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Dynamic behavior of bubbles during extracorporeal shock-wave lithotripsy
1Shock Wave Research Center, Tohoku University, Sendai, Japan. kodama@ifs.tohoku.ac.jp
Ultrasound in Medicine & Biology
|August 8, 1998
Summary
Investigating air bubble interactions with tissues and shock waves reveals how cavitation bubbles cause damage during extracorporeal shock-wave lithotripsy, impacting medical procedures.
Area of Science:
- Biophysics
- Biomaterials Science
- Medical Physics
Background:
- Extracorporeal shock-wave lithotripsy (ESWL) uses shock waves to break kidney stones.
- Cavitation bubbles generated during ESWL can cause unintended tissue damage.
- Understanding bubble-tissue interactions is crucial for improving ESWL safety and efficacy.
Purpose of the Study:
- To investigate the interaction mechanism between air bubbles and biological surfaces under shock wave exposure.
- To clarify the tissue damage mechanisms induced by cavitation bubbles during lithotripsy.
- To correlate bubble dynamics with observed histological damage.
Main Methods:
- Air bubbles attached to gelatin, rat livers, and aortas were subjected to underwater shock waves (10.2 MPa).
- Bubble collapse dynamics were recorded using high-speed cinematography.
- Histochemical and histological evaluations assessed liver cell damage.
Main Results:
- Bubbles migrated away from surfaces with oscillatory growth/collapse post-shock wave interaction.
- Liquid jet penetration depth and damage pit radius correlated with initial bubble radius.
- Histology showed nuclei elongation/splitting and increased cell density in damaged liver regions.
Conclusions:
- Bubble-surface interactions under shock waves are complex, involving migration and oscillatory dynamics.
- Initial bubble size is a key factor determining the extent of liquid jet penetration and surface damage.
- Observed histological changes in liver cells provide direct evidence of shock wave-induced cavitation damage relevant to ESWL.