Principal Investigators:
Azaria J-J.T. Rein MD, Clare P O'Donnell MD, Steven D Colan, MD, Gerald R Marx, MD.

Abstract:
With advanced biventricular pacing modalities, there is an increased need for knowledge of left-sided atrioventricular interval and of measurement of interatrial activation time. However, analysis of mechanical activation of the two atria combined with simultaneous study of the atrial electromechanical coupling is practically non-available. Tissue Doppler technology especially when associated with storage and analysis of raw tissue velocity and electrocardiographic data allows unlimited simultaneous interrogations of tissue motion velocity at a high spatial and temporal resolution. Hence, the purpose of this study was to analyze the mechanical events and electromechanical coupling simultaneously in both atria and ventricles using tissue velocity imaging raw data collected during the period of late diastole to early ventricular contraction.

Methods and results - High frame rate images containing raw tissue velocity data and ECG tracings were acquired in 36 normal subjects (age 21.5 ± 13.9 years). Tissue velocity data were readily obtained in all subjects. Using offline analysis, it was possible to identify revealed the various phases of activation and electromechanical coupling in right and left atrium. Three periods were identified: PA, the time interval from the onset of electrocardiographic P wave to the tissue velocity onset of atrial contraction, representing the atrial electromechanical delay; AV, the atrioventricular interval time from the onset of the atrial contraction to the ventricular isovolumic contraction; and QIVC, the ventricular electromechanical delay between the onset of the QRS and the ventricular isovolumic contraction.

Status:
Submitted to Circulation