Microbubbles associated with mechanical heart valves: Their relation with serum lactic dehydrogenase levels

Background There has been no consensus about the prevalence and mechanism o f generation of microbubbles in mechanical prosthetic heart valves (PHV). T he aim of this study was to determine the prevalence of microbubbles in PHV and their relation to serum lactic dehydrogenase (LDH) levels. Methods and Results We prospectively studied 150 normally functioning mitra l PHV (98 bileaflet and 52 monoleaflet) in 150 patients with the use of tra nsesophageal echocardiography with a multiplane 5-MHz probe. None of the pa tients had an aortic prosthetic valve. Blood was drawn to determine serum L DH level. None of the patients had any factors that might affect the LDH le vel other than the PHV related hemolysis. Patients with spontaneous echo co ntrast in the left atrium that might affect the assessment of the microbubb les were excluded. We devised a method to determine the amount of microbubb les for each PHV. Microbubbles were detected in 118 (79%) of 150 PHV, inclu ding 97 (99%) of 98 bileaflet valves and 21 (40%) of 52 monoleaflet (tiltin g disk) valves (P < .0001). Intraobserver variability was not statistically significant for the determination of the amount of microbubbles (z = 1.7, P = .08). There was a strong correlation between serum LDH levels and the a mount of microbubbles (r(s) = 0.69, P < .001). Conclusions Microbubbles were detected in more patients than reported previ ously. They were found to be associated more with the bileaflet than the mo noleaflet PHV. Sorin monoleaflet valves were associated with microbubbles s ignificantly less often than the others. There was a strong correlation bet ween serum LDH levels and microbubble counts, which suggests that hemolysis may be related to microbubble formation.