Visualization of the site of the onset of ventricular depolarization by acceleration mode “Tissue Doppler Imaging” technique

Abstract

Tissue Doppler imaging (TDI) is a relatively new echocardiographic technique that shows regional myocardial wall velocities. The aim of this study was to evaluate the potential value of acceleration mode TDI technique for the visualization of the origin of ventricular activation site using the model of right ventricular pacing. Twenty-seven patients with implanted permanent pacemakers were studied by acceleration mode TDI, 4 of these patients were pacemaker dependent. Parasternal and apical chamber views were recorded on video tape by using acceleration mode TDI technique during sinus rhythm with preserved atrioventricular conduction in 23 subjects who were not pacemaker-dependent, and also during right ventricular apical pacing in VVI mode in 27 subjects in whom pacing lower rate was increased if necessary. Fifty images recorded during sinus and pacing rhythm in cineloop were examined by two independent observers who were unaware of the rhythm patterns and by the same observer on two different occasions for localizing the site of onset of ventricular acceleration. The origin of ventricular activation during sinus rhythm started at basal septal part of the ventricle and during pacing started at apical part of the ventricle was considered as correct localizations. The origin of ventricular depolarization was correctly localized for 46 of 50 images (92%) and 44 of 50 images (88%) by the first and the second observers, respectively. Concordant results between observers appeared in 48 of 50 (96%) of images. The diagnostic accuracy of the concordant results was 44 of 48 (91.6%) images. The kappa for interobserver variability was 0.77 (p<0.001), and for intraobserver variability was 0.64 (p<0.001) and 0.63 (p<0.001) for the first and the second observers, respectively. These results suggest that acceleration mode TDI can be used to detect the initial ventricular excited position and seems to have a potential value for localizing of the origin of normal or abnormal myocardial depolarization.

Quantitative Assessment of Myocardial Acceleration in Normal Left Ventricle with Velocity Vector Imaging

“…TDI‐derived myocardial acceleration map has been used to detect the onset of myocardial acceleration in response to electrical excitation 7–12 . However, strong angle dependency limits the application of all TDI techniques.…”

“…TDI‐derived acceleration only allows measurements of the motion that is in parallel to the ultrasound beam, so accelerations of lateral, inferior, posterior septum, and partial anterior walls cannot be detected in short‐axis views. Furthermore, currently applied methods for analysis of time‐sequential changes in myocardial acceleration in LV walls are based on the visual assessments of inward motion and color‐coded format from two‐dimensional myocardial acceleration map 7–12 . They are highly subjective and limited by substantial reader variability.…”

“…Myocardial acceleration is proportional to the change of velocity over time and is more sensitive to the rapid change of tissue motion than velocity. Several studies have reported the ability of the two‐dimensional myocardial acceleration map derived from TDI to localize the sites of origin of myocardial contraction in response to electrical excitation and of the accessory atrioventricular pathways 7–12 …”

“…If the site of initial contraction of a ventricular arrhythmia or in WPW syndrome is recognized as the position of onset of myocardial acceleration, 7–12 the onset and propagation of myocardial acceleration in the normal left ventricular (LV) wall should be well coincided with cardiac conductive system 9 . However, the distribution and values of myocardial acceleration in the normal LV have not been well studied.…”

Three-dimensional motion measurements using feature tracking

“…Doppler imaging is widely used for blood flow measurements, and tissue Doppler imaging (TDI) has been described in several studies [7]- [10]. However, Doppler is limited by its one-dimensional nature, angle sensitivity, and framerate slowdowns from multiple interrogating pulses.…”