LOW-FREQUENCY OF CLINICALLY SILENT CIRCULATING EMBOLI IN PATIENTS WITH MITRAL-VALVE PROLAPSE OR PATENT FORAMEN OVALE DETECTED BY BIGATED TRANSCRANIAL DOPPLER ULTRASOUND

Patent foramen ovale (PFO), but not uncomplicated mitral valve prolaps e (MVP), is a possible source of cardiac embolism to the brain. There are only a few reports on the frequency of clinically silent circulati ng microemboli in these two conditions. We performed 1-hour recordings of one middle cerebral artery in 4 patients with MVP and 14 patients with PFO to detect circulating microemboli. For the identification of microembolic signals we used blinded off-line evaluation and bigated t ranscranial Doppler sonography (sampling from two different depths in the vessel). Microembolic signals were detected conventionally in 3 ou t of 14 patients with PFO (3, 8, and 14 microemboli/h), and in none ou t of the 4 patients with MVP. The absence of microembolic signals in p atients with MVP and the low frequency of microemboli in patients with PFO reflect the different embolic potential of these two cardiac abno rmalities.