Laser Ablation Of Varicose Veins Research Articles

Deep vein thrombosis after sclerotherapy and endovenous laser ablation of varicose veins - an observational study.

Background: The risk of developing deep vein thrombosis (DVT) after endovenous ablation of varicose veins varies in the literature. Little is known about the characteristics of this complication and associated factors. This study aimed: 1) to study the occurrence of DVT after ultrasound-guided foam sclerotherapy (UGFS) alone or combined with endovenous laser ablation (EVLA) for lower-limb varicose veins; 2) to identify factors associated with DVT. Patients and methods: The study included all outpatients aged 18 years or older who underwent UGFS and EVLA or UGFS alone at the University Hospital of Zurich between 2011 and 2015. Data were extracted from the hospital electronic medical record. Patients were surveyed about their level of pain after the procedure and their level of satisfaction with the procedure. Duplex ultrasound was used to assess the deep venous system 7-10 days and 6-8 months after the procedure. Regression analysis was used to examine the association of patient and procedure characteristics with the development of DVT. Results: A total of 334 patients (561 procedures performed in 393 different sessions) were included: 73% of the patients underwent combined UGFS and EVLA and 27% underwent UGFS alone. DVT occurred in 24 (7.2%) patients, of whom 88% underwent combined procedures and 17% underwent interventions involving both the great and small saphenous veins on the same session. DVT occurred in 8.2% of patients receiving thromboprophylaxis and in 9.5% of patients not receiving thromboprophylaxis. DVT occurred in 5.2% of women and 11.9% of men. No factors associated with a diagnosis of DVT after intervention were identified. Pain and satisfaction levels did not differ between patients with and without DVT. Conclusions: This study adds to the knowledge of the risk of DVT following UGFS alone or combined with EVLA. Further studies are needed to revise thromboprophylaxis.

Clinical efficacy of sodium aescinate administration following endovenous laser ablation for varicose veins.

Endovenous interventions and minimally invasive procedures are effective in the management of varicose veins. However, they can cause postoperative discomfort. To evaluate the clinical efficacy of sodium aescinate (SA) in improving edema, pain, vein-specific symptoms, and quality of life in patients following endovenous laser ablation (EVLA) for varicose veins. In this single-center randomized controlled trial (RCT), patients were allocated into two groups: in Group A, 60mg SA was administered twice daily for 20days, and in Group B (control), no venoactive drug was prescribed. The Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification system for chronic venous disorders was used to assess the varicose veins. The circumferences of the calf and ankle were recorded for evaluating edema. The 10-point Visual Analog Scale (VAS), Venous Clinical Severity Score (VCSS), and Aberdeen Varicose Veins Questionnaire (AVVQ) were used to measure the pain intensity, overall varicose vein severity, and patient's quality of life, respectively. The study included 87 patients (mean age, 59.9 ± 10.7years; 54 men) with CEAP class C2-C5 varicose veins who underwent EVLA and phlebectomy or foam sclerotherapy. The calf circumference recovered quicker in Group A than in Group B by days 10, 21, and 30 (difference from baseline was 1.04 ± 0.35 vs 2.39 ± 1.15 [p < .001], 0.48 ± 0.42 vs1.73 ± 1.00 [p < .001], and 0.18 ± 0.64 vs 0.82 ± 0.96 [p < .001], respectively). The ankle circumference recovered quicker in Group A than in Group B by days 10 and 21 (the difference from baseline was 1.37 ± 0.52 vs 2.36 ± 0.93 [p < .001] and 0.58 ± 0.60 vs 1.14 ± 0.88 [p = .002], respectively). Pain relief was achieved quicker in Group A than in Group B (0.257 ± 1.097 [p = .0863] vs 0.506 ± 1.250 [p = .0168] by day 21). There were no significant differences in the VCSS and AVVQ scores between both groups. There were no drug-related adverse effects. SA, in combination with compression therapy, can relieve edema and alleviate pain in patients following EVLA for varicose veins.

