Duplex ultrasonography scanning for chronic venous disease: Patterns of venous reflux

Duplex ultrasonography scanning for chronic venous disease: Patterns of venous reflux K e n n e t h A. Myers, F R A C S , R o b e r t W. Ziegenbein, MSc, Ge H u a Zeng, M D , and P. G e o f f r e y M a t t h e w s , F R A C P , Melbourne, Australia

Purpose: Patterns of flow in superficial and deep veins and outward flow in medial calf perforators were studied by duplex ultrasonography scanning in 1653 lower limbs in 1114 consecutive patients. This study compares results in 776 limbs with primary uncomplicated varicose veins with those in 166 limbs with the complications oflipodermatosclerosis or past venous ulceration. Methods: Duplex scanning determined whether superficial and deep veins were occluded or showed reflux and whether outward flow occurred in medial calf perforators with calf muscle contraction. Results: Two proximal deep veins were occluded. When limbs with primary uncomplicated varicose veins, lipodermatosclerosis, or past ulceration were compared, superficial reflux alone was seen in 55%, 39%, and 38%, deep reflux alone was seen in 2%, 7%, and 8%, and combined superficial and deep reflux was seen in 18%, 34%, and 48%, respectively. Superficial reflux affected the long saphenous system alone in 58%, 57%, and 40%, the short saphenous system alone in 18%, 18%, and 26%, and both the long and short saphenous systems in 24%, 25%, and 34%, respectively. Limbs with ulceration more frequently showed superficial reflux (p < 0.05), and all limbs with complications more frequently showed short saphenous reflux (p < 0.05) and deep reflux (p < 0.01) specifically in the posterior tibial veins (p < 0.01). Outward flow was seen in medial calf perforators in 57%, 67%, and 66%, respectively; it occurred more frequently in all limbs with complications (p < 0.05). Isolated outward flow in perforators without superficial or deep reflux was seen in 10%, 10%, and 2%, respectively. Conclusions: Most limbs with complications had superficial reflux either alone or combined with deep reflux, and few had deep reflux alone. Reflux was more frequent in posterior tibial veins for limbs with complications compared with those with uncomplicated primary varicose veins. Outward flow in perforators was common in limbs with complications and with uncomplicated primary varicose veins, but isolated outward flow in perforators was uncommon. Treatment directed to the superficial veins alone may be sufficient for most patients with complications. (J VAsc SURG 1995;21:605-12.)

Conventional teaching is that lipodermatosclerosis or ulceration most often result from past deep venous thrombosis followed by deep and perforator vein recanalization with loss o f their valves or from chronic congestion in deep veins connected to the perforators, which causes secondary valvular incompetence. Terms such as the post-thrombotic syndrome, deep venous insufficiency, and perforator

From the Departments of Surgery and Medicine, Monash University and Monash Medical Centre, Melbourne. Presented at the Sixth Annual Meeting of the AmericanVenous Forum, Wailea, Maui, Hawaii, Feb. 23-25, 1994. Reprint requests: K.A. Myers, 158 Lennox St., Richmond, 3121, Melbourne, Australia. Copyright © 1995 by The Society for Vascular Surgery and International Societyfor CardiovascularSurgery,North American Chapter. 0741-5214/95/$3.00 + 0 24/1/61752

incompetence have become synonymous with the complications. These problems have led to the use o f treatment to interrupt perforators or to repair or replace valves in the deep veins. These beliefs are now being questioned. Recent studies show that extensive deep venous reflux is not common, deep venous reflux alone is very uncommon, and superficial venous reflux is frequently present in limbs with complications1-7; outward flow in perforators is c o m m o n in patients without complications and even in healthy subjects, sl~ This study used duplex ultrasonography scanning to further explore patterns o f venous flow at various sites in relation to the clinical presentations. PATIENTS AND METHODS Patients. This was a prospective study involving duplex ultrasonography scanning to assess 1653 605

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Table I. The sites of venous reflux Complicated venous disease Sites of reflux Superficial alone Deep alone Superficial and deep No reflux Superficial reflux Long saphenous alone Short saphenous alone Long and short saphenous Deep reflux Common femoral Superficial femoral Popliteal Posterior tibial Total

Uncomplicated primary varicose veins (%) 429 18 137 192

(55) (2) (18) (25)

LDS 27 5 24 14

(39) (7) (34) (20)

