Harmonic power Doppler contrast echocardiography:: Preliminary clinical results

Background: In fundamental and second harmonic echocardiography new contrast media opacify the cavities and reduce the difference in the gray level between the cavity and the myocardium thus obscuring the borders of the myocardium. Objectives: The aim of the study was to examine the potential usefulness of second harmonic power Doppler imaging (HPD) in providing adequate delineation of the myocardium from the Left ventricular (LV) and right ventricular (RV) cavities during intravenous contrast echocardiography. Using HPD, microbubbles in a cavity or a tissue are imaged as colored pixels superimposed on a conventional B-scan image. Methods: In a pilot study, three healthy volunteers and two patients with ischemic heart disease were investigated using an ATL-HDI 3000 echo system. Four chamber views were obtained using fundamental B-scan, harmonic B-scan two-dimensional echocardiography (H2D) and HPD following intravenous injections of 3 g Levovist(R). Results: Using intermittent scanning/recording, H2D and HPD provided intensive and homogenous contrast effects in the RV and LV cavities. Good delineation of the myocardium was found in all subjects using HPD, whereas in two of three volunteers and in one of two patients ventricular septal and apical endocardial borders were obscured during H2D. No obvious change in myocardial backscatter was visually found with H2D. However, in all three healthy volunteers and in one of two patients, HPD recordings demonstrated patchy and reticular patterns in the myocardium, which were different from the homogenous signals in the LV cavity. These are consistent with imaging of intramyocardial coronary vessels. Conclusions: HPD with intravenous Levovist is feasible. This technique demonstrated good delineation of ventricular cavities from the myocardium as well as presence of visible contrast in the myocardium. This pilot study justifies further clinical trials to evaluate the clinical benefit of this approach.