Pulsed Laser Fiber Delivery for High-Energy Tissue Ablation
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Solution Overview
Problem
Existing methods for delivering high pulsed laser power through optical fibers for tissue ablation face challenges such as fiber damage due to hot spots, limited energy density carrying capacity, and potential thermal damage during procedures like lead extraction and atherectomy.
Innovation Solution
The use of a multimode laser with a highly multimode output, characterized by an M2 parameter of at least 30, is employed to transmit high energy pulses through optical fibers. This approach reduces the prevalence of fiber damage and allows for higher energy density pulses to be transmitted safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high peak power pulses are delivered through optical fibers for tissue ablation, then effective tissue ablation is achieved, but fiber damage occurs due to hot spots and selective heating
Solution Approach 1:
The single high peak power pulse is segmented into multiple lower peak power sub-pulses delivered in rapid succession. This segmentation reduces the peak power demand on any single pulse, thereby eliminating hot spots and selective heating that cause fiber damage, while the cumulative energy delivery maintains effective tissue ablation capability.
Solution Approach 2:
Instead of delivering one continuous high peak power pulse, the system uses periodic action by delivering multiple short sub-pulses separated by brief intervals. This periodic delivery allows thermal diffusion between pulses, preventing heat accumulation and selective heating in the fiber, thus avoiding fiber damage while maintaining ablation effectiveness.
2Productivity
If high fluence pulses are used for effective tissue ablation, then ablation efficiency is improved, but thermal damage to surrounding material increases
Solution Approach 1:
The laser delivers multiple sub-pulses with periodic timing intervals that allow thermal diffusion between pulses. This periodic action maintains high cumulative fluence for effective ablation while the intervals prevent excessive heat accumulation that would cause thermal damage to surrounding tissue, thus resolving the contradiction between ablation efficiency and thermal damage.
Solution Approach 2:
The system changes the temporal parameters of pulse delivery by using multiple shorter sub-pulses instead of one long pulse. This parameter change allows the cumulative energy delivery to achieve high ablation efficiency while the shorter individual pulse duration and intervals between pulses prevent thermal diffusion into surrounding material, reducing thermal damage.
3Reliability
If beam homogenization methods are used to eliminate hot spots, then fiber damage is reduced, but device complexity increases
Solution Approach 1:
Instead of adding complex beam homogenization optical components, the system changes the temporal parameters of pulse delivery by using multiple sub-pulses. This parameter change inherently eliminates hot spots and selective heating through reduced peak power, achieving fiber damage reduction without increasing device complexity with additional homogenization components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The described system achieves a higher damage threshold and enables the transmission of pulses with higher energy density than previous systems, while minimizing the risk of fiber damage and thermal injury during ablative procedures.
Implementation Method 1
the UV laser adds enough energy to disrupt the molecular bonds of the surface tissue, which effectively disintegrates into the air in a tightly controlled manner through ablation rather than burning
Implementation Method 2
ultra-violet (UV) light has many advantages, as it is well absorbed by biological matter and organic compounds
Implementation Method 3
The laser energy is also strongly absorbed and leads to sharp local elevation of temperature and results in generation of strong mechanical forces leading to photo-acoustic and photo-thermal ablation
Implementation Method 4
leads to sharp local elevation of temperature
Implementation Method 5
results in generation of strong mechanical forces leading to photo-acoustic and photo-thermal ablation
Implementation Method 6
generation of strong mechanical forces leading to photo-acoustic and photo-thermal ablation
Data Source
AI summary
Systems for enabling delivery of very high peak power laser pulses through optical fibers for use in ablation procedures preferably in contact mode. Such lasers advantageously emit at 355 nm wavelength. Other systems enable selective removal of undesired tissue within a blood vessel, while minimizing the risk of damaging the blood vessel itself, based on the use of the ablative properties of short laser pulses of 320 to 400 nm laser wavelength, with selected parameters of the mechanical walls of the tubes constituting the catheter, of the laser fluence and of the force that is applied by the catheter on the tissues. Additionally, a novel method of calibrating such catheters is disclosed, which also enables real time monitoring of the ablation process. Additionally, novel methods of protecting the fibers exit facets are disclosed.