Electrical wavefront fusion in heart failure patients with left bundle branch block and cardiac resynchronization therapy: Implications for optimization

Determinants of the time-to-peak left ventricular dP/dt (Td) and QRS duration with different fusion strategies in cardiac resynchronization therapy

“…The diagrammatic ( Figure 5 ) shows how LV pre-/postexcitation and MPP may affect LVAT, RVAT and QRSd differently. The diagram is an ideal representation of electrode positions in 2D, following the principle of electrical cancellation caused by refractoriness of the myocardial tissue after excitation when two or electrical wave-fronts meet ( 18 ). Shortening the LVAT with the recruitment of excitable tissue from two areas is also an effect of multipoint pacing ( 4 , 19 ).…”

Cardiac resynchronization therapy optimization in nonresponders and incomplete responders using electrical dyssynchrony mapping

“…The protocol for calculating CRI and generating EDMs has previously been described. 5,6 Patients had device interrogation and ECG with CRT off to assess native conduction. Nine anterior and 9 posterior electrodes were placed over the upper torso, and electrograms were superimposed.…”

“…We have previously described this methodology and how to measure it in detail Q17 and demonstrated that patients with underlying LV activation delay and adequate LV lead placement who received CRT respond electrically to CRT in a characteristic manner across a wide range of AVD/VVD. 5,6 In these patients, an OSL is present for each EDM obtained at a given LV pacing vector and we programmed patients to a setting along this OSL. Since the OSL was shifted to the left of the simultaneous BiV pacing line in all but 1 patient, LV preactivation during BiV pacing or LV-only pacing at optimal AVD was usually necessary.…”

“…We have previously explained the physiological reason for this finding. 6 Simultaneous BiV pacing cannot achieve optimal synchrony in most patients because at short AVD the RVp wavefront is ahead of the LVp wavefront and at long AVD the native wavefront is even further ahead of the LVp wavefront. 5 Nineteen patients (48.7%) were programmed to LV-only pacing with a mean AVD of 112 6 39 ms (54.6% 6 12.0% of the PR interval).…”

Determination of sensed and paced atrial‐ventricular delay in cardiac resynchronization therapy

“…We have developed a noninvasive, electrocardiographic methodology (based on the concept of wavefront fusion) for quantifying electrical synchrony during CRT over a wide-range of clinically relevant and practical AVDs and ventricular-ventricular delays (VVD) called electrical dyssynchrony mapping (EDM). 4,5 Optimization of CRT programming using this methodology in nonresponders and incomplete responders resulted in significant improvements in LV size, systolic function and mechanical dyssynchrony. 6 In the present study we describe how this methodology for measuring electrical dyssynchrony can be used to better understand the physiology of wavefront fusion during atrial sensing/pacing, and how it can be used to determine the electrically optimal SAVD/PAVD offset during LV-only pacing and BiV pacing.…”