High-energy shock waves pyrotherapy. A new concept in extracorporeal tumour therapy

High-intensity shock waves (HISW) waves can produce rapid and intense tissue heating. We have studied a novel device capable of simultaneous shock wave generation, focusing and extracorporeal delivery along with imaging of the proposed target. Shock waves are generated by piezo-electric crystals and target a focal point of 10 x 2 mm. In a preliminary study, three groups of land race pigs received HISW to discrete points on the liver parenchyma. There was no mortality in any group. Cardiovascular monitoring revealed that HISW did not induce any haemodynamic changes during treatment and that core temperatures and liver function tests were unaffected by this therapy. Ultrasound monitoring during treatment demonstrated discreet hyperechoic areas with acoustic shadowing suggesting cavitation. Animals killed immediately after 48 h of HISW therapy had discrete necrotic cylinders within the liver with a mean diameter of 2 cm (+0.21 SD). Histological examination revealed a pattern of necrosis and vascular changes suggestive of ischaemia. In addition, there were areas of coagulative necrosis consistent with thermal injury. Animals killed at 2 months had necrotic cavities which had become surrounded by mature fibrosis. These early results indicate that high energy shock waves delivered extracorporeally can cause specific destruction of liver tissue by focused hyperthermia and cavitation. Clinical studies of this device are required to assess the possible virtue of HISW in the treatment of liver and other tumours.