Double pass 595 nm pulsed dye laser at a 6 minute interval for the treatment of port-wine stains is not more effective than single pass.

BACKGROUND: Pulsed dye laser (PDL) is the first choice for treatment of port wine stains (PWS). However, outcome is highly variable and only a few patients achieve complete clearance. The objective of the study was to compare efficacy and safety of single pass PDL with double pass PDL at a 6 minute interval. METHODS: We conducted a randomized within-patient controlled study on PWS resistant to multiple single pass PDL treatments. In each patient two similar PWS areas were randomly allocated to PDL treatment (595 nm, 7 mm spot size, 1.5 mseconds pulse duration) using, as a control treatment, a single pass (12 J/cm(2)) or, as a new treatment, a double pass PDL (11 J/cm(2), second pass 6 minutes after the first pass). Both test areas were treated two times, 8 weeks apart. PWS clearance was assessed by two blinded dermatologists, and by color measurement (L*a*b) using reflectance spectroscopy, at 3 months follow-up. RESULTS: Sixteen out of 17 included patients completed follow-up. The mean number of treatments before inclusion was 15. Overall color assessed by spectrophotometer showed no improvement for either single or double pass PDL. Blinded Physician Global Assessment and Patient Global Assessment showed a high variability in outcome, with mostly only moderate improvement of the PWS for either single pass or double pass PDL. Furthermore, there was no significant difference in any of the outcomes between single pass and double pass PDL. CONCLUSION: At the chosen settings and after two treatment sessions, double pass PDL at a 6 minute interval does not result in improved clearance of PWS as compared to single pass treatment.

Laser-induced (endo)vascular photothermal effects studied by combined brightfield and fluorescence microscopy in hamster dorsal skin fold venules.

The putative features of the (endo)vascular photothermal response, characterized by laser-induced thermal denaturation of blood and vessel wall constituents, have been elucidated individually, but not simultaneously in dynamic, isolated in vivo systems. A hamster dorsal skin fold model in combination with brightfield/fluorescence intravital microscopy was used to examine the effect of laser pulse duration and blood flow velocity on the size of the thermal coagulum, its attachment behavior, and laser-mediated vasomotion. The size of the coagulum and the extent of vasoconstriction and latent vasodilation were proportional to the laser pulse duration, but pulse duration had no effect on coagulum attachment/dislodgement. Blood flow velocity exhibited no significant effect on the studied parameters. The (endo)vascular photothermal response is governed predominantly by laser energy deposition and to a marginal extent by blood flow velocity.

25 years of laser assisted vascular anastomosis (LAVA): what have we learned?

OBJECTIVES: Laser assisted vascular anastomosis (LAVA) has been developed to a stage where clinical use is within reach. Advantages of LAVA are minimal vessel damage, faster operation and the potential for minimally invasive application. DESIGN: A Medline literature search was performed on vessel welding combined with cross-referencing. RESULTS: Four different lasers have mostly been used for LAVA, always in combination with stay sutures. The CO(2) laser has only been used in the early period. Without solder, mean leaking point pressures (LPP) of 754 mmHg (n=75) were obtained, only slightly lower than in suture controls (LPP=915 mmHg, n=82). At follow-up the percentage of aneurysms was high (overall 12% in n=486). Although Argon LAVA showed moderate success (LPP=146 mmHg, n=125), the first clinical application has been successfully performed. Diode LAVA in combination with solder and dye resulted in an acceptable LPP of 409 mmHg (n=163) in larger vessels, with a low incidence of aneurysm formation (1% in n=107). CONCLUSION: At present the diode laser is the most popular. Solder developments resulted in stronger welds and might make stay sutures redundant. The combination of CO(2) laser and solders has not been evaluated and deserves further investigation.

The old spontaneously hypertensive rat as a model for transmyocardial laser revascularisation research.

Animal models used in transmyocardial laser revascularisation (TMLR) research lack the increased fibrosis observed in patients with chronic myocardial ischaemia. This pathology has also been described in patients with chronic elevated afterload, and therefore we evaluated the spontaneously hypertensive rat (SHR) as a model for TMLR research. We compared (1) the myocardial pathology of SHR with the pathology of three TMLR patients, (2) the reaction to TMLR in SHR and human myocardium using three different lasers, and (3) myocardial hypoxia in SHR myocardium and (healthy) Wistar rat myocardium. SHR and human myocardium both showed increased fibrosis and a similar myocardial reaction to TMLR (comparable morphology of fibrotic TMLR channel scars). More hypoxic cells were observed in SHR than in Wistar control rat myocardium. The similarities between SHR and human chronic ischaemic myocardium make the SHR a suitable model for TMLR research.

