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418 Vascular Surgery
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foot vein has been believed to accurately reflect deep venous pressure changes
with calf exercise. Recent data throw considerable doubt on this long-held
assumption [16].
Air-plethysmography is a non-invasive test of calf venous pump and can be used
to assess surgical outcome [17]. Residual volume correlates with ambulatory venous
pressure. However, venous filling index (VFI
) has been a more consistent index of
90
reflux with normalization after corrective surgery [18, 19].
Venous endothelial injury that occurs with deep venous surgery takes about 6
weeks to heal [20]. Patients should be anticoagulated adequately during this vulnerable period. With proper management, the thromboembolic complication rate is
surprisingly low [21]. Patients who have suffered from previous bouts of thromboembolism and those with known hypercoagulable abnormalities are under
increased risk of recurrent thrombosis and are candidates for long-term or even
permanent anticoagulation. [Q2: A]
Once thought a rarity, primary deep venous reflux comprises about 30–40
percent of all deep venous reflux in centers active in deep venous reconstruction.
Differentiating “primary” deep venous reflux from secondary or post-thrombotic
reflux is problematic. The presentation and clinical features may be similar.
Negative history for prior DVT may be unreliable as some thromboses are silent;
and others might have been overlooked ascribing limb pain to trauma or orthopedic surgery that initiated it. Preoperative venography is a poor guide, and surgical
exploration of the valve station is often the final arbiter [22]. Some patients with
primary reflux develop actual distal thrombosis that can be recurrent. Correction of
proximal reflux in this group of patients may alleviate these recurrent symptoms
Fig. 44.1.
opening the vein; they traverse the valve attachment lines, taking a bite of the free edge of each redundant
valve cusp. When tied down, the valve attachment lines are brought together while tightening the valve cusps.
Reprinted from J Vasc Surg, vol. 32, Raju S, Berry MA, Neglen P, Transcommissural valvuloplasty: technique and
results, pages 969–76, © 2000, with permission from The Society for Vascular Surgery.
Technique of transcommissural valvuloplasty. Transluminal sutures are placed from outside without
Venous Ulcers Associated with Deep Venous Insufficiency 419
[23]. Conversely, deep venous thrombosis initiates by unknown mechanisms eventual development of reflux in adjacent and remote valve stations [24].
Correction of primary deep venous reflux by internal valvuloplasty was first
described by Kistner in 1964. Subsequently, he described an external technique as
well. A variety of open and closed techniques (Fig. 44.1) for correction of primary
and post-thrombotic deep venous reflux are currently in use [25, 26]. The internal
valvuloplasty technique has provided excellent results [21, 23, 27–29] and
remains the standard (Fig. 44.2). The newer techniques provide a wider choice
that may be more appropriate in certain circumstances, and yield clinical results
similar to the original internal technique [21, 30]. Direct valvuloplasty may be
feasible in some cases of post-thrombotic reflux where the valves have escaped
destruction [22, 31]. Axillary vein valve transfer is the standard commonly used for
correction of post-thrombotic reflux. It can be used with some modifications even
in trabeculated veins with surprisingly good long-term patency and clinical success
[32]. Arm swelling after axillary vein harvest is rare. [Q3: C]
The recent introduction of vein stent technology has decreased the number of
valve reconstructions in our institution. Post-thrombotic syndrome is known to be
due to a combination of obstruction and reflux in the majority of patients [33]. Use
of intravascular ultrasound (IVUS) has shown that Cockett’s syndrome (alias
May–Thurner syndrome) is surprisingly frequent in “primary” reflux as well [34].
Correction of the obstructive component with stent placement in thrombotic and
non-thrombotic cases results in excellent relief of pain and swelling and the patency
rate is quite good [35]. Even totally occluded iliac veins can be successfully recanalized and stented [36]. Venous stasis ulcers are generally believed to be the result of
reflux, not obstruction. Yet this relatively simple percutaneous outpatient stent
technique results in healing of about 60 percent of venous stasis ulceration [37],
even when the associated reflux remains uncorrected. Iliac vein stent placement is
Fig. 44.2. Internal valvuloplasty technique.
