Ultrasound accelerates thrombolysis of acutely induced platelet-rich thrombi similar to those in acute myocardial infarction.
BACKGROUND
Although sonothrombolysis has been studied for development of recanalization that is safer and more efficacious than the methods currently used, there have been no studies of the efficacy of sonothrombolysis for the platelet-rich thrombi that typically cause acute myocardial infarction (AMI). The effects of adding ultrasound (US) to pharmacological lysis of platelet-rich thrombi was examined in a rabbit model of femoral artery occlusion.


RESULTS
In 35 rabbits, the right femoral artery was balloon-injured repeatedly at 4-week intervals to induce platelet-rich thrombi. Two hours after the induction of occlusive thrombi, 27,500 IU/kg tissue plasminogen activator (tPA) were injected via an ear vein, with or without transcutaneous US (continuous wave, 1 MHz, 0.75 W/cm2), or 13,750 IU/kg tPA was administered with US (n=10). Significantly higher rates of successful thrombolysis (Thrombolysis In Myocardial Infarction grade 3) were observed with US (90.0%) than without it (10.0%), irrespective of the dose of tPA used (p<0.01). The peak flow velocity in affected femoral arteries was significantly higher with US (p<0.01), and histological examination confirmed complete dissolution of thrombi. However, the thrombi were not affected by US alone (n=5).


CONCLUSIONS
US facilitates thrombolysis of platelet-rich thrombi and could be a useful component of thrombolytic therapy following AMI.
Kawata
Hiroyuki
H
First Department of Internal Medicine, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan. hkawata@naramed-u.ac.jp
Naya
Noriyuki
N
Takemoto
Yasuhiro
Y
Uemura
Shiro
S
Nakajima
Tamio
T
Horii
Manabu
M
Takeda
Yukiji
Y
Fujimoto
Shinichi
S
Yamashita
Atsushi
A
Asada
Yujiro
Y
Saito
Yoshihiko
Y
D000792:Angiography; D000818:Animals; D001792:Blood Platelets / Q000473:pathology; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005263:Femoral Artery / Q000000981:diagnostic imaging* / Q000473:pathology; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006331:Heart Diseases / Q000150:complications / Q000473:pathology / Q000628:therapy*; D008297:Male; D009203:Myocardial Infarction / Q000209:etiology*; D011817:Rabbits; D015912:Thrombolytic Therapy / Q000379:methods*; D013927:Thrombosis / Q000150:complications / Q000473:pathology / Q000628:therapy*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*; D014464:Ultrasonic Therapy / Q000379:methods*; D014463:Ultrasonography
D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator