Pulse arrival time variation as a non-invasive marker of acute response to cardiac resynchronization therapy

Figures

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  Figure 1. Measurements and assessment of the changes in PAT and Td in a representative animal in (A) and in a representative patient in (B). In the left subpanel in A, signals were recorded during LBBB with RV free wall pacing. There is a dyssynchronous contraction with wide QRS, where the electrical activation sequence is early in the septal electrode and last in the lateral one. In the right subpanel, CRT abolished the dyssynchronous contractions at start systole, reducing the delay of pressure rise; hence, both PAT and Td are shortened. The left subpanel in B shows signals recorded during a heartbeat with LBBB and RV pacing and the right subpanel with BiV pacing. In the right subpanel, BiV pacing resynchronizes the electrical activation and shortens Td and PAT. BiV, biventricular; CRT, cardiac resynchronization therapy; dP/dt, pressure derivative; EMG, electromyogram; LBBB, left bundle branch block; LV, left ventricle; PAT, pulse arrival time; RV, right ventricle; Td, time-to-peak left ventricular dP/dt.

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  Figure 2. Results from the animal study. (A) Correlation between PAT and Td was calculated for all animals with all pacing modes and intrinsic conduction with narrow QRS pooled. (B) Preload dependence of haemodynamic indices in a representative animal. The plot shows the indices as the end-diastolic volume (EDV) was reduced (towards the left) during the constriction of the caval veins. The values are in percent of the initial values at the start of constriction when EDV is at its highest (100%). The pressure and volume indices are drastically reduced with a reduction of preload, while PAT and Td are much less preload dependent with a small increase with lower EDV. (Cand D) Box plots of changes in PAT and Td, respectively, relative to baseline from the six animal experiments. Induction of LBBB increased both indices, while CRT returned them closer to baseline values. RV free wall pacing resulted in an additional prolongation due to the extra time for the activation to reach the LV as explained in the text. Pacing with the LV lead on the lateral wall shortened PAT the most. BiV, biventricular; CRT, cardiac resynchronization therapy; dP/dt, pressure derivative; LBBB, left bundle branch block;…

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  Figure 3. Results from the patient study. (A) Correlation between PAT and Td was calculated for all patients with all pacing modes pooled. (B) Bland–Altman plots showing the agreement between ΔPAT and ΔTd. The bias (1.96 SD) was 4.3 (13.8) ms. The data were pooled from all patients. Black, solid line indicate the bias, while dashed lines signify bias ± 1.96 SD. (C and D) Box plots from the 10 responders of changes in PAT and Td, respectively, relative from LBBB with the two non-responders added as filled in circles. Biventricular pacing with LV lead placement on the lateral wall created a greater shortening of the indices than pacing from an anterior position. The two non-responders showed no reduction of either PAT or Td in any pacing configuration. BiV, biventricular; LBBB, left bundle branch block; LV, left ventricle; PAT, pulse arrival time; RV, right ventricle; SD, standard deviation; Td, time-to-peak left ventricular dP/dt; ΔPAT: relative change in pulse arrival time from LBBB. ΔTd, relative changes in time-to-peak LV dP/dt from LBBB. *P<0.05 compared with LBBB. ‡P<0.05 compared with BiV pace anterior. §P<0.05 compared with BiV pace lateral wall.