Figure 10

TSI in the apical 4 chamber views showing the effect of right ventricular pre-excitation on interventricular septal and right ventricular free wall delay. At baseline with LV pre-excitation of 20 ms there is marked delay in interventricular septum and RV free wall shown in orange color in A. VV of 0 ms reduces this interventricular septal and RV free wall delay (B). RV pre-excitation of 10 ms improves this further (C) and RV pre-excitation of 15 ms abolishes remaining mild delay in the interventricular septum (D). There is appearance of a small area of delay in the left ventricular apex (shown in red in C and D) with RV pre-excitation. There was progressive improvement in LV strain with RV pre-excitation as shown in Figure 11.