313: Quantification of left ventricular mechanical dyssynchrony by conductance catheter in the failing heart: Effect of biventricular pacing

Abstract

Mechanical dyssynchrony is important codeterminant of cardiac dysfunction in heart failure. We evaluated new indexes to quantify temporal and spatial aspects of mechanical dyssynchrony derived from on-line segmental conductance catheter signals. To test the feasibility and usefulness of our approach, we determined cardiac function and left ventricular (LV) dyssynchrony in normal (n=6) and failing canine hearts (rapid pacing: 180 min-1, 12 weeks, n=7) before and after biventricular pacing. Segmental signals were defined as dyssynchronous at each time point if its change were opposite to the simultaneous change in the total LV volume. Overall dyssynchrony was calculated as the mean of the segmental dyssynchronies during systole (DYSsys) and diastole (DYSdias). Ineffective blood shifting within the LV (IBF) was calculated as the sum of the absolute volume changes of all segments and subtracting the total absolute total volume change and expressed as percent fraction of total effective flow. Mechanical dispersion (DISP) was assessed by segmental lag times. LV contractility was described by the slope of the endsystolic pressure-volume relationships (Ees). Pacing induced heart failure led to significantly reduced Ees. Indexes of LV dyssynchrony were increased in the heart failure group. Biventricular pacing improved Ees by reduction of mechanical dyssynchrony (Table 1). Pacing induced heart failure in canines leads to reduced LV contractility and significant LV mechanical dyssynchrony which can be improved by biventricular pacing. The proposed indexes provide additional, new and quantitative information on temporal and spatial aspects of mechanical dyssynchrony and may refine diagnosis of cardiac dysfunction and evaluation of interventions. Table 1 Control Heart Failure Biventricular pacing Ees 6.9 ± 1.0 2.3 ± 0.3 3.7 ± 0.2† DYSsys 9 ± 8 39 ± 7 12 ± 7† DYSdias 3 ± 2 41 ± 7 13 ± 6† DISP 18 ± 7 70 ± 15 27 ± 7† IBF 11 ± 4 66 ± 12 23 ± 7† p < 0.05 vs control †p < 0.05 vs heart failure Open table in a new tab