Extracorporeal Shock Wave Therapy Devices Research Articles

Are Extracorporeal Shock Waves Just a Therapeutic Tool?

Focused extracorporeal shock wave therapy (ESWT) has been successfully used to treat musculoskeletal conditions, but ESWT stimulates nociceptors, causing pain deep in the tissue during treatment. The occurrence of pain during ESWT is a side effect, but it can help identify painful sites and assess minimum (MiTI) and maximum (MaTI) pain thresholds to ESWT pressure stimuli. This topic has received limited attention in literature. This observational study describes a specific approach to using ESWT to study pain in 71 patients. The approach proposes moving the ESWT transducer head of the device over the entire joint surface, progressively increasing the energy level until the patient experiences pain. In the study, MiTI and MaTI were 0.218 ± 0.090 and 0.416 ± 0.165 mJ/mm2 in the affected joint and 0.282 ± 0.128 and 0.501 ± 0.174 mJ/mm2 in the contralateral homologous healthy joint, being significantly lower in the affected joint (MiTI: p < 0.001 and MaTI: p = 0.003, respectively). ESWT induced pain in 94.37% of the sites with the highest subjective pain and in a greater number of sites (204) than digital pressure (123) (p < 0.001). All sites with digital pressure pain also had ESWT pain. These results suggest that the ESWT device may be useful in investigating pain in musculoskeletal conditions and tailoring therapy.

Effectiveness of the rehabilitation program in patients with lumbar osteochondrosis and motor stereotype disorders using shock wave therapy

The study included 80 patients aged 22-44 (31.7±4.4) years with lumbar osteochondrosis with impaired motor stereotype and myotonic reaction of the lumbar-pelvic region muscles. The patients were randomized into two homogeneous groups depending on the physical rehabilitation program: in the main group a combination of shock wave therapy (SWT) with the Masterplus MP200 extracorporeal shock wave therapy device (5 procedures with a frequency of 11 Hz, an impact force of 3.8-4.0 bar, intervals of 5-7 days) with a program of relaxing exercises according to the method of K. Levit was used; in the control group – only exercises program. The developed program of physical rehabilitation proved its effectiveness by a significant decrease in pain intensity indicators (p&lt;0.001) by VAS scale, ODI disability level (p&lt;0.001) and SKT kinesiophobia level (p &lt;0.01), a significant increase in the spine mobility (p&lt;0.05) and the lumbar spine mobility (p&lt;0.05), flexion in the hip joints (p&lt;0.05). The range of movements during extension, adduction and abduction of the hip joints also increased but not significantly. Normalization of the extensor muscle tone of the lumbar spine was observed in 87.5% of cases, the gluteus muscle tone – in 30.0%, and the piriformis muscle tone – in 27.5%. The frequency of registration of error patterns in the active combined movement of the lumbar segments and the pelvis decreased to 37.5% of cases as a whole. The developed program of physical rehabilitation proved to be effective compared with the results of the isolated application of relaxing exercises with a significant improvement by VAS scale (p&lt;0.05), ODI (p&lt;0.05) and SKT (p&lt;0.05); normalization of the tone of the lumbar extensor muscles and the restoration of control of active movements in the lumbar-pelvic region are more often noted in more than a third of patients.

Review of the Current Status of Low Intensity Extracorporeal Shockwave Therapy (Li-ESWT) in Erectile Dysfunction (ED), Peyronie's Disease (PD), and Sexual Rehabilitation After Radical Prostatectomy With Special Focus on Technical Aspects of the Different Marketed ESWT Devices Including Personal Experiences in 350 Patients.

