A randomized clinical trial to assess the impact of laser power with constant linear endovenous energy density on outcomes of endovenous laser ablation (SLEDGE trial).

OBJECTIVE: To date, conflicting evidence has been reported regarding the energy settings to use during endovenous laser ablation (EVLA). In the present study, we evaluated the outcomes of EVLA of the great saphenous veins (GSVs) using different power settings with the same linear endovenous energy density (LEED) of ∼70 J/cm. METHODS: We performed a single-center, randomized, controlled noninferiority trial with a blinded outcome assessment of patients with varicose veins of the GSV who underwent EVLA with a wavelength of 1470 nm and a radial fiber. The patients were randomly assigned to three groups according to the energy setting: group 1, 5 W power and an automatic fiber traction speed of 0.7 mm/s (LEED, 71.4 J/cm); group 2, 7 W and 1.0 mm/s (LEED, 70 J/cm); and group 3, 10 W and 1.5 mm/s (LEED, 66.7 J/cm). The primary outcome was the rate of GSV occlusion at 6 months. The secondary outcomes were pain intensity along the target vein the next day and at 1 week and 2 months after EVLA, the necessity for analgesics, and the occurrence of significant complications. RESULTS: From February 2017 to June 2020, 245 lower extremities of 203 patients were enrolled. Groups 1, 2, and 3 included 83, 79, and 83 limbs, respectively. At 6 months of follow-up, 214 lower extremities were examined with duplex ultrasound. GSV occlusion was observed in 72 of 72 limbs (100%; 95% confidence interval [CI], 100%-100%) in group 1 and 70 of 71 limbs (98.6%; 95% CI, 97%-100%) in groups 2 and 3 (P < .05 for noninferiority). No difference was found in the pain level, necessity for analgesics, or rate of any other complications. CONCLUSIONS: The technical results, pain level, and complications of EVLA were not associated with the combination of energy power (5-10 W) and the speed of automatic fiber traction when a similar LEED of ∼70 J/cm was reached.

Calf muscle pump pressure-flow cycle during ambulation.

OBJECTIVE: Calf muscle pump (CMP) failure contributes to the severity and progression of chronic venous disease. Attempts to improve CMP function through resistance exercise have failed to improve chronic venous disease severity or quality of life, partially because the selection of the type of exercise was based on the assumption that the CMP ejects blood from the intramuscular venous sinuses (VSs), which has never been tested in humans. In the present study, we investigated the real-time changes in the pressure and size of the VS during the entire gait cycle of ambulation. METHODS: We studied 12 lower extremities of nine healthy volunteers at rest and while walking on a treadmill at three different speeds (60, 90, and 120 steps/min). The changes in the VS cross-sectional area (CSA) and pressure were measured. Myography of the gastrocnemius muscle (GCM) and anterior tibial muscle (ATM) was used to register muscle activity. The relationship between the phases of the gait cycle and the measured parameters was analyzed using video records of all experiments. RESULTS: The observed timing of events was consistent among all limbs studied. At rest, with the participants standing still, the VS pressure and CSA was 70.3 ± 4.2 mm Hg and 23.3 ± 14.6 mm2, respectively. During ambulation, at the first half of the stance, the GCM and ATM eccentrically contract, and the pressure is low (17 ± 8 mm Hg, 20 ± 12 mm Hg, and 29 ± 13 mm Hg at 1, 1.5, and 2 Hz, respectively), and the VS is collapsed. When the heel starts rising (the second half of the stance), the GCM concentrically contracts, the pressure increases, reaching its maximum value (143 ± 37, 134 ± 46, and 128 ± 41 mm Hg), and the VS opens, reaching its maximal size (1.8 ± 1.4 and 2.3 ± 2.2 mm2 at 1 and 1.5 Hz, respectively), followed by collapse of the VS. During the swing phase, the GCM relaxes, and the ATM concentrically contracts, resulting in a rapid decrease in pressure (2.6 ± 4.7, 1.1 ± 6.2, and -4.7 ± 3.2 mm Hg). The VS CSA remained negligible. CONCLUSIONS: The GCM concentric contraction was associated with a simultaneous increase in VS pressure and CSA. GCM relaxation with ATM concentric contraction coincided with a decrease in VS pressure to negative values. The VSs do not fill but remain empty during the swing phase of ambulation, acting, not as a reservoir, but as a conduit, transferring blood from the network of intramuscular veins to the axial deep veins.

Blood flow from competent tributaries is likely contributor to distally increasing reflux volume in incompetent great saphenous vein.

