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Brain microembolic counts during extracorporeal circulation depend on aortic cannula position
W Müllges1, D Franke, W Reents
1Department of Neurology, Julius Maximilians University Hospital, Würzburg, Germany. wolfgang.muellges@mail.uni-wuerzburg.de
Ultrasound in Medicine & Biology
|July 31, 2001
Summary
Using an elongated aortic cannula during cardiac surgery significantly reduces brain microemboli compared to standard short cannulas. However, this method does not entirely prevent microembolism or alter the preference for the left hemisphere.
Area of Science:
- Neurology
- Cardiovascular Surgery
- Biomedical Engineering
Background:
- Thrombofibrinous and gaseous microemboli frequently occur during extracorporeal circulation in cardiac surgery patients.
- Previous research indicates a tendency for these microemboli to affect the left cerebral hemisphere.
Purpose of the Study:
- To investigate if positioning the aortic cannula tip in the aorta descendens, versus the aorta ascendens, reduces brain microemboli during cardiac surgery.
- To determine if this altered cannula placement affects the hemispheric preference of microemboli.
Main Methods:
- A randomized trial involving 60 patients undergoing coronary artery bypass grafting.
- Patients were assigned to either a short aortic cannula (aorta ascendens) or an elongated cannula (aorta descendens).
- Continuous intraoperative transcranial Doppler sonography with bilateral embolus detection was performed on 29 patients.
Main Results:
- The elongated aortic cannula group showed significantly fewer high-intensity transient signals (HITS) compared to the short cannula group (223 vs. 994).
- HITS counts per minute were also significantly lower in the aorta descendens group (p < 0.02).
- The observed preference for microemboli in the left hemisphere was consistent across both groups, suggesting individual anatomical influences.
Conclusions:
- Elongated aortic cannulas can substantially reduce, but not completely eliminate, brain microembolism during extracorporeal circulation.
- The hemispheric asymmetry of microemboli appears to be influenced by individual patient anatomy rather than cannula placement alone.