Ulceration 36 8 46 6

(38) (8) (48) (6)

327 (58) 104 (18) 135 (24)

29 (57) 9 (18) 13 (25)

33 (40) 21 (26) 28 (34)

95 59 79 33 776

14 11 12 12 70

30 27 33 24 96

(61) (38) (51) (21)

(48) (38) (41) (41)

(56) (50) (61) (44)

LDS, Lipodermatosclerosis. The numbers of limbs are shown, and the percentages are expressed as a proportion of all limbs for each clinical presentation and for the numbers of limbs with superficial or deep reflux.

lower limbs in 1114 consecutive patients referred with possible chronic venous disease. Four hundred seventy-two limbs with uncomplicated varicose veins that had recurred after previous surgery on the long saphenous vein were studied, and 239 limbs were studied to evaluate aching or swelling without apparent superficial venous disease. These limbs were excluded from this presentation. This leaves 776 limbs with uncomplicated primary varicose veins, 70 limbs with lipodermatosclerosis, and 96 limbs with past venous ulceration referred to as "complications." Although some physicians referred most patients with appreciable venous disease, others tended not to refer those considered to have obvious evidence of uncomplicated primary varicose veins caused by long saphenous involvement alone. This evidence was based on clinical grounds and results of continuouswave Doppler ultrasonography so that the group with uncomplicated primary varicose veins may have been distorted by exclusion of some patients with long saphenous involvement alone. Lipodermatosclerosis and ulceration correspond to class 2 and 3, respectively, as recommended by the Subcommittee on Reporting Standards for Venous Disease. ~2 The limbs considered to have lipodermatosclerosis in this article all had severe changes. Patients with past venous ulceration were all classified by clinical criteria together with ankle/brachial pressure indexes to exclude significant arterial disease. If active ulceration was involved, duplex scanning was deferred until the ulcer was healed by conservative measures. In no case was it necessary to operate to achieve healing between the time of presentation and the scan.

Duplex scanning. A gray-scalc Diasonics DRF 400 scanner (Diasonics, Milpitas, Calif.) was used for the first 113 studies, and ATL Ultramark 9 colorDoppler duplex scanners (Advanced Technology Laboratories, Bothell, Wash.) were used for the remainder of the studies. A previous article describing the ability to detect crural veins 13 suggested that little difference existed between each machine for demonstrating venous reflux. All studies were performed in one unit. The long and short saphenous veins, the common femoral, superficial femoral, and popliteal veins, and the three sets of crural veins were studied. A separate analysis detailing the frequency of reflux in crural veins 14showed that reflux almost always included the posterior tibial veins so that results for the other crural veins are not provided to simplify the presentation. The superficial and deep veins were examined for patency and competence. The patients were studied while they stood supported on the edge of a couch with weight placed on the opposite side. The thigh was externally rotated and moderately flexed at the hip to allow easy access to the groin, thigh, and back of the knee. The leg was dependent, and posterior tibial veins were examined by approaches previously described) 3 Upward flow in deep and superficial veins resulted from squeezing the calf muscles for approximately 0.5 seconds, and the site of the squeeze was varied to find the best site to get the maximum outflow for each limb. A pneumatic cuff technique was not used. Reflux was diagnosed if retrograde flow occurred after release and persisted for more than 0.5 seconds. We did not attempt to

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Fig. 1. Frequency of (A) superficial (sup.) and deep venous reflux, (B) sites of superficial venous reflux (LS, long saphenous; SS, short saphenous), (C) sites of deep venous reflux (CF, common femoral; SF, superficial femoral; POP, popliteal; PT, posterior tibia[), and (D) levels of deep venous reflux (one to four contiguous levels) according to clinical presentation.

quantitate reflux. Reflux into the long or short saphenous veins was invariably associated with reflux in the common femoral or popliteal veins above the saphenous junctions so that deep reflux at either site was diagnosed only if retrograde flow extended to below either saphenous junction. Medial calf perforators were detected by observing a vein passing through the deep fascia, which is a very distinct band on the B-scan, and confirming its identity by observing augmented flow on color Doppler imaging after squeezing the calf muscles proximal to the site of examination. The fifll length of the leg was examined behind the tibia. Outward flow in the perforator was diagnosed if color Doppler flow was seen in the appropriate direction during isometric calf muscle contraction by forcible plantar-flexion against resistance. Diameters of the perforators were not analyzed. Statistics. Significance of difference between limbs with primary uncomplicated varicose veins and limbs with complications was assessed by chi-squared analysis with Yates correction.

