In vitro study for the evaluation of transluminal aspiration as a novel treatment option for thrombosis in the HeartWare HVAD

Analysis of gradual diameter thrombectomy stent in vitro

Objective

To analyze the effect of gradient thrombectomy stent in vitro.

Methods

The cerebrovascular fluid circulation model was made and fixed on the test table. About 0.9% sodium chloride injection was injected to the vascular model through a miniature water pump to circulate it. Four kinds of thrombus products containing different red blood cell (RBC) volumes of 0, 5, 40, and 80% were placed at the target location as thrombus. Each type of thrombus was removed five times using SOLITAIRE stent and gradient thrombectomy stent. The thrombectomy effects were observed by comparison of the two types of stents.

Results

Thrombus containing 80% volume of RBC escaped thrombus fragments during thrombectomy with both stents. Thrombus containing 0% volume of RBC (rich in fibrin) had poor chimerism with stents. In the thrombus containing 0% RBC volume, there was no statistically significant difference between the two stents (p = 1). Thrombus removal was successful in all cases.

Conclusion

The gradient thrombectomy stent is as effective as the currently used thrombectomy stent in vitro studies, and there is much room for improvement.

Experimental Evaluation of the Effectiveness of Aspiration-Based Techniques to Treat Different Types of Acute Thromboembolic Occlusions in the Femoropopliteal Vascular System Using an In Vitro Flow Model

PURPOSE

In this in vitro study, the effectiveness and safety of four aspiration-based techniques for thrombectomy are evaluated for three types of thrombi in a flow model simulating the femoropopliteal segment.

MATERIAL AND METHODS

Red, white, and mixed thrombi were produced in a standardized manner and used to simulate occlusion of a superficial femoral artery using a pulsatile flow model. Four techniques were compared: aspiration alone, aspiration + stent retriever, exposing thrombus to laser by an excimer laser system and a laser catheter + aspiration, and aspiration + mechanical fragmentation by a separator. Rate of first-pass recanalization, embolic events, and number of embolized fragments > 1 mm were compared.

RESULTS

Aspiration alone, stent retriever, laser, and separator differed in rates of first-pass recanalization (53.3%; 86.6%; 20%; and 100%) and embolic events (40%; 93.3%; 73.3%; and 60%). Number of embolized fragments was lowest with aspiration and higher with separator, laser, and stent retriever. Rates of first-pass-recanalization (75%; 75%; and 45%) and embolic events (65%; 60%; and 75%) differed for red, white, and mixed thrombi. The mixed thrombus caused the highest number of embolized fragments, which was particularly high using the stent retriever.

CONCLUSION

Additional use of mechanical techniques significantly enhances the effectiveness of thrombectomy but simultaneously provokes more embolism. Laser seems to negatively alter the structure of a thrombus and thus diminishes the effectiveness, while provoking embolism. All techniques had lowest effectiveness, but highest embolism with the mixed thrombus. This was particularly striking when a stent retriever was used with the mixed thrombus.