420 Vascular Surgery
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currently the first choice in combined obstruction/reflux, and does not preclude
later open surgery such as valve reconstruction or venous bypass if the stent were to
fail. It is often combined with percutaneous laser ablation of the saphenous vein
when reflexive. Saphenous ablation can be carried out safely, even in the presence of
chronic deep venous obstruction (secondary varix) [38].
References
1. Raju S, Neglen P. Popliteal vein entrapment: a benign venographic feature or a pathologic entity?
J Vasc Surg 2000;31(4):631–41.
2. Beebe HG, Bergan JJ, Bergqvist D, et al. Classification and grading of chronic venous disease in the
lower limbs. A consensus statement. Eur J Vasc Endovasc Surg 1996;12(4):487–91; discussion 491–2.
3. Rutherford RB, Padberg FT, Jr, Comerota AJ, Kistner RL, Meissner MH, Moneta GL. Venous severity
scoring: an adjunct to venous outcome assessment. J Vasc Surg 2000;31(6):1307–12.
4. Launois R, Rebpi-Marty J, Henry B. Construction and validation of a quality of life questionnaire in
chronic lower limb venous insufficiency (CIVIQ). Qual Life Res 1996;5:539–54.
5. Scott J, Huskisson EC. Graphic representation of pain. Pain 1976;2(2):175–84.
6. Raju S, Owen S, Jr, Neglen P. Reversal of abnormal lymphoscintigraphy after placement of venous
stents for correction of associated venous obstruction. J Vasc Surg 2001;34(5):779–84.
7. Neglen P, Raju S. A comparison between descending phlebography and duplex Doppler investigation in the evaluation of reflux in chronic venous insufficiency: a challenge to phlebography as the
“gold standard”. J Vasc Surg 1992;16(5):687–93.
8. Masuda EM, Kistner RL. Prospective comparison of duplex scanning and descending venography in
the assessment of venous insufficiency. Am J Surg 1992;164(3):254–9.
9. Masuda EM, Kistner RL, Eklof B. Prospective study of duplex scanning for venous reflux: comparison of Valsalva and pneumatic cuff techniques in the reverse Trendelenburg and standing positions.
J Vasc Surg 1994;20(5):711–20.
10. Neglen P, Egger III JF, Raju S. Hemodynamic and clinical impact of venous reflux parameters. J Vasc
Surg 2004;40:303–19.
11. Morano JU, Raju S. Chronic venous insufficiency: assessment with descending venography.
Radiology 1990;174(2):441–4.
12. Negus D, Fletcher EW, Cockett FB, Thomas ML. Compression and band formation at the mouth of
the left common iliac vein. Br J Surg 1968;55(5):369–74.
13. Neglen P, Raju S. Intravascular ultrasound scan evaluation of the obstructed vein. J Vasc Surg
2002;35(4):694–700.
14. Raju S, Neglén P, Carr-White PA, Fredericks RK, Devidas M. Ambulatory venous hypertension: component analysis in 373 limbs. Vasc Surg 1999;33:257–67.
15. Kistner RL, Eklof B, Masuda EM. Deep venous valve reconstruction. Cardiovasc Surg 1995;3:129–40.
16. Neglen P, Raju S. Ambulatory venous pressure revisited. J Vasc Surg 2000;31(6):1206–13.
17. Christopoulos D, Nicolaides AN, Galloway JM, Wilkinson A. Objective noninvasive evaluation of
venous surgical results. J Vasc Surg 1988;8(6):683–7.
18. Sakuda H, Nakaema M, Matsubara S, et al. Air plethysmographic assessment of external valvuloplasty in patients with valvular incompetence of the saphenous and deep veins. J Vasc Surg
2002;36(5):922–7.
19. Criado E, Farber MA, Marston WA, Daniel PF, Burnham CB, Keagy BA. The role of air plethysmography in the diagnosis of chronic venous insufficiency. J Vasc Surg 1998;27(4):660–70.
20. Raju S, Perry JT. The response of venous valvular endothelium to autotransplantation and in vitro
preservation. Surgery 1983;94(5):770–5.
21. Raju S, Fredericks RK, Neglen PN, Bass JD. Durability of venous valve reconstruction techniques for
“primary” and postthrombotic reflux. J Vasc Surg 1996;23(2):357–66; discussion 366–7.
