External therapeutic ultrasound (ETUS) can enhance the thrombolytic efficacy of streptokinase in patients with ST elevation myocardial infarction (MI), especially in those who present long after the onset of symptoms, according to researchers at the 2003 American Heart Association (AHA) meeting in Orlando.
Dr. Xuedong Shen and colleagues from the Cardiac Center of Creighton University in Omaha, NE, randomized 94 ST-segment elevation MI patients to recombinant streptokinase (1,500,000u) or streptokinase plus ETUS. The group excluded candidates in whom thrombolysis was contraindicated.
Based on the time from symptom onset to thrombolytic therapy delivery, each group was further divided into subgroups, representing those who presented within six hours of symptom onset, or those who presented six hours or longer after symptom onset.
"Thrombolytic therapy is widely used to treat patients with ST-segment elevation MI; however, TIMI grade 3 flow is achieved only in 50%-70% of patients by regular intravenous thrombolysis," Shen said. "While enhancing the efficacy of thrombolytic agents by ETUS had been observed in many animal studies, it has not been confirmed in humans."
In the trial, ETUS was used at 0.8 MHz with 50% duty cycle at a power output of 1.4 W/cm2.
Successful reperfusion was defined as at least more than one of the following: TIMI grade 3 flow on coronary angiography; elevated ST segment decreased at least 50% within two hours after treatment; and chest pain that disappeared within two hours after treatment was administered.
Results showed that successful reperfusion was achieved in 34% of patients presenting six hours or earlier after the start of symptoms, and who received conventional streptokinase alone versus 74% in the streptokinase plus ultrasound group (p< 0.01).
Successful reperfusion occurred in 13% of patients presenting six hours or later after the start of symptoms who were assigned to streptokinase alone, compared with 53% in the streptokinase plus ETUS group (p< 0.05). Results in the streptokinase plus ETUS group are especially noteworthy, since patients presenting late are not considered good candidates for reperfusion therapy, Shen said. Two patients had mild scald, and there were no cases of reinfarction.
Shen explained that while the mechanism by which ETUS accelerates thrombolysis is unclear, acoustic cavitation is the mostly likely possibility. "It works by promoting transportation of the drug into the thrombus," he said.
By Jill SteinAuntMinnie.com contributing writer
December 9, 2003
Copyright © 2003 AuntMinnie.com
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=100&q=70&w=100)
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