Although the literature of the positive effects of penile low intensity extracorporeal shockwave therapy is meanwhile substantial, there are substantial differences regarding both the sources of energies and extracorporeal shockwave therapy (ESWT) devices. To provide an overview on the energy range and energy differences of the 6 currently marketed ESWT devices along with personal ESWT experiences in 350 patients. This review includes all published preclinical and clinical penile ESWT studies with evaluation of the technical differences of the 6 ESWT devices and the personal experiences with these 6 devices in ED and PD. The main outcomes measures were success rates in ED (International Index of Erectile Function-erectile function change, conversion of phosphodiesterase type 5 inhibitors non-responders) and PD (change in deviation and plaque size), differences of used sources of energy, and energy flux densities (EFDs). 3 different sources of energies are used, that is electromagnetic, electrohydraulic, and piezoelectric .The devices markedly distinguish in the available spectrum of the EFD ranging between 0.09 and 0.55 mJ/mm². In terms of the biological effects, the relevant energy parameters are-6 dB and the 5 MPa focus, which differ substantially between the ESWT devices. In addition, a great variability in the treatment protocols and applied energy is obvious. The preliminary own experiences with low intensity extracorporeal shockwave therapy in 160 ED non-responders and 190 patients with PD with success rates of 45% and 47%, respectively, are reported. Positive results were published with all 6 ESWT devices in question in patients with organic ED but with huge differences regarding the EFD and the total energies applied. There is growing evidence that concentrated treatment protocols and increasing energies may yield better results. In this context, it may be argued that at least some of the published studies were markedly underpowered .Owing to the paucity of published studies, the literature of the effects of ESWT in PD and for penile rehabilitation after pelvic surgery is currently not conclusive. Porst H. Review of the Current Status of Low Intensity Extracorporeal Shockwave Therapy (Li-ESWT) in Erectile Dysfunction (ED), Peyronie's Disease (PD), and Sexual Rehabilitation After Radical Prostatectomy With Special Focus on Technical Aspects of the Different Marketed ESWT Devices Including Personal Experiences in 350 Patients. Sex Med 2021;9:93-122.

Comparison of extracorporeal shock-wave therapy and wrist-extensor splint application in the treatment of lateral epicondylitis: a prospective randomized controlled study.

BackgroundExtracorporeal shock-wave therapy (ESWT) and wrist-extensor splints (WESs) are two commonly used methods in the treatment of lateral epicondylitis. In this study, the efficacy of these two methods was compared.MethodsThe study was planned as a prospective randomized controlled study. A total of 67 patients were enrolled. The patients were divided into two groups: group 1 received ESWT (32 patients) and group 2 received WES (35 patients). Patients in group 1 underwent four sessions of ESWT once every week. In each session, an ESWT device at 10–12 Hz, 2,000 pulses, and 1.6–1.8 bar pressure was used. Patients in group 2 used a wrist splint, holding the wrist at 30°–45° extension for 4 weeks. Patients were assessed for handgrip strength, pain at rest, pain while working, and quality of life. Data were collected before and after treatment (at weeks 4, 12, and 24). A visual analog scale was used to evaluate pain at rest and while working, a hand dynamometer for handgrip strength, subscales of the SF36 Health Survey to evaluate quality of life, and the Turkish version of the patient-rated tennis-elbow evaluation was used to evaluate functioning of the affected arm during various daily life activities.ResultsIn both ESWT and WES groups, although there were considerably significant improvements (P<0.001) in the parameters evaluated (pain at rest and while working, handgrip strength, Patient-Rated Tennis Elbow Evaluation, Nirschl score, and SF36 subscales) were observed at 4, 12, and 24 weeks compared to pretreatment values, there was no statistically significant difference between the two groups in terms of our evaluation parameters at the three time points (P>0.05).ConclusionBoth ESWT and WES applications were found to yield significantly superior results when compared to pretreatment values. In comparison of the two groups, on the other hand, there was no statistically significant difference.

Extracorporeal Shock Wave Therapy in Dupuytren's Disease.