22. Raju S, Fredericks RK, Hudson CA, Fountain T, Neglen PN, Devidas M. Venous valve station
changes in “primary” and postthrombotic reflux: an analysis of 149 cases. Ann Vasc Surg
2000;14(3):193–9.
23. Masuda EM, Kistner RL. Long-term results of venous valve reconstruction: a four- to twenty-oneyear follow-up. J Vasc Surg 1994;19(3):391–403.
24. Killewich LA, Bedford GR, Beach KW, Strandness DE, Jr. Spontaneous lysis of deep venous thrombi:
rate and outcome. J Vasc Surg 1989;9(1):89–97.
Venous Ulcers Associated with Deep Venous Insufficiency 421
25. Raju S, Berry MA, Neglen P. Transcommissural valvuloplasty: technique and results. J Vasc Surg
2000;32(5):969–76.
26. Raju S, Hardy JD. Technical options in venous valve reconstruction. Am J Surg 1997;173(4):301–7.
27. Perrin M. Reconstructive surgery for deep venous reflux: a report on 144 cases. Cardiovasc Surg
2000;8(4):246–55;2000;8:246–55.
28. Eriksson I. Reconstructive venous surgery. Acta Chir Scand Suppl 1988;544:69–74.
29. Sottiurai VS. Surgical correction of recurrent venous ulcer. J Cardiovasc Surg (Torino)
1991;32(1):104–9.
30. Camilli S, Guarnera G. External banding valvuloplasty of the superficial femoral vein in the treatment of primary deep valvular incompetence. Int Angiol 1994;13(3):218–22.
31. Raju S, Fountain T, Neglen P, Devidas M. Axial transformation of the profunda femoris vein. J Vasc
Surg 1998;27(4):651–9.
32. Raju S, Neglen P, Doolittle J, Meydrech EF. Axillary vein transfer in trabeculated postthrombotic
veins. J Vasc Surg 1999;29(6):1050–62; discussion 1062–4.
33. Johnson BF, Manzo RA, Bergelin RO, Strandness DE, Jr. Relationship between changes in the deep
venous system and the development of the postthrombotic syndrome after an acute episode of lower
limb deep vein thrombosis: a one- to six-year follow-up. J Vasc Surg 1995;21(2):307–12; discussion
313.
34. Neglen P, Berry MA, Raju S. Endovascular surgery in the treatment of chronic primary and postthrombotic iliac vein obstruction. Eur J Vasc Endovasc Surg 2000;20(6):560–71.
35. Raju S, Owen S, Jr, Neglen P. The clinical impact of iliac venous stents in the management of chronic
venous insufficiency. J Vasc Surg 2002;35(1):8–15.
36. Raju S, McAllister S, Neglen P. Recanalization of totally occluded iliac and adjacent venous segments. J Vasc Surg 2002;36(5):903–11.
37. Neglen P, Thrasher TL, Raju S. Venous outflow obstruction: an underestimated contributor to
chronic venous disease. J Vasc Surg 2003;38(5):879–85.
38. Raju S, Easterwood L, Fountain T, Fredericks RK, Neglen PN, Devidas M. Saphenectomy in the presence of chronic venous obstruction. Surgery 1998;123(6):637–44.
45. Venous Ulcers Associated with
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Superficial Venous Insufficiency
Gudmundur Danielsson and Bo Eklöf
A 59-year-old female secretary was referred for evaluation and treatment of a
non-healing painful ulcer on the medial aspect of her right lower leg. The ulcer
had been recurrent almost every year for the past 9 years, often healing during
the winter season. She had since early childhood been overweight (currently
87 kg, 170 cm, body mass index 30) and had difficulty in using compression
stocking. She was otherwise healthy. She had two children, the first child born
when she was 32 year of age and her second child 2 years later. After the birth of
her second child she began to notice varicose veins on the lower leg on both sides
and she often felt tiredness and heaviness in the leg in the afternoon. There was
no history of deep venous thrombosis. She had been on birth control pills for
10 years and was currently on hormone replacement therapy because of severe
postmenopausal symptoms. She had been treated at a local dermatological clinic
for the past 2 years and was now being evaluated by a vascular surgeon. Clinical
evaluation showed that she had 5 × 5 cm well-granulated ulceration above the
right median malleolus which was surrounded by brownish leathery skin. She
had slight swelling of the right leg with large varicosities below the knee. The left
leg had large varicosities below the knee but no swelling or skin changes. Doppler
examination revealed clear reflux in the groin that could be followed over both
great saphenous veins (GSV) down the thigh. A possible minimal reflux was also
noted in the popliteal fossa on the right side, although it was difficult to confirm
this when the Doppler examination was repeated. Foot arteries were palpable on
the dorsum of the foot on both sides.
