The role of perforators in chronic venous insufficiency

Abstract

Thesis

Venous ulcers (VU) consume considerable resources in healthcare systems, up to 1% of healthcare budgets in industrialized countries. Best practice guidelines (GLs) incorporate evidence-based diagnostic and therapeutic recommendations in a cost-effective manner and have been associated with improved and less costly outcomes for many diseases.

Objectives

To determine whether there are common elements in GLs for VU and their evidentiary strength.

Methods

A systematic analysis of GLs for VU that were identified through clinicaltrials.gov, a government-sponsored website, and from experts outside the USA.

Results

Ten of 12 GLs on VU (7 North America and 5 Europe) were evidence-based, with the majority using the GRADE method. Only two had been developed or updated within the last three years. Venous duplex and ankle ABIs were recommended in all. Debridement was suggested in two, while simple non-adherent wound dressings were favoured in nine, and hydrocolloid in two. Only one GL discussed a range of dressing options, dependent on the condition of the VU. High pressure multi-layer compression bandages were favoured in 10. Only two focused on the importance of improving ankle joint mobility.

Conclusions

While there are numerous evidence-based GLs for VU, the majority may lag recent developments in the field. There is consensus on the elements for dressings and compression among the various GLs, which should facilitate the development of a common consensus GL, similar to that for DVT/PE. To improve patient care and reduce wasted resources, it is imperative for specialty societies to develop this consensus document.

Keywords

chronic venous insufficiency incompetent perforating veins treatment

Background and evolution of methods for treating incompetent perforating veins

Incompetent perforating veins (ICPVs) have been ascribed an important role in the pathophysiology of advanced chronic venous insufficiency (CVI) – clinical, aetiological, anatomical and pathological elements (CEAP) Class 4 → Class 6 and their ablation has been employed as treatment for venous ulcers for over a century.¹ This therapeutic strategy is based on the concept that ablation of ICPVs reduces superficial venous hypertension and as a result alters the microcellular events of leukocyte trapping and cytokine release. The purposes of this paper are: (1) to review the indications for treatment; (2) to review the evidence for the effectiveness and safety of the various methods for ablating ICPVs; and (3) to outline the advantages and limitations of current and proposed techniques.

Over 90 years ago in two successive landmark papers, Homans emphasized the value of interrupting ICPVs as a component of reducing superficial venous hypertension for treating venous ulcers,^1,2 while 20 years later Linton developed the open surgical approach to ligate ICPVs through a subfascial medial calf incision, which bears his name.³ The morbidity of the open surgical approach with wound slough, however, prompted modification of the incision's location and size, such as ‘the posterior stocking seam incision’, which avoids an incision through the lipodermatosclerotic tissue of the medial calf.⁴ Outcomes from numerous observational studies with high ulcer recurrence rates combined with a significant incidence of wound morbidity led to a decreased use of this procedure in the 1980s.⁵

A less invasive approach

To avoid the slough-prone area of the lower medial calf and to ligate ICPVs, Hauer employed endoscopic techniques to gain access to the subfascial space more proximally in the calf through better tissue. Existing devices such as the bronchoscope or mediastinascope were used for the optical source and the instrument port for conventional surgical instruments.⁶ The development of the subfascial tunnel was somewhat crude and created by blunt dissection with the tip of the scope. To some surgeons this technique with its limited and narrowed field made visualization of the ICPVs challenging, particularly in accessing the lower perforating veins. Influenced by the advantages of the laparoscopic approach, which at that time was being used for cholecystectomy, we applied this technique to ablation of ICPVs. The laparoscopic light source and optics permitted visualization of the perforating veins on a video screen, while a separate working port was introduced for dissection and clipping/division of ICPVs by miniaturized laparoscopic instruments.⁷ With this technique a paratibial fasciotomy can also be carried out in a more controlled manner. Gloviczki et al. ⁸ subsequently popularized the use of a thigh tourniquet and CO₂ for the laparoscopic approach, which has been used by many surgeons in the USA. Subfascial endoscopic ligation of incompetent perforating (SEPS) provided two important advantages: (1) skin incisions could be made distant and above the lipodermatosclerotic tissue of the medial calf; and (2) ICPVs were directly visualized and ablated – both factors reduced the morbidity of surgery.⁵ The volume of SEPS worldwide increased dramatically in the mid-1990s and early 2000 and has resulted in over 50 published series.⁹ SEPS has become the index procedure to assess the therapeutic efficacy of ICPV treatment, because SEPS has provided us with the most evidence on ICPV ablation. Certainly, with the older open approach all ICPVs were exposed and available for ablation. The minimally invasive approach of SEPS is advantageous, but may be associated with missed ICPVs.¹⁰ As new less invasive techniques for ICPV ablation are developed, one must be mindful of the competing interests of scientific evidence and technology. The evidence for the efficacy of perforator interruption, as with the open approach or with SEPS, previously learned from multiple studies, may be forgotten as new less invasive technology emerges.¹¹

Newer alternative techniques

Physicians have been treating ICPVs directly for over a century. Sclerotherapy of ICPVs was initially based on palpation of the ICPV and ablation with liquid sclerosant solution, but now sclerotherapy may be carried out under ultrasound visualization and with foam sclerosant. The application of endovenous thermal ablation techniques to the treatment of ICPVs (PAPS) may also employ local anaesthesia in an ambulatory setting.¹² Both of these minimally invasive approaches to interruption of ICPVs can be based in an office or procedure room. Dependent upon the caliber of the device for PAPS direct trauma to the compromised tissue of the medial calf can be minimized, but like SEPS, it is highly operator dependent. As pointed out earlier, each new successive technology, particularly if less invasive than the preceding technology, brings with it an increase in utilization.¹¹

Anatomy

Perforating veins traverse various fascial spaces, dependent upon their vertical location along the leg, and connect the superficial with the deep system. Paired small arteries travel with these veins. Calf perforating veins were first accurately drawn and described by Von Loder, a Russian anatomist,¹³ and detailed by John Gay¹⁴ in his Lettsomian lectures. Linton provided the modern description of the anatomy and the role of perforators in his clinical and anatomic study.¹ More recently, Mozes et al. ¹⁵ carried out extensive anatomic studies in 40 normal cadaver limbs which had undergone corrosion cