Yu index of longitudinal tissue Doppler dyssynchrony
Yu index of longitudinal tissue Doppler dyssynchrony is the standard deviation of time to peak systolic velocities from the onset of the QRS complex. This is calculated after determining the time to peak systolic velocities from 12 sites. A value of 32 or more milliseconds is considered to be significant dyssynchrony. Measurement of dyssynchrony is used to assess the possibility of improvement with cardiac resynchronization therapy in heart failure. Region of interest for evaluation of dyssynchrony are placed in basal and mid left ventricular segments in three apical views: four chamber, two chamber and long axis.
John Gorcsan 3rd, Olusegun Oyenuga, Phillip J Habib, Hidekazu Tanaka, Evan C Adelstein, Hideyuki Hara, Dennis M McNamara and Samir Saba evaluated Yu index along with other measures of echocardiographic cardiac dyssynchrony and correlated with long term survival after cardiac resynchronization therapy (CRT) . Study population was 229 consecutive patients with Class III-IV heart failure, with ejection 35% or less, and QRS width of 120 milliseconds or more, awaiting CRT. After adjustment for confounding baseline variables of ischemic etiology and QRS width, independent predictors of outcome were Yu Index and radial strain dyssynchrony (p<0.05).
- John Gorcsan 3rd, Olusegun Oyenuga, Phillip J Habib, Hidekazu Tanaka, Evan C Adelstein, Hideyuki Hara, Dennis M McNamara, Samir Saba. Relationship of Echocardiographic Dyssynchrony to Long-Term Survival After Cardiac Resynchronization Therapy. Circulation. 2010 Nov 9;122(19):1910-8.