Objectives:We investigated the use of extracorporeal shock wave therapy (ESWT) in patients with Dupuytren’s Disease (DD) palmar nodules in an attempt to reduce the contracture, alleviate the pain (if any), increase the range of motion and quality of life, and delay a probable surgery in the long term.Methods:Patients with DD who presented to our hand surgery clinic and fulfilled the inclusion criteria were enrolled. The treatment was performed by the same physician using the ESWT device once a week for six weeks. The patients were evaluated with the VAS score, Quick-DASH questionnaire, and MAYO wrist score, and their grip strength was measured using a Jamar dynamometer.Results:The mean age of the 23 patients included in the study was 51 years. There was a significant improvement in the second measurement of VAS and DASH scores compared with the preoperative values. The increase in the second and final follow-up measurements of the MAYO score and grip strength results compared with the preoperative values was found significant. The table-top test results turned negative in 16 patients.Conclusion:We can suggest that ESWT in the early term can be preferred over costly injections and surgical intervention options as it increases the quality of life and delays the recurrence of contractures.

Effects of Next-Generation Low-Energy Extracorporeal Shockwave Therapy on Erectile Dysfunction in an Animal Model of Diabetes.

PurposeGene therapy, stem cell therapy, and low-energy extracorporeal shockwave therapy (ESWT) have been investigated as treatments for refractory erectile dysfunction (ED), but inconclusive evidence has been obtained. We investigated the effect of a next-generation electromagnetic cylinder ESWT device on an animal model of ED.Materials and MethodsDiabetes mellitus (DM)-induced rats were divided into 3 groups: group 1, control; group 2, DM; and group 3, DM+ESWT. Rats were treated with ESWT 3 times a week for 2 weeks. After the treatment course, intracavernous pressure was measured and the corpus cavernosum and cavernous nerve were evaluated.ResultsIn the DM group, all parameters predicted to be significantly lower in the ED model had statistically significantly decreased (p<0.01). As a measurement of erectile function, intracavernous pressure was evaluated. The DM+ESWT group exhibited significantly restored erectile function compared to the DM group (p<0.05). Moreover, ESWT treatment restored smooth muscle content, as assessed by Masson's trichrome staining (p<0.05). Finally, corporal tissue and the dorsal nerve were evaluated by immunohistochemistry, Western blotting, and ELISA. After ESWT treatment, vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), platelet endothelial cell adhesion molecule-1, cyclic guanosine monophosphate, and neuronal nitric oxide synthase (nNOS) expression levels were restored to levels in the DM group (p<0.05).ConclusionsElectromagnetic cylinder ESWT device resulted in increased VEGF, nNOS, and eNOS expression; reduced smooth muscle atrophy; and increased endothelial cell regeneration in a DM-associated ED model. Our data suggest that safe and effective application could be possible in future clinical studies.

An Evaluation of the Efficacy of ESWT and Placebo-ESWT Treatment for Chronic Plantar Fasciitis

The aim of this study was to evaluate the short-term effectiveness on heel pain and daily activities of extracorporeal shock wave therapy (ESWT) and placebo- ESWT in the treatment of chronic plantar fasciitis. A total of 42 patients diagnosed with chronic plantar fasciitis ongoing for at least 6 months were randomly separated into 2 groups. Group 1 (study group, n=21) were administered a total of 5 sessions of ESWT treatment at once a day for days with an EMS (Electro Medical System) Swiss DolorClast Master ESWT device at frequency 10-15 Hz, 2-3 bar pressure with 2000 shocks per session. Group 2 (control group, n=21) were administered placebo-ESWT. The pain levels were evaluated with a Visual Analog Scale (VAS) and the heel pain together with range of movement and activities with Roles-Maudsley (RM) scoring. Comparisons were made of the values pre-treatment and at 1 week and 5 weeks post-treatment. In the VAS values of the study group, a decrease was determined of 43.39% in post-treatment week 1 and of 70.37% in week 5 compared to pre-treatment values. The RM pain score reduced by 28.4% in week 1 and by 56.79% in week 5. In the control group, the VAS scores reduced by 17.13% and 16.03% and the RM scores by 8.86% and 11.4% respectively at weeks 1 and 5 post-treatment. The reductions in the treatment and control groups were found to be statistically significant and when the changes were compared between the two groups, the differences were found to be statistically significant. The treatment group was determined to have made statistically significantly more improvement than the control group. ESWT was seen to be a safe and effective treatment choice with short-term efficacy in the treatment of chronic plantar fasciitis.

