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Original Scientific Articles

Title of this article

Quantitative Assessment of Superficial Venous Insufficiency Using Duplex Ultrasound and Air Plethysmography

Brief title

Quantitative Assessment of Superficial Venous Insufficiency

The authors

Takashi Yamaki M.D. Motohiro Nozaki M.D. Kenji Sasaki M.D.

Correspondence to :

Takashi Yamaki M.D.

Department of Plastic and Reconstructive Surgery

Tokyo Women’s Medical University

8-1, Kawada-cho, Shinjuku-ku, Tokyo

162-8666, JAPAN

TEL : 81-3-3353-8111

FAX: 81-3-3225-0940

E-mail : yamaki-t@po.iijnet.or.jp

Yamakit@aol.com

Presented at the Eleventh Annual Meeting the American Venous Forum, Dana Point,

CA. Feb. 18-21, 1999 No competing interests declared.

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ABSTRACT

Objective : The purpose of this study was to quantitatively evaluate

venous reflux in limbs with isolated superficial venous insufficiency

using color duplex ultrasound. In addition, air plethysmography (APG)

was used to investigate possible correlations of duplex-derived peak

velocity, duration of reflux, and CEAP classification.

Methods : One hundred and forty-six legs in 109 patients with

isolated superficial venous insufficiency refluxing throughout the length

of the limb were selected for prospective study by duplex scan.

Reflux was defined as duration of reflux > 0.5 seconds. This study

was conducted in a university hospital. Venous reflux was evaluated

with the patients standing, by the duration of reflux, retrograde peak

velocity, reflux volume at the saphenofemoral and saphenopopliteal

junction as well as the greater saphenous vein in the thigh. Values

obtained by APG were the venous volume (VV), venous filling index

(VFI), ejection fraction (EF), and residual venous fraction (RVF). A

significant difference was defined as p < 0.05.

Three groups of limbs were analized. Group A limbs with a

retrograde peak velocity > 30 cm/s and a duration of reflux < 3

second ; Group B with a retrograde peak velocity > 30 cm/s and a

duration of > 3 s, and Group C with a retrograde peak velocity < 30 cm/s

and a duration of reflux > 3 s.

Results : Group A and B contained 103 limbs and 24 of these

were in CEAP C5 and C6. Group C contained 43 limbs, none of

which were in Class 5 and 6. APG demonstrated significant reflux

in group A, and VFI were significantly higher compared to group B

and group C (p = .0007, p = .0064, respectively). A significant correlation

was demonstrated between peak retrograde reflux velocity and VFI.

Conclusions : Severe chronic venous insufficiency is found in limbs

with high reflux velocity (> 30 cm/s) and the duration of reflux does

not correlate with severe chronic insufficiency.

Key words : chronic venous insufficiency, duplex scans, air

plethysmography

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INTRODUCTION

Chronic venous insufficiency (CVI), including chronic edema,

hyperpigmentation, and frank ulceration is caused by primary valvular

incompetence and postthrombotic venous damage. Recently, duration of

reflux > 0.5 seconds has been widely used to define presence of

valvular reflux. Such reflux can be detected easily. As several

investigators have reported that the duration of reflux correlates with

the severity of venous reflux.1,2 we have chosen to study this

phenomenon.

The role of superficial insufficiency in the production of venous

ulceration has been described by many.3,4,5,6 Labropoulos7 reported that

ulceration occurred when the entire greater saphenous vein (GSV) was

involved although his study paid little attention to duration of reflux.

Neither was retrograde peak velocity analyzed in relation to the

severity of venous reflux. Labropoulos stated that the incidence of

venous ulceration due to isolated superficial venous insufficiency was

23%.7 Our study shows an incidence of 38.7%.8

The present study was undertaken to quantitatively correlate venous

reflux with isolated superficial veins using color duplex ultrasound and

air plethysmography. The principle objective was to investigate possible

correlation of the duplex-derived peak velocity and duration of reflux

with the CEAP classification (clinical, etiologic, anatomic and

pathophysiologic) of each limb.9

METHODS

From May, 1994 to December, 1998, 613 limbs in 492 patients

with primary varicose veins were subjected to duplex examination of

the venous system in the Department of Plastic and Reconstructive

Surgery at Tokyo Women’s Medical University. The examination

included greater saphenous, lesser saphenous, common femoral, superficial

femoral, popliteal, gastrocnemius, mid-thigh and calf perforating veins.

