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.