Transmyocardial laser revascularisation and other treatment modalities for angina pectoris.

Ischaemic heart disease is one of the leading causes of morbidity and mortality in the western world. This paper provides an overview of the different treatments for one of the most common manifestations of ischaemic heart disease: angina pectoris. Besides the currently available conventional methods, several alternative treatments are described, with a special focus on transmyocardial laser revascularisation.

Comparison of normal piglet bladder damage after PDT with oral or intravesical administration of ALA.

5-Aminolaevulinic-acid (ALA) can be used as an alternative drug in photodynamic therapy of the bladder, since the selective formation of protoporphyrin IX (PpIX) in the tumour and the virtual absence of induced skin photosensitivity are theoretically advantageous for clinical use. A preclinical study was performed, using an in vivo normal piglet bladder model, in order to determine the maximum drug and light doses for reversible tissue damage. Various ALA doses were administered either orally or instilled in the bladder and different radiant exposures were applied. Bladder biopsies were taken at regular intervals and tissue damage was investigated histologically. After oral ALA-administration the PpIX concentration was determined in plasma, erythrocytes and various tissues. In the case of oral administration, reversible bladder damage was observed using 60-75 mg/kg ALA combined with a radiant exposure of 100 J/cm(2) (direct radiant exposure plus scattered 632 nm light) 5-7 h later. For an oral ALA dose of up to 150 mg/kg, the maximum PpIX concentration is reached at approximately 5 h following administration and in neither skin nor bladder tissue is PpIX present at 10-11 h after administration. This ALA dose combined with a radiant exposure of 200 J/cm(2) produces irreversible bladder damage (extensive necrosis and ulceration). In the case of intravesical instillation for 4-4.75 h, an ALA dose of 2.5 g in 50 ml phosphate buffered saline and a radiant exposure of 100 J/cm(2) are still too high to obtain reversible tissue damage; at this dose one of the 13 pigs developed a shrunken bladder with a fibrotic, thickened bladder wall. These drug and light combinations reported above should be regarded as upper limits in pigs and can serve as an indication for the toxicity of the treatment in a clinical setting.

Angiogenesis three months after clinical transmyocardial laser revascularization using an excimer laser.

BACKGROUND AND OBJECTIVE: We present for the first time histologic findings 3 months after clinical transmyocardial laser revascularization using a XeCl excimer laser. STUDY DESIGN/MATERIALS AND METHODS: Histology was performed on a patient who died from a noncardiac cause 3 months post-excimer TMLR. RESULTS: In the treated myocardium, no patent channels were found but scars were seen with a linear distribution and in continuity with circumscribed small fibrotic endocardial and epicardial scars. The scars were highly vascularized by new vessels, ranging from small capillaries to large thin walled, and sometimes branching ectatic vessels. Sprouting of vessels into the adjacent myocardium was also observed. CONCLUSION: These results suggest that angiogenesis might play a role in the clinical improvement after TMLR.

Laser, fibrin glue, or suture repair of peripheral nerves: a comparative functional, histological, and morphometric study in the rat sciatic nerve.

OBJECT: This study was undertaken to evaluate CO2 laser-assisted nerve repair and compare it with nerve repair performed with fibrin glue or absorbable sutures. METHODS: In eight rats, the sciatic nerve was sharply transected and approximated using two 10-0 absorbable sutures and then fused by means of CO2 milliwatt laser welding (power 100 mW, exposure time 1 second per pulse, spot size 320 microm), with the addition of a protein solder (bovine albumin) to reinforce the repair site. The control groups consisted of eight rats in which the nerves were approximated with two 10-0 absorbable sutures and subsequently glued using a fibrin sealant (Tissucol), and eight rats in which the nerves were repaired using conventional microsurgical sutures (four to six 10-0 sutures in the perineurium or epineurium). Evaluation was performed 16 weeks postsurgery and included the toe-spreading test and light microscopy and morphometric assessment. The motor function of the nerves in all groups showed gradual improvement with time. At 16 weeks, the motor function was approximately 60% of the normal function, and there were no significant differences among the groups. On histological studies, all nerves revealed various degrees of axonal regeneration, with myelinated fibers in the distal nerve segments. There were slight differences in favor of the group treated with laser repair, in terms of wound healing at the repair site. In all groups, the number of axons distal to the repair site was higher compared with those proximal, but the axon diameter was significantly less than that in control nerves (p < 0.05). There were no significant differences in the number, density, or diameter of the axons in the proximal or distal nerve segments among the three nerve repair groups (p < 0.05), although there was a trend toward more and thicker myelinated axons in the distal segments of the laser-repaired nerves. CONCLUSIONS: It was found that CO2 laser-assisted nerve repair with soldering is at least equal to fibrin glue and suture repair in effectiveness in a rodent model of sciatic nerve repair.