The saphenosfemoral and saphenopopliteal junctions were assessed with

the patients standing with distal manual compression followed by

sudden release.7 The remainder of venous system was examined with

the patients sitting. Superficial venous incompetence was detected when

the duration of reflux was greater > 0.5 seconds.10 Deep vein and

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perforating vein reflux were also determined if the duration of relux

exceeded 0.5 seconds. Perforating vein incompetence was examined with

the patients in the sitting position facing the examiner.7,8 According

to this examination criteria, 146 limbs in 109 patients with isolated

superficial venous insufficiency were selected for present study. These

had venous reflux along the entire segment of either GSV (from

groin to ankle) or LSV (from popliteal fossa to ankle). The clinical

manifestations of these limbs were classified according to the CEAP

method of reporting in venous disease.9 All of the patients could be

classified into varicose veins (class 2), edema (class 3), skin changes

(class 4), or chronic ulceration (class 5 or class 6). The mean age of

the patients was 52.9±11.5 years. Reflux in the GSV was found in

111 limbs (LSV in 27, and both the GSV and LSV in 8). A

total of 36 limbs were classified as class 2, 18 as class 3, 68 as

class 4, 16 as class 5, and 8 as class 6. Patients with arterial

insufficiency were identified based on an ankle-brachial pressure index <

0.8 and were excluded from the study.

According to the duration of reflux along with the retrograde

peak velocity, limbs were categorized into three groups : those with a

retrograde peak velocity > 30 cm/sec and a duration of reflux < 3 seconds

(Group A), peak velocity > 30 cm/sec and duration of reflux > 3seconds

(Group B), and retrograde peak velocity < 30 cm/sec and a duration of

reflux > 3 seconds (Group C).

In Group A, there were 26 men and 43 women ranging in age

from 33 to 73 (mean 56 years). In Group B, there were 8 men

and 26 women with ages ranging from 24 to 74 years (mean 53

years). In Group C, there were 9 men and 34 women with ages

ranging from 24 to 86 years (mean 53 years).

Color duplex scan : A color duplex scanner (LOGIQ 500MD :, GE

Medical Sytems, Milwaukee, Wisconsin, USA) with a 5 to 10 MHz

transducer was used for this study. The duration of reflux and

retrograde peak velocity were measured at the saphenofemoral junction

(SFJ), in the GSV in the thigh, and in the lesser saphenous vein

(LSV) at the saphenopopliteal junction (SPJ).8 Reflux flow calculated

using the equation :

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Reflux Flow (ml/sec) = Peak Velocity x Area (r2).

The vessel cross-sectional area was calculated from the diameter,

assuming a circular shape.

APG : APG measurements were performed as described by

Nicolaides11 using APG Model 1000 (ACI Medical Inc., Sun Valley,

California, USA) following color duplex scanning. The data obtained

by APG were the venous volume on standing (VV), the venous

filling index (VFI), the ejection fraction (EF) and the residual venous

fraction (RVF). VFI is the average rate of increase in the VV.

Calf muscle pump function is indicated by EF which is a measure

of the percentage of the ejection volume after one tiptoe maneuver.

RVF is a measure of the percentage of the VV remaining in the

calf after 10 tiptoe maneuvers which is thought to reflect the

ambulatory venous pressure.12 A total of 12 normal volunteers

underwent APG-testing for comparison.

Statistics. Statistical analysis was performed using Wilcoxon’s

non-parametric rank sum test. Values are expressed as the mean±the

standard deviation. A significant difference was recorded when the p

value was < 0.05. Correlations between duplex and APG-derived

parameters are analyzed using Pearson’s correlation coefficient method.

Complete correlations are considered when correlation coefficient was

1.00 or -1.00.

RESULTS

According to this examination criteria, superficial combined with

deep vein incompetence was detected in 75 limbs, and superficial

combined with perforating vein incompetence was found in 75 limbs.