RESULTS Deep venous obstruction. Only two limbs had occluded veins proximal to the crural veins: one superficial femoral vein in a limb with lipodermatosclerosis and one popliteal vein in a limb with past venous ulceration. Superficial and deep venous reflux. In regards to all limbs with primary varicose veins, lipodermatosderosis, or past ulceration (Table I), superficial reflux alone was seen in 55%, 39%, and 38%, deep reflux alone in 2%, 7%, and 8%, and both superficial and deep reflux in 18%, 34%, and 48%, respectively (Fig. 1, A). For the limbs with superficial reflux, the long saphenous system alone was affected in 58%, 57%, and 40%, the short saphenous system alone in 18%, 18%, and 26%, and both in 24%, 25%, and 34%, respectively (Fig. 1, B). Thus long saphenous reflux was seen in 82%, 83%, and 74%, and short saphenous reflux was seen in 42%, 43%, and 60%, respectively, in limbs with superficial reflux in the three clinical groups; a higher frequency of short saphenous reflux was seen in limbs with complica-

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~NO REFLUX IEREFLUX

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O-

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Fig. 2. Proportion of limbs with (A) superficialand(B) deep venous reflux in all limbs according to clinical presentation.

tions (53%) compared with those with primary uncomplicated varicose veins (42%) (p < 0.05). Deep reflux occurred more frequently in the common femoral veins than in the superficial femoral veins and more frequently in the popliteal veins than in the posterior tibial veins in each clinical group; reflux in posterior tibial veins occurred more fiequently in limbs with complications (43%) compared with those with uncomplicated primary varicose veins (21%) (p < 0.01), but no difference was seen for the other sites of deep reflux (Fig. 1, C). Multilevel deep reflux occurred more frequently in limbs with ulceration compared with those with uncomplicated primary varicose veins (10 < 0.05) (Fig. 1, D). Thus superficial reflux either alone or combined with deep reflux was seen in 73%, 73%, and 86%, respectively, for the three clinical groups so that superficial reflux occurred more frequently in limbs with ulceration compared with those with uncomplicated primary varicose veins (i0 < 0.05) (Fig.

2, A). Deep reflux either alone or combined with superficial reflux was seen in 20%, 41%, and 56%, respectively, for the three clinical groups so that deep reflux occurred more frequently in all limbs with complications compared with those with uncomplicated primary varicose veins (i0 < 0.01) (Fig. 2, B). Outward flow in medial calf perforators. Outward flow was observed in medial calf perforators in 57%, 67%, and 66%, respectively, for all limbs with primary varicose veins, lipodermatosclerosis, or past ulceration (Table II); it occurred more frequently in all limbs with complications than in those with uncomplicated primary varicose veins (40 < 0.05) (Fig. 3,A). If superficial reflux occurred in the three clinical groups, outward flow in perforators was observed in 63%, 76%, and 68%, respectively, and if deep reflux occurred, outward flow in perforators was observed in 69%, 69%, and 72%, respectively; the frequency was no different in limbs with associated superficial (Fig. 3, B) or deep (Fig. 3, C) venous reflux. Isolated outward flow in medial calf perforators without deep or superficial reflux was observed in 10%, 10%, and 2%, respectively, of the three clinical groups. DISCUSSION The conventional concept is that lipodermatosclerosis or venous ulceration complicating chronic venous disease predominantly results from loss of valve function in deep and perforating veins, which leads to chronic congestion in calf muscle venous plexuses so that muscle contraction ejects blood at high pressures through perforators. This ejection causes damage to overlying tissues. This problem would require a proximal reservoir for blood to reflux down into the leg during muscle relaxation, and the reservoir would need to be connected to the deep muscle plexuses and then to surface veins without any intervening competent valves, because once blood has been expelled past a competent valve, it cannot return to the calf muscle plexuses. This study found that the larger proportion of limbs with complications had no deep reflux at any level down the limb and that few showed incompetence of all deep valves. Most had superficial reflux either alone or combined with deep reflux. Outward flow in medial calf perforators was more likely with complications but was also common in limbs with uncomplicated varicose veins. Isolated outward flow in perforators was uncommon and occurred no more frequently than in limbs without complications. It may be that limbs with complications simply have more severe venous disease possibly because of

