Proposal of Optimal Vasoconstrictive Drugs to Protect Against Extracorporeal Shockwave Lithotripsy Induced Renal Injury

Purpose Since the 1980s, extracorporeal shockwave lithotripsy (ESWL) has been the first‐line therapy for non‐invasive removal of kidney stones. However, in recent years it has become apparent that acute injury and hemorrhage from ESWL can precipitate chronic conditions such as hypertension and diabetes. In 2006, a paper by Willis et al. suggested that pretreating of the kidney with a low energy shockwave before the ESWL procedure decreased lithotripsy induced renal injury in a porcine model. It is proposed that the protective mechanism of pretreatment is due to the renal artery vasoconstrictive effects of ESWL decreasing renal perfusion and therefore mechanical vascular insult. Methods A literature search was performed from 1985 to 2020 on the effects of various drugs (epinephrine, NSAIDs, adenosine, synthetic human angiotensin II), which were reviewed by available data on strength and duration of effect, as well as side effects that may affect procedure prognosis. Drugs with a rapid onset of action and a half life that did not extend beyond the duration of the procedure were preferred over those with slower effects and longer half‐lives. Finally, drugs were assessed for effects adverse to ESWL, such as anticoagulation and hypertension, which could decrease the procedure prognosis. Results The literature review done in the present search elucidates human synthetic angiotensin II and epinephrine as potential drugs for experimental protective vasoconstriction in EWSL. Both drugs had short half lives between 5 and 30 minutes with limited potential for side effects when administered locally. Discussion ESWL studies measuring the renal protective effects of pretreatment shock wave are currently performed in porcine and human trials. These studies have shown a decrease in renal resistive index, suggesting renal arterial vasoconstriction and decreased renal perfusion as the protective mechanism. The present work suggests pharmacologic agents that could induce similar renal protective effects prior to ESWL treatment. In selecting a drug for ESWL priming, vasoconstrictive drugs were chosen based on speed of onset, duration of effect, and potential side effects. Effect duration was particularly scrutinized as ESWL procedures generally last under 60 minutes, and any vasoconstriction beyond the time course of the procedure may precipitate vascular damage of intrarenal vessels and tubular necrosis, both of which cause decreased GFR. The primary advantage of ESWL pretreatment is in shifting vasoconstriction from after to during the ESWL. This suggests that drug effects may not have to last the entire procedure duration, but rather up to the point that mechanically‐induced vasoconstriction commences. As angiotensin II (15–30 min) and epinephrine (5 min) have short half lives, IV administration of these drugs could be titrated against the genesis of ESWL vasoconstriction. Conclusion This literature review lays the foundation for further experimentation by proposing angiotensin II and epinephrine as optimal renal protective agents for ESWL. Support or Funding Information None