Abstract 16640: Conductive Biomaterial Enhanced Electrical Propagation Across a Left Ventricular Scar After a Myocardial Infarction
Introduction: After an MI, hydrogels such as chitosan have been used clinically to stabilize the LV free wall and prevent dilation. We chemically modified chitosan with the charge-carrying conductive polymer, polypyrrole (PPy), yielding a biomaterial with eight times greater electrical conductivity than chitosan alone.
Hypothesis: Chitosan-PPy (C-PPy) will enhance propagation of electrical impulses in the scar and improve synchronous contraction of cardiac regions after MI.
Methods: Chitosan (C), C-PPy or saline (S) were injected into infarct regions of adult rats (n=8/group) 7 days post-MI. Electrical activity and cardiac conduction and function were assessed with ECG, echocardiography, pressure-volume (PV) analysis, and Langendorff-perfused epicardial optical mapping. Inducibility of ventricular arrhythmias was assessed by programmed electrical stimulation (PES). Myocardial tissue resistance was measured ex vivo.
Results: Twelve weeks post-injection, duration of QRS and QTc was increased in S- and C-treated hearts, but maintained in C-PPy-treated hearts (11.8±3.3 and 104.8±13.3 (ms) vs. 15.9±1.4 and 169.0±17.1 in S; 15.2±1.3 and 181.9±27.9 in C, p<0.01), suggesting less maladaptive ventricular remodeling associated with slowing of depolarizing and repolarizing conduction in the C-PPy group. Optical mapping demonstrated that C-PPy-treated hearts had faster cross-scar conduction velocities measured on the epicardial surface (62.5±3.3 (cm/s) vs. 45.3±10.9 in S; 48.9±4.4 in C, p<0.05). PES induced fewer ventricular arrhythmias in C-PPy-treated than S- and C-treated hearts (p<0.01). Ex vivo, C-PPy-treated heart tissue had lower myocardial tissue resistance (p<0.05) than the other groups. Fractional shortening was enhanced in C-PPy-treated hearts (33.7±3.3% vs. 25.3±2.7 in S; 28.2±2.0 in C, p<0.01) which had increased stroke work and better maintained (lower) end systolic volume (p<0.05).
Conclusions: C-PPy improved heart function by augmenting synchronized contraction and conduction velocity. The incidence of inducible arrhythmias was reduced. This new biomaterial may prevent progressive ventricular dilatation and accomplish the benefits of resynchronization therapy in patients with a widened QRS after an MI.
Author Disclosures: S. He: None. J. Wu: None. W. Yin: None. Z. Shao: None. R.D. Weisel: None. R. Li: Research Grant; Significant; Heart and Stroke Foundation of Canada grant (G140005765).
- © 2016 by American Heart Association, Inc.