Acoustic field characterization of the Duolith: Measurements and modeling of a clinical shock wave therapy device

Extracorporeal shock wave therapy (ESWT) uses acoustic pulses to treat certain musculoskeletal disorders. In this paper the acoustic field of a clinical portable ESWT device (Duolith SD1) was characterized. Field mapping was performed in water for two different standoffs of the electromagnetic head (15 or 30 mm) using a fiber optic probe hydrophone. Peak positive pressures at the focus ranged from 2 to 45 MPa, while peak negative pressures ranged from -2 to -11 MPa. Pulse rise times ranged from 8 to 500 ns; shock formation did not occur for any machine settings. The maximum standard deviation in peak pressure at the focus was 1.2%, indicating that the Duolith SD1 generates stable pulses. The results compare qualitatively, but not quantitatively with manufacturer specifications. Simulations were carried out for the short standoff by matching a Khokhlov-Zabolotskaya-Kuznetzov equation to the measured field at a plane near the source, and then propagating the wave outward. The results of modeling agree well with experimental data. The model was used to analyze the spatial structure of the peak pressures. Predictions from the model suggest that a true shock wave could be obtained in water if the initial pressure output of the device were doubled.

Temporal and spatial characteristics of nonlinear acoustic field generated by an extracorporeal shockwave therapy device: Modeling and measurements

Extracorporeal shock wave therapy (ESWT) refers to the use of focused shock pulses to treat certain musculoskeletal disorders. Although the technology is used clinically, acoustic characteristics of ESWT fields and their relation to the bioeffects induced are not fully understood. In the present work, the acoustic field of a clinical ESWT device (Duolith SD1) was characterized in water using a combined measurement and modeling approach. Simulation model was based on the nonlinear KZK equation; the boundary condition was based on the pressure waveforms measured in a plane 5 mm away from the therapy head. The model was used to simulate and to analyze pressure waveforms along the axis of the therapy head, 2D spatial distributions of peak pressures, and the shock structure. The modeling results were found in a good agreement with experimental data. Simulations performed for different initial source pressure amplitudes showed that a shock is not formed at the focus, even at the maximum operational level of the device. Predictions from the modeling at higher output settings suggest that a true shock would develop if the initial pressure output were doubled. [Work supported in parts by RFBR 12-02-31830 and 12-02-31418 grants and student stipend from the French Government.]

Characterization of the acoustic field of a clinical electromagnetic shockwave therapy device.

Extracorporeal shockwave therapy devices are used in clinical settings for different medical applications such as orthopedics and urology. Having several clinical devices out in the field creates a challenge when comparing treatments and energy deposition mechanisms between different devices. In this work, the field of an electromagnetic shockwave device (Duolith SD1 T‐Top, Storz) was characterized using a fiber optic hydrophone (FOPH2000, RP Acoustics). The acoustic field from two hand‐held probes was measured: one probe was focused (with different length coupling cones) and the second one was a ballistic (radial therapy) probe. With the focused probe, measured pressures ranged from 45 MPa peak‐positive to 12 MPa peak‐negative. Axial and transverse beam profiles were acquired while analyzing the peak‐positive and peak‐negative pressures at each machine energy level and pulse repetition frequency. The focused source showed an extended −6 dB peak‐positive focal region along the axis of propagation and shorter in the orthogonal planes to the propagation (30 × 3 × 3 mm3). Linear scans along the axis of propagation showed quadratic decay distal to the focus. Measured peak‐negative pressures were higher pre‐focal than post‐focal. The results compared qualitatively, but not quantitatively with manufacturer specifications. [Work supported by NIH AR053652.]

