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Open Access Research article

Can pulsed ultrasound increase tissue damage during ischemia? A study of the effects of ultrasound on infarcted and non-infarcted myocardium in anesthetized pigs

Göran K Olivecrona1, Bjarne Madsen Härdig1*, Anders Roijer1, Mattias Block2, Edgars Grins3, Hans W Persson4, Leif Johansson2 and Bertil Olsson1

Author Affiliations

1 Department of Cardiology, Lund University, SE-22185 Lund, Sweden

2 Department of Pathology, Lund University, SE-22100 Lund, Sweden

3 Departement of Anaesthesiology, Lund University, SE-22100 Lund, Sweden

4 Electrical Measurements, Lund Institute of Technology, SE-22100 Lund, Sweden

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BMC Cardiovascular Disorders 2005, 5:8  doi:10.1186/1471-2261-5-8

Published: 15 April 2005

Abstract

Background

The same mechanisms by which ultrasound enhances thrombolysis are described in connection with non-beneficial effects of ultrasound. The present safety study was therefore designed to explore effects of beneficial ultrasound characteristics on the infarcted and non-infarcted myocardium.

Methods

In an open chest porcine model (n = 17), myocardial infarction was induced by ligating a coronary diagonal branch. Pulsed ultrasound of frequency 1 MHz and intensity 0.1 W/cm2 (ISATA) was applied during one hour to both infarcted and non-infarcted myocardial tissue. These ultrasound characteristics are similar to those used in studies of ultrasound enhanced thrombolysis. Using blinded assessment technique, myocardial damage was rated according to histopathological criteria.

Results

Infarcted myocardium exhibited a significant increase in damage score compared to non-infarcted myocardium: 6.2 ± 2.0 vs. 4.3 ± 1.5 (mean ± standard deviation), (p = 0.004). In the infarcted myocardium, ultrasound exposure yielded a further significant increase of damage scores: 8.1 ± 1.7 vs. 6.2 ± 2.0 (p = 0.027).

Conclusion

Our results suggest an instantaneous additive effect on the ischemic damage in myocardial tissue when exposed to ultrasound of stated characteristics. The ultimate damage degree remains to be clarified.