Rationale and objectives: The authors perform an in vitro evaluation of the thrombolytic efficacy and the amount of "downstream" embolization induced by two new mechanical thrombectomy devices when applied to clots trapped in a temporary vena cava filter.
Methods: The first device used was a 22.5-kHz prototype intravascular ultrasound device with a flexible 0.8-mm (.032-inch) titanium 2-mm ball-tipped wire probe ensheathed in a 7-French teflon guide catheter. The device was inserted through a 10-French steering catheter. Under fluoroscopic control, ultrasound energy (26 +/- 4 watts/cm2, maximal longitudinal catheter tip amplitude 54 microm) was applied to 10 Ultravist-filled porcine thrombi (mean, 3500 mg). The second device, the Angiojet catheter, was applied to five Ultravist-filled porcine thrombi (mean, 3640 mg). The thrombi were treated while trapped in a temporary Günther vena cava filter (Cook Europe, Bjaverskov, Denmark) mounted in a vena cava flow model. The resultant "downstream" emboli were trapped in two tandem filters of decreasing pore size and weighed.
Results: Mean thrombus dissolution rate was 53% +/- 22% standard deviation (SD) for the ultrasound device (n = 10) and 63 % +/- 8% SD for the Angiojet (n = 5) (difference statistically significant at P = 0.03). For the ultrasound device, the mean embolic particle weight caught by the filters with mesh widths of 1 mm and 0.1 mm was 42% +/- 14% SD and 4% +/- 2% SD, respectively, of the initial thrombus weight. For the Angiojet, the respective numbers were 35% +/- 16% SD and 3% +/- 1% SD. Mean treatment time was 216 +/- 45 seconds SD for the ultrasound device and 153 +/- 21 seconds SD for the Angiojet.
Conclusions: The thrombolytic efficacy of the Angiojet was significantly greater and the treatment time was significantly shorter than that of the ultrasound device. Both systems had a high embolization rate.