Intracorporeal pneumatic shock application for the treatment of chronic plantar fasciitis: a randomized, double blind prospective clinical trial

Plantar fasciitis (PF) is a common clinical condition that usually resolves with non-operative treatments. Extracorporeal shock wave therapy (ESWT) has been used in the treatment of chronic PF not responding to other conservative measures; however, ESWT devices are expensive and available for daily practice in only few centers (In developing countries). A pneumatic lithotripter is a cheap and readily available device which uses pneumatic shock application for the intracorporeal lithotripsy. The aim of this study was to investigate the clinical efficacy of intracorporeal pneumatic shock therapy (IPST) application for the treatment of chronic PF using a cheap and readily available pneumatic lithotripter. A randomized, double-blind, placebo-controlled study was conducted. A total of 50 patients with clinically and radiologically confirmed PF were randomly allocated to either an active- (treatment) (n = 25) or inactive (placebo) (n = 25) group. Under local anesthesia and posterior tibial nerve block, a rigid probe was directly introduced into the calcaneal spur under fluoroscopic control; a standard protocol of 1,000 shock was applied during a single session into the calcaneal spur. The main outcome measure was the patients' subjective assessment of pain by means of a Visual Analog Scale (VAS) and the Roles and Maudsley Score before the treatment and 6 months later. At the 6 months, the rate of successful outcomes (excellent + good results) in the treatment group (92%) were significantly higher comparing to the control group (24%) (P < 0.001). Heel pain measured 6 months after using the VAS were 2.04 +/- 1.67 in treatment group and 7.16 +/- 1.57 in control group as compared to 8.92 +/- 1.22 and 9.12 +/- 1.23 before the commencement of the treatment. No complications attributable to the procedure such as rupture of the planter fascia, hematoma, or infection were observed during the study. This pilot study showed that IPST is an effective and safe method of treatment of patients with chronic PF not responding to conservative measures. IPST application should be considered before surgical intervention when the extracorporeal shock devices are not available for daily practice. However, further evaluation of this novel treatment is necessary to understand the exact mechanism of action.

Extracorporeal shock‐wave therapy for treating chronic pelvic pain syndrome: a feasibility study and the first clinical results

To investigate the feasibility and clinical outcome of extracorporeal shock-wave therapy (ESWT) for patients suffering from chronic pelvic pain syndrome (CPPS). The study included 34 patients who had had CPPS for >or=3 months, who were investigated in two subsequent studies. ESWT was administered using a perineal approach with two different standard ESWT devices with and without an ultrasonographic positioning system. The follow-up was at 1, 4 and 12 weeks after ESWT, to evaluate the effects on pain, quality of life and voiding. Imaging studies and changes in prostate-specific antigen (PSA) were used to investigate the safety and side-effects of ESWT. All patients completed the treatments and follow-up; there were statistically significant improvements in pain and quality of life after ESWT. Voiding conditions were temporarily improved but with no statistical significance. Perineal ESWT was easy and safe to administer with no anaesthesia on an outpatient basis. Side-effects could be excluded clinically, by imaging studies and by changes in PSA level. Perineal ESWT must be considered as a promising new therapy for CPPS, in particular as it is easy to apply and causes no side-effects.

Extracorporeal Shockwave Therapy Versus Placebo for the Treatment of Chronic Proximal Plantar Fasciitis: Results of a Randomized, Placebo-Controlled, Double-Blinded, Multicenter Intervention Trial

Extracorporeal shockwave therapy (ESWT) has demonstrated efficacy in the treatment of recalcitrant proximal plantar fasciitis. The objective of this investigation was to compare the outcomes of participants treated with a new ESWT device with those treated with placebo. A total of 172 volunteer participants were randomized in a 2:1 active-to-placebo ratio in this prospective, double-blind, multicenter trial conducted between October 2003 and December 2004. ESWT (n=115) or placebo control (n=57) was administered on a single occasion without local or systemic anesthesia or sedation, after which follow-up was undertaken. The primary outcomes were the blind assessor's objective, and the participant's subjective assessments of heel pain during the first 3 months of follow-up. Participants were also followed up to 1 year to identify any adverse outcomes that may have been related to the shockwave device. On the visual analog scale, the blind assessor's objective assessment of heel pain displayed a mean reduction of 2.51 in the shockwave group and 1.57 in the placebo group; this difference was statistically significant (P=.045). On the visual analog scale, the participant's self-assessment of heel pain displayed a mean reduction of 3.39 in the shockwave group and 1.78 in the placebo group; this difference was statistically significant (P<.001). No serious adverse events were observed at any time. It was concluded that ESWT was both efficacious and safe for participants with chronic proximal plantar fasciitis that had been unresponsive to exhaustive conservative treatment.