Question 1
What should be the next step in this patient evaluation?
A. Measurement of ankle-brachial index.
B. Duplex ultrasound scanning of the venous system.
C. Plethysmography.
423
424 Vascular Surgery
D. Ascending phlebography.
E. Biopsy of the ulcer.
Doppler measurement revealed a normal ankle/brachial index with systolic blood
pressure 130 in both legs and right arm. Duplex ultrasound scanning of the venous
system performed with the patient in 60° reversed-Trendelenburg position, using
pneumatic cuff with automatic inflation/release on the lower leg to evaluate the
reflux, showed bilateral reflux in the GSV, from the common femoral vein down to
below knee, as well as two incompetent perforator veins on the medial aspect of the
right calf with a diameter of 4 mm. The diameter of the GSV at the groin was 12 mm
on the right side and 9 mm on the left side. The reflux time exceeded 4 s in both GSV,
with peak reverse flow velocity more than 30 cm/s. Reflux less than 0.5 s was noted in
the lesser saphenous vein on right side. No reflux was present in the deep veins
except for minimal reflux in the common femoral vein with reflux duration of
approximately 1 s on the right side. There were no signs of post-thrombotic changes.
Question 2
How should this patient be classified?
A. Leg ulcer.
B. Varicose ulcer.
C. C6,S,Ep,As,p,d,Pr.
D. C2,3,4b,5,6,S,Ep,As,p,d,Pr2,3,11,18.
The patient was classified according to the CEAP (clinical, (a)etiological, anatomical,
pathophysiological) classification based on history and results of duplex ultrasound.
Question 3
Which of the following is not regarded as a risk factor for venous ulcer?
A. Diabetes.
B. Essential hypertension.
C. Smoking.
D. Overweight.
E. Resistance to activated protein C.
Question 4
What would be appropriate management for the right leg in this patient?
A. Conservative treatment with below-knee compression bandage, rest and leg
elevation.
Venous Ulcers Associated with Superficial Venous Insufficiency 425
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B. High ligation and stripping of GSV to below knee, with local extirpation of vari-
cose veins.
C. High ligation of GSV with extirpation of varicose veins.
D. Obliteration of GSV using laser or radiofrequency heating with local extirpation
of varicose veins.
E. Sclerotherapy with or without foam.
Question 5
How should the incompetent perforator veins be managed?
A. Subfascial endoscopic perforator surgery (SEPS).
B. Ligation through Linton–Cockett incisions.
C. Disregard them.
D. Ligation through small skin incisions.
E. Duplex-guided sclerotherapy.
Question 6
How should the left leg be managed?
A. Observation.
B. Sclerotherapy.
C. High ligation and stripping of GSV and local extirpation of varicose veins.
D. Obliteration of GSV using laser or radiofrequency heating and local extirpation
of varicose veins.
The patient was treated with four-layer compression therapy until the operation
day, which was postponed for 4 months. The ulcer and the swelling both decreased
during this period; the ulcer measured 2 × 2 cm the day before operation. Both the
right and the left leg GSV were treated with the closure method using radiofrequency derived heating, and varicose veins on the lower leg were extirpated through
multiple small incisions. Intraoperative duplex ultrasound scanning revealed that
both GSV were occluded with no sign of reflux and the deep veins were patent with
no sign of deep venous thrombosis. No specific treatment was performed for the
incompetent perforator veins. The patient was discharged the same day after
uneventful postoperative recovery and was scheduled for new duplex ultrasound
scanning after 2 and 7 days. The postoperative duplex ultrasound scanning was
normal, with no sign of deep venous thrombosis, and the remnant of GSV was
occluded. The patient continued with four-layer bandaging and went back to work
on the fifth day after operation. The ulcer was healed at the last visit, which was
4 weeks later. Treatment with compression stocking during the daytime was
planned for another 6 months.