Laser pulse impact on rat mesenteric blood vessels in relation to laser treatment of port wine stain.

BACKGROUND AND OBJECTIVE: To study the impact of laser pulses on animal microvasculature as a model for laser treatment of port wine stains. STUDY DESIGN/MATERIALS AND METHODS: Rat mesenteric blood vessels were irradiated with a laser pulse (585 nm, 0.2-0.6 ms pulse duration, 0.5-30 J/cm(2) radiant exposure). Video microscopy was used to assess vessel dilation, formation of intravascular thrombi, bubble formation, and vessel rupture. Changes in reflection during a laser pulse were measured by simultaneously recording the temporal behavior of the incident and reflected signals. RESULTS: A threshold radiant exposure of approximately 3 J/cm(2) was found for changes in optical properties of blood in vivo, confirming previous in vitro results. Often, laser exposure induced a significant increase in vessel diameter, up to three times the initial diameter for venules and four times for arterioles, within 200 ms after laser exposure. Arterioles were more likely to dilate than venules. Sometimes, immediately after the pulse, round structures, interpreted as being gas bubbles, were seen within the vessel lumen. CONCLUSIONS: A variety of phenomena can occur when blood vessels of sizes comparable to those in port wine stains are irradiated with laser pulses as used in port wine stain treatment. Thrombus formation and vessel rupture have been described before from histological sections of laser-irradiated port wine stains. However, vessel dilation and formation of non-transient gas bubbles as found in this study have not been described before.

Effect of CO(2)-Milliwatt laser on peripheral nerves: part II. A histological and functional study.

In order to further explore the role of laser for microneural repair, the early and late effects of CO(2) laser irradiation on intact rat sciatic nerves were investigated. A total of 48 rat sciatic nerves were exposed to 100-mW laser power with a pulse duration of 1.0 s and a spot size of 320 microm. In one-half of the nerves, albumin solder was applied to the nerve followed by laser irradiation. The results were evaluated up to 94 days after surgery with functional toe-spreading test, and light and transmission electron microscopy. Irradiation of the nerve resulted in almost no deficit in the motor function. A subperineurial degeneration of myelinated and unmyelinated axons is observed in the first 2 weeks after laser irradiation, while the central part of the nerve remains undamaged. The degeneration is followed by axonal regeneration with subsequent maturation of nerve fibres in time. No excessive intraneural or extraneural scarring was seen. In the soldered nerves, the solder elicits an inflammatory reaction upon the epineurium in the first week after irradiation. By week 1, the solder is completely absorbed. After 2 weeks, the inflammatory reaction ceases and by week 4, no residual reaction is seen. At 12 weeks, only minimally disarranged epineurium is seen with otherwise normal neural architecture. In conclusion, CO(2) laser irradiation at 100 mW with pulses of 1.0 s has no long term negative effects on nerve function and morphology. Therefore, these laser settings can be safely applied for laser-assisted nerve repair.

Distribution of steroidogenic enzymes involved in androgen synthesis in polycystic ovaries: an immunohistochemical study.

