Myocardial fibrosis, resulting from ischemic injury, increases tissue
resistivity in the infarct area, which impedes heart synchronous
electrical propagation. The uneven conduction between myocardium and
fibrotic tissue leads to dys-synchronous contraction, which progresses
towards ventricular dysfunction. We synthesized a conductive
poly-pyrrole-chitosan hydrogel (PPY-CHI), and investigated its
capabilities in improving electrical propagation in fibrotic tissue, as
well as resynchronizing cardiac contraction to preserve cardiac
function. In an in vitro fibrotic scar model, conductivity increased in
proportion to the amount of PPY-CHI hydrogel added. To elucidate the
mechanism of interaction between myocardial ionic changes and electrical
current, an equivalent circuit model was used, which showed that
PPY-CHI resistance was 10 times lower, and latency time 5 times shorter,
compared to controls. Using a rat myocardial infarction (MI) model,
PPY-CHI was injected into fibrotic tissue 7 days post MI. There, PPY-CHI
reduced tissue resistance by 30%, improved electrical conduction across
the fibrotic scar by 33%, enhanced field potential amplitudes by 2
times, and resynchronized cardiac contraction. PPY-CHI hydrogel also
preserved cardiac function at 3 months, and reduced susceptibility to
arrhythmia by 30% post-MI. These data demonstrated that the conductive
PPY-CHI hydrogel reduced fibrotic scar resistivity, and enhanced
electrical conduction, to synchronize cardiac contraction.
