Release of cardiac bio-markers during high mechanical index contrast-enhanced echocardiography in humans

Background: Recent experimental data have shown that the combined exposure of rodent hearts to high acoustic pressure and ultrasound contrast agents can induce vascular injury and cell damage. The aim of the present work was to test whether similar effects can be observed in humans. Methods and results: Twenty patients underwent simultaneous arterial and coronary sinus blood sampling during contrast-enhanced echocardiography using Perfluorocarbon-enhanced Sonicated Dextrose Albumin. Control subjects were compared to groups of patients exposed to either high mechanical index (MI = 1.5) triggered second harmonic (1.3-2.6 MHz) imaging or low mechanical index (MI = 0.2) real-time power modulation imaging for 15 min. No significant changes arterio-venous differences in lactate, total creatine kinase (CK) and myoglobin occurred over time in the three groups. Similarly, the arterio-venous difference in CK-MB and troponin I remained stable over time in control and low-MI patients. By contrast, these two parameters progressively increased over time in the high-MI group (P < 0.05 vs. baseline and vs. controls). Conclusion: Our data suggest that high-MI contrast-enhanced echocardiography can cause subclinical release of cardiac bio-markers in humans, while low-MI real-time imaging appears to be safer.