Optional inferior vena cava filter retrieval with retained thrombus: an in vitro model

Area of Science:

• Vascular Surgery
• Interventional Radiology
• Medical Device Engineering

Background:

• Inferior vena cava (IVC) filters are used to prevent pulmonary embolism.
• Retrieval of IVC filters with trapped thrombus poses a risk of embolization if the thrombus is not removed with the filter.

Purpose of the Study:

• To develop an in vitro model to assess the fate of trapped thrombus during the retrieval of optional IVC filters.
• To quantify the amount of thrombus recovered with different IVC filter models.

Main Methods:

• An in vitro IVC flow model was constructed using a glycerol/water solution.
• Three optional IVC filters (Recovery, Günther-Tulip, OptEase) were tested.
• Mature thrombus (porcine) of varying masses (<1g and >1g) was trapped and retrieved according to manufacturer protocols.

Main Results:

• The mass of thrombus retrieved with the filters was significantly less than the initial thrombus burden.
• The OptEase filter removed the highest percentage of thrombus in smaller clot groups (43%), while the Recovery filter was most effective in larger clot groups (4%).
• Significant variability in thrombus retrieval was observed across filter types and initial thrombus sizes.

Conclusions:

• In vitro models demonstrate that IVC filter retrieval removes only a fraction of trapped thrombus.
• Caution is advised during the removal of IVC filters, especially when large thrombi are present, due to the risk of pulmonary embolism.