TRANSCRANIAL DOPPLER DETECTION OF MICRO-EMBOLI IN PROSTHETIC HEART-VALVE PATIENTS - DEPENDENCY UPON VALVE TYPE

Transcranial Doppler ultrasound has revealed the existence of cerebrov ascular microemboli in asymptomatic patients with prosthetic heart val ves. We investigated the relation between the presence and number of e mboli signals and valve type. Patients with six types of prosthetic va lves (Bjork-Shiley monostrut, Medtronic-Hall, Carbomedics, ATS, Carpen tier-Edwards standard, Carpentier-Edwards supraannular) were examined using transcranial Doppler ultrasound in two centers. The monitoring t ime was 30 min over the right middle cerebral artery. All patients wer e stabilized on warfarin at the time of study. Microemboli signals wer e identified by their characteristic audiovisual signal and on subsequ ent spectral analysis, based on accepted criteria. A standard neurolog ic questionnaire was completed by all patients. The prevalence of micr oemboli signals varied between 49% (Medtronic Hall) and 97% (Bjork-Shi ley monostrut), while their number varied between 1 [0-3] (Carpentier- Edwards standard) and 187 [136-240] (Bjork-Shiley monostrut) per hour (median and 95% CI). Both parameters were significantly higher in pati ents with Bjork-Shiley monostrut valves compared to the other patient groups. There were no significant differences in the prevalence of neu rologic complications among the groups examined (overall 16%), or in e mboli numbers between symptomatic and asymptomatic patients. The preva lence and quantity of microemboli signals in patients with prosthetic heart valves, as detected by transcranial Doppler, is dependent upon v alve type. The clinical significance of these microemboli signals rema ins to be further evaluated.