Comparative analysis of femtosecond, picosecond, and nanosecond laser techniques for transseptal puncture: An in vitro study with pathological correlation.

Background: Advanced precision laser technologies for transseptal puncture are still under exploration. Femtosecond lasers, renowned for their high precision and minimal collateral damage, exhibit significant potential in transseptal puncture applications.

Objective: This study investigated the feasibility, effectiveness and pathological effects of femtosecond, picosecond, and nanosecond lasers for transseptal puncture in vitro.

Methods: Three different pulsed laser systems (femtosecond, picosecond, and nanosecond) were utilized for atrial septal puncture in fresh porcine hearts. The femtosecond laser operated at 1064 nm wavelength with 179 fs pulse width and 500 kHz repetition rate; the picosecond laser at 1962 nm with 52 ps pulse width and 60 MHz repetition rate; and the nanosecond laser at 1064 nm with 70 ns pulse width and 60 kHz repetition rate. With a focused spot size of approximately 100 μm, the power density ranged from 25.50 to 51.00 kW/cm (corresponding to energy densities of 0.05-0.10 J/cm for femtosecond, 424.40-848.80 μJ/cm for picosecond, and 0.42-0.85 J/cm for nanosecond lasers). Scanning diameters varied from 0.50 to 3.00 mm at a constant speed of 1 mm/s. Measurements of puncture diameter and thermal damage were taken using a digital optical microscope, with pathological examination evaluating tissue structure and injury extent. Multiple linear regression models were used to evaluate the effects of laser types, power, and scanning diameter on puncture outcomes. P < 0.05 was considered statistically significant.

Results: Using a focused spot size of 100 μm at power densities of 25.50-51.00 kW/cm (2.0-4.0 W), the femtosecond laser (500 kHz, 0.05-0.10 J/cm) and picosecond laser (60 MHz, 424.40-848.80 μJ/cm) achieved complete penetration across 0.50-3.00 mm scanning diameters, with puncture diameters of 0.51-3.02 mm and 0.51-3.01 mm respectively. The nanosecond laser (60 kHz, 0.42-0.85 J/cm) penetrated only at 0.50 mm scanning diameter and partially at 1.00 mm (3 W-4 W), with significantly smaller diameters (P < 0.001). Multiple regression showed scanning diameter primarily determined puncture size (β = 0.992, P < 0.001), while both power (β = 1.798, P = 0.002) and scanning diameter (β = 2.604, P < 0.001) affected thermal damage, with nanosecond (β = 6.515, P = 0.017) and picosecond lasers (β = 5.595, P = 0.039) showing greater thermal effects than femtosecond laser. Histologically, thermal damage progressed from minimal carbonization at 2 W to moderate-severe eosinophilic degeneration at 4 W… CONCLUSIONS: Transseptal puncture using laser systems demonstrated feasibility, particularly with femtosecond laser showing favorable outcomes in precision and thermal control under specified parameters, exhibit significant clinical potential. Further studies are needed to investigate the underlying mechanisms.

Key Messages: What is already known about this subject? Femtosecond lasers, characterized by their high peak power and minimal thermal damage, are expected to have potential clinical applications in transseptal puncture techniques. What does this study add? The effects of femtosecond, picosecond, and nanosecond lasers on ex vivo porcine atrial septum puncture were studied at varying power levels and puncture diameters. The results showed that femtosecond lasers had superior puncture capabilities compared to nanosecond lasers, with significantly higher thermal damage observed in the nanosecond laser. How might this impact on clinical practice? Ex vivo experiments with advanced lasers, particularly femtosecond lasers, have shown promising clinical feasibility. We will plan to pursue further research based on current findings.