Ultrasonographic Study of Micro-embolic Signal from the Heart.

We undertook TCD examination combined with transesophageal echocardiography (TEE) and measurements of hematological markers for coagulation, fibrinolysis and platelet function to clarify the clinical significance of micro-embolic signals derived from the heart. We examined nine patients with prosthetic valves including two with cardioembolic stroke (CE) and 11 CE patients without prosthetic valves. All the patients were receiving anticoagulation therapy at the time of the study. TCD study demonstrated 3-54/30 min micro-embolic signals in six of the nine patients with prosthetic valves, but no signal in those without valve replacement. TEE study demonstrated cavitation phenomenon in eight of the nine patients with prosthetic valves, but in none of the patients without valve replacement. No other findings of TEE or hematological examination were correlated with the frequncy of micro-embolic signals. These results indicate a close relationship between cavitation phenomenon and micro-embolic signals in patients with prosthetic valve. Ordinary anticoagulation (INR: international normalized ratio 2.0-3.0) does not reduce the frequency of micro-embolic signals in patients with prosthetic heart valve. However, very high intensity anticoagulation (INR>3.5) might decrease the frequency of micro-embolic signals. Further studies are necessary to clarify the clinical significance of microembolic signals.