"Endovenous Laser Ablation of Varicose Veins: A Comprehensive Review of a Minimally Invasive Treatment Approach"

"Endovenous Laser Ablation of Varicose Veins: A Comprehensive Review of a Minimally Invasive Treatment Approach"

Closed randomized comparative study of great saphenous vein crossectomy laser ablation versus standard laser technique to minimize recurrence in the treatment of primary varicose veins

Background Incompetence at the saphenofemoral junction (SF) is the most common cause (70%) of varicose veins. Endovenous laser ablation (EVLA) uses laser energy to ablate incompetent axial veins selectively and was originally described for the treatment of GSV reflux and its related varicosities. The venous system is a network of interconnected vessels; any preserved inflow of the saphenous-femoral mouth can cause postoperative recurrence. However, according to the literature, the greatest risk of recurrence is associated with the stump of the GSV of venous tributaries, including great venous trunks parallel to the GSV in the thigh. Aim of the work Comparison of the standard endovenous laser ablation technique (1.5–2 cm from SFJ) versus crossectomy ablation for the treatment of varicose veins regarding recurrence of reflux and incidence of endovenous heat-induced thrombus (EHIT) in the first week. Patients and methods In all, 80 patients admitted to Ain Shams University Hospitals and Alexandria Armed Forces Hospital from Jan. 1st, 2021 to Jan. 30th, 2023 participated in the study. The patients were divided evenly into two groups: Participants were randomly assigned to one of the trial groups using the sealed envelope method.Group A was treated by ablation of the great saphenous vein at the saphenofemoral junction (0 cm from SFJ) using 1470 nm radial double-ring diode laser fibers (ELVeS Radial 2ring™ fiber) and Biolitec Ceralas E1470/15 W laser machine. Group B was treated by ablation of the great saphenous vein at 1.5–2 cm from the saphenofemoral junction using the same laser fiber and machine. Ablation was done after putting an appropriate amount of tumescent anesthesia (500 mg lidocaine, 1 mg of epinephrine, and 12.5 mEq sodium bicarbonate added to a 1-liter solution of 0.9% normal saline). The ultrasound machine was used for the accurate placement of the laser fiber. Postoperative duplex was done on day 1, 1 week, and at 6, 12, and 18 months. Results Mean age: 39.28+/– 12.27 years in both groups; M/F: 23/17 in the first group, 20/20 in the second group. Postoperative duplex showed the absence of reflux in both groups after 1 day, after 6 months. One patient (2.5%) in group A and four patients (10%) in group B showed recurrent reflux, while recurrent refluxes were observed in one case (2.5%) in group A and five cases (12.5%) in the other group after 12 and 18 months of follow-up. One patient (2.5%) developed superficial thrombophlebitis along the course of the ablated great saphenous vein in both groups while extension to the deep veins was not detected in both groups. Conclusion Crossectomy (ablation at 0 cm at SFJ) ablation of varicose veins with 1470 radial double rings and nm diode laser with an appropriate amount of tumescent showed better results with less recurrence rate due to neovascularization or tributaries left than the standard technique of endovenous laser ablation of varicose veins (1.5–2 CM from SFJ). Along with showing a lesser incidence of thermal propagation into the deep system (EHIT) both crossectomy and standard techniques showed the same complication rate regarding venous thrombosis.

The safest power to be applied in relation to diameter of the vein to give maximal benefit with least complications in endovenous laser ablation of varicose veins

Background Over the years, there have been significant advancements in the treatment of varicose veins. In most surgical settings, the open procedure is still the primary approach. Yet, the popularity of less invasive procedures like EVLA and RFA has produced fantastic outcomes. Objective to assess the safest power of laser which gives maximal effect and least complications in ablation of varicose veins. Methodology A prospective observational study inducing EVLA of different laser power settings (7W &amp; 10W) with preoperative assessment then follow up by CEAP &amp; VCSS and duplex ultrasound measuring great saphenous vein (GSV) diameter and also post-operative complications and time to return to work. Results This study included 50 patients (52 limbs). The Patients were distributed as regard laser power used into two groups (7W, 10W) of 26 limbs for each one. As regard GSV measures changes, there was highly statistically significant decrease in GSV diameter after 1 m and after 3 m compared to preoperative, with P value P&lt;0.001, among patients group. Also, there is higher number of cases with GSV&gt;10 mm in power of laser ‘10w’ group compared to ‘7w; group, with P value (P&lt;0.001); while there is no statistically significant difference between power of laser 7w versus 10w, because all patients ≤10 mm after 1 month and after 3 months, with P value &gt;0.05.Statistically there was no significant difference between 7W &amp; 10W groups as regards time to return to work, CEAP scores and postoperative complications except the significant difference in Pain over the treated vein being less in 7W laser power group. Conclusion For endovenous laser ablation of varicose veins, both 7W and 10W laser power are indicated. They are risk-free and provide the greatest impact with the fewest difficulties for the chosen vein diameter. In our investigation, we came to the conclusion that patients with small GSV diameter required low laser power (7W), while those with large GSV diameter required high laser power (10W).

