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Figure 5.15. Activation maps
from two patients who
responded to CRT. Native
rhythm (top) and BIV pacing
(bottom) maps are shown for
each patient. Format is similar
to Figure 5.13. Pacing sites are
marked by asterisks. From
Jia et. al. [304] with permission
of Elsevier.

Non-responders to CRT

Figure 5.16 shows examples from patients who did not respond to CRT. In patient #8
(Figure 5.16A), the electrode was placed in lateral LV. Activation from this site captured the LV

basal region of delayed activation. However, a new functional line of block emerged on the
antero-lateral wall. The wave front was forced to pivot around it and activate a large region of the
anterior LV very late, at 132 ms. This was later than the latest activation during native rhythm
(120 ms), actually aggravating electrical dyssynchrony. In patient #4 (Figure 5.16B) lead placement
was on anterior LV. Activation of the LV lateral wall was much slower during CRT than in native

rhythm, taking twice as long to reach the basal LV (at 187 ms) and causing further deterioration of
electrical synchrony. Note that the examples above also serve to illustrate that the substrate is
dynamic and depends on the intervention (pacing); upon pacing, lines of block and regions of

slow conduction that existed in native rhythm may disappear and others emerge. Another