Cell Unexcitability and Electrotonic Coupling Phenomenon Analysis of Ablation-Created Lesions: A Study Case with Ablated Explanted Human Heart.

This study investigates the effects of radiofrequency ablation $(RFA)$ - created lesions on an explanted human heart in wedge preparation by simultaneous endo and sub-endo optical mapping. The heart in Langendorff perfusion was ablated under 40 W. The ventricle was stained with $Vm$ sensitive dye Di-4-ANBDQPQ and two excitation light bands of different penetration depths were used $(red= {\it 660} nm$ , green $=525nm$ ) to perform a conduction velocity $(CV)$ difference analysis for identification of $CV$ alternans. The relative change in fluorescence $(\Delta F/F)$ traces were analyzed before and after ablation. Local activation time $(LAT)$ was determined by the 50% approach. Local $CV$ was obtained using the circle method, and $RFA$ created lesions were characterized by examining the $CV$ alternans correlated with transmural heterogeneities. The presence of $CV$ alternans results from reduced excitability in a non-homogeneous lesion consisting of excitable and non-excitable cells. The absence of $CV$ alternans in optical mapping with green light and their presence with deep-red light illustrates incomplete ablation across the ventricular wall or non-homogeneous ablation in the mid-myocardial layer. The presence of an intramural scar impairs the efficacy of the $RFA$ procedure, suggesting $a$ need for alternative ablations strategies.