426 Vascular Surgery
Commentary
Investigation of both the arterial and the venous system is mandatory in cases of
non-healing ulcer on the leg. Although Doppler examination had only revealed a
clear reflux in GSV it is worthwhile to continue with duplex ultrasound scanning as
deep venous incompetence and post-thrombotic changes can otherwise be overlooked. This is especially important when reflux is noted at the back of the knee
where it is difficult with certainty to differentiate between deep venous reflux in the
popliteal vein and reflux in the lesser saphenous vein. Although the history (no
claudication or rest pain, no diabetes) and the location of the ulcer (medial aspect of
lower leg) strongly suggest a venous ulcer, sometimes an arterial component is also
present that might reduce the ability of the ulcer to heal. Palpable pulse on the
dorsum of the foot (dorsalis pedis) or behind the medial malleolus (posterior tibial
artery), as was evident in this case, almost rules out an arterial component.
Although plethysmography can estimate the overall venous function it is not
mandatory as a first line of investigation. Obtaining an ascending phlebography is
also not necessary as it does not add any information that duplex ultrasound scanning does not provide and it is also an invasive method with the risk of complications. Non-healing ulcer with unusual appearance should be considered for other
aetiology and investigated with biopsy in the early stage of evaluation. [Q1: A, B]
The old concept that the majority of venous ulcers are due to previous deep
venous thrombosis [1, 2] has been altered during the last 20 years when duplex
ultrasound studies have shown the importance of primary reflux in all venous segments [3–7]. Superficial venous incompetence is often noted to be the sole pathology in patients presenting with non-healing venous ulcer [8]. Formerly the venous
ulcer was often judged as being related to a post-thrombotic condition without any
objective diagnosis. Because of the benign course of varicose veins in the majority
of patients with superficial venous incompetence, the need for thorough evaluation
is often neglected. Formerly used classifications of chronic venous disease used the
term varicose ulcer if varicose veins were present, or post-thrombotic ulcer if they
were less evident or if there was a previous history of deep venous thrombosis. The
importance of classification, based on findings from duplex ultrasound scanning,
has become more evident during the last decades as treatment and prognosis is
largely dependent on the background history and the results of clinical investigation. CEAP (clinical, (a)etiological, anatomical, pathophysiological) classification
has gained more acceptance as the “gold standard” for classifying all aspects of
venous pathology such as clinical class, aetiological background, anatomical distribution and pathophysiological findings (Table 45.1). There is a clear correlation
between the CEAP clinical class and the venous function as measured by plethysmography (foot volumetry), indicating that the clinical classification has a realistic
meaning concerning the functional evaluation of venous disease. The duration of
reflux in venous segments, on the other hand, does not correlate with clinical class,
but the peak reverse flow velocity is significantly higher in patients with skin
changes/ulcer (C4–C6) [9]. The basic part of CEAP indicates the highest clinical
class (C6, active venous ulcer) and the anatomical distribution in superficial, perforator or deep system (As, p, d) with reflux (Pr). S is added behind clinical class to
indicate that the patient is symptomatic. The basic classification is sufficient for
most clinical doctors. [Q2: C, D] The detailed version of CEAP is used when more
information is needed as in longitudinal studies comparing treatment alternatives
Venous Ulcers Associated with Superficial Venous Insufficiency 427
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Table 45.1. CEAP classification
Clinical classification
C0: no visible or palpable signs of venous disease
C1: telangiectases or reticular veins
C2: varicose veins
C3: oedema
C4a: pigmentation and/or eczema
C4b: lipodermatosclerosis and/or atrophie blanche
C5: healed venous ulcer
C6: active venous ulcer
S: symptoms including ache, pain, tightness, skin irritation, heaviness, muscle cramps, as well as other
complaints attributable to venous dysfunction
A: asymptomatic
Aetiological classification
Ec: congenital
Ep: primary
Es: secondary (post-thrombotic)
En: no venous aetiology identified
