Varicose veins can be treated by multiple procedures, such as high ligation and stripping, endovenous thermal ablation (EVTA) including endovenous laser ablation (EVLA) and radiofrequency ablation (RFA) and non-thermal non-tumescent (NTNT) method which include endovenous glue treatment and mechanochemical ablation (MOCA). Each method has specific strengths and weaknesses and shows slightly different treatment success rates.

However, for treating varicose veins unlike other methods, EVTA currently maintains an IA grade in ESVS 2022 guidelines. EVLA uses 3rd and 4th generation hydrophilic laser wavelengths and has a higher treatment success rate with less damage caused to perivascular tissue and more action on the vascular wall with the development of radial catheters [1-5]. However, a tumescent solution is required to reduce heat damage to surrounding tissue and induces swelling in this tissue. The infusion of the tumescent solution requires more operation time and may cause discomfort by bruising due to the use of anesthesia injection needles.

With the introduction of the NTNT method, ablation is possible without the use of the tumescent solution and postoperative discomfort and surgical time is reduced without heat damage occurring [6]. However, for Clarivein^®, a representative MOCA method, the closing rate is less than that of EVTA when used with in great saphenous vein (GSV) with a diameter of ≥6.5 mm. Currently, MOCA is also classified as grade IIb A in ESVS 2022 guidelines in GSV treatment [7,8].

Ultrasound guided foam sclerotherapy (UGFS), which is used to treat varicose veins, can be not only used for treating truncal veins of GSV but also for treating tributaries. However, UGFS has a lower closing rate than EVLA, RFA or surgery [9,10]. This is classified as grade IIb B in ESVS 2022 guidelines, only when used for truncal GSV of ≤6 mm in diameters. UGFS shows a lower success rate due to the dilution of the sclerosant in the blood [11].

Therefore, in this study, we used a fourth-generation 1940-nm laser (Diotec^®, KR) with radial fiber (Diotec^®, KR), and UGFS (sodium tetradecyl sulfate [STS] Fibrobein^®, 3%) simultaneously for thermochemical ablation of GSV without the use of a tumescent solution and called it laser-assisted sclerotherapy (LAST; a kind of thermochemical ablation).

From January 1 to June 30, 2023, 86 of GSV from 50 patients who underwent LAST at Chengmac hospital were enrolled in this retrospective study (Table 1). The diameter of the GSVs was between 3 to 8 mm. Exclusion criteria was vascular malformations such as Klippel-Trenaunay syndrome, GSV with perforator reflux and recurrent varicose vein.

Table 1 . Patients demographics.

Female:Male, N	36 (72%):14 (28%)
Age, mean±SD	57.09±11.28
CEAP category
C1:C2:C3:C4:C5–6	0:23:22:4:1 (0%:46%:44%:8%:2%)
GSV diameter, mm, mean±SD
Proximal GSV	6.57±0.94
Distal GSV	4.37±0.98
Length of treated vein, cm, mean±SD	65.49±9.40
Length of above knee GSV	42.32±3.2

GSV: great saphenous vein..

[Procedure]

EVLA was conducted in the order of accessary veins, tributaries and truncal vein by a single operator under sedation by using propofol. The lower calf site of GSV was punctured and a 5 Fr sheath was inserted. After the insertion of a radial fiber, ablation was started with a laser tip below 0.5 cm of the saphenofemoral junction (SFJ) and a laser power of 4.5 W. The pullback speed was approximately 1 cm/s without the use of a tumescent solution. If the muscle or skin was close to the vein, a faster ablation was performed to minimize damage to surrounding tissues. Ablation was performed only on the above knee GSV to avoid saphenous nerve damage. When the diameter of the vein was reduced to <3 mm or stiffness was felt while the laser tip was pulled back, we judged that the vein was sufficiently constricted and the endothelium was destroyed. The required number of laser ablations was about 1–2, 2–3, 3–4, and 4–5 times for blood vessels with a diameter of 3–4, 4–5, 5–6, and 6–8 mm, respectively (Table 2). If more ablation is performed than necessary, the diameter of the vein becomes too small, which can cause difficulties in catheter insertion for catheter directed foam sclerotherapy (CDFS). During the procedure, the carbonization of the laser tip was carefully removed for efficient cauterization. And then with a 3% STS mixed with CO₂ gas at a ratio of 1:4, CDFS was performed by a 5 F hydrophilic catheter (Meritmedical impression^®, Australia). Three percent foam sclerosant was injected 1 cc below 2 cm of the SFJ and then another 1 cc of foam was injected respectively after 5 cm, 6 cm, 7 cm, 8 cm, and 9 cm pullbacks. Compressing the SFJ with an ultrasonic probe prevented the sclerosants from crossing into the deep vein. During the injection, the thigh was swept by hand distally allowing foam to spread into the below-knee GSV and tributaries. In some cases, too much tortoise veins were removed by phlebectomy.

