The memory loss that you suffer, I feel, is unrelated to the microemboli seen by your neurologist. It is likely a consequence of the cardiac surgery that you have had. Using sensitive neuropsychological methods, it has been shown that the majority of elderly patients undergoing open heart surgery suffer subtle cognitive difficulties for several months post-operatively. The problem, however, improves with time and is reversible in most patients. Not all microemboli are clots.
Air bubbles can cause similar signals.
Methods have been proposed to distinguish clots or platelets from gas, but these are not routinely practised except in academic or research applications in some departments with special expertise in this area. The use of TCD for predicting stroke risk and monitoring therapy in prosthetic valve patients is specially problematic. The are several indicators that appear to imply that the majority of microemboli in this situation are indeed gaseous from microcavitation of blood from turbulence around the valve. No clear response of the HITS frequency is noted with coumadin and other therapies that are known to be highly efficacious in preventing strokes in the prosthetic valve situation. This information is provided for general medical education purposes only.