Tracking Early Systolic Motion for Assessing Acute Response to Cardiac Resynchronization Therapy in Real Time

Figures

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  FIGURE 1. (A) Schematic illustration of placement of the combined sonomicrometry crystals and IM-EMG sensors and the electromagnetic tracking (EM) sensors. The red arrow indicates the change in the distance that was measured between the sensors. Only one of the three epicardial LV free wall EM and sonomicrometry sensor pairs are shown for simplicity. (B) Representative displacement traces measured with EM tracking sensors during baseline and LBBB. The red traces mark the contraction during systole. The black triangle marks the end of the early contraction, while the black dots mark the point where full contraction is achieved which is then used to calculate SFI. AVC = aortic valve closure.

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  FIGURE 2. Septal flash index, measured by sonomicrometry and EM sensors, and SWEDV values measured in baseline, LBBB, and all three biventricular pacing sites. Induction of LBBB changed all measurements from baseline, while CRT returned them closer to baseline values.

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  FIGURE 3. (A) Representative case of a heartbeat comparing the change in the left ventricular septal-to-lateral wall diameter measured with the two different sensors where the measurements of the EM tracking sensors align with the ones obtained with sonomicrometry. (B) Representative case where the EM tracking sensors did not capture the rapid early contraction. (C) Difference between diameter changes measured with sonomicrometry and EM sensors for all recordings.

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  FIGURE 4. (A) Relation between SWEDV and SFI calculated with sonomicrometry from one experiment where different ranges of response were measured from different LV lead placements. There is a clear trend towards a reduction of SFI with improvement of LV function. (B) Relation between SWEDV and SFI calculated with sonomicrometry from one experiment where the points obtained through different lead placements are clustered together.