Using optical mapping to analyze action potentials in different regions of the heart (normal zone (N), peri-infarct zone (P), and infarct zone (I) of the myocardial infarction heart), it was found that compared to the MI group, the incidence of EADs/DADs (precursors of arrhythmias) in the peri-infarct region increased sharply, while ionic cocktail treatment reduced the incidence of EADs/DADs. Simultaneously, the ionic cocktail decreased the dispersion of action potential duration and calcium transient duration, improved the electrophysiological homogeneity between the infarct zone and the normal zone, thereby exerting anti-arrhythmic effects.
(A) The representative image of a heart is prepared for optical mapping. The red dotted box indicates the ventricle; infarct region is in the apical left ventricle; the stimulating electrode is at the apex of the heart (the white triangle). (B) The representative maps of amplitude (top) and APD90 (bottom) in the ventricle of the heart among different groups. Region 1 (R1) or normal area (N) is indicated with green square, region 2 (R2) or peri-infarct area (P) is indicated with black square, and region 3 (R3) or infarct area (I) is indicated with purple square. The heatmap scale bar indicates the amplitude (F/∆F, top) or action potential duration (ms, top). (C) Representative traces of optical action potential (AP) from different areas among different groups. Black arrow indicates EAD/DAD.Scale bar, 100 ms. (D) The incidence rate of EAD/DAD. N represents no EAD/DAD appeared; A represents EAD/DAD appeared. The quantified (E) APD90,(F) CaD90, (G) IQR of APD90 (a measure of APD90 dispersion). (H) IQR of CaD90 (a measure of CaD90 dispersion) calculated from optical maps among different groups. The difference value of (I) APD90 and (J) CaD90 between infarct area and normal area. (K) APD90 and (L) CaD90 between infarct area and peri-infarct area
Optical mapping was performed in a rat model of myocardial infarction (28 days post‑ligation) by intravenous injection of an ionic cocktail to study its effects on cardiac electrophysiology. Electrocardiograms and action potential recordings under sinus rhythm and S1S1 pacing stimulation revealed that severe ventricular fibrillation occurred 28 days after myocardial infarction. Phase mapping of conduction indicated significant reentry phenomena in the infarcted hearts. Moreover, the incidence of ventricular fibrillation decreased after intervention with the ionic cocktail, confirming that the ionic cocktail possesses certain anti‑arrhythmic effects.
(A-C) Example of CaT maps (upper panel) at progressively faster pacing rates and CaT traces from the location indicated with a box in the upper maps (lower panel). (D) Calculation diagram of CaT alternans. (E) Quantification of CaT alternans at progressively faster pacing rates. (F) Incidence of discordant alternans during baseline and reperfusion.
Exploration (IF 22.5)
doi: 10.1002/EXP.20230067.