OBJECTIVE: Venous reflux is the sole pathophysiologic process in primary chronic venous disease and its progression. We hypothesize that the reflux volume (RV) increases along a great saphenous vein (GSV) in a distal direction. We aimed to compare simultaneously measured RV in the upper and lower GSV segments in a thigh. METHODS: Patients meeting the inclusion criteria were enrolled (70 limbs of patients with primary incompetence of the GSV) and consented to this participate in the single-center study. Patients were stratified into two groups: incompetent terminal valve and competent terminal valve. A cross-section area of the GSV was measured at the upper (CSA1, cm2) and distal (CSA2, cm2) points in a thigh. A cross-section area of each tributary that joined with the GSV between the points was measured, and their total cross-section area was calculated (CSAtrib). After a distal cuff compression-decompression maneuver, a time average mean velocity (cm/s) and reflux duration (seconds) were measured at both points simultaneously. The RV (mL) was calculated for each point (RV1 and RV2). The difference in absolute values of ΔRV (mL) and its relative changing (ΔRV, %) were calculated. RESULTS: The main result was RV increases caudally from saphenofemoral junction (SFJ) to the knee level (RV1 12.7 ± 8.4 and RV2 20.5 ± 14.0 mL; P < .0001). There was no difference between CSA1 and CSA2 (0.34 ± 0.17 and 0.33 ± 0.17 cm2, respectively; P = .9) but the time average mean velocity was a statistically significant different in two points (7.3 ± 3.9 and 11.4 ± 5.7 cm/s, respectively; P < .0001). All of the tributaries between the points were competent. CONCLUSIONS: The RV in the GSV increases caudally from SFJ to the knee level. The observed RV was an aggregate of all GSV tributaries' flow and the flow via the SFJ if incompetent.

Venous reflux in the great saphenous vein is driven by a suction force provided by the calf muscle pump in the compression-decompression maneuver.

OBJECTIVE: The gravitational pressure gradient is considered the driving force of venous reflux. The results from our previous study demonstrated that gravitational force is not a necessary condition for the occurrence of venous reflux. We hypothesized that a force exists in addition to gravity that drives venous reflux. The present study was designed to test this hypothesis by measuring the acceleration of blood flow during venous reflux in a clinical study and by simulating reflux ex vivo in physical models. METHODS: A total of 80 lower extremities of 80 patients with primary incompetence of the great saphenous vein were included in the present study. The cross-sectional area of the great saphenous vein, peak velocity of venous reflux (PV), and time required to achieve the PV (Δt, seconds) were measured on duplex ultrasound scans taken with the patient in the standing rest position. Noncycling operator-dependent distal cuff inflation-deflation was used as the reflux provoking maneuver. The acceleration of venous reflux (areflux) was calculated as areflux = PV/Δt in m/s2. Physical models were used to demonstrate the difference in acceleration between the free-fall stream and the flow forced by suction. RESULTS: The magnitude of areflux was greater than gravity in 24 of 80 extremities (30%), with a range of 9.83 to 24.13 m/s2. The maximum observed value of areflux was approximately 2.5g (24.13 m/s2). The areflux weakly, but statistically significant inversely, correlated with the subject height (r = -0.26; P = .001). The difference in water flow acceleration was 2.5 times between the free-fall model and suction model (9.07 ± 0.2 m/s2 vs 23.32 ± 2.6 m/s2, respectively). CONCLUSIONS: The acceleration of blood flow during reflux exceeded the value of gravitational acceleration, suggesting the action of an additional nongravitational force. The calf muscle pump might create such force by negative pressure during muscle diastole.

Reflux volume is determined by ejected blood volume from the calf venous reservoir.