Outcomes of different laser power used in endovenous laser ablation of varicose veins

Outcomes of different laser power used in endovenous laser ablation of varicose veins

Drill from Military to Operating Theater and Safe Reuse of Single-Use Items to Combat the Cost of Optical Fibers and Consumables in Endovenous Laser Ablation of Varicose Veins

Introduction: Can the tandem arrangement of operating theater setup to perform a surgical drill similar to military, together with safe reuse of single-use items combat the cost of consumables of endovenous laser ablation (EVLA)? Methods: Operation pathway of EVLA consisted of cleaning and draping of patient (step 1), access to the affected vein and infiltration of tumescent local anesthesia (step 2), endovenous ablation (step 3), ultrasound-guided microfoam sclerotherapy (step 4), and chemical sterilization of consumables (step 5). Dedicated theater lists for EVLA were arranged to treat several patients per session in a prearranged operating theater. When the step 5 is completed on the first patient, the step 1 on the next patient was performed using sterilized optical fiber (OF) as a cycle while minimizing patient changeover time. Number of patients treated with each session of OF and time taken for step 1 to step 4 was recorded and analyzed. Results: A total of 140 patients treated using eight OFs during December 2019 to December 2022. Average number of patients treated with a single OF and during a single session of fiber is 17.5 (9–23) and 4.2 (3–7), respectively. Average time taken for step 1 was 7.83 min, step 2 was 7.95 min, step 3 was 1.57 min, and step 4 was 6.36 min. All the procedures were performed using four chemically re-sterilized guidewires and introducer sheaths. Conclusion: Tandem arrangement of operating theater to perform EVLA procedure similar to military drill can optimize the utilization of OFs and consumables.

A Study of Venous Thromboembolism Onset Following Endovenous Laser Ablation for Varicose Veins

A Study of Venous Thromboembolism Onset Following Endovenous Laser Ablation for Varicose Veins

FEATURES AND STRUCTURE OF THE COMPLICATIONS OF ENDOVENOUS LASER ABLATION

The aim of the research work: to analyze the structure, frequency and features of complications after endovenous laser ablation in patients with varicose veins of the lower extremities. An open, prospective study was conducted, which included 208 consecutive patients with varicose veins of the lower extremities. All patients underwent endovenous laser ablation of varicose veins and investigated the structure and features of the development of postoperative complications. Pathological reflux of blood in the trank of the great saphenous vein of the lower extremity was diagnosed in 206 cases, isolated reflux in the trank of the small saphenous vein was observed in 24 (10.4 %) limbs, in 16 patients EVLA was performed simultaneously in the small and large saphenous veins). One or more adverse events were reported by 94 patients (45.2%) during the first 2 weeks after treatment, and pain was the most common symptom in the study patients, with complaints reported by 82 (39.4 %) patients with a mean value immediately after treatment). The second most common complication of endovenous laser ablation was ecchymosis, which developed in 44 (19.1% extremities). Tissue induration and hyperpigmentation along the coagulated vein were observed in 5.2% and 3.9%, respectively. Manifestations of transient paresthesia and wound infection were observed in 0.4% of cases, in 2 (0.9 %) patients after EVLA in the great saphenous vein. In the postoperative period serious adverse events developed, such as EHIT II and in 3 (1.4 %) cases asymptomatic distal deep vein thrombosis. Endovenous laser ablation is an effective method of treating varicose veins of the lower extremities with a high safety profile. Clear standardization of the procedure and postoperative monitoring will minimize the risks of postoperative complications and eliminate them in a timely manner.

COMPLICATIONS AND EVALUATION OF QUALITY OF LIFE IN PATIENTS AFTER LESS-INVASIVE TREATMENT OF VARICOSE VEINS OF THE LOWER EXTREMITIES.

