Significant hemolysis is present during irreversible electroporation of cardiomyocytes in vitro.

BACKGROUND

Pulsed field ablation (PFA) of atrial fibrillation is a new method in clinical practice. Despite a favorable safety profile of PFA in atrial fibrillation ablation, rare cases of renal failure, probably due to hemolysis, have recently been reported.

OBJECTIVE

The aim of this study was to determine the rate of hemolysis and cardiac cell death during in vitro PFA with different electric field intensities.

METHODS

Blood samples from healthy volunteers and mouse HL-1 cardiomyocyte cell lines were subjected to in vitro irreversible electroporation using 216 bipolar pulses, each lasting 2 μs with intervals of 5 μs, repeated 20 times at a frequency of 1 Hz. These pulses varied from 500 V to 1500 V. Cell-free hemoglobin levels were assessed spectrophotometrically, and red blood cell microparticles were evaluated by flow cytometry. Cardiomyocyte death was quantified with propidium iodide.

RESULTS

Pulsed field energy (1000 V/cm, 1250 V/cm, and 1500 V/cm) was associated with a significant increase in cell-free hemoglobin (0.32 ± 0.16 g/L, 2.2 ± 0.96 g/L, and 5.7 ± 0.39 g/L; P < .01) and similar increase in the concentration of red blood cell microparticles. Significant rates of cardiomyocyte death were observed at electric field strengths of 750 V/cm, 1000 V/cm, 1250 V/cm, and 1500 V/cm (26.5% ± 5.9%, 44.3% ± 6.2%, 55.5% ± 6.9%, and 74.5% ± 17.8% of cardiomyocytes; P < .01).

CONCLUSION

The most effective induction of cell death in vitro was observed at 1500 V/cm. This intensity was also associated with a significant degree of hemolysis.