Selective laser ablation of venous thrombus: Implications for a new approach in the treatment of pulmonary embolus

LaMuraglia, Glenn M.; Anderson, R. Rox; Parrish, John A.; Zhang, Danyi; Prince, Martin R.

doi:10.1002/lsm.1900080507

Cited by 21 publications

(8 citation statements)

References 11 publications

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“…There are two major findings in this study: (1) Solidstate, pulsed-wave, mid-infrared laser irradiation can induce fibrinolysis by mechanical disruption of the lased clot, in contrast to selective thrombolysis, which is achieved by other wavelength lasers, such as the pulsed dye-laser [11]; (2) thin fibrin fibers are more resistant than thick fibers to the photoacoustic effect of this wavelength energy.…”

Section: Discussionmentioning

confidence: 99%

Photoacoustic fibrinolysis: Pulsed-wave, mid-infrared laser-clot interaction

et al. 1996

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Objectives: The purpose of this study was to determine whether a mid-infrared laser can induce selective fibrinolysis and to analyze the effect of altered fibrin structure (thin vs. thick fibers) on laser-clot interaction. Background: Mechanical disruption of thrombus can be achieved with balloon angioplasty, sonication, and thermal energy. Thrombi avidly absorb light in the mid-infrared optical spectrum due to their high water content. This phenomenon provides a potential for mid-infrared lasers as a source for selective thrombolysis. As fibrin is the essential component of clot, a study of mid-infrared laser-fibrin interaction is warranted. Methods: Clots of varying fibrin structure were lased in cuvettes with a solid-state, pulsed-wave, mid-infrared laser (2.1 micron, 500 mJ/pulse, 250 msec pulse length). Total pulse energies of 5 Joules (J), 10 J, 37.5 J, 75 J, and 112.5 J were tested. Protein content of the extruded fluid was measured by optical density absorbance at 280 nm. Th e amount of released material was studied as a function of lasing energy and clot structure. SDS-polyacrylamide gel electrophoresis was applied for analysis of protein bands in order to identify unique protein bands released by the selective effect of laser fibrinolysis. Results: A threshold for mid-infrared laser induced fibrinolysis was found; application of up to 20 J of energy did not result in dissolution. As lasing energy was increased above 37.5 J, the structure of these gels was mechanically destroyed and 12.4 +/- 6.7% (mean +/- SEM) of the original content of protein was released. Electrophoresis revealed that lased gels did not release any unique protein band. Lased, thin fibers released significantly less protein than thick fibers, indicating that they are more resistant to the effect of this wavelength of energy. Conclusions: Mid-infrared laser can induce in-vitro photoacoustic dissolution of fibrin clots. However, this wavelength laser achieves fibrinolysis by me chanical destruction of the target clot rather than by a selective effect, as induced by the pulsed-dye laser. A threshold exists for energy levels required. Thin fibrin fibers, with their high elastic modulus (i.e., gel rigidity) appear more resistant than thick fibers to the effect of lasing at this wavelength.

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Section: Discussionmentioning

confidence: 99%

Photoacoustic fibrinolysis: Pulsed-wave, mid-infrared laser-clot interaction

et al. 1996

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“…The linear absorption coefficients of Nd:YAG laser light for oxyhaemoglobin, deoxyhaemoglobin and melanin are 5 cm -1, 0.5 cm -1 and 20 cm -1, respectively [1,[16][17][18]. Since the amount of thermal energy generated by an absorbing structure is a function of the quanta of light initially absorbed, one would expect melanin granules to radiate more heat than blood (even though other important factors have to be taken into account).…”

Section: (A) Absorption By Blood and Melanin And Other Optical Considmentioning

confidence: 99%

Induction of vascular haemostasis by Nd:YAG laser light in melanin-rich and melanin-free tissue

