This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Suchkova, V. Articles by Francis, C. W. Search for Related Content PubMed PubMed Citation Articles by Suchkova, V. Articles by Francis, C. W.

(Circulation. 1998;98:1030-1035.)
© 1998 American Heart Association, Inc.

Basic Science Reports

Enhancement of Fibrinolysis With 40-kHz Ultrasound

Valentina Suchkova, MD, PhD; Farhan N. Siddiqi, BS; Edwin L. Carstensen, PhD; Diane Dalecki, PhD; Sally Child, MS; ; Charles W. Francis, MD

From the Vascular Medicine Unit, Department of Medicine, and Department of Electrical Engineering (E.L.C., D.D., S.C.), University of Rochester and the Rochester Center for Biomedical Ultrasound, Rochester, NY.

Correspondence to Charles W. Francis, MD, Vascular Medicine Unit, PO Box 610, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY 14642. E-mail charles_francis{at}medicine.rochester.edu

Background—Ultrasound at frequencies of 0.5 to 1 MHz and intensities of 0.5 W/cm² accelerates enzymatic fibrinolysis in vitro and in some animal models, but unacceptable tissue heating can occur, and limited penetration would restrict application to superficial vessels. Tissue heating is less and penetration better at lower frequencies, but little information is available regarding the effect of lower-frequency ultrasound on enzymatic fibrinolysis. We therefore examined the effect of 40-kHz ultrasound on fibrinolysis, tissue penetration, and heating.

Methods and Results—¹²⁵I-fibrin–radiolabeled plasma clots in thin-walled tubes were overlaid with plasma containing tissue plasminogen activator (tPA) and exposed to ultrasound. Enzymatic fibrinolysis was measured as solubilization of radiolabel. Tissue attenuation and heating were examined in samples of porcine rib cage. Fibrinolysis was increased significantly in the presence of 40-kHz ultrasound at 0.25 W/cm², reaching 39±7% and 93±11% at 60 minutes and 120 minutes, compared with 13±8% and 37±4% in the absence of ultrasound (P<0.0001). The acceleration of fibrinolysis increased at higher intensities. Attenuation of the ultrasound field was only 1.7±0.5 dB/cm through the intercostal space and 3.4±0.9 dB/cm through rib. Temperature increments in rib were <1°C/(W/cm²).

Conclusions—These findings indicate that 40-kHz ultrasound significantly accelerates enzymatic fibrinolysis at intensities of 0.25 W/cm² with excellent tissue penetration and minimal heating. Externally applied 40-kHz ultrasound at low intensities is a potentially useful therapeutic adjunct to enzymatic fibrinolysis with sufficient tissue penetration for both peripheral vascular and coronary applications.

Key Words: fibrinolysis • ultrasonics • tissue

This article has been cited by other articles:

				T. Ogata, T. Kitazono, J. Kuroda, K. Kamei, M. Kamouchi, H. Ooboshi, S. Ibayashi, and M. Iida A Case of Recanalized Cardioembolic Stroke: Possible Effect of Transcranial Color-Coded Real-time Sonography on Thrombolytic Therapy J. Ultrasound Med., April 1, 2005; 24(4): 561 - 565. [Full Text] [PDF]

				A. V. Alexandrov, C. A. Molina, J. C. Grotta, Z. Garami, S. R. Ford, J. Alvarez-Sabin, J. Montaner, M. Saqqur, A. M. Demchuk, L. A. Moye, et al. Ultrasound-Enhanced Systemic Thrombolysis for Acute Ischemic Stroke N. Engl. J. Med., November 18, 2004; 351(21): 2170 - 2178. [Abstract] [Full Text] [PDF]

				A. V. Alexandrov Ultrasound Identification and Lysis of Clots Stroke, November 1, 2004; 35(11_suppl_1): 2722 - 2725. [Abstract] [Full Text] [PDF]

				T. Ishibashi, M. Akiyama, H. Onoue, T. Abe, and H. Furuhata Can Transcranial Ultrasonication Increase Recanalization Flow With Tissue Plasminogen Activator? Stroke, May 1, 2002; 33(5): 1399 - 1404. [Abstract] [Full Text] [PDF]

				C. W Francis and V. N Suchkova Ultrasound and thrombolysis Vascular Medicine, August 1, 2001; 6(3): 181 - 187. [Abstract] [PDF]

				A. V. Alexandrov, W. S. Burgin, A. M. Demchuk, A. El-Mitwalli, and J. C. Grotta Speed of Intracranial Clot Lysis With Intravenous Tissue Plasminogen Activator Therapy : Sonographic Classification and Short-Term Improvement Circulation, June 19, 2001; 103(24): 2897 - 2902. [Abstract] [Full Text] [PDF]

				L. Robinson, A. V. Alexandrov, and J. C. Grotta Clototripsy? Response Stroke, August 1, 2000; 31(8): 2024 - 2025. [Full Text] [PDF]

				V. N. Suchkova, R. B. Baggs, and C. W. Francis Effect of 40-kHz Ultrasound on Acute Thrombotic Ischemia in a Rabbit Femoral Artery Thrombosis Model : Enhancement of Thrombolysis and Improvement in Capillary Muscle Perfusion Circulation, May 16, 2000; 101(19): 2296 - 2301. [Abstract] [Full Text] [PDF]

				R. J. Siegel, S. Atar, M. C. Fishbein, A. V. Brasch, T. M. Peterson, T. Nagai, D. Pal, T. Nishioka, J.-S. Chae, Y. Birnbaum, et al. Noninvasive, Transthoracic, Low-Frequency Ultrasound Augments Thrombolysis in a Canine Model of Acute Myocardial Infarction Circulation, May 2, 2000; 101(17): 2026 - 2029. [Abstract] [Full Text] [PDF]

				A. V. Alexandrov, A. M. Demchuk, R. A. Felberg, I. Christou, P. A. Barber, W. S. Burgin, M. Malkoff, A. W. Wojner, and J. C. Grotta High Rate of Complete Recanalization and Dramatic Clinical Recovery During tPA Infusion When Continuously Monitored With 2-MHz Transcranial Doppler Monitoring Stroke, March 1, 2000; 31(3): 610 - 614. [Abstract] [Full Text] [PDF]