In vitro characterization of radiofrequency ablation lesions in equine and swine myocardial tissue

Figures

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  Fig. 1. Schematic representation of the in vitro set-up. Myocardial tissue (A) was suspended in a bath with isotonic saline at 37 °C. Flow was created by a pump (B) with flow velocity at the level of the myocardial tissue set at 0.35 m/s. The ablation catheter (C) was mounted in a holder with a dynamometer (D) to maintain the catheter tip perpendicular to the tissue with a constant contact force of 20 g. The indifferent electrode (E) was placed in the bath and a resistor of 25 Ω (F) was placed between the indifferent electrode and the ablation generator (G).

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  Fig. 2. Measurements to analyse lesion dimensions and calculate the volume are shown on a schematic representation (left) and on a tissue sample of an ablation lesion in equine ventricular myocardium (right). The maximum depth (A), maximum diameter (B), depth at maximum diameter (C) and surface diameter (D) were measured.

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  Fig. 3. Bar charts present the maximum lesion diameter (a, d), lesion depth (b, e) and lesion volume (c, f) for each setting. Chart a-c present lesion dimensions for the equine right and left atrium. Chart d-f present lesion dimensions for equine and swine right ventricle. Error bars indicate the standard deviation. Bars with different letters indicate significant differences between settings (P < 0.05) within each group (right atrium, left atrium and equine right ventricle and swine right ventricle).

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  Fig. 4. Ablation lesions in the right ventricular wall of equine and swine hearts after 2,3,5-triphenyl tetrazolium chloride staining. Viable myocardium is stained dark red, whereas the necrotic ablation lesion remains unstained. It is noted that an increase in power or duration of radiofrequency energy led to an increase in lesion depth, diameter and volume.