Introduction. Purkinje system and false tendons (FTs) are related to ventricular arrhythmia, but the association between Purkinje fibers and FTs is not clear. This study investigated the associations of anatomical and electrophysiological characteristics between Purkinje fibers and FTs. Methods and Results. We optimized the protocol of Lugol’s iodine solution staining of Purkinje fibers to study the anatomical structure and originated a novel electrophysiological mapping method, named the direct visual mapping (DVM) method, to study the electrophysiological characteristics. By using the above-mentioned innovations in 12 dogs, we found the following. (1) There was no Purkinje fiber found 0.5 cm–1.0 cm below the valve annulus or on the leaflets or chordae tendineae of the mitral valve or adjacent to the top 1/3 of the papillary muscle. (2) Purkinje fibers existed in all FTs, including smaller and tiny FTs. (3) The Purkinje fibers contained in the FTs extended from the proximal to the distal end, and their electrophysiological characteristics were similar to the fibers on the endocardium, including anterograde, retrograde, and decremental conduction and automaticity. Conclusions. Purkinje fibers are commonly found in FTs. The electrophysiological characteristics of the Purkinje fibers contained in FTs are similar to the fibers on the endocardium. FTs might have an anatomical and electrophysiological basis for ventricular arrhythmia.

Objective. To explore the quantitative adjustment of ablation index (AI) under different baseline impedance to achieve similar lesion dimensions. Methods. (1) Keeping the AIs relatively constant, the lesion dimensions in different baseline impedances were studied. (2) According to Joule's law, Q=I²RT, keeping the current (I) unchanged, the powers corresponding to different baseline impedances can be obtained. Under different baseline impedances and corresponding powers, the swine hearts were ablated for 30s in simulated human circumstances. The baseline impedances, the lesion dimensions, and AIs were recorded. And the derivation of empirical formula was achieved according to the AIs and baseline impedance values in similar lesions dimension. (3) Basic AI and baseline impedance (AI₀/R₀) were set as 400/120Ω in the common AI groups and 550/120Ω in the high AI groups, AI values in different baseline impedances were calculated using the empirical formula, and the corresponding lesion dimensions were measured to verify this formula. Results. (1) Higher baseline impedances were related to smaller lesion dimensions at similar AIs. (2) The lesion dimensions were roughly the same after modulating the baseline impedance and power to keep the electric current relatively constant. The relationship between AI and R fitted with experimental data is AI=1.9933R+203.61 (r=0.9649), and the formula derived is ΔAI=(AI₀203)/R₀×ΔR. (3) Under the guidance of the empirical formula, there was no significant difference in lesion dimensions between the standard group and the formula guiding groups when AI₀=400, but there was a shrinking tendence when AI>700. Conclusion. The lesion depths are negatively correlated with baseline impedance at a certain AI. The relationship between baseline impedance and AI is ΔAI=(AI₀203)/R₀×ΔR. It is verified that when the AI is not too high, the empirical formula can be used to guide the quantitative adjustment of AIs at different baseline impedance, and the lesion depths achieved are roughly the same.

Aims: The study aims to investigate the impact of key parameters of pulsed field ablation (PFA) on lesion depth, including voltage (V), pulse width (PW), number of pulses (P), and ablation number (N), using potato models.Methods: Potatoes are utilized as a display of the irreversible electroporation lesion. The key ablation parameters were varied systematically to explore its influences on lesion depths.Results and conclusion: The key ablation parameters have varying degrees of influence on lesion depths, following the order of PW>V; V>P; PW>P; N>P. Lesion depths increased with higher values of V and P. However, when the total number of pulses reached 9,600, there was no significant increase in injury depth.

Installing digital subtraction angiography (DSA) equipment in an ambulance can provide crucial image guidance for the emergency medical service of cardiovascular diseases. However, the commonly used C-arm is too large to be directly installed in a narrow ambulance. This article presents a compact redundant prismatic-revolute hybrid joints radiography robot that can be installed inside an ambulance to provide DSA imaging. An analytical solution, along with a self-motion algorithm based on the continuous quantum particle swarm algorithm, is proposed to achieve accurate motion control and real-time joint avoidance for the radiography robot. The experimental results indicate that the maximum error of the radiography robot is 0.42 mm, which meets the requirements for DSA image collection. During the in vivo experiment, DSA images provided by the radiography robot guided the successful placement of a stent in the internal thoracic artery of a beagle. This verifies the feasibility of the proposed analytical solution in ensuring accurate motion control of the radiography robot.