Fankhauser

et al. 1992

Doc Ophthalmol

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Haemostasis was effected in vessels of melanin-rich (MR: choroid) and melanin-free (MF: mesentery) rabbit tissue irradiated with a cw-Nd:YAG laser. The following parameters were employed: - pulse duration: 200 ms (MR) and 100 ms (MF); focal spot diameter: 200 microns (MR) and 80 microns (MF); pulse energies: 100-250 mJ (MR) and 0.5-1 J (MF); irradiances: 1.6-4.0 kW cm-2 (MR) and 1-2 x 10(2) kW cm-2 (MF). In melanin-rich tissue, laser energy is absorbed principally by melanin granules contained within the stromal melanocytes. The heat generated in these structures radiates into the surrounding tissue where it is dissipated. The damage thus incurred by the endothelium of blood vessels encompassed within this field triggers the haemostatic mechanism whereby blood flow is arrested. This effect is realized by the formation of an occluding plug of platelets, which is stabilized by the deposition of fibrin, particularly in capillaries, and to a lesser degree in larger vessels of the vascular lamina. In melanin-free tissue, haemoglobin serves as the primary site of energy absorption, which is thus shifted from the stroma to the vessel lumen. Irradiation of vessels in such tissue leads to thermocoagulation of plasma proteins and consequent stasis of blood flow.

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“…Clinical trials have demonstrated the efficacy of laser thrombolysis for coronary vessels [6,8,10,11]. An excellent review of lasers in cardiology was written by Topaz [10] and includes sections on the use of lasers for treatment of acute myocardial infarction and for peripheral laser angioplasty.…”

Section: Introductionmentioning

confidence: 99%

“…Laser thrombolysis, the clearing of thrombus-obstructed arteries by means of laser energy, has been investigated extensively and demonstrated in clinical situations [1][2][3][4][5][6][7][8][9][10][11]. Clinical trials have demonstrated the efficacy of laser thrombolysis for coronary vessels [6,8,10,11].…”

Section: Introductionmentioning

confidence: 99%

Laser thrombolysis using long pulse frequency-doubled Nd:YAG lasers

Viator¹,

Prahl²

1999

Lasers Surg. Med.

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Background and Objective: Laser thrombolysis is a means for clearing blood clots in occluded arteries. Many researchers have studied the mechanisms of clot ablation, and research clinicians have used the technique to treat myocardial infarction with a number of different laser systems. Specifically, a 1-sec pulsed dye laser has been used clinically to remove blood clots in coronary arteries. As a comparative study, the ablation characteristics of lasers with pulse durations in the ranges of 50-150 sec and 2-10 msec were investigated. Two frequencydoubled Nd:YAG lasers at 532 nm were used in this study. Ablation threshold and ablation efficiency of gel phantoms and thrombus using these two lasers were measured and compared with the results of the pulsed dye laser. The pulsed dye laser in this study operated at 522 nm. Study Design/Materials and Methods: Gelatin samples with 150 cm −1 absorption coefficient at 532 nm and animal clot were confined to 3-mm silicone tubes to measure ablation parameters. Additional samples with 150 cm −1 absorption coefficient at 522 nm were prepared for use with the pulsed dye laser. A fluorescence technique and photographic bubble detection were used to determine ablation threshold. A spectrophotometric technique was used to determine ablation efficiency. Results: The ablation threshold of the gel phantoms for all three lasers was determined to be 17 ± 2 mJ/mm 2 . Ablation efficiency for the gel phantoms was 1.7 ± 0.1 g/mJ. Clot had an ablation efficiency of 2.9 ± 1.0 g/mJ. Conclusions: Ablation threshold and efficiency are independent of laser pulse duration for 1-sec, 50-150-sec, and 2-10-msec pulses (P < 0.05).

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Selective laser ablation of venous thrombus: Implications for a new approach in the treatment of pulmonary embolus

Cited by 21 publications

References 11 publications

Photoacoustic fibrinolysis: Pulsed-wave, mid-infrared laser-clot interaction

Photoacoustic fibrinolysis: Pulsed-wave, mid-infrared laser-clot interaction

Induction of vascular haemostasis by Nd:YAG laser light in melanin-rich and melanin-free tissue

Laser thrombolysis using long pulse frequency-doubled Nd:YAG lasers

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