Transcranial Doppler detection of cerebral microemboli during left heart catheterization

The role of transcranial Doppler ultrasonography (TCD) in individual risk assessment of embolic complications and the development of prevention strategies during coronary angiography remains to be determined. The purpose of this study was to assess the prevalence, time of occurrence and potential significance of microembolic signals (MES) detected with TCD during femoral left heart catheterization. TCD monitoring of the right and left middle cerebral artery was performed in 51 consecutive patients (36 men, 15 women) who were referred for coronary angiography. Percutaneous coronary angioplasty was performed during the same procedure in 16 patients. MES were counted manually during and after (off-line analysis) the procedure. Two patients were excluded from analysis because of the absence of an adequate acoustic temporal window. No neurological event occurred within 24 h in the 49 included patients. MES were detected in all except 2 patients (mean number 17.1 +/- 12.8 per patient), mainly during left ventriculography (38%) and contrast media injection into the coronary arteries (55%), suggesting their gaseous origin. There was no statistically significant association between the number of MES and patient age, cardiovascular history and risk factors, or catheterization results. The presence of coronary artery disease was inversely related to the number of MES (15.8 +/- 0.3 compared to 21.8 +/- 0.2 per patient when a normal angiogram was present; p < 0.05). In conclusion, although asymptomatic microemboli commonly occur during left heart catheterization, the majority of them are probably of gaseous origin, since they occurred predominantly during contrast media injection in this study, and were not related to cardiovascular history or to atheroma risk factors. Because air embolism has been reported to be harmful, attempts to reduce its occurrence during catheter-based procedures could be pertinent.