Venous microemboli in patients with artificial heart valves

Detection of microemboli signals (MES) in patients with artificial heart va lves has been extensively described, but the underlying material remains un clear. We assumed that the detection of MES in the jugular vein of patients with prosthetic valves would clearly argue for gaseous embolic material, s ince formed emboli are unable to cross through the capillaries. Methods and Results: Twenty-five patients with artificial heart valves, 15 patients wi th asymptomatic carotid artery disease, and 25 normal controls were examine d. Monitoring was performed simultaneously over the dominant jugular vein a nd the ipsilateral middle cerebral artery for 30 min per subject, using 2-M Hz transducers of a color duplex scanner for the jugular vein and a pulsed- wave Doppler for the middle cerebral artery. Data were harvested in an eigh t-channel digital recorder and MES counts evaluated by two separate observe rs. MES prevalence in the middle cerebral artery was 100, 13 and 0% in pati ents with artificial heart valves, asymptomatic carotid artery disease, and normal controls, respectively. No MES were detected in the jugular veins o f patients with carotid artery disease or in normal controls, while their p revalence was 68% in patients with artificial heart valves. The interobserv er agreement was satisfactory. Conclusion: Our results suggest that the emb olic material of at least a part of MES in patients with artificial heart v alves is gaseous.