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Table II. The number of lower limbs with outward flow in medial calf perforators related to the clinical presentations and the presence of superficial or deep venous reflux Complicated venous disease Sites of reflux All limbs Perforators seen Perforators not seen Superficial reflux Perforators seen Perforators not seen Deep reflux Perforators seen Perforators not seen N o reflux Perforators seen Perforators not seen

Uncomplicated primary varicose veins (%)

LDS

Ulceration

441 (57) 335

47 (67) 23

63 (66) 33

356 (64) 210

39 (74) 14

56 (68) 26

107 (69) 48

20 (70) 9

39 (72) 15

76 (40) 116

7 (50) 7

2 (33) 4

LDS, Lipodermatosclerosis. The percentages are the proportion of limbs with outward flow at each site.

development of inherent weakness of deep and perforator veins as has previously been shown for superficial veins, is The findings challenge the conventional belief that complications result from deep and perforator venous disease and suggest that superficial reflux is the most common cause. Ambulatory venous pressure studies, photoplethysmography, and air plethysmography demonstrate valvular insufficiency in limbs with complications. 1622 However, the pressure required to compress superficial veins by a thigh tourniquet varies from 40 to 300 mm Hg 23 so that it is difficult to distinguish superficial from deep reflux for any of these tests, because a tourniquet may either fail to prevent superficial reflux or cause deep venous obstruction. Past reports involving continuous-wave Doppler ultrasonography showed more frequent deep reflux than in this s t u d y , 24'2s predominantly in crural veins. 26 Studies with duplex ultrasonography have generally shown that superficial reflux occurs more frequently and deep reflux less frequently in limbs with complications than was previously recognized and that deep reflux is most often localized. 26 Hanrahan et al.3 found superficial, deep, or combined reflux in 36%, 6%, and 43%, respectively, in 95 limbs with class 3 disease. Lees and Lambert6 found that the frequency was 56%, 2%, and 36%, respectively, for 98 limbs with class 2 or 3 disease. Only one study reported that deep reflux was more common and superficial reflux less common, and most limbs still had combined superficial and deep reflux. 7 Moulton et al.27 reported that severe disease was more frequently associated with combined deep and super-

ficial reflux and that patterns of reflux in limbs with complications were similar to those in this study. Complications are frequently referred to as the "postthrombotic syndrome." A study of patients with past deep vein thrombosis proven by venography then assessed by continuous-wave Doppler ultrasonography 5 to 10 years later showed that more than two thirds had popliteal or posterior tibial valve incompetence.2s Similar reports involving duplex scanning found superficial femoral reflux in 37%, popliteal reflux in 58%, and posterior tibial reflux in 18% by 1 year after thrombosis29; the limbs with deep reflux were those who lysed their thrombus slowly?° However, others hold that the larger proportion who have complications from chronic venous disease do not have evidence of past deep vein thrombosis. 3'31In this study deep venous obstruction below the inguinal region appeared to be a rare reason for complications, but few patients were examined for possible iliac or inferior vena caval occlusion, and partial narrowing of diseased veins may cause functional resistance to flow? 2 A previous report showed that some 95 % of posterior tibial veins could be visualized, la but it is not possible to know whether the remainder were occluded or simply not detected. It is difficult to see how deep reflux can cause the chronic congestion held to be the basis for complications, if any competent deep valves exist. This study did not support a role for deep venous reflux down axial veins from the groin to the ankle. Air plethysmography shows that the ejection volume during a single tiptoe exercise is 50 to 180 ml in legs with uncomplicated varicose veins and 8 to 140 ml in legs

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Fig. 3. Proportion of limbs with outward flow in medial calf perforators (seen) according to (A) clinical presentation and (B) presence of superficial or deep reflux.