The aim: To analyze the occurrence of complications and evaluate the quality of life in patients who got less-invasive treatment methods using endovenous laser ablation of varicose veins of the lower extremities in the early and late postoperative periods. Materials and methods: The study was conducted with the participation of 100 patients treated in 2019-2020 by one team of surgeons for varicose veins of the lower extremities with symptoms of chronic venous insufficiency C2-C4 (CEAP classification). Depending on the performance of endovenous surgical interventions, all patients were divided into two study groups. Results: In assessing the quality of life associated with health, according to the CIVIQ 2 questionnaire, it was found that in the presence of varicose veins in the superficial veins of the lower extremities, indicators decrease both in general and on all studied scales (pain, physical, psychological and social). However, when using endovenous laser ablation without miniphlebectomy, after 6 months of observation, recurrence of varicose veins of the lower extremities was noted, which was not observed in patients of the first group. Conclusions: The use of less-invasive interventions with ultrasound guidance positively affects patients' quality of life with varicose veins of the lower extremities, both in the early and prolonged postoperative periods.

Twenty Years’ Experience with Endovenous Laser Ablation for Varicose Veins: A Critical Appraisal of the Original Procedure

Objective: A critical appraisal of the original procedure of endovenous laser ablation (EVLA) for varicose veins. Method: Evaluation of all practical aspects of the procedure. Results: EVLA procedures are performed in a strictly ambulatory setting with tumescent local anesthesia (TLA). Technical improvements have resulted in the need for fewer incisions and re-punctures, less ecchymosis, and fewer technical failures. Administration of an appropriate amount of TLA via an infusion pump has reduced the risk of nerve injury, administration time, and pain during the procedure. Use of a 1470-nm diode laser and a radial fiber have significantly improved patient satisfaction and reduced the occurrence of complications such as pain, tightness, ecchymosis, and the need for additional procedures. Lastly, there are only a few indications left for high ligation and stripping. Conclusion: Over the past 20 years, EVLA has evolved into an effective, cost-efficient, and safe procedure that provides high patient satisfaction.

A Novel Venous Puncture Method for Endovenous Laser Ablation of Varicose Veins in the Lower Limbs Using Smaller Diameter Optical Fiber

A Novel Venous Puncture Method for Endovenous Laser Ablation of Varicose Veins in the Lower Limbs Using Smaller Diameter Optical Fiber

Endovenous Laser Ablation of Varicose Veins Using Radial Slim Fibers

直径5 mm以上の側枝静脈瘤を有する大伏在静脈弁不全の患者44名に対して，細径ファイバー（ELVeS radial 2ring slim fiber, 直径1.27 mm）を用いて血管内レーザー焼灼を行い，さらに16 G静脈留置針で静脈瘤を穿刺し内腔へファイバーを挿入，出力5 Wでレーザー焼灼を行った．93%の症例で9割以上の瘤消失が確認され，血栓性静脈炎や皮膚熱傷などの有害事象はみられなかった．

The clinical outcomes of endovenous microwave and laser ablation for varicose veins: A prospective study

BackgroundThis study investigates the clinical outcomes of endovenous microwave ablation and endovenous laser ablation for varicose veins. MethodsA total of 139 patients who underwent endovenous microwave ablation and 145 patients who underwent endovenous laser ablation were included in this multicenter study. The clinical outcomes and complications were assessed at 1, 6, and 12 months after the procedure. The effect on quality of life was assessed by the Aberdeen Varicose Vein Questionnaire and the EuroQol Group 5-Dimension Self-Report Questionnaire. ResultsThe endovenous microwave ablation group had a shorter procedure time than the endovenous laser ablation group (42.58 ± 15.62 minutes vs 65.46 ± 24.38 minutes, P < .01), and no significant differences were observed in the other procedure parameters. The incidences of induration (20.26% vs 31.06%) and ecchymosis (13.07% vs 22.98%, P < .05) were lower in the endovenous microwave ablation group. The rates of temporary paresthesia (9.80% vs 18.01%) and residual varicosities (8.61% vs 16.77%, P < .05) were lower in the endovenous microwave ablation group at 1 month. There were no significant differences in paresthesia or saphenous vein closure rates between the groups at 6 and 12 months. Both groups had significant improvements in their Aberdeen Varicose Vein Questionnaire and EuroQol Group 5-Dimension Self-Report Questionnaire scores post-procedure, and no significant differences in Aberdeen Varicose Vein Questionnaire and EuroQol Group 5-Dimension Self-Report Questionnaire scores were confirmed. However, local recurrence below the knee was lower in the endovenous microwave ablation group (2.34% vs 8.46%, P < .05) after 12 months. ConclusionOur results confirmed that the endovenous microwave ablation procedure demonstrated a shorter procedure time, lower complication, and local recurrence than the endovenous laser ablation procedure.

