Biology Reference
In-Depth Information
1. INTRODUCTION
Shock waves are transient short-term sonic pulses with a high-peak
pressure up to 100 Mpa, followed by a negative pressure of about
5-10 MPa. They have rapid rise times of the order of nanoseconds and short
pulse durations ranging up to 5
s. Shock waves are induced electro-
hydraulically and then reflected by a focusing device with either parabolic
or ellipsoid geometry. The spatial shape of the pressure field depends on
the form of this reflector, and shock waves may therefore be applied in a
focused or a defocused manner. Moreover, shock waves can be applied
extra- or intracorporeally and either low- or high energy levels may be used.
Focused shock waves are used to disintegrate solid aggregations such as
kidney stones or solid deposits in tissues (calcified tendons) that usually con-
tain minerals. For these applications, a high energy level is necessary in order
to destroy the kidney stones or calcifications. The high energy transmission
in cases of focused shock wave treatment necessitates intravenous sedation or
even general anesthesia as this procedure is often very painful. Defocused
shock waves are administered in soft tissue diseases such as chronic wounds
or ulcerations, and recent applications include ischemic heart disease too
(
Zimpfer et al., 2009
). Defocused shock waves display a different shape of
acoustic pressure distribution and hence a larger tissue area is affected.
Accordingly, defocused low-energy shock wave treatment does not induce
pain in most cases.
Although most shock wave treatments are applied extracorporeally
(extracorporeal shock wave treatment, ESWT), this treatment does not pro-
duce satisfactory results in all cases. In this situation, the use of intracorporeal
shock waves may be suggested, for example, endoscopic intracorporeal
shock wave lithotripsy for the treatment of bile stones refractive to tradi-
tional endoscopic methods (
Attila, May, & Kortan, 2008
).
Shock wave treatment may also be divided into high- and low-transfer-
energy categories. While both treatment modalities are of therapeutic value,
high-energy shock wave treatments are typically used for the destruction of
solid aggregations inside or outside tissues, whereas low-energy treatment is
administered for tissue repair and regeneration (
Mittermayer et al., 2012
).
The use of shock waves as a therapeutic approach has a relatively short
history. Shock wave treatment was first used for the destruction of urinary
stones, including those in the kidney, in the 1980s (
Chaussy et al., 1982
).
A decade later, two groups reported successful treatment of calcifying
m
