![]() If the drum were tighter, it would create a higher number of compressions and relaxations in 1 second and its frequency might be 40Hz. If there are 20 cycles of compression and relaxation in 1 second, its frequency is 20Hz. ![]() For example, if a drum membrane is percussed once, depending on its tightness, it will create a faster or slower propagation of compression and relaxations. Hertz (Hz) is the international system of unit for frequency, which is equal to the number of repeated compressions and relaxations per second. Frequency is the number of times a disturbance is propagated during a specified time interval. Sound waves are often described by their frequency and amplitude ( figure 1). Therefore energy, but not mass, is propagated along the medium through a chain reaction of compressions and relaxations as individual particles are displaced from and return to their initial positions When a drum is percussed the vibration of the drum skin induces a disturbance in the molecules of gas (medium) immediately adjacent to the drum skin, which collide with the molecules of gas adjacent to them (compression), but then return to their initial positions (relaxation). An example of a sound wave is the percussion of a drum. In our context we will be focusing on sound waves, which can be thought of as the propagation of compression followed by relaxation of particles of a medium. We also describe the different shockwave machines currently available and assess their potential clinical utility.Ī wave is a disturbance in a medium that transports energy without permanently transporting matter. In this article we explain the physics of shockwaves by establishing a foundation regarding the basics of waves, specifically soundwaves. To appreciate the science as well as subtleties in the evidence for and against the variety of different Li-ESWT devices available for the treatment of ED, it is imperative to understand the underlying physics and biological effects behind low intensity shockwaves. Although most urologists have a general framework of how a shock can lead to break-up of stones, it is difficult to conceptualize how low energy shockwaves can lead to enhancement of erectile function. For several years, urologists have harnessed the biologic effects of shockwaves with ESWL (extracorporeal shock wave lithotripsy). Compounding this is skepticism regarding the mechanism of action of Li-ESWT. Unfortunately, different clinical trials have employed different treatment protocols with different devices, and it remains unclear if these devices have equivalent treatment efficacy. ĭespite this evidence, Li-ESWT is not Food and Drug Administration (FDA) approved and is considered investigational in the United States (US), and available to patients under clinical trial protocols. Nonetheless, there are several high quality randomized clinical trials and multiple meta-analyses that demonstrate a clinically significant benefit to Li-ESWT in the treatment of ED. In the ensuing years, many international trials have investigated Li-ESWT for ED, but the results have been equivocal and mired in critiques regarding heterogeneity of these studies. ![]() demonstrated significant improvement in erectile function in men treated with Li-ESWT versus placebo. Over the past decade, Li-ESWT (Low-intensity Extracorporeal Shockwave Therapy) has emerged as a controversial treatment modality for erectile dysfunction (ED).
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