Anatomic classification
As: superficial veins
Ap: perforator veins
Ad: deep veins
An: no venous location identified
Pathophysiological classification
Pr: reflux
Po: obstruction
Pr,o: reflux and obstruction
Pn: no venous pathophysiology identifiable
(Table 45.2). For more detailed information regarding the disease and its effect on
daily life it is possible to use a venous severity scoring system [11]. Venous severity
scoring is used as a complement to the CEAP classification (Fig. 45.1). Some
medical conditions are clearly a risk factor for venous ulcer while others are less
important. Venous ulcers are overrepresented in patients with diabetes although it
is not clear if it is the venous pathology or if it is the diabetic microangiopathy that
is the reason for this. Neither essential hypertension nor smoking is a proven risk
factor for venous ulcer. The prevalence of varicose veins is increased in overweight
individuals but the role of obesity is less clear when it comes to the risk of developing skin changes or ulcer. The apparent association between overweight and varicose veins in women suggests that it is a risk factor even in the more severe form of
chronic venous disease [12–14]. In a consecutive series of 272 patients with chronic
venous disease investigated with duplex ultrasound scanning, 58 per cent of
patients with healed or open ulcer (C5–C6) had body mass index >30 kg/m
2
(obese)
as compared to 15 per cent of those with varicose veins but without skin changes or
ulcer [15]. [Q3: A, B, C] Most thrombophilic conditions are risk factors for deep
venous thrombosis and venous ulceration, as is resistance to activated protein C
[16]. The prevalence of thrombophilia is high in patients with venous ulceration
despite no history or duplex ultrasound findings of deep venous thrombosis [17].
428 Vascular Surgery
Table 45.2. Advanced CEAP
Same as basic CEAP with the addition that any of 18 named venous segments can be utilised as locators for
venous pathology.
Superficial veins:
1. telangiectases/reticular veins
2. great saphenous vein above knee
3. great saphenous vein below knee
4. small saphenous vein
5. non-saphenous veins
Deep veins:
6. inferior vena cava
7. common iliac vein
8. internal iliac vein
9. external iliac vein
10. pelvic: gonadal, broad ligament veins, other
11. common femoral vein
12. deep femoral vein
13. femoral vein
14. popliteal vein
15. crural: anterior tibial, posterior tibial, peroneal veins (all paired)
16. muscular: gastrocnemial, soleal veins, other
17. perforating veins, thigh
18. perforating veins, calf
Surgical treatment is mandatory in cases of isolated superficial incompetence as
the likelihood of ulcer recurrence otherwise will remain high. Conservative treatment alone with below-knee compression had not been successful in keeping the
ulcer healed, but it is important to continue with compression therapy while the
ulcer is open and for some time after operation. Four-layer bandage is effective in
healing venous ulcer [18]. High ligation with stripping of the GSV down to below
the knee, with local extirpation of varicose veins, is the method of choice. It
decreases the risk of ulcer recurrence and has a low incidence of nerve damage to
the saphenous nerve. Stripping of the vein from the groin to the ankle increases the
risk of damage to the saphenous nerve (5 per cent versus 29 per cent), although the
recurrence rate is still the same [19]. Just doing high ligation without stripping
the vein is less feasible as the recurrence rate is significantly higher [20]. Other
promising methods for ablation of the refluxing GSV have emerged recently and
might become the methods of choice in the future. As the diameter of the GSV was
less than 15 mm it was possible to use the radiofrequency closure method to obliterate the vein. The main advantage of using less invasive methods is increased patient
satisfaction, as the recovery time after operation has been reported to be shorter.
Follow-up time up to 5 years with the radiofrequency method indicates that the
method is durable. The long-term results after ablation of GSV using laser technique or foam sclerotherapy are still unknown. [Q4: B, D]
The varicose veins on the lower leg are dealt with by using multiple stab incisions
and bringing them out using hooks. The cosmetic results are better and the risk of
nerve damage is less. Care should be taken not to operate close to the ulcer area as
healing problems and infection are more common if the incisions are made in
damaged skin.
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