Concomitant superficial, deep and perforating vein incompetence was

detected in 51 limbs. Deep combined with perforating vein

incompetence was detected in 9 limbs. Isolated deep and perforating

vein incompetence were detected in 19 and 15 limbs respectively.

Isolated superficial venous reflux was detected in 369 limbs in 303

patients. This accounts for 60.2 % of all limbs examined. A total of

146 limbs were examined by both color duplex ultrasound and APG.

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The correlation between the duration of reflux and the retrograde

peak velocity measured at the SFJ and SPJ with the clinical

symptoms are shown in Figure 1.

In Group A, 17 limbs were class 5 and 6, 37 were class 4,

and 15 were class 2 and 3. Overall, 54 of 69 limbs were in

class 4, 5 and 6 (78.2%).

In Group B, 7 limbs were class 5 and 6, 20 were class 4,

and 7 were class 2 and 3. Overall, 27 of 34 were in class 4,

5, and 6 (79.4%).

In Group C, no limbs were in class 5 and 6, 11 were in

class 4, and 32 were in class 2 and 3. Overall, only 11 of 43

limbs were in class 4, 5, and 6 (25.6%) (Table I A, B).

The incidence of venous ulceration in Group A and Group B was

23.4% and 20.6% respectively. None of the limbs in Group C

showed chronic ulceration.

There were significant differences between the retrograde peak

velocity and the reflux volume between the three groups (Table II).

There was a significant difference in the duration of reflux between

Group A and Group B and Group C. However, the GSV diameter in

Group A did not differ from those in Group B.

The APG data are presented in Table III. There was no

significant difference between the EF values of the three groups, but,

significant difference was found in VFI between the groups. The

RVF values were significantly higher in Group A than in Group B.

The only value which is statistically significant difference between

Group B and Croup C was VFI.

VFI and RVF values in normal volunteers were significantly

lower than Group C, however, there was no significant difference in

EF values between the normal volunteers and the patients with

venous insufficiency.

The correlation between duplex-derived and APG-derived parameters

are presented in Table IV. No significant correlations were found

between the duration of reflux and any of the APG-derived

parameters measured at the SFJ and GSV (Table V). On the other

hand, there was a significant correlation between the peak velocity at

the SFJ and GSV, and the APG-derived value for VFI. Similarly,

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there was a significant correlation between the peak velocity and VFI

at the SPJ.

DISCUSSION

There are several noninvasive methods for assessing venous reflux.

Recently, color duplex ultrasound and APG have replaced both

ascending and descending phlebography, and venous pressure

measurements in the evaluation of reflux. Duplex scan allows direct

visualization of the anatomical location and extent of the venous

incompetence as does phlebography. But duplex-derived retrograde peak

velocity cannot be determined by phlebography or venous pressure

measurement.

Venous reflux can be elicited manually or by pneumatic

tourniquet release in order to measure the retrograde peak velocity.

Szendro examined standing subject by manual compression of the calf

muscles followed by sudden release and found that 95% of healthy

limbs had the duration of reflux in the deep veins less than 0.5

s.13 Sarin, using manual calf compression in the standing position,

showed that the duration of reflux of limbs with significant venous

reflux exceeded 0.5 s in both the deep and superficial veins.14 van

Bemmelen studied duration of deep venous reflux in 32 limbs and

found that the duration of reflux in 95% of the limbs was < 0.5

seconds. 15 Araki found that there was no difference between

pneumatic tourniquet release and manual compression and release16 so

we used manual compression because it is more comfortable for the

patients.

