Augmentation of in-stent clot dissolution by low frequency ultrasound combined with aspirin and heparin. An ex-vivo canine shunt study

Vascular Physiology and Thrombosis Research Laboratory of the Atherosclerosis Research Center, Cedars-Sinai Medical Center, Division of Cardiology, Room 5314, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA.
Thrombosis Research (Impact Factor: 2.45). 02/2003; 112(1-2):99-104. DOI: 10.1016/j.thromres.2003.10.023
Source: PubMed


Ultrasound can accelerate clot dissolution in vitro and in vivo. We used an ex vivo canine shunt to investigate low frequency ultrasound effects on platelet-rich stent thrombosis.
Nitinol stents were expanded to 2 mm in diameter in two perfusion chambers in a parallel shunt and exposed to flowing arterial blood at 2100 s(-1) to generate stent thrombi (n=224 perfusion runs). Dethrombotic effects were assessed during treatment with saline and combined treatment with aspirin and heparin. One stent was exposed to ultrasound (27 kHz, 1.4 W/cm2), while the other was not. Stent thrombi were weighed before and after treatment. There was no significant effect of ultrasound during saline infusion. Treatment with aspirin+heparin alone reduced thrombus weight by 37+/-25% (18.9+/-6.1 to 11.8+/-7.7 mg, p<0.0001). Combined treatment with aspirin+heparin+ultrasound produced a 49+/-23% reduction in thrombus weight (19.0+/-6.3 to 9.6+/-7.8 mg, p<0.0001). The reduction in thrombus weight was significantly greater in aspirin+heparin+ultrasound compared with aspirin+heparin alone (p=0.04).
Transcutaneous ultrasound significantly enhances dethrombotic effect of aspirin plus heparin on preformed stent thrombi. These findings suggest the potential of ultrasound as an adjunct to antithrombotic therapy to improve effectiveness without increasing the risk of bleeding complications during treatment of vascular thrombosis.

6 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ultrasound (US) is one of the most common modalities used in intervention for musculoskeletal disorders, although its effectiveness is debated. The purpose of this case report is to describe the intervention, including the use of US, in the management of a large rectus sheath hematoma (RSH) in a patient receiving anticoagulant therapy. The patient was a 62-year-old woman with RSH who was receiving oral anticoagulant therapy and had a history of bouts of coughing. Computed tomographic scans verified the diagnosis of RSH. The report describes the patient examination, management, intervention, and outcomes. The intervention, including the use of US therapy, may have enabled a rapid resolution of the hematoma. This case report illustrates how US may be a useful modality for complementary management of RSH, helping the reabsorption of the hematoma.
    No preview · Article · May 2005 · Physical Therapy
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cardiovascular diseases are a major cause of mortality in the developed world. Efficacy of thrombolysis plays an important role in the management of acute myocardial infarction and cerebral insult both in the acute event and in the long-term outcome of these patients. New adjunctive strategies have been tested, therefore, to make thrombolytic therapies more effective and safer. Ultrasound Thrombolysis is a technique which showed promising results under in vitro conditions and in animal studies. Now clinical trials have to prove if it is also feasible for clinical application. This report gives an overview on different technical approaches and their current performances in the clinical setting. All original articles are chronologically ordered in tables providing detailed information on each study concerning experimental design, acoustical parameters and thrombolysis outcome.
    No preview · Article · Aug 2005 · Thrombosis and Haemostasis
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recent studies show that low-intensity ultrasound (US) increases endothelial nitric oxide (NO) levels in different models both in vitro and in vivo. Ischemia-reperfusion (I/R) injury is characterized by endothelial cell dysfunction, mainly as a result of altered shear stress responses associated with vasoconstriction, reduced capillary perfusion and excessive oxidative stress. This review provides an overview of the microvascular effects of low-intensity US and suggests that US exposure can be a method to provide tolerance to I/R damage. The hamster cheek pouch, extensively used in studies of I/R-induced injury, has been characterized in terms of changes of arteriolar diameter, flow and shear stress. The low-intensity US exposure reduces vasoconstriction and leukocyte adhesion and increases capillary perfusion during postischemic reperfusion. These effects may be the result of enhanced fluctuations in shear stress exerted by the flowing blood on the vessel wall. The fluctuations in turn are due to mechanical perturbations arising from the difference in acoustical impedance between the endothelial cells and the vessel content. We believe that periodic pulses of US may also cause a sustained reduction of oxidative stress and an enhanced endothelial NO level by increasing oscillatory shear stress during postischemic reperfusion. Low-intensity US exposure may represent a safe and novel important therapeutic target for patients with acute coronary syndromes and for treatment of chronic myocardial ischemia. (E-mail: [email protected] /* */).
    No preview · Article · Jun 2007 · Ultrasound in Medicine & Biology
Show more