Biological effects of tandem shock waves demonstrated on magnetic resonance.

OBJECTIVES: The shock wave is used for the treatment of kidney stones, eventually of gall stones, for more than 20 years. It is a pressure wave, which breaks through soft tissues easily and it is possible to focus it into a small volume. The excellent results of the treatment of concrements led to considerations about another usage of the shock wave. The research is now concentrated on the possibility of the damage to tumour tissues. METHODS: In contrast to concrements tumour tissues are not different from healthy tissues as for their acoustic attributes. That is why a new source of shock waves was used in this work. The source allows generating two successive shock waves focused into a common focus, so-called tandem shock waves. The biological effects of the tandem shock waves generated by the new source on rats hepatic tissue and rabbit femoral muscle in vivo were studied in this work. The damage is demonstrated by magnetic resonance imaging. RESULTS: MR images showed tissue damage in focus. There was damage of the liver tissue, muscle and also stomach wall. CONCLUSIONS: We found that the tandem shock waves are able to damage the acoustically homogeneous soft tissue in the focus, i.e. in the depth. In tissues in front of the focus, there is, however, no damage (Fig. 10, Ref. 15).

Effects of tandem shock waves combined with photosan and cytostatics on the growth of tumours.

Shock waves, pressure waves manifested as a sharp increase in positive pressure followed by a decrease and the negative part of the wave, are not only used to treat concrements in medicine. Recently, research has been focused on the possibility of their use for damaging the tumour tissue. In contrast to concrements, which are different from the surrounding tissue by their acoustic impedance, the tumour tissue has the same acoustic impedance as the surrounding soft tissue. Therefore, we have developed a new source of shock waves, which is based on the principle of multichannel discharge. This new source generates two successive shock waves (tandem shock waves). The first shock creates acoustic non-homogeneity and cavitations in the tissue, and the second shock is damped in it. In this work we demonstrated the effect of tandem shock waves on the muscle tissue in depth. The damage is shown on the images from the magnetic resonance imaging and histological sections. In the further part of the experiment, we investigated the in vivo effects of tandem shock waves in combination with Photosan and cisplatin on the tumour tissue. The application of tandem shock waves resulted in the inhibition of tumour growth, compared with controls, in both parts of the experiment. The largest inhibition effect was observed in the groups of tandem shock waves combined with Photosan and in the second part with cisplatin.

Biological effects of two successive shock waves focused on liver tissues and melanoma cells.

A new generator of two successive shock waves focused to a common focal point has been developed. Cylindrical pressure waves created by multichannel electrical discharges on two cylindrical composite anodes are focused by a metallic parabolic reflector - cathode, and near the focus they are transformed to strong shock waves. Schlieren photos of the focal region have demonstrated that mutual interaction of the two waves results in generation of a large number of secondary short-wavelength shocks. Interaction of the focused shockwaves with liver tissues and cancer cell suspensions was investigated. Localized injury of rabbit liver induced by the shock waves was demonstrated by magnetic resonance imaging. Histological analysis of liver samples taken from the injured region revealed that the transition between the injured and the healthy tissues is sharp. Suspension of melanoma B16 cells was exposed and the number of the surviving cells rapidly decreased with increasing number of shocks and only 8 % of cells survived 350 shocks. Photographs of cells demonstrate that even small number of shocks results in perforation of cell membranes.

[Effect of ultrasonic shock waves on the bone-bone cement interface]. / Pusobení ultrazvukové rázové vlny na spojení kostního cementu s kostí.

PURPOSE OF THE STUDY: Identification of the impact of ultrasound shock wave on the integration of bone cement in the bone and the examination of a potential application of this method in order to facilitate the extraction of cemented implants, mainly femoral component of total hip arthroplasty. MATERIAL: We used pig proximal femurs from which we made fragments involving approximately one third to one half of the profile of the bone and Palacos bone cement. METHOD: We made a groove in the cancellous bone, pressed bone cement with a wire loop in the cavity and let it harden. The samples were divided by random selection into two groups. Samples from A group were exposed to ultrasound shock waves and group B served as a control group. Then we measured the force needed for the extraction of the cement plug from the bone. RESULTS: Our measuring has shown an evident decrease of the force necessary for the extraction of the bone cement after the application of ultrasound shock wave. We did not find out any macroscopically evident damage of the bone cement or of the surrounding cortical bone. DISCUSSION: The results of our measuring are influenced by a different shape and size of the examined samples which also substantially differ from the situation when a stem of the endoprosthesis is implanted in the femoral canal and is surrounded by a cement mantle. As concerns risks associated with the application of the shock wave in this indication there is a risk of a fracture of the cortical bone around THR stem (the literature does not mention this complication) and a risk of the increase of pressure in the medullary cavity of the femur combined with a risk of fat embolism. In our view this increase of pressure is comparable with the effect of the implantation of femoral component. This method cannot be used for releasing cementless implants as the surrounding cortical bone gets damaged before the implant is released. CONCLUSION: Ultrasound shock wave is still used rarely in orthopaedics, however, the existing results are promising in many aspects. Of great importance is the fact that it is a non-invasive method. The field dealt with by this work covers only experiments in vitro but the results provide hope for a future clinical use.

