Abstracts - ISMST - International Society for Medical Shockwave ...

Abstracts
1. Potential Roles of Cavitation in Tissue Angiogenesis -
Observations from Cavitation Monitoring during Shockwave Therapy
Michael Chang
Institution: Physical Medicine Institute, WA, USA
Device and producing company: OssaTron (SanuWave), D-Actor (Storz Medical)
Introduction: Cavitation may play an important role in Shockwave Therapy (SWT) bringing desirable biological responses,
such as angiogenesis/regeneration, thrombolysis, or disrupting bacteria biofilms. Therefore, designing SWT protocol
including cavitation control is important to achieve desirable clinical outcomes.
Methods: Real-time cavitation was monitored using B-mode ultrasonography during SWT for various chronic
musculoskeletal conditions using either the OssaTron or D-Actor.
Results: Occurrence of cavitation highly depends on shockwave applications as well as characteristics of the target tissue.
Presence of cavitation is usually more obvious with SWT using a high-energy focused shockwave device than a low-energy
unfocused pressure wave device. Cavitation is more easily seen in tissues with high fluid or vascular contents. Cavitation
tends to scatter around soft tissue-bone interfaces or wherever there is high negative pressure. With high shockwave
intensity, fast application rate and high cumulative pulses, persistent and wide spread cavitation within target tissue may be
observed.
Discussion: Cavitation often first occurs within blood vessels. There is apparent dynamic interaction between cavitation
and shockwaves, exerting unique stress/stimulation on vascular cells. The stress may also disrupt vessel walls introducing
intra-vascular contents into interstitial space, seeding wider spread cavitation. These events may participate in important
bio-mechanisms for tissue angiogenesis. If excessive cavitation occurs, tissue/organ injury may result.
Conclusion: Shockwaves exert their unique influence on vasculatures through both production of cavitation and interaction
with the cavitation. Cavitation may prove to be one of the most important factors that should be carefully controlled to
achieve safety and efficacy for future clinical applications of SWT in medicine. Further investigation into cavitation control in
various clinical settings is needed.
2. Energy transmission with radial pressure waves
Pavel Novak
Institution: Storz Medical AG, Tägerwilen, Switzerland
Device and producing company: Masterpuls MP200, Storz Medical AG
Introduction: Radial pressure waves are typically generated pneumatically when a projectile, accelerated by compressed
air, hits a stationary transmitter. Pressure waves are usually referred to either as EPAT (Extracorporeal Pulse Activation
Therapy), or as RSWT (Radial Shockwave Therapy). The “classification” as shock waves is (along with marketing issues)
based on the fact that both wave types are mechanical pulses and their therapeutic effect is similar for many indications.
As a result, the same physical parameters for their description (MPa, mJ/mm²) as well as the same measurement methods
are used for radial pressure waves as for focused shock waves. This approach leads to misinterpretation, because radial
pressure waves have significantly different physical properties (pulse amplitude, pulse shape, frequency range) than
focused shock waves.
Methods: Low frequency pressure waves cannot be measured in a water bath like shock or ultrasound waves can. They
can only be measured by calibrated force transducer within a tissue phantom.
Results: The measurements confirm that the energy transmitted into the tissue by low frequency pressure waves is
significantly higher than the energy transmitted by the ultrasound pulse (which is generated in parallel) and has much lower
penetration depth and energy.
Discussion: Considering pressure waves as shock waves results in incorrect observations and is not consistent with
observed biological effects. Observed therapeutic effects are due to the low frequency pressure waves.
Conclusion: The attempt to consider and quantify the pressure waves as shock waves results in misinterpretation of the
observed effects. It prevents recognizing and optimizing the true benefits achievable by pulse activation therapy (EPAT).
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