidney, and spleen. All nine respondents select a manufacturer brand or embolic agent based on the site they intend to embolize. The respondents also use one or more of the following devices for embolization: microspheres, beads, coils, liquid embolic agents, and vascular plugs.

All respondents have discontinued use of one or more of the embolization particles. Six report discontinuing use of a microsphere as a result of performance issues; four discontinued use of a specific microsphere/embolic because they state that good data is unavailable to show that it works; and four stopped using a microsphere because of poor patient outcomes.

Only one respondent states not having any problems or concerns with embolization particles. All others verbalized concerns or problems with embolization. Four of the nine report that some microspheres do not work well with catheters. More specifically, these particles frequently clump and are not calibrated well. Seven respondents indicate that many complications are associated with the skill of the IR; the inappropriate selection of an agent for a particular vascular bed and injecting too much or too little embolic at an inappropriate rate. Several respondents emphasize the importance of training and good imaging equipment for management and placement of microcatheters. In addition, experience using microspheres plays a large role in patient outcomes. Another respondent reports that the material in one microsphere has caused a reaction in some people who are allergic to eggs.

When discussing patient complications associated with multiple types of embolic devices, respondents did not report a difference among currently marketed microspheres. Finally, one respondent believes that embolization works and works well, and complications such as reflux may be largely dependent on the particle size.

Special Studies and Surveys are two of many tools the Agency is using to evaluate the public health impact of the potential problems associated with the use of medical devices. Additionally, FDA continues to receive adverse event reports from its Medical Device Reporting program. FDA will also continue to make use of the literature and other published information. FDA scientific, medical, nursing and engineering staff are made aware of the survey results as needed. If FDA believes there is a significant risk of adverse events as noted from the survey, it will combine those results with data gained from the other sources. FDA will work with the manufacturers and health care professional organizations to make important information known to the clinical community. Additionally, FDA continues to work with manufacturers to ensure the development, testing and promulgation of methods for reducing the risk associated with these devices and to minimize the complications from adverse events that may occur in the course of normal usage. If the results of any survey raise serious concerns about the safety of these devices, FDA may convene an Ad Hoc group of clinical and manufacturing representatives to discuss further actions.

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