APG, a noninvasive diagnostic tool, has proved to be an attractive

tool for evaluating venous function. Christopoulos reported that an

increase in the VFI correlates with the clinical severelity of venous

disease. 17 Normal lims have a VFI < 2 ml/sec, and VFIs > 5 ml/sec are

considered abnormal.11 A VFI > 7 ml/sec is associated with a high

incidence of severe chronic venous insufficiency,11 and the VFI is

considered to be a good predictor of venous reflux.18 Although, there

was a significant difference in VFI between limbs with group C and

those with normal volunteers, the limbs with group C is considered

by no means abnormal in this regard. The EF and RVF reflect

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calf muscle-pump function, and RVF is thought to provides a useful

assessment of the ambulatory venous pressure.19 EFs less than 40%,

and RVFs greater than 40% are considered to be abnormal.9

The role of superficial venous insufficiency in the development of

venous ulceration has been demonstrated by several authors. Shami3

obtained favorable results with performing saphenous vein stripping for

patients with ulcer. Labropoulos20 reported 84% of his patients with

leg ulceration had superficial reflux. He also noted that venous

ulceration is highly associated with reflux throughout of the length of

the GSV or with extensive reflux in both the GSV and LSV.7 In

this study we have found that if duplex-derived duration of reflux

and the peak velocity are taken into account, ulceration is associated

with incompetence along the entire GSV as well as high retrograde

peak velocity.

The present study suggests that a burst of reflux, like a water

hammer with superficial venous reflux peak velocity > 30 cm/sec

combined with duration of reflux < 3 seconds (Group A) is highly

associated with severe CVI.

Several investigators have tested the relationship between

APG-derived parameters and clinical severity. Nicolaides’ laboratory

reported a good correlation of VFI with the incidence of ulceration,17

and Nicolaides showed that the combination of VFI and EF had

prognostic significance for the development of ulceration.11 On the

other hand, van Bemmmelen reported that APG parameters do not

effectively distinguish limbs with chronic venous insufficiency from

limbs with uncomplicated varicose veins.21 He described that as a

group, VFIs of legs with ulcers and dermatitis were significantly

higher compared to those with varicose veins, but he found a great

deal of individual overlap. He also showed that combination of VFI

and EF do not improve the discrimination.

Correlation of APG-derived parameters with duplex-derived parameters

are also demonstrated by several investigators. Weingarten showed that

the VFI is the only APG measurement that correlates with the

duration of reflux and that the RVF is the only measurement which

significantly correlates the mean total-limb reflux time.1 Welch et al.

reported that the duration of reflux of the superficial femoral vein

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and popliteal vein increased as the clinical symptoms progress, but

found no correlation between the duration of reflux at the SFJ, in

the GSV and the clinical severity.2 Rodriguez also tested venous

reflux at SFJ, GSV and LSV, and showed that duration of reflux

in individual veins did not reflect the magnitude of the reflux volume,

and that even total duration of reflux did not correlate with the

APG-derived VFI.22

In the current study, we found that increased duration of reflux

does not correlate with APG-derived VFI. However, there is a

significant correlation between VFI and peak velocity at the SFJ and

SPJ, and a moderate correlation at GSV reflux. However, EFs and

RVFs have only poor correlations with duplex-derived parameters.

Retrograde flow calculated by duplex scanning is another parameter

of venous reflux. Bergan demonstrated a lack of correlation between

the total quantity of reflux and clinical manifestation.23 In contrast,

Vasdekis stated that the flow at peak reflux > 10 ml/sec is highly

associated with skin changes.24 He also found that reflux volume in

limbs with only superficial venous insufficiency with skin changes is

significantly greater than those with no skin changes. van Bemmelen

suggests the reason for this discrepancy between duplex scanning and

APG is that they do not measure the same reflux because of the

effect of arterial inflow on plethysmographic measurement.

In this study, the duration of reflux in individual veins showed

only weak correlations with the APG-derived parameters and clinical

severity in patients with isolated superficial incompetence. If we

consider the the duration of reflux alone in the evaluation of venous

reflux, such superficial incompetence alone did not correlate with ulcer

formation. However, we found a significant correlation between the

retrograde peak velocity and the duration of reflux measured at the

SFJ and the SPJ. EF and RVF weakly correlate with overall reflux.

These findings suggest that the retrograde peak reflux velocity > 30 cm/s

and the duration of reflux < 3 s is a better indicator of severe

chronic insufficiency. A large volume can reflux at high peak

velocity in short amount of time, and a low volume can reflux at

a slow velocity in a longer period of time. The criteria for venous

incompetence using duplex-derived retrograde peak velocity along with

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furation of reflux could have strong impacts on clinical evaluation of

CVI.

