Septal Deformation Patterns Delineate Mechanical Dyssynchrony and Regional Differences in Contractility

Abstract

Background-Response to cardiac resynchronization therapy depends both on dyssynchrony and (regional) contractility.We hypothesized that septal deformation can be used to infer integrated information on dyssynchrony and regional contractility, and thereby predict cardiac resynchronization therapy response. Methods and Results-In 132 cardiac resynchronization therapy candidates with left bundle branch block (LBBB)-like electrocardiogram morphology (left ventricular ejection fraction 19Ϯ6%; QRS width 170Ϯ23 ms), longitudinal septal strain was assessed by speckle tracking echocardiography. To investigate the effects of dyssynchronous activation and differences in septal and left ventricular free wall contractility on septal deformation pattern, we used the CircAdapt computer model of the human heart and circulation. In the patients, 3 characteristic septal deformation patterns were identified: LBBB-1ϭdouble-peaked systolic shortening (nϭ28); LBBB-2ϭearly systolic shortening followed by prominent systolic stretching (nϭ34); and LBBB-3ϭpseudonormal shortening with less pronounced late systolic stretch (nϭ70). LBBB-3 revealed more scar (

Computer Modelling for Better Diagnosis and Therapy of Patients by Cardiac Resynchronisation Therapy

“…Using the CircAdapt model containing wall segments representing the RV free wall, septum and LV free wall, they were able to demonstrate how double-, early-and late-peak septal strain patterns could originate from different combinations of a true electrical substrate of mechanical dyssynchrony whether or not in combination with regional differences in myocardial contractility (see Figure 5). 35 A recent clinical study supported these findings and showed that double-and early-peak septal strain patterns are highly predictive for CRT response. 43 In another CircAdapt study, during gradual pre-excitation of the septum compared with the LV free wall, the time to peak shortening in the septum shortened in two major steps, providing a poor quantitative reflection of true dyssynchrony.…”

“…35,36 In early-activated regions, a rapid early systolic fibre shortening was found, followed by strongly reduced late systolic shortening. Later-activated regions were characterised by early systolic lengthening followed by pronounced systolic shortening.…”

Mechanistic Evaluation of Echocardiographic Dyssynchrony Indices

“…10,12,13 Deformation events were temporally aligned through the ECG-traces, using the onset of the QRS complex as zero strain reference. Global longitudinal strain was used for further analyses.…”

“…It enables realistic beat-to-beat simulation of cardiovascular mechanics and hemodynamics under a wide variety of (patho-)physiological circumstances, including ventricular mechanical dyssynchrony. 13,[18][19][20] Three thick-walled segments representing the LV free wall (LVFW), the interventricular septum (SEPT), and the RV free wall are mechanically coupled in a junction and ventricular mechanical interaction is incorporated by the equilibrium of tensile forces in the junction. In each cardiac wall, the myofiber stress-strain relation is determined by a 3-element muscle model describing active and passive cardiac myofiber mechanics.…”

Left Ventricular Activation Imaging by 3-Dimensional Speckle-Tracking Echocardiography

“…In patients with LBBB, early systolic septal wall motion, also called septal flash, are often observed. [18][19][20] This slight motion has been noted as an important factor that induces LV dyscoordination and has been reported as a significant predictor of CRT response. Therefore, this novel function could contribute to more accurate assessment of dyssynchrony compared with that provided by currently available systems.…”