Table 2 . Energy needed for ablation.

Number of ablation of truncal vein of GSV	Total energy, mean±SD	LEED (J/cm), mean±SD
1	189±23	4.5±0.54
2	378±21	9±0.50
3	547±19	13±0.44
4	701±21	16.7±0.48
5	890±25	21.2±0.59
Average	541±2	12.88±0.5

GSV: great saphenous vein, LEED: linear endovenous energy density..

The degree of pain was measured at 2 hours after procedure and the wearing of compression stockings with early ambulation were encouraged. Follow-up was conducted at 1 week, 1 month, and 6 months.

Three of the 86 GSV observed for >6 months showed mild reflux on GSV below-knee level but with no symptoms and reflux disappeared with only one additional UGFS. Various energy levels were needed according to the number of ablations and are summarized in Table 2. The laser energy for ablating accessory veins and tributaries was not included in this study. Three percent STS was used 4.5±0.4 cc. Operation time per GSV was about 8±2 minutes and it was determined according to the number of ablations including accessary vein, tributaries and vascular conditions during CDFS. The VAS score was 2.5±0.6 2 hours after surgery.

The closure rate was 100% at 6 months. In all patients, the VCSS score was improved (6.2±1.2 to 0.9±0.2) at 6 months. Symptoms such as bruising and swelling caused by needles were also relatively mild because no tumescent was used. The SFJ stump was approximately 0.5±0.35 cm and endovenous heat induced thrombosis (EHIT) was not observed (Table 3). Systemic events such as visual disturbance and headache caused by sclerosants did not occur. No serious side effects such as deep vein thrombosis occurred. Seven GSV showed mild skin irritation, but most of them disappeared within a month. Five GSV showed mild tenderness due to thrombophlebitis and most patients fully recovered within a month after supportive treatment such as taking nonsteroidal anti-inflammatory drugs. However, two GSV with a diameter of about 8 mm required percutaneous thrombectomy using an 18 G needle. because thrombophlebitis was severe despite of a supportive care (Table 4).

Table 3 . Results.

1 GSV
Sclerosant (3% STS, 1:4), cc, mean±SD	4.5±0.4
Operation time, min, mean±SD	8±2
VAS score (post OP 2 hr), mean±SD	2.5±0.6
Truncal vein occlusion rate (6M)	100%
VCSS score (pre OP/6M), mean±SD	6.2±1.2/0.9±0.2
SFJ stump, cm, mean±SD	0.5±0.35

GSV: great saphenous vein, VAS: visual analogue scale, VCSS: venous clinical severity score, SFJ: saphenofemoral junction..

Table 4 . Complications and managements.

	N (86)	Recovery, within
Skin irritation	7 (8%)	1 month
Thrombophlebitis reaction	5 (5.8%)	1 month (NSAID)
Severe thrombophlebitis reaction	2 (2.3%)	2 month (NSAID+ thrombectomy)
EHIT, systemic events by sclerosant, DVT, hematoma, infection, burn, severe nerve damage, bleeding, allergic reaction	No

EHIT: endovenous heat induced thrombosis, DVT: deep vein thrombosis, NSAID: nonsteroidal anti-inflammatory drug..

