OBJECTIVE: Mechanical removal of intravascular clots in addition to administration of tissue plasminogen activator are both desirable for improved outcome in acute embolic stroke. We have developed a novel endovascular catheter system for rapid and reliable mechanical recanalization of cerebral embolisms with little or no requirement for fibrinolytic agents. Here, we describe the evaluation of this device in vitro. MATERIALS: Pulsed liquid jets were generated and ejected from the catheter exit by accelerating cold physiological saline (4 degrees C, 40 mL/h) using the energy of a pulsed holmium:yttrium-aluminum-garnet (YAG) laser (3 Hz, 1.2 W). Accessibility beyond the tortuous cavernous portion of the internal carotid artery to the M1 and A1 regions was confirmed using a transparent model of the human cerebral artery. Mechanical characteristics of the liquid jets were evaluated with a high-speed camera. Liquid jets of physiological saline or urokinase solution (1,200 IU/mL) were exposed to artificial thrombi made of human blood under temperature monitoring. Remnants of thrombi were collected and incubated at 37 degrees C for 10 min for estimation of fibrinolysis rates. RESULTS: The jet velocity (maximum: 5 m/s) was controlled by changing the laser energy. The fibrinolysis rates (mean+/-SD) after exposure to jets of saline or urokinase solution for 45 s were 62.2+/-16.4 and 94.0+/-3.4%, respectively, and were significantly better than the rate of 8.1+/-2.0% with administration of urokinase alone. The local temperature rise was less than 8 degrees C. CONCLUSIONS: The results show that the laser-induced liquid jet catheter system may be a powerful tool for mechanical destruction of emboli and augmentation of the effect of fibrinolytic agents beyond the tortuous part of the internal carotid artery.
OBJECTIVE: Mechanical removal of intravascular clots in addition to administration of tissue plasminogen activator are both desirable for improved outcome in acute embolic stroke. We have developed a novel endovascular catheter system for rapid and reliable mechanical recanalization of cerebral embolisms with little or no requirement for fibrinolytic agents. Here, we describe the evaluation of this device in vitro. MATERIALS: Pulsed liquid jets were generated and ejected from the catheter exit by accelerating cold physiological saline (4 degrees C, 40 mL/h) using the energy of a pulsed holmium:yttrium-aluminum-garnet (YAG) laser (3 Hz, 1.2 W). Accessibility beyond the tortuous cavernous portion of the internal carotid artery to the M1 and A1 regions was confirmed using a transparent model of the human cerebral artery. Mechanical characteristics of the liquid jets were evaluated with a high-speed camera. Liquid jets of physiological saline or urokinase solution (1,200 IU/mL) were exposed to artificial thrombi made of human blood under temperature monitoring. Remnants of thrombi were collected and incubated at 37 degrees C for 10 min for estimation of fibrinolysis rates. RESULTS: The jet velocity (maximum: 5 m/s) was controlled by changing the laser energy. The fibrinolysis rates (mean+/-SD) after exposure to jets of saline or urokinase solution for 45 s were 62.2+/-16.4 and 94.0+/-3.4%, respectively, and were significantly better than the rate of 8.1+/-2.0% with administration of urokinase alone. The local temperature rise was less than 8 degrees C. CONCLUSIONS: The results show that the laser-induced liquid jet catheter system may be a powerful tool for mechanical destruction of emboli and augmentation of the effect of fibrinolytic agents beyond the tortuous part of the internal carotid artery.