Pulmonary artery pressure changes during ethanol embolization procedures to treat vascular malformations: Can cardiovascular collapse be predicted?

PURPOSE: Ethanol has been used for embolization of vascular malformations. Cardiovascular collapse, although rare, has been reported, occurring immediately to a few hours after ethanol embolization. The pathophysiology has been theoretically attributed to direct toxicity to the cardiac conduction system or pulmonary artery (PA) vasospasm leading to cardiovascular collapse. Because of cardiovascular collapse in one patient at the authors' institution, it was standard of care at the time of this study to monitor the pulmonary artery pressures during ethanol embolization. This study was conducted to clarify the effect of ethanol on the PA pressure during these procedures. METHODS: Data from 92 ethanol embolization procedures performed on 56 patients with vascular malformations between May 2001 and May 2003 are reported. PA and noninvasive cuff systemic pressures were recorded before and after each injection and also before and after the entire procedure. Upper limit for volume of ethanol used during these procedures was drawn at 1 mL/kg. Simple and multiple linear regression analyses were done to study factors affecting changes in PA and systemic blood pressure. RESULTS: For each injection, ethanol volume averaged 3.1 mL per injection. The systolic systemic and PA systolic pressures increased by 2.3 and 1.0 mm Hg, respectively. Amount of ethanol injected and systemic blood pressure changes were predictive of change in PA blood pressure. During the entire procedure, systemic systolic blood pressure increased by an average of 11.6 mm Hg, and PA systolic blood pressure by 5 mm Hg. Change in systemic blood pressure was a strong predictor of, and volume of ethanol was a weak predictor of, change in PA blood pressure. CONCLUSION: The mild rise in PA blood pressure in the patients during ethanol embolization correlated strongly with minor elevation in systemic blood pressure throughout the procedure, which the authors believe is related to pain from the ethanol injection causing sympathetic stimulation, even when patients are under general anesthesia. The minimal rise in PA blood pressure during these procedures does not elucidate the cause of the rare complication of cardiovascular collapse during ethanol embolization.