Ultrafast imaging of tissue ablation by a XeCl excimer laser in saline

Preisack, Melitta B.; Neu, W.; Nyga, Ralf; Wehrmann, Manfred; Haase, Karl K.; Karsch, Karl R.

doi:10.1002/lsm.1900120511

Cited by 20 publications

(8 citation statements)

References 18 publications

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“…In contrast to earlier observations, in vitro [9][10][11][12] and in vivo [13,14] studies have demonstrated the explosive nature of tissue ablation by excimer laser pulses: Each ablative laser pulse absorbed by tissue or by blood will induce a rapidly expanding and imploding water vapor bubble (lifetime up to 300 s, diameter up to 3 mm) and stress waves. We demonstrated that within tissue, the explosive water vapor bubble expansion separates tissue layers [13].…”

Section: Introductionmentioning

confidence: 70%

Saline flush during excimer laser angioplasty: Short and long term effects in the rabbit femoral artery

et al. 1998

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Background and Objective: In this study, the effect of flushing saline on arterial wall damage (medial ruptures and necrosis), intimal hyperplasia, and arterial remodeling was determined. During excimer laser coronary angioplasty saline is flushed to reduce the size of explosive water vapor bubbles formed by intraluminal delivery of excimer laser pulses in blood. Methods In the femoral artery of the rabbit, 600 excimer laser pulses (308 nm, 50 mJ/mm2 per pulse, 20 Hz) were delivered coaxially over a length of 20 mm in 10 bursts of 3 seconds each. In 24/48 procedures, saline was flushed (0.2 ml/s) via the guidewire channel. After 2 and 56 days, microscopic and angiographic results were compared. Results At 2 days, as compared to lasing in blood, saline flush had drastically reduced the incidence of dissections (2/12 vs. 11/12, P < 0.002), but had increased the extent of medial and adventitial necrosis. The latter is attributed to direct irradiation of the arterial wall. After 56 days, in the saline group, in the middle‐distal part of treated segments, medial necrosis without intimal hyperplasia was observed. However, at the edges of these lesions, intimal hyperplasia and arterial shrinkage reduced the lumen. Conclusion Flushing saline during coaxial excimer laser pulse delivery significantly reduced the incidence of vessel wall ruptures, and prevented intimal hyperplasia formation in part of the lesion. The histologic findings at 56 days are attributed to the optical window which the saline flush provides for direct ultraviolet light irradiation of the arterial wall. Lasers Surg. Med. 23:128–140, 1998. © 1998 Wiley‐Liss, Inc.

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Section: Introductionmentioning

confidence: 70%

Saline flush during excimer laser angioplasty: Short and long term effects in the rabbit femoral artery

et al. 1998

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“…Further refinement probably should be directed at ensuring work. Previous investigators have suggested that pressure transients might be due to volume expansion and/or implosion of cavitation bubbles, to hypersonic shock waves, or to microplasma formation [19,20]. The physical basis for potentially detrimental effects, strong absorption of 308-nm radiation by blood, plaque, and contrast, with consequent conversion of radiation into the energy of vaporization, is well documented [2 1-24].…”

Section: Discussionmentioning

confidence: 99%

Development of a new technique for reducing pressure pulse generation during 308‐nm excimer laser coronary angioplasty

Tcheng

Wells

Phillips

et al. 1995

Cathet. Cardiovasc. Diagn.

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Despite expectations that excimer laser ablation would result in a low incidence of coronary dissection, studies have documented a 15-20% incidence of dissection (including a 4-6% incidence of clinically significant dissection) during excimer interventions. This investigation sought to determine if pressure pulses produced by the exposure of fluid phase media (blood and contrast) to 308-nm excimer radiation might contribute to untoward outcomes. Pressure pulses generated in these media were quantitated to be > 100 atm. In vitro ablation of porcine aorta in the presence of blood or contrast resulted in tissue dissection, while ablation in pure crystalloid did not. Next, a "flush and bathe" technique designed to replace all blood and contrast with crystalloid was applied to a pilot population of 57 consecutive patients. There were no rhythm disturbances or laser-related clinically significant dissections in this group, and the clinical success rate was 95%. In summary, this report quantitates a potential etiology for excimer dissection and suggests that replacement of blood and contrast with crystalloid might improve procedural and clinical success rates.

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“…Photoacoustic waves and probe contact pressure assist tissue ablation [3,7,241 by providing additional energy for bond dissociation and debris removal. Generation of bubbles and subsequent shock waves have been shown to occur at energy densities below the water vaporization threshold [31, thereby lysing cell membranes [lo] and producing explosive ejection of ablated tissue [25]. Whereas it is possible for ablation products to be trapped between the tissue and probe in certain laser procedures, the high level of tissue hydration inherent with ab interno sclerostomy procedures and the easy deformity of soft ocular tissue prevent such entrapment of ablation debris.…”

Section: Composite Ablation Mechanismmentioning

confidence: 99%

Rate‐dependent, nonlinear photoablation of ocular tissue at 308 nm

Schallen¹,

Awh²,

Juan³

1994

Lasers Surg Med

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To quantify the dependence on pulse repetition rate of 308 nm laser ablation in ocular tissue and elucidate the photoablation mechanisms involved, 85 full-thickness ab interno sclerostomies were created in six human donor eyes using an 800-microns-diameter quartz optical fiber. A laser pulse duration of 135 ns, fluence of 31 mJ/mm2, and a fixed repetition rate between 5 and 40 Hz were used for 38 sclerostomies; the remaining 47 sclerostomies were completed at various laser settings during initial experimentation. Surprisingly, the numbers of pulses required for complete penetration of the optical fiber through the fixed tissue thickness were not constant as expected but decreased nonlinearly with increasing repetition rate. This demonstrates that the 308 nm excimer laser cuts ocular tissue significantly more rapidly per pulse at higher repetition rates. To explain this nonlinearity, we propose a composite ablation mechanism composed of photochemical, thermal, mechanical, and optical effects in varying proportions.

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Ultrafast imaging of tissue ablation by a XeCl excimer laser in saline

Cited by 20 publications

References 18 publications

Saline flush during excimer laser angioplasty: Short and long term effects in the rabbit femoral artery

Saline flush during excimer laser angioplasty: Short and long term effects in the rabbit femoral artery

Development of a new technique for reducing pressure pulse generation during 308‐nm excimer laser coronary angioplasty

Rate‐dependent, nonlinear photoablation of ocular tissue at 308 nm

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