To find an explanation for the possible working mechanism of laparoscopic ovarian electrocautery for the treatment of anovulation in polycystic ovarian syndrome (PCOS), we evaluated the distribution of steroidogenic enzymes involved in the synthesis of ovarian androgens in surgical pathology specimens of entire polycystic ovaries. A total of 13 formalin-fixed and paraffin-embedded samples of the ovaries of patients with clinically proven PCOS were immunostained with specific antibodies against cholesterol side-chain-cleavage enzyme (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17alpha-hydroxylase (P450c17) and adrenal 4-binding protein (Ad4BP), a transcription factor of steroidogenic enzymes. Follicular theca cells of all ovaries demonstrated marked immunoreactivity for Ad4BP, P450scc, 3beta-HSD and P450c17. Granulosa cells of seven ovaries expressed Ad4BP, while granulosa cells of three ovaries also showed P450scc. In the granulosa cells of all ovaries, 3beta-HSD and P450c17 immunoreactivity was not observed. In the stroma, luteinized cells of most ovaries demonstrated Ad4BP, P450scc, 3beta-HSD and P450c17 immunoreactivity, but at a much lower level compared with the follicular theca cells. Non-luteinized stromal cells sporadically demonstrated Ad4BP, P450scc, 3beta-HSD and P450c17 immunoreactivity. The stromal steroidogenic cells were mainly located in the ovarian cortex, except for some hilus steroidogenic cells. These data demonstrate that in polycystic ovaries, androgens are mainly produced in the follicular theca cells and to some extent in luteinized stromal cells. This suggests that the working mechanism of laparoscopic electrocautery of the ovary is primarily explained through the reduction of ovarian hyperandrogenism by coagulation of follicular theca cells and concomitant stroma.

Alternative surgical exposure of the rat heart in vivo using a simple abdominal approach.

Access to the heart in laboratory rats is usually performed via a median sternotomy or a lateral thoracotomy. An alternative, less traumatic approach to the in vivo rat heart with improved survival is described. The technique uses an upper median laparotomy extending alongside the xyphoid bone. The xyphoid bone is retracted in a rostral direction, and a T-shaped cut is made in the diaphragm thus opening the thoracic cavity. Using a retractor the opening in the diaphragm is spread and the heart is exposed. We performed this abdominal approach in 23 anaesthetised and mechanically ventilated (for 2 h) rats and found physiologic intra-operative haemodynamics, a good postoperative recovery and 0% mortality.

Effect of a modified Nd:YAG laser technique on neuroma formation: An experimental study in rat sciatic nerve.

BACKGROUND AND OBJECTIVES: Traumatic transection of a peripheral nerve is inherently associated with the development of neuroma at the end of the proximal stump, often leading to therapy-resistant pain. This study was designed to evaluate whether the neodymium:yttrium aluminum garnet (Nd:YAG) laser could prevent neuroma formation after neurectomy. STUDY DESIGN/MATERIALS AND METHODS: The sciatic nerves of 14 rats were diffuse coagulated by defocused Nd:YAG laser (12 W power), and subsequently transected with additional focused laser energy. The control group consisted of contralateral nerves transected by microscissors. The nerves were reexposed at different time intervals up to 9 weeks after surgery, and evaluation consisted of macroscopy, and light and transmission electron microscopy. RESULTS: True neuroma formation could not be observed after laser transection, and only five nerves formed a neuromatous bulb, with minimal adhesions to surrounding tissue. Microscissor transection resulted in widespread amputation neuromas, consisting of regenerating axons and connective tissue, and nervous tissue regenerating into surrounding tissue. Laser-transected nerves showed degenerative changes of the axons and myelin, while proliferation of Schwann cells could not be observed. No outgrowth of axons could be observed outside the coagulated proximal stump. An epi/perineurial layer was present, covering the nerve stumps. Microscissor-transected nerves showed proliferation of fibroblasts and Schwann cells, forming minifascicles, and vigorous outgrowth of axons into the tissue and even into the distal nerve stump. CONCLUSIONS: Within the limitations of this study it is concluded that the formation of amputation neuromas is suppressed by Nd:YAG laser application by thermal coagulation of the nerve and suppression of Schwann-cell proliferation.

Clinical outcome after unilateral oophorectomy in patients with polycystic ovary syndrome.