In conclusion, proposed criteria based on the duplex-derived

parameters is immediately useful in the quantitative evaluation of

superficial venous insufficiency. Only APG-derived VFI correlates with

venous reflux, and EF and RVF do not have important role in the

discrimination of the clinical severity. It could be that stripping of

GSV would be an appropriate operation in patients with Group A and

Group B because a large amount of reflux causes the severe chronic

symptoms. However, less radical methods, including high flush ligation

at the SFJ (including ligation of groin tributary veins) combined with

sclerotherapy and duplex-guided sclerotherapy for GSV incompetence

could be indicated in patients with group C.

Ackowledgments

We thank Dr. John J Bergan, Department of Surgery, University

of California, San Diego, for valuable comments.

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REFERENCES

1. Weingarten MS, Czeredarczuk M, Scovell S, et al. A correlation

of air plethysmography and color- flow - assissted duplex scanning in

the quantification of chronic venous insufficiency. J Vasc Surg

1996 ; 24 : 750-4

2. Welch HJ, Young CM, Semegran AB, et al. Duplex assessment

of venous reflux and chronic venous insufficiency : the significance

of deep vein reflux. J Vasc Surg 1996 ; 24 : 755-62

3. Shami SK, Sarin S, Cheatle TR, et al. Venous ulcers and the

superficial venous system. J Vasc Surg 1993 ; 17 : 487-90

4. Christopoulous D, Nicolaides AN, Szendro G. Venous reflux :

quantitation and correlation with clinical severelity of venous

disease. Br J Surg 1988 ; 75 : 352-6

5. Christopoulous D, Nicolaides AN, Galloway JMD, et al.

Objective noninvasive evaluation of venous surgical results. J Vasc

Surg 1988 ; 8 : 683-7

6. Bello M, Scriven M, Hartshorne T, et al. Role of superficial

venous surgery in the treatment of venous ulceration. Br J Surg

1999 ; 86 : 755-9

7. Labropoulos N, Leon M, Nicolaides AN, et al. Superficial venous

insufficiency : correlation of anatomic extent of reflux with clinical

symptoms and signs. J Vasc Surg 1994 ; 20 : 953-8

8. Yamaki T, Nozaki M, Sasaki K. Color duplex ultrasound in the

assessment of primary venous leg ulceration. Dermatol Surg 1998 ;

24 : 1124-1128.

9. Porter JM, Moneta GL. International consensus commitee on

chronic venous disease. Reporting standard in venous disease : an

update. J Vasc Surg 1995 ; 21 : 635-45.

10. Nicolaides AN, Sumner DS. Investigation of patients with deep

venous thrombosis and chronic venous insufficiency. London : Med-

Orion Publishing Co., 1991 : 1-73

11. Nicolaides AN, Christopoulos D. Quantification of venous reflux

and outflow obstruction with air plethysmography. In : Bernstain EF,

editor. Vascular diagnosis. St. Louis : Mosby, 1993 : 915-21.

12. Nicolaides AN, Hussein MK, Szendro G, et al. The relation of

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venous ulceration with ambulatory venous pressure measurements. J

Vasc Surg 1993 ; 17 : 414-9

13. Szendro G, Nicolaides AN, Zukowski AJ, et al. Duplex scanning

in the assessment of deep venous incompetence. J Vasc Surg

1986 ; 4 :237-42

14. Sarin S, Sommerville K, Farrah J, et al. Duplex ultrasonography

for assessment of venous valvular function of the lower limb. Br

J Surg 1994 ; 81 : 1591-5

15. van Bemmelen PS, Bedford G, Beach K, et al. Quantitative

segmental evaluation of venous valvular reflux with duplax

ultrasound scanning. J Vasc Surg 1989 ; 10 : 425-31

16. Araki CT, Back TL, Padberg FT Jr, et al. Refinements in the

ultrasonic detection of popliteal vein reflux. J Vasc Surg 1993 ;

