SYSTEMIC GASEOUS MICROEMBOLI DURING LEFT ATRIAL CATHETERIZATION - A COMMON OCCURRENCE

Objective: Gaseous microemboli during cardiac surgery have been implic ated as a potential cause of postoperative neurologic injury. Any moni toring technique that exposes the systemic circulation to atmospheric pressure could introduce gaseous microemboli, causing cerebral microem bolization. The incidence of carotid artery gaseous microemboli was st udied during left atrial catheter insertion. Design: Prospective clini cal study. Setting: Tertiary care university hospital. Participants: T welve patients undergoing elective cardiac surgery. Interventions: Per ioperatively, a 5-MHz continuous wave Doppler probe was positioned ove r the left carotid artery to maximally record blood flow signals. The criteria used for detecting a gaseous microembolus were a sudden incre ase in the amplitude of the visual signal by 30% and a characteristic audible sound.Measurements and Main Results: Numbers of microemboli at three time points (before and during left atrial catheter insertion a nd during catheter flushing) were assessed using the friedman test. No emboli were detected before left atrial catheter insertion. When comp ared with the preinsertion time period, statistically (p < 0.05) signi ficant numbers of gaseous microemboli were found in six patients durin g catheter insertion (3 +/- 1 microemboli; range 1 to 7 microemboli) a nd in five patients during catheter flushing (5 +/- 2 microemboli; ran ge 1 to 12 microemboli). There was a tendency for patients with lower filling pressures to entrain more microemboli during insertion (r = 0. 44; p = 0.149). No patient showed evidence of gross neurologic dysfunc tion postoperatively, although sensitive neurologic testing was not pe rformed. Conclusions: Left atrial catheter insertion and flushing can cause systemic gaseous microemboli in more than 50% of patients. Altho ugh the number of microemboli introduced is relatively small, extreme care should be used during left atrial catheter insertion. Copyright ( C) 1995 by W.B. Saunders Company