The objective of this study is to report retrospectively on the clinical outcome of unilateral oophorectomy in 14 women with polycystic ovary syndrome who had undergone this treatment 14-18 years ago in our hospital for clomiphene citrate-resistant anovulation and long standing infertility or for severe hirsutism. The main outcome measures were menstrual cycle, pregnancy, hirsutism, testosterone concentrations, and premature ovarian failure. Unilateral oophorectomy restored regular menstrual cycles in 12 of the 14 patients. Thirteen years later, nine out of 12 patients still had regular menstrual cycles. Ten patients wished to become pregnant. Seven of them conceived spontaneously. Eleven patients complained of severe hirsutism. After unilateral oophorectomy, hirsutism regressed subjectively in six. Testosterone blood concentrations decreased significantly within the first year after unilateral oophorectomy in 11 patients. None of the women entered menopause within 14-18 years after surgery. Our results indicate that unilateral oophorectomy restores ovulatory function for many years in the majority of patients and does not result in premature ovarian failure. However, unilateral oophorectomy should not be recommended as a standard treatment for clomiphene citrate-resistant patients with polycystic ovary syndrome.

Pneumothorax monitoring by remittance measurement: comparison between experimental model and animal studies.

Pneumothorax monitoring by remittance measurement in neonatology is investigated using model experiments. The results are compared to previous animal experiments. A multifibre probe is used to measure the change in remittance at 632.8 nm and 790 nm as a function of the thickness of a layer of air between a model chest wall (optically matched to piglet chest walls) and a model lung. An increase in thickness of this layer of air results in a decrease in remittance. Only when a relatively thin model chest wall is used (thickness 4 or 6 mm) and detection fibres are at some distance from the source, is this decrease in remittance preceded by an initial increase in remittance. Relative changes in remittance are larger at 790 nm then at 632.8 nm. The results in general correspond to the results of the animal experiments. However, not all results of the animal experiments could be explained. We conclude that our assumptions for the model experiments did not cover all aspects of the development of a pneumothorax and dynamic models with changing optical properties should be used instead. In conclusion, the results in general confirm and help understand the results of the animal experiments and indicate that pneumothorax monitoring by remittance measurement is feasible.

Transmyocardial laser channels.

We present 2-dimensional echocardiographic images of laser-made channels in the myocardium in an experimental model and in a patient treated with transmyocardial laser revascularization.

Optical absorption of blood depends on temperature during a 0.5 ms laser pulse at 586 nm.

Optical properties are important parameters in port wine stain laser treatment models. In this study we investigated whether changes in blood optical properties occur during a 0.5 ms laser pulse. Blood from three volunteers was irradiated in vitro with laser pulses (radiant exposure 2-12 J cm-2, wavelength 586 nm, pulse length 0.5 ms). Reflection and transmission coefficients, measured using double integrating spheres, decreased slightly during the first part of the pulse. At 2.9 J cm-2 radiant exposure, the reflectance increased, independent of total radiant exposure of the pulse. This was caused by blood coagulation. A second sudden increase in reflection and a significant increase in transmission occurred near 6.3 J cm-2 and was accompanied by a "popping" sound, indicating rapid expansion of bubbles due to blood vaporization. A multilayered model of blood was used to fit calculated transmission coefficient curves to the measurements and determine temperature-dependent optical blood absorption. Heat diffusion was shown to be of minor importance. A 2.5-fold increase in absorption for temperatures increasing from 20 to 100 degrees C, accurately describes transmission coefficients measured up to 2.9 J cm-2.

In vitro double-integrating-sphere optical properties of tissues between 630 and 1064 nm.

The optical properties (absorption and scattering coefficients and the scattering anisotropy factor) were measured in vitro for cartilage, liver, lung, muscle, myocardium, skin, and tumour (colon adenocarcinoma CC 531) at 630, 632.8, 790, 850 and 1064 nm. Rabbits, rats, piglets, goats, and dogs were used to obtain the tissues. A double-integrating-sphere setup with an intervening sample was used to determine the reflectance, and the diffuse and collimated transmittances of the sample. The inverse adding-doubling algorithm was used to determine the optical properties from the measurements. The overall results were comparable to those available in the literature, although only limited data are available at 790-850 nm. The results were reproducible for a specific sample at a specific wavelength. However, when comparing the results of different samples of the same tissue or different lasers with approximately the same wavelength (e.g. argon dye laser at 630 nm and HeNe laser at 632.8 nm) variations are large. We believe these variations in optical properties should be explained by biological variations of the tissues. In conclusion, we report on an extensive set of in vitro absorption and scattering properties of tissues measured with the same equipment and software, and by the same group. Although the accuracy of the method requires further improvement, it is highly likely that the other existing data in the literature have a similar level of accuracy.