OBJECTIVE: This study investigated the relationship between the ejected blood volume from the calf venous reservoir and the reflux volume (RV) during the automatic cuff inflation-deflation maneuver in limbs with incompetent great saphenous vein. METHODS: There were 48 patients with chronic venous disease (C1-5, Ер, Аs, Pr2,3) included in the study. A noncycling operator-dependent distal cuff inflation-deflation was used as the reflux-provoking maneuver. Duplex ultrasound was used to measure the cross-sectional area of the common femoral vein and great saphenous vein as well as hemodynamic parameters (time-averaged mean velocity and flow duration) of the outflow during cuff inflation and reflux during cuff deflation. The cuff pressure was set at 60, 90, and 120 mm Hg sequentially. The RV flow rate (Q), RV, anterograde ejection volume (EV), and ratio RV/EV (reflux index, IR) were calculated for each pressure setting. RESULTS: RV correlated with EV and Qreflux (r2 = 0.366 and r2 = 0.647, respectively; P < .0001). Qreflux was not significantly different between different cuff inflation pressures. RV and EV were statistically different at different cuff pressure settings (analysis of variance, P < .0001). The IR was almost identical at different pressure settings (0.43 ± 0.23 at 60 mm Hg, 0.43 ± 0.20 at 90 mm Hg, and 0.42 ± 0.19 at 120 mm Hg). CONCLUSIONS: The amount of reflux is primarily determined by the value of EV in a distal cuff compression-decompression maneuver. Both the ratio RV/EV (IR) and RV were related to the severity of the disease, more severe forms having larger IR and RV values.

The immediate effect of physical activity on ultrasound-derived venous reflux parameters.

OBJECTIVE: Ultrasound-derived reflux volume (RV) has a low correlation with the clinical severity of chronic venous disease, as well as other hemodynamic parameters. The difference in methodology of measurements could be a possible explanation. The purpose of this study was to investigate the immediate effect of calf pump activity used in the functional methods on ultrasound-measured venous reflux parameters. METHODS: Patients with primary incompetence of the great saphenous vein (GSV) were recruited for the study. The diameter of the GSV, cross-sectional area in square centimeters, time average velocity in centimeters per second, and reflux duration (RT) in seconds were measured by duplex ultrasound examination. The RV flow rate (Q) in milliliters per second and RV in milliliters were calculated. The measurements were performed standing at rest before and 60 seconds after physical exercise (30 lifts to tiptoes at a frequency of 1 time per second). A decrease in the volume of reflux after exercise was calculated (DRV = RV [after] - RV [before]/RV [before] × 100%.) Automatic distal compression-decompression (120 mm Hg) was used as a provocation maneuver. RESULTS: There were 61 patients included in the study. Before exercise, reflux parameters were: RT = 4.85 seconds (interquartile range [IQR], 3.71-6.00 seconds); Q = 3.89 mL/second (IQR, 2.03-5.81 mL/second); and RV = 17.05 mL (IQR, 10.32-25.34 mL). After physical exercise, they changed to RT = 2.86 seconds (IQR, 2.14-3.33 seconds); Q = 3.61 mL/second (IQR, 2.06-6.37 mL/second); RV = 10.07 mL (IQR, 6.08-16.48 m:); and DRV = 40.9%. The changes in RT and RV values were statistically significant. DRV was inversely related to both the GSV diameter and the Venous Clinical Severity Score (r = -0.56, and r = -0.41, respectively; P < .0001). CONCLUSIONS: Venous reflux decreases within 1 minute after the end of the exercises. Reduction of the volume of retrograde flow occurs only owing to the shortening of reflux time, and not the flow rate, suggesting that venous reflux is influenced by exercise-induced changes in the volume of the venous reservoir.

Gravity force is not a sole explanation of reflux flow in incompetent great saphenous vein.

OBJECTIVE: This study aimed to evaluate the impact of gravity, reservoir size, and competence of the ostial valve on venous reflux in different body positions. METHODS: Our study included 61 lower limbs with primary incompetence of the great saphenous vein (GSV). The diameter of the GSV and its cross-sectional area, time-averaged mean velocity (TAMEAN), and reflux time (RT) were measured with duplex ultrasound with pulsed wave Doppler. Reflux volume (RV) and reflux volume flow rate (Q) were calculated. The measurements were carried out in three body positions: horizontal, A; seated upright with stretched legs, B; and vertical, C. Distal automatic cuff compression-decompression (120 mm Hg) was used as a provocation maneuver. RESULTS: There was 100% occurrence of reflux in the patient positions B and C. Reflux was observed in 91.8% of cases in position A. All reflux parameters (TAMEAN, RT, Q, RV) and the size of the vein were significantly different in the three studied positions. The patient's height did not influence the magnitude of change in reflux parameters. All reflux parameters increased more significantly when the position changed from A to B than from B to C (TAMEAN, +103% and +37%; GSV diameter, +33% and +5%; RV, +408% and +65%, respectively). CONCLUSIONS: Observed positional changes in reflux parameters suggest that gravitational forces are not a sole explanation for reflux flow in incompetent GSV. It is likely that the gravitational effect on venous flow is mediated by the changes in vein diameter and the total volume of the venous reservoir of the leg.