with deep venous disease. 18 It can be calculated that the deep veins below the groin would need to almost double their diameter during calf muscle contraction to hold such a volume and provide a reservoir for reflux, and this occurrence has not been observed by duplex scanning. However, reflux into the profunda femoris vein was not studied, and this could be an alternate source for tilling. 24,33 Electrical calf muscle stimulation and mechanical compression of the foot expel comparable volumes from the leg, 34 and deep reflux is reduced by compressing the foot venous plexus, 35 suggesting that this reservoir may have been underestimated in the past. Previous studies show that dilated superficial veins could be the reservoir for reflux causing complications.l,~,36 Air plethysmography has shown that blood is not adequately expelled from the leg because of impaired calf muscle function in limbs with complications, ~8-22but this problem could lead to superficial stasis just as much as deep stasis, if the predominant disease is in the superficial veins. It may be that blood is expelled out by muscle contraction from deep veins or the calf muscle plexuses into

superficial varicose veins through the saphenous junctions or perforator veins to then return into the muscle plexuses through perforator veins during calf muscle relaxation. The group from the Middlesex Hospital 81° note that it has long been known that some perforators have no valves, that others have valves that direct flow outwards, that flow in perforators during walking normally occurs in both directions, and that outward flow is commonly seen in medial calf perforators in limbs with uncomplicated varicose veins and in normal contralateral limbs. Earlier studies involving indirect investigations suggested that outward flow in perforators frequently was not associated with deep venous reflux, although many limbs showed severe physiological disturbances. 37 More recent studies have used duplex scanning to assess the patterns of association. Hanrahan et al.3 found that the frequency of outward flow in perforators in 95 limbs with class 3 disease was 53% with superficial reflux alone and 73% with combined superficial and deep reflux and that only 8% of all limbs had isolated perforators with no

JOURNAL OF VASCULARSURGERY Volume 21, Number 4

superficial or deep reflux. Lees and Lambert 6 observed outward flow in perforators in 22% of 202 limbs without skin changes and in 34% of 98 limbs with skin changes where superficial reflux alone occurred, and in 54% and 66%, respectively, for limbs with combined superficial and deep reflux, whereas only 8% and 2% of each clinical group, respectively, had isolated perforators without superficial or deep reflux. Some surgeons now consider that it is not appropriate to routinely divide perforators, ~ because this procedure frequently does not prevent ulcer recurrence.n Darke and Penfold 38 treated 87 patients with long saphenous incompetence and outward flow in perforators by long saphenous ligation alone with excellent results. A study involving indirect investigations before and after surgery showed no benefit from ligating perforators. 36 Akesson et al? 9 studied 31 limbs with ulceration treated by two stage operations and found that venous reflux and venous hypertension were reduced by the first operation to excise superficial veins but not by the second operation to ligate perforators. Various pathogenic mechanisms can lead to complications, and each should be examined, for example, by duplex scanning. It should be inappropriate to embark on treatment until the functional and anatomic disease has been identified for each individual. Occasionally duplex scanning will show isolated extensive deep venous reflux, which may then be suitable for deep vein repair or replacement, isolated perforator incompetence, which requires their interruption, or the patient in whom the long saphenous vein is the major outflow vessel, in which case the long saphenous vein should be preserved. However, complications are predominantly associated with superficial reflux in most cases. A prospective study would be appropriate to assess whether limbs with lipodermatosclerosis or venous ulceration would be best managed by treating the superficial veins alone rather than by ligating perforators. We are indebted to many surgeons who have worked in the Irvine Laboratory for Cardiovascular Research at St. Mary's Hospital, London, for their incisive thoughts relating to venous disease. REFERENCES

1. Hoare MC, Nicolaides AN, Miles CR, et al. The role of varicose veins in venous ulceration. Surgery 1973;92: 450-3. 2. van Bemmelen PS, Bedford G, Beach K, Strandness DE. Status of the valves in the superficial and deep venous system in chronic venous disease. Surgery 1990;109:730-4.