Patency of Anterior Accessory Saphenous Vein Following Endovenous Laser Ablation for Varicose Veins: Bare-Tip Versus Radial Fiber

Introduction - Anterior accessory saphenous vein (AASV) insufficiency is one of the most common causes of late recurrence after endovenous laser ablation (EVLA) for great saphenous vein (GSV) insufficiency1)2). Therefore, reduction of the AASV patency rate after EVLA can be associated with better long-term results. The aim of this study is to compare the patency rate of saphenofemoral junction tributaries after EVLA between bare-tip and radial fibers. Methods - We reviewed 375 limbs in 339 patients undergoing EVLA for GSV insufficiency. The bare-tip fiber with a 980-nm diode laser was used in 299 limbs (group B). The radial fiber with a 1470-nm diode laser was used in 76 limbs (group R). Concomitant ablation of AASV or high ligation of GSV was not included in this study. Patients who had previous EVLA, high ligation and stripping were excluded. Duplex ultrasound scanning was performed 3 months after EVLA to assess occlusion of the ablated GSV and patency of the saphenofemoral junction tributaries including the AASV, the posterior accessory saphenous vein (PASV) and the superficial epigastric vein (SEV) in both groups. Student-t tests and chi square tests were used to compare two groups. Results - The total occlusion rate of the ablated GSV at 3 months after EVLA was 100% in group R and 99% in group B, p = 0.999. The patent AASV was detected significantly (p = 0.004) less in group R (33 limbs, 43%) than in group B (184 limbs, 62%), whereas the PASV patency rate was similar (p = 0.815) in both groups (16% in group R, 15% in group B, p = 0.815). The SEV occlusion rate was 4% in group R and 1% in group B, p=0.101. There was no difference in age, gender, body mass index, CEAP classification and the proximal GSV diameter in both groups. Laser power was smaller in group R (8.9 +/- 0.9 W) than in group B (9.4 +/- 0.6 W), p < 0.001, however, linear endovenous energy density did not differ between the groups (79.9 +/- 13.6 J/cm in group R, 78.3 +/- 9.2 J/cm in group B, p = 0.198). The distance between the tip of the fiber and the common femoral vein was shorter in group R (9.7 +/- 2.4 mm) than in group B (17.5 +/- 4.9 mm), p < 0.001. Conclusion - EVLA using a radial fiber archived better occlusion rates of AASV. This result can be attributed to the position of the laser fiber tip closer to the saphenofemoral junction. Our study suggests that EVLA using a radial fiber will reduce the risk of late recurrence caused by AASV insufficiency in the treatment of GSV varicose veins. References1)J Vasc Surg. 2016; 63: 420-428.2)Eur J Vasc Endovasc Surg. 2011; 41: 685-690.

Venous thromboembolism complications after endovenous laser ablation for varicose veins and role of duplex ultrasound scan