Electromagnetic Emission of High-Energy Extracorporeal Shockwave Lithotripsy to the Shoulder does not Cause Disruption of Bispectral Index Monitoring of Propofol or Sevoflurane Anesthesia

To the Editor: Hemmerling et al. (1,2) in a recent series of case reports appearing in Anesthesia & Analgesia displayed disruptions of bispectral index (BIS) monitoring (Aspect Medical Systems Newton, MA) with a shoulder shaver device (1) and with the use of an otorhinolaryngology electromagnetic positioning system (2). We examined the effect on BIS monitoring of an electromagnetic emitter of a high-energy extracorporeal shockwave therapy (ESWT) lithotripter applied to the shoulder. After Graz Medical University ethics committee approval, and written informed consent, 6 adult patients underwent shoulder ESWT lithotripsy for symptomatic rotator cuff calcareous tendinopathy under propofol general anesthesia (group 1, 3 patients) or sevoflurane-nitrous oxide (N2O) (group 2, 3 patients). BIS “Quattro” sensors were placed on patients’ foreheads and connected to a BIS XP monitor (version 3.4). Data were captured from the Serial Port onto a laptop computer every 5 s, after verifying a signal quality index of >95% and electrodes impedance of <5 kΩ. The smoothing window was set at 30 s. Anesthesia was induced with fentanyl 1.5 μg/kg and propofol 2–3 mg/kg, followed by rocuronium 600 μg/kg to facilitate tracheal intubation. Anesthesia was maintained with either propofol 100–150 μgkg−1min−1 and remifentanil 0.1–0.3 μgkg−1min−1 (group 1) or sevoflurane 1 MAC with 60% N2O in oxygen (group 2). All patients underwent electromagnetic induction of high-energy shockwave lithotripsy to the shoulder (Minilith SL1; Storz Medical, Kreuzlingen, Switzerland). The energy flux density in the therapy focus was 0.5 mJ/mm2 of a total of 2000–3000 impulses. In all 6 patients, BIS tracings indicated a signal quality index of >95%. With induction of anesthesia the mean ± sd BIS value declined to 28.4 ± 2.7. Anesthesia was maintained at BIS 36.7 ± 3.1 before the start of ESWT. The mean BIS value during ESWT was 37.2 ± 2.7, whereas the BIS value in the 10 min after the switching the ESWT off remained at 37.9 ± 3.4 before starting to increase with termination of anesthesia (Fig. 1). During the anesthesia maintenance phase, using the paired Student’s t-test there was no statistically significant difference between mean BIS values before and during (P = 0.2384) ESWT or between during and after (P = 0.2198) switching the ESWT off. There was no significant difference in electromyelogram values before, during, and after ESWT.Figure 1.: Mean Bispectral Index (BIS) and electromyography (EMG) during extracorporeal shockwave therapy (ESWT) in six patients.The literature reports demonstrating artifactual increases in BIS give the impression that electric devices applied to the shoulder “similar” to the shoulder shaver (1), or devices generating an electromagnetic field (2), are likely to result in erroneous BIS readings. In the former case, BIS suddenly increased from 40 to 60 during the activity of endoscopic shoulder shaver oscillations and decreased equally abruptly after the end of the use of the shaver device (1). Our modest study suggests that the new BIS algorithm is properly shielded against shoulder vibrations caused by the electromagnetic shock wave emitter. In the latter report, switching a three-dimensional otorhinolaryngology electromagnetic positioning device increased the BIS from 40 to 60–90 despite increased anesthetic drug doses, during both propofol and sevoflurane maintenance of anesthesia. We failed to find any suggestion that outside electromagnetic field generated during ESWT altered the BIS. This may reflect further refinement of the BIS to exclude such artifacts or may reflect a difference in the electromagnetic fields between that generated by the ESWT device compared with the electromagnetic positioning device. Despite these negative findings, the electroencephalogram (EEG) waveform is easily altered by artifacts. The possibility of artifact should always be considered when evaluating the information obtained from computerized EEG monitors. Ashraf A. Dahaba, MD, MSc, PhD Helmar Bornemann, MD Department of Anaesthesiology and Intensive Care Medicine [email protected] Peter H. Rehak, PhD Biomedical Engineering and Computing Unit of the Department of Surgery Helfried Metzler, MD Department of Anaesthesiology and Intensive Care Medicine Graz Medical University Graz, Austria

