DOPPLER MICROEMBOLIC SIGNALS IN CHILDREN WITH PROSTHETIC CARDIAC VALVES

Background and Purpose The aim of this study was the evaluation of the prevalence and counts of Doppler microembolic signals (MES) in childr en with prosthetic cardiac valves and their comparison to those obtain ed in corresponding adult patients. Patients and Methods Nine children and 43 adults with ATS valves implanted in the aortic position were m onitored over both middle cerebral arteries with transcranial Doppler ultrasound. MES were identified on-line according to standard criteria . Heart rate and rhythm, valve type, size and duration, patients' heig ht, International Normalized Ratio, and prevalence of neurological com plications were obtained from all study participants. Results MES prev alence and counts were significantly higher in children compared with adult patients (100% versus 25.5% and 58 [18.5 to 115.5] versus 5.5 [2 to 10.5], median, 95% CI, respectively). No corresponding differences in valve size or duration of valve implant were evident; but children had faster heart rates and were significantly smaller compared with a dults. A positive correlation between patients' size, heart rate, and MES counts was noted. Conclusions MES counts in children with mechanic al prosthetic valves are significantly higher compared with those in c orresponding adults. We hypothesize that this is due to (1) the shorte r distance between aortic valve and middle cerebral artely, since cavi tation bubbles have a short life span and are bound to dissolve with t ime. and (2) the faster heart rate in children, resulting in a higher number of valve closures per minute.