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3. Hanrahan LM, Araki CT, Rodriguez AA, Kechejian GJ, LaMorte WW, Menzoian JO. Distribution of valvular incompetence in patients with venous stasis ulceration. J VASCSURG 1991;13:805-12. 4. Mastroroberto P, CheUo M, Marchese AR. Distribution of valvular incompetence in patients with venous stasis ulceration. J VAsc SURG 1992;16:307. 5. Shami SK, Sarin S, Cheafle TR, Scurr JH, Coleridge Smith PD. Venous ulcers and the superficial venous system. J VASC SUXG 1993;17:487-90. 6. Lees TA, Lambert D. Patterns of venous reflux in limbs with changes associated with chronic venous insufficiency. Br J Surg 1993;80:725-8. 7. Neglen P, Raju S. A rational approach to detection of significant reflux with duplex Doppler scanning and air plethysmography. J VASCSURG 1993;17:590-5. 8. McMullin GM, Coleridge Smith PD, Scurr JH. Which way does blood flow in the perforating veins of the leg? Phlebology 1991;6:127-32. 9. McMulfin GM, Scott HJ, Coleridge Smith PD, Scurr JH. A reassessment of the role of perforating veins in chronic venous insufficiency. Phlebology 1990;5:85-94. 10. Sarin S, Scurr JH, Coleridge Smith PD. Medial calf perforators in venous disease: the significance of outward flow. J VASC SURG 1992;16:40-6. 11. Bumand K, Lea Thomas M, O'Donnell T, Browse NL. Relation between postphlebitic changes in the deep veins and results of surgical treatment of venous ulcers. Lancet 1976; 1:936-8. 12. Porter MD, Rutherford RB, Clagett GP, et al. Reporting standards in venous disease. J VASCSUiKG1988;8:172-81. 13. Ziegenbein RW, Myers ICA, Zeng GH, Matthews PG. Duplex scanning for chronic venous disease: a technique for examination of the crural veins. Phlebology 1994. 14. Ziegenbein RW, Myers KA, Zeng GH, Matthews PG. Duplex scanning for chronic venous disease: the incidence of reflux in crural veins. Phlebology I995. 15. Clarke GH, Vasdekis SN, Hobbs ~IT,Nicolaides AN. Venous wall function in the pathogenesis of varicose veins. Surgery 1992;111:402-8. 16. Nicolaides AN, Miles C. Photoplethysmography in the assessment of venous insufficiency. J VASCSURG1987;5:40512. 17. Nicolaides AN, Hussein MK, Szendro G, Chtistopoulos D, Vasdekis S, Clarke H. The relation of venous ulceration with ambulatory venous pressure measurements. J VASC SURG i993;17:414-9. 18. Belcaro G, Christopoulos D, Nicolaides AN. Lower extremity venous hemodynamics. Ann Vasc Surg 1991;5:305-10. 19. Welkie J, Comerota AJ, Katz ML, Aldridge SC, Kerr RP, White JV. Hemodynamic deterioration in chronic venous disease. J VAsc SURG i992;16:733-40. 20. Christopoulos DG, Nicolaides AN, Szendro G, Irvine AT, Bull M-L, Eastcott HHG. Air-plethysmography and the effect of elastic compression on venous hemodynamics of the leg. J VASC SURG 1987;5:148-59. 21. Welkie JF, Comerota AJ, Kerr RP, Katz ML, layheimer EC, Brigham RA. The hemodynamics of venous ulceration. Ann Vasc Surg 1992;6:1-4. 22. Gillespie DL, Cordts PR, Hartono C, et al. The role of air plethysmography in monitoring results of venous surgery. J VASC SUinGI992;16:674-8. 23. McMullin GM, Coleridge Smith PD, Scurf JH. A study of

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32. Neglen P, Raju S. Detection of outflow obstruction in chronic venous insufficiency. J Vasc SURG 1993;17:583-9. 33. Eriksson I, Almgren B. Influence of the profunda femoris vein on venous hemodynamics of the limb. J VASC SURG 1986; 4:390-5. 34. Laverick MD, McGivern RC, Crone MD, Mollan RAB. A comparison of the effects of electrical calf muscle stimulation and the venous foot pump on venous blood flow in the lower leg. Phlebology 1990;5:285-90. 35. Cheatle TR, McMullin GM, Scurf JH. Deep vein reflux is reduced by compression of the foot venous plexus. Phlebology 1991;6:75-7. 36. Stacey MC, Burnand KG, Layer GT, Pattison M. Calf pump function in patients with healed venous ulcers is not improved by surgery to the communicatingveins or by elastic stockings. Br J Surg 1988;75:436-9. 37. Zukowski A}', Nicolaides AN, Szendro G, et al. Haemodynamic significance of incompetent calf perforating veins. Br J Surg 1991;78:625-9. 38. Darke SG, Penfold C. Venous ulceration and saphenous ligation. Eur J Vase Surg 1992;6:4-9. 39. Akesson H, Brudin L, Cwikiel W, Ohlin P, Plate G. Does the correction of insufficient superficial and perforating veins improve venous function in patients with deep venous insufficiency? Phlebology 1990;5:113-23.

Submitted March 9, 1994; accepted Nov. 1, 1994.

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