A suppressor to prevent direct wave-induced cavitation in shock wave therapy devices

Cavitation plays a varied but important role in lithotripsy. Cavitation facilitates stone comminution, but can also form an acoustic barrier that may shield stones from subsequent shock waves. In addition, cavitation damages tissue. Spark-gap lithotripters generate cavitation with both a direct and a focused wave. The direct wave propagates as a spherically diverging wave, arriving at the focus ahead of the focused shock wave. It can be modeled with the same waveform (but lower amplitude) as the focused wave. We show with both simulations and experiments that bubbles are forced to grow in response to the direct wave, and that these bubbles can still be large when the focused shock wave arrives. A baffle or "suppressor" that blocks the propagation of the direct wave is shown to significantly reduce the direct wave pressure amplitude, as well as direct wave-induced bubble growth. These results are applicable to spark-gap lithotripters and extracorporeal shock wave therapy devices, where cavitation from the direct wave may interfere with treatment. A simple direct-wave suppressor might therefore be used to improve the therapeutic efficacy of these devices.

Acoustic regulation of extracorporeal shock wave (ESW) therapy devices in the U.S

The focused, large amplitude pressure fields produced by ESW lithotripsy devices were shown in the early 1980s to provide an efficient means for fragmenting urinary tract calculi. More recently, orthopedic applications of intense pressure pulses for pain relief and fracture healing have been developed. Under the US Medical Device Amendments of 1976, ESW therapy devices were deemed Class III, meaning that a pre-market application typically would be supported by both pre-clinical and clinical studies. This classification still applies, except for ESW lithotripters indicated for fragmenting kidney and ureteral calculi. These devices were reclassified to Class II in 2000, resulting in a simpler path to market in which a demonstration of substantial equivalence to a currently marketed device is sufficient. As part of its regulatory responsibility to address the safety and effectiveness of these devices, particularly with regard to acoustic output, the US Food and Drug Administration has recognized two International Electrotechnical Commission (IEC) standards for ESW lithotripters, one covering field measurements (IEC 61846) and the other dealing with labeling and other safety aspects (IEC 60601-2-36). Although these standards were designed primarily for lithotripsy, the FDA has used them where applicable in the regulatory analysis of other ESW therapy devices.

Detecting cavitation in vivo from shock-wave therapy devices

Extracorporeal shock-wave therapy (ESWT) has been used as a treatment for plantar faciitis, lateral epicondylitis, shoulder tendonitis, non-unions, and other indications where conservative treatments have been unsuccessful. However, in many areas, the efficacy of SW treatment has not been well established, and the mechanism of action, particularly the role of cavitation, is not well understood. Research indicates cavitation plays an important role in other ultrasound therapies, such as lithotripsy and focused ultrasound surgery, and in some instances, cavitation has been used as a means to monitor or detect a biological effect. Although ESWT can generate cavitation easily in vitro, it is unknown whether or not cavitation is a significant factor in vivo. The purpose of this investigation is to use diagnostic ultrasound to detect and monitor cavitation generated by ESWT devices in vivo. Diagnostic images are collected at various times during and after treatment. The images are then post-processed with image-processing algorithms to enhance the contrast between bubbles and surrounding tissue. The ultimate goal of this research is to utilize cavitation as a means for optimizing shock wave parameters such as amplitude and pulse repetition frequency. [Work supported by APL internal funds and NIH DK43881 and DK55674.]