The combined use of using EVLA and UGFS for varicose vein treatment has been recently studied. A method of reducing the diameter by generating GSV spasms with UGFS without the use of a tumescent solution and then followed by EVLA with less energy has been suggested [12]. There is a method of performing EVLA on the above knee GSV and UGFS on the below-knee GSV but requires the infusion of a tumescent solution [13]. However, the method presented in the current study, LAST performs CDFS after EVLA without the use of a tumescent solution. This mechanism is different from the combined method attempted earlier. EVLA acts as a rotator to damage the vein wall in MOCA.

LAST can reduce operation time by avoiding the injection of a tumescent solution and can efficiently ablate veins because the tributaries are visible. In addition, postoperative pain can be reduced by eliminating local edema and pain caused by the tumescent solution. But there is no tumescent local anesthesia, the need for IV sedation or spinal anesthesia for operation can be a limitation.

In the latest study, EVLA was conducted with a radial fiber and 1940-nm laser, linear endogenous energy density (LEED) was reported 53 J/cm with a closure rate of 100% at 6 months and 96.5% at 2 years after operation [3]. In another study, the LEED was 17.8–53 J/cm and the 1-, 12-, and 24-month closure rates were 99.2%, 96.3%, and 96% respectively [4]. In the other study, the 6-month and 1- and 2-year closure rates were reported as 99%, 96.9%, and 95.9% respectively, while the LEED was reported as 41.2±8.6 J/cm [5]. In this study, only 12.88±0.5 J/cm LEED in average was required for ablations due to the use of sclerosant. But it is difficult to compare with other studies because the follow-up period is short, although effective ablation is possible with lesser laser energy.

In the case of Clarivein^®, a type of MOCA, the closure rate gradually decreases as the GSV diameter increases [14]. Flebogrief^® has not yet showed long-term results [15]. When using Clarivein^®, 2% STS is mainly used, and no criteria are currently available for which concentration of STS is the most ideal. However, for LAST, repeated heat energy damages the endothelium of vein enabling effective ablation with sclerosants. In most cases of the GSVs with diameter of >8 mm, vein contraction was insufficient even with more than six laser ablations. This phenomenon is considered to be caused by insufficient heat energy transfer to the walls of vein due to by large volumes of blood present. In these cases, conventional EVLA was performed because of possibility of postoperative recanalization or concerns about thrombophlebitis caused by large blood clots. As this is the first attempt with this technique, limiting the target is considered to be a limitation of this study.

Veins with a diameter >8 mm are considered as very large saphenous veins. A larger GSV is associated with lower rates of successful occlusion and high rates of EHIT in studies of RFA and EVLA [16,17]. In this study, no EHIT was observed, but this is considered as an important point if LAST is performed on larger GSVs in the future.

According to the literature, it is recommended not to use more than 10 cc of 3% STS when performing MOCA and when it is used with 2%, the maximum recommended amount is around 15 cc and in most cases both legs can be treated within that amount [18]. Despite these quantitative limitations, one Austrian study reported that even when using 3% STS up to 15 cc was safe without side effects [19]. Treatment of both legs was possible within quantitative recommendations with using a 3% STS for LAST.

Vos et al. [20] reported induration (12%–18%), superficial venous thrombosis (2%–13%), hematoma (1%–11%), deep vein thrombosis (0%–11%), and hyperpigmentation (5%) as possible complications after MOCA but injury of nerve and skin, infection was not reported. In this study, thrombophlebitis developed in five GSV (5.8%) cases and severe thrombophlebitis in two GSV (2.3%) following LAST. Since no tumescent solution was used around the vein, LAST can cause minor skin irritation caused by heat energy, but most of these side effects are self-limiting.

LAST showed a good closure rate in the early midterm follow-up period. Compared with EVLA, efficient ablation was possible with lesser energy and the pain index was lower at 2 hours after procedure. The operation time can be shortened since there is no infusion of a tumescent solution.

The dose of laser energy and sclerosant can be optimized to reduce side effects or discomfort of patients while maintaining successful occlusion rate. Since the long-term success rate is not yet guaranteed, more follow-up observation is needed.

The authors declare no conflicts of interest.