Abstract 328: Effects of Sympatho-excitation on Directional Anisotropy in Ventricular Myocardium
Introduction: Control of electrical propagation exerted by the sympathetic nervous system is has not been quantified in-depth.
Methods: High-resolution mapping (64-electrode plaque, 8x8, 1.96cm2) of the anterior LV myocardium in porcine model (n=6) was performed before & during left stellate ganglion stimulation (LSGS). Activation times (AT), activation recovery intervals (ARIs), conduction velocities (CV), and CV anisotropy were obtained during pacing. Ex vivo diffusion tensor MRI and histology were performed to define myocardial fiber orientation in the mapped regions.
Results: LSGS shortened ARI (314.3±7.8ms vs. 287.8±6.6ms, p<0.001). At baseline, longitudinal CV (CVL) was greater than transverse CV (CVT) (1.2±0.2m/s vs 0.7±0.1m/s, p<0.001). LSGS did not increase CVL(1.16±0.16m/s vs 1.17±0.15m/s, p=0.2), or CVT (0.67±0.07m/s vs 0.7±0.04m/s, p=0.2). However, CV in the retrograde direction along fiber orientation was significantly increased by LSGS (0.7±0.05m/s vs 0.9±0.06m/s, p<0.01). This resulted in a significant reduction in directional anisotropy (CVantegrade/CVretrograde) along fiber direction (1.6±0.3 vs 1.3±0.3, p<0.001), but not CVL/CVT (1.78±0.2 vs. 1.66±0.2 for BL and LSGS, respectively, p>0.2). Heterogeneity of activation (ATdisp) was greater in the transverse than longitudinal direction (20±2ms2/cm2 vs. 13±1.5ms2/cm2, p= 0.022). LSGS decreased transverse ATdisp to 18±1.8 ms2/cm2 (p=0.015), but not longitudinal ATdisp.
Conclusion: Cardiac sympatho-excitation modulates CV and ATdisp in a fiber orientation-dependent manner. These uneven changes may contribute to arrhythmogenic mechanisms seen during sympatho-excitation.
Author Disclosures: O.A. Ajijola: None. A. Khahera: None. E. Aliotta: None. O. Kwon: None. K. Nakamura: None. T. Irie: None. D.B. Ennis: None. K. Shivkumar: None.
- © 2015 by American Heart Association, Inc.