ObjectiveA nationwide survey was conducted in Japan to determine the incidence of venous thromboembolism (VTE) after endovenous thermal ablation for varicose veins and to investigate its pathogenic background. MethodsThe survey targeted all cases of endovenous thermal ablation between January 2011 and December 2013. Based on this survey, a retrospective study of patients who developed endovenous heat-induced thrombosis (EHIT) of classes 2 to 4, no EHIT-related deep venous thrombosis (DVT), and pulmonary embolism (PE) was conducted. Lower extremity venous ultrasound was performed within 72 hours and at 1 to 3 months postoperatively in all institutions. We investigated factors associated with the occurrence of complications and the usefulness of postoperative ultrasound. ResultsSurvey responses were collected from 213 institutions. Endovenous laser ablation was performed for 43,203 patients (EHIT 2 in 318 patients, EHIT 3 in 50 patients, EHIT 4 in 7 patients, other DVTs in 24 patients, and PE in 3 patients). The incidence of VTE complications was 1.0% for EHIT 2, 0.11% for EHIT 3, 0.013% for EHIT 4, 0.063% for other DVTs, and 0.0067% for PE based on the adjusted population. Sex, age, obesity, origin of the varicose vein, vein diameter, and preoperative Caprini score were not strong indicators of VTE complications. Of 50 patients with EHIT 3, there were 35 patients who had EHIT 3 during the first postoperative ultrasound session. In one patient, EHIT 3 progressed to EHIT 4 despite initiation of anticoagulant therapy. Of seven patients with EHIT 4, only one patient had EHIT 4 at the first postoperative ultrasound examination. Because ultrasound performed before the occurrence of EHIT 4 revealed that three patients had EHIT 2 or EHIT 3, EHIT 4 could have possibly been predicted by ultrasound. Of three patients with PE, two developed PE before ultrasound, and EHIT was not detected by ultrasound in one of those patients before PE developed. Anticoagulant therapy was administered in most patients with EHIT 3 and all patients with EHIT 4 and PE, with favorable outcomes. ConclusionsThe incidence of VTE complications after endovenous laser ablation was low. Furthermore, the value of performing postoperative ultrasound for VTE management seems to be low because the occurrence of severe VTE complications could not be predicted by lower extremity venous ultrasound. Although the perioperative detection of VTE complications by this modality resulted in the early administration of anticoagulant therapy and may have contributed to improved prognosis, the number of those patients was limited.

Recent Developments and Mechanism of Action of Endovenous Laser Ablation for Varicose Veins

Recent Developments and Mechanism of Action of Endovenous Laser Ablation for Varicose Veins

Compression Therapy after Endovenous Laser Ablation for Varicose Veins

Compression Therapy after Endovenous Laser Ablation for Varicose Veins

Foam Sclerotherapy and Laser Ablation of Varicose Veins: Newer Option in Bangladesh Perspective

Background: Varicose vein is one of the most common vascular conditions in the adult population. These are conventionally treated with surgical high ligation of Sapheno-femoral junction and stripping of Great Saphenous Vein (GSV) with multiple phlebectomy. The aim of this study was to highlight the technical considerations in performing endovenous laser ablation of varicose vein, understanding the importance and role of Duplex Machine and Tumescent anesthesia with evaluation of outcome.Methods: In this retrospective study we examined the records of 297 limbs of 220 patients operated at Vascular Care Centre at Dhaka, Bangladesh between October 2013 and October 2015. Among them 1 year follow up was performed in 118 patients. Patients were contacted through telephone calls and mobile SMSs with requests for follow up.Results: Vast majority of the patients had a smooth recovery. Significant pain was present in only 10% of patients for 1week after laser therapy and 3% of patients noted bruising in thigh for 2 weeks. Among the 118 patients who reported for follow up at 12 months, 113 (96%) showed effective persistent occlusion of GSV.Conclusion: EVLA of varicose vein is gaining popularity day by day in Bangladesh. It has become established as a safe and effective treatment option for varicosities caused by GSV incompetence. Foam sclerotherapy with Sodium tetradecyl sulphate replacing the multiple phlebectomy may be a suitable adjunct. Quick return to normal activities, fewer wound infections, less leg pain and leg bruising are strongly associated with these endovenous techniques compared with Saphenous vein stripping.Cardiovasc. j. 2018; 10(2): 140-144

Moving heat source in a confined channel: Heat transfer and boiling in endovenous laser ablation of varicose veins

Motion of a moving laser light heat source in a confined volume has important applications such as in endovenous laser ablation (EVLA) of varicose veins. This light heats up the fluid and the wall volume by absorption and heat conduction. The present study compares the flow and temperature fields in a horizontal tube of 4mm inner diameter in three idealizations of the EVLA procedure: water with a bare fiber tip, water with a carbonized layer on the fiber tip, and blood. Without boiling, the convection patterns in water and blood are similar and Grashof numbers are high enough to guarantee buoyancy induced flow and axial mixing, while preserving some stratification. A carbonized layer at the fiber tip promotes boiling in water at moderate laser powers. Boiling bubbles in water rapidly detach from the tip, with or without a carbonized layer, and promote mixing and a locally homogeneous temperature field. At 15W laser power and 4mm/s pullback speed in blood, a gas bubble may be formed that sticks at the fiber tip, causing strong local heating and possibly fiber damage.