Experimental ultrasonic angioplasty: Disruption of atherosclerotic plaques and thrombi in vitro and arterial recanalization in vivo

Abstract

To investigate the use of high energy ultrasound as an alternative energy for angioplasty, an experimental ultrasonic angioplasty device was developed. The device was studied in two bioassay systems: an in vitro system for the disruption of atherosclerotic plaques and thrombi and an in vivo system for the recanalization of occluded canine femoral arteries. In vitro, sonication efficiently reduced the size of the plaques. Atheromatous plaques (n = 11) disrupted at a rate of 21 +/- 8 s/cm2; complicated plaques (n = 14) disrupted at a rate of 132 +/- 45 s/cm2 (p less than 0.001). Histologic examination revealed that the disruption of the plaques took place without concurrent damage to the media or adventitia. Ninety percent of the disrupted plaque debris had a diameter of less than 20 microns and was composed primarily of cholesterol monohydrate crystals. Solid thrombus (n = 5) weight was reduced from 1.6 +/- 0.2 to 0.4 +/- 0.1 g (p less than 0.0001) after 20 s of sonication. In vivo, sonication resulted in recanalization in all seven arteries tested in seven dogs. The obstruction was reduced from 93 +/- 11% to 18 +/- 7% (p less than 0.001). On histologic examination, the arterial wall injury index was found to be 1.56 +/- 0.42 in the test arteries compared with 1.37 +/- 0.47 in the control arteries (p = NS). The disruption of atherosclerotic plaques and thrombi, together with the efficient recanalization of the occluded arteries, demonstrates the potential of ultrasound angioplasty as a catheter-based technique for angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasound-enhanced tissue plasminogen activator thrombolysis in an in vitro porcine clot model

“…A higher rate of intracranial hemorrhagic complications is associated with higher rt-PA dose in clinical rt-PA thrombolytic treatment [10]. In the absence of rt-PA, kilohertz-frequency ultrasound has been found to disrupt peripheral arterial and venous thrombi in animal models [11][12][13][14]. However, the use of ultrasound without a thrombolytic drug has had limited clinical success to date.…”

Effect of 40-kHz Ultrasound on Acute Thrombotic Ischemia in a Rabbit Femoral Artery Thrombosis Model

“…Previous reports have shown that US can accelerate fibrinolysis in vivo, but they differ from our findings in several respects. In some reports, thrombi were mechanically disrupted in vitro 22,23 or in animal models 23,24 with wires vibrating at US frequencies in the absence of plasminogen activator, and this approach has been tested in small studies in patients with coronary 25 or peripheral 26,27 arterial occlusion and with occluded coronary bypass grafts. 28 This treatment requires endovascular positioning of the wire, and it can result in vessel wall damage, excessive heating, and distal embolization of clot fragments.…”

Pulsed-high intensity focused ultrasound enhanced tPA mediated thrombolysis in a novel in vivo clot model, a pilot study

“…However, the ultrasound technology employed for directly inducing thrombolysis has involved procedures that are either invasive (e.g. via catheter based techniques) [3][4][5][6] or rely on ultrasound mechanisms such acoustic cavitation [7], which is potentially damaging to surrounding tissues [8]. Ultrasound has also been combined with thrombolytic agents in in vitro and in vivo models with improved rates of thrombolysis [1].…”