Reduced rate of microembolism by optimized aortic cannula position does not influence early postoperative cognitive performance in CABG patients.

Background And Purpose: The number of microemboli as measured by Doppler ultrasound during coronary artery bypass grafting (CABG) can be reduced by positioning the arterial cannula into the aorta descendens. The aim of this study was to prospectively evaluate whether this alternative aortic cannulation procedure leads to better neuropsychologic outcome early after surgery along with embolus reduction.

Methods: Sixty patients with elective CABG were randomized to either using a short aorta ascendens cannula or an elongated cannula placed in the aorta descendens. All patients were tested by seven neuropsychologic tests preoperatively. Intraoperative embolus detection could be performed by transcranial Doppler in 32 patients. The neuropsychologic tests could be repeated serially until the 9th postoperative day in 54 patients. Patient groups did not differ in terms of preoperative psychometric performance and of the surgical characteristics except cannula positioning. All data were analyzed by a blinded assessor.

Results: Neuropsychologic test scores showed in all individual patients a transient decline with subsequent recovery, but did not differ significantly between the groups except for the letter cancellation test at discharge favoring the patients with the longer cannula (102.3 +/- 11.6 vs. 94.5 +/- 11.5 mean +/- SD; p = 0.025). In the subgroup who had Doppler sonography, neuropsychologic test scores did not differ between the groups. However, microembolic signals were markedly reduced in patients with the elongated cannula (median 174.5 vs. 413.0; p = 0.011).

Conclusions: Though reducing brain microembolism, use of an elongated aortic cannula does not appear to influence overall cognitive performance early after CABG in this pilot study.