18 : 742-8

17. Christopoulos D, Nicolaides AN, Szendro G. Venous reflux :

quantification and correlation with the clinical severelity of chronic

venous disease. Br J Surg 1988 ; 75 : 352-6

18. Criado E, Farber MA, Marson WA, et al. The role of air

plethysmography in the diagnosis of chronic venous insufficiency. J

Vasc Surg 1998 ; 27 : 660-70

19. Comerota AJ, Harada RN, Eze AR, et al. Air plethysmography :

a clinical review. Int Angiol 1995 ; 14 : 45-52

20. Labropoulos N, Leon M, Geroulakos G, et al. Venous

hemodynamic abnormalities in patients with leg ulceration. Am J

Surg 1995 ; 169 : 572-4

21. van Bemmelen PS, Mattos MA, Hodgson KJ, et al. Does air

plethysmography correlate with duplex scanning in patients with

chronic venous insufficiency ? J Vasc Surg 1993 ; 18 : 796-807

22. Rodriguez AA, Whitehead CM, McLaughlin RL, et al. Duplex-

derived valve closure times fail to correlate with reflux flow

volumes in patienta with chronic venous insufficiency. J Vasc

Surg 1996 ; 23 : 606-10

23. Bergan JJ. Clinical application of duplex testing in treatment of

primary venous stasis, varicose veins. In : van Bemmelen PS,

Bergan JJ, eds. Quantitative measurement of venous incompetence.

Austin : RG Landis, 1992 : 78-104

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24. Vasdekis SN, Clarke H, Nicolaides AN. Quantification of venous

reflux by means of duplex scanning. J Vasc Surg 1989 ; 10 :670-7

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Figure 1. A.

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Table I.

CEAP Classification Group A Group B Group C Total

Class 2 10 2 24 36

Class 3 5 5 8 18

Class 4 37 20 11 68

Class 5 12 4 0 16

Class 6 5 3 0 8

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Table II.

Blood Flow

Parameter

Duration of

reflux (s)

Peak velocity

(cm/s)

Diameter

(cm)

Refluxed volume

(ml/s)

Group A 2.02±0.65* 79.90±42.23* 1.17±0.23 122.80±107.68†

Group B 4.00±1.12 60.99±22.98¶ 1.05±0.25¶ 102.80±65.82¶

Group C 4.87±2.84 15.79±7.99 0.74±0.22 15.34±12.46

Values are the mean±SD.

*Group A versus Group B, p < .0001 †Group A versus Group B, p = .0002 ¶Group B versus Group C, p < .0001

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Table III.

APG Parameter VFI (s) EF (%) RVF (%)

Group A 6.13±2.55* 41.50±17.35 50.79±17.68+

Group B 4.97±1.86† 44.35±16.13 33.82±17.79

Group C 2.73±1.26‡ 53.33±16.27 23.32±16.20¶

Normal volunteers 0.97±0.34 58.81±13.03 4.38±5.22

Values are the mean±SD.

*Group A versus Group B, p = .0007 + Group A versus Group B, p = .036 †Group B versus Group C, p = .0064 ‡Group B versus Normal volunteers, p = .0022 ¶Group B versus Normal volunteers, p = .0076

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Table IV.

Duration of reflux (s) APG

VFI EF RVF

SFJ -0.413 0.034 -0.272

GSV -0.447 -0.039 -0.277

LSV -0.530 -0.089 -0.293

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Table V.

Peak velocity (ml/s) APG

VFI EF RVF

SFJ 0.726 -0.062 0.299

GSV 0.579 0.069 0.333

LSV 0.704 -0.014 0.445

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LEGENDS Figure I. The Duration of Reflux and Peak Retrograde Reflux Velocity Correlated with the Clinical Symptoms for Patients with Isolated Superficial Venous Incompetence. A. : Correlation of CEAP C2 and C3 with

the Duration of Reflux and Peak Retrograde Reflux Velocity

B. Correlation of CEAP C4, C5 and C6 with the Duration of Reflux and Peak Retrograde Reflux Velocity

Table I. The Frequencies of the CEAP Clinical Grades. Table II. Duration of Reflux and Peak Retrograde Reflux Velocity.

Table III. APG-derived Parameters. Table IV. Correlations Between the VCTs and APG-derived Parameters. Table V. Correlations Between the Peak Retrograde Reflux Velocity and APG-derived Parameters.