Short-term effects of extracorporeal shock waves on microcirculation

Extracorporeal shock wave application (ESWA) has the potential to qualify as an adjuvant therapy option for soft tissue disorders such as chronic wounds. As of today, little is known about its exact mechanism of action. For a better understanding of the pathophysiology, we investigated the effect of ESWA on microcirculation and leukocyte-endothelial interaction.

Intravital fluorescent microscopy was used to quantify microcirculatory parameters in the ears of hairless mice (n = 30). Values were obtained just before and 10 min after the ESWA (500 shots, 1 Hz, duration 500 s). Mice were randomly divided into three groups undergoing different shock wave intensities (energy flux density: control: 0.00 mJ/mm(2); low level: 0.015 mJ/mm(2); and higher level (hl): 0.04 mJ/mm(2); n = 10 mice per group). Histologic evaluations were taken after completion of the experiments.

A significant increase in the venular diameter was observed in both the groups that underwent ESWA compared with the control group (hl: 118%, low level: 117%, and control: 96%; P < 0.004). Edema formation increased significantly in group I (P = 0.002). ESWA provoked an arteriolar constriction (hl: 93% versus control: 104%; P = 0.019) 10 min after treatment. The highest value of venular blood flow was found in group hl. Moreover, shock waves increased significantly the number of sticking leukocytes immediately after application (hl: 274%, P = 0.003).

ESWA has a significant and immediate impact on microcirculation with endothelial integrity loss and increase of adherent leukocytes as part of a proinflammatory process. Although a dilation of venules was caused, arterioles primarily show a constriction. The study shows alterations in microcirculation that could help understand the mechanism of action in the future.