Ethanol is an effective ablative agent used for the treatment of certain solid organ tumors and vascular malformations (VMs). The egress of ethanol beyond the target tissue can be associated with significant changes to the cardiopulmonary system that can lead to cardiac arrest. This article reviews the contemporary role of ethanol in tumor and VM treatment and discusses the physiological mechanisms of acute pulmonary hypertension and cardiovascular collapse. The importance of periprocedural recognition of the hemodynamic changes that can occur with the use of ethanol and the treatment of this condition are discussed.