Abstract W P176: Relationship Between Right-to-Left Shunting and Microembolic Signals on Transcranial Doppler Monitoring

Abstract

Background: Transcranial doppler-monitoring (TCM) has been used to identify patients at risk for embolic stroke and aids in identification of stroke mechanism. Limited data exists on the occurrence of microembolic signals (MES) on TCM and the presence of right-to-left shunting (RLS), most commonly through a patent foramen ovale. Our objective was to determine if a relationship exists between the presence of a RLS on transcranial doppler-bubble (TCB) and MES on TCM, and if the degree of shunting correlated with increased number of MES. Methods: A retrospective chart review was conducted of 113 inpatients that underwent both TCB for the detection of a RLS and TCM during their admission for ischemic stroke at the Cleveland Clinic between 2011 and 2012. TCM was performed for 20 minutes in all patients. Both TCM and TCB used standardized protocols and machines. Data collected included demographics, presence of a shunt, and stroke mechanism. Results: Mean age of the study cohort was 57.9 years and 46.9% were female. RLS on TCB was found in 30.1% of patients and MES were seen on TCM in 33.6% of patients. The occurrence of MES was similar in patients with and without RLS (38.2% vs. 31.6% respectively) (p=0.50). In patients with undetermined stroke mechanism and RLS, there was a trend towards higher occurrence of MES (42.9% vs 30.8%, p=0.35). No significant difference was seen between the occurrence of MES and degree of shunting according to Spencer Grades I-IV (p=0.48). Patients with MES and RLS had an insignificantly greater number of MES than patients without RLS (59.8 vs 10.8. p=0.33). This difference in the number of MES was more pronounced in patients with undetermined stroke etiology (73.1 vs 14.4, p=0.42). Conclusions: There was no overall relationship between RLS and MES on TCM. However, the number of MES in patients with positive TCM was greater in those with a RLS compared to those without RLS, particularly in patients with undetermined stroke mechanism. Although, more data is needed, in patients with strokes of undetermined etiology, the presence of MES on TCD may suggest the presence of a RLS, especially if the number of MES is high.