[Effect of shock waves on hip prosthesis implantation (preliminary report)]. / Pusobení rázové vlny na implantovanou kycelní náhradu (predbezné sdelení).

Revision of total hip arthroplasty has increased dramatically and it began to be a big problem, because of the number of reoperation is growing directly with the number of primoimplantation. Extraction of bone cement from the canal of the femur is timely and technically very difficult and related with many complications. Therapy by ESWL was applicated in clinical praxis for the first time in the therapy of urolithiasis and then choledocholithiasis. Now it is used in orthopedy for the therapy of pseudoarthrosis, entesopathia and anthores. In our experiment we used models of pork femur to which we implanted the endoprothesis to bone cement. We expouned these samples to ESWL and controlled the ability of releasing of the endoprothesis. We replayed the experiment for four times after an abnormal number of shockwaves (more than 8,000 shocks), in two cases endoprothesis release spontaneously, in one case we needed a little power to release it and in the four cases the releasing was not achieved. These results show the probable influence of the shockwaves between the layers metal-cement and cement-bone spongiosa.

[Biological effects of interacting shock waves. A modeling study of the effects of interacting shock waves using erythrocyte hemolysis]. / Biologické úcinky interagujících rázových vln. Modelová studie úcinku IRV s vyuzitím stanovení hemolýzy erytrocytu.

AIM: The effects of high-energy shock wave on tissues were discussed in literature. The shock wave sources which were used for experiments were developed for stone fragmentation. The side effects of the applicators are generally low. Increase of shock wave pressure induce bigger negative pressure amplitude and this may cause significantly bigger side effects. We used tow shock waves, with time interval of 5 microseconds. In our opinion, the first shock wave causes acoustic inhomogenity in shock wave focus and therefore second shock wave acts in a region with different acoustic parameters. The second shock wave may loss energy in the focus area by dissipation or absorption. We termed the coupled shock waves as "interacting shock waves". METHODS AND RESULTS: Hemolysis of erythrocytes was used for examination of biological toxicity. Shock wave pressure was 80 MPa, the ratio of positive to negative pressure of single shock waves is 30. For correlation we applied 50 and 100 single shock waves and 50 or 100 couples of two shock waves. Hemolysis after 50 simple shock waves was 4.28 times lower compared with hemolysis after the same number of coupled shock waves (interacting shock waves). CONCLUSION: After 50 couples of shock waves hemolysis is 2.14 times higher compared with 100 single shock waves. This result suggests that the hypothesis of some interaction existing between two shocks applied in a very short time interval make future study rightful.

[Shock-wave lithotripsy in the treatment of 12 patients with choledocholithiasis using an apparatus manufactured in Czechoslovakia]. / Litotrypse rázovou vlnou pri lécbe 12 nemocných s choledocholitiázou na Ceskoslovenském zarízení.

Lithotripsy by shock wave was performed in 12 patients with choledocholithiasis using the authors' own apparatus. The shock wave is created by an electric spark and the concentration is made by a rotational semi-elipsoid. The pressures attained in the second focus are 150 MPa. The focusing of the stones and the setting to the site of maximal pressures is made by means of two X-ray projections. Patients were indicated for the procedure when the method of endoscopic extraction had failed. Before the procedure a nasobiliary drain was inserted and after administration of analgesia on average 520 shocks were applicated. During the procedure no complications were observed. Fragmentation was achieved in 11 patients. Spontaneous release of fragments was recorded in five of the patients and in 6 during the check-up ERCP endoscopic extraction was made.

Extracorporeal shock-wave lithotripsy of the common bile duct stone with ultrasound localization.

Extracorporeal shock-wave lithotripsy with ultrasonographic localization of the common bile duct stone was successfully performed. The apparatus used is described and the advantages and disadvantages of ultrasonographic versus X-ray common bile duct stone localization are discussed.

[A simple model for verifying the effects of a focused shock wave from our generator on erythrocytes and lymphocytes]. / Jednoduchý model pro overení úcinku vlastního zdroje fokusované rázové vlny exponováním erytrocytu a lymfocytu.

Biological effects of the focused shock wave produced by the generator of our own construction were observed on the erythrocyte and lymphocyte suspension as a model. Erythrocyte haemolysis located into the small volume of the 1.4 ml focus was observed in the dependence on the number of shocks. After 10 shocks it does not exceed 15%. In the previous experiments this particular dosage caused a complete destruction of the bile stone of about 1 cm size. Increase of kalium concentration in correspondence to the degree of haemolysis was discovered in the erythrocyte suspension. Effects of shock wave were observed also in lymphocytes, where no change of blastic transformation in the decrease of the life span approximately by 2% was proved. Regular measurements proved minimum damage of blood cells in given experimental conditions and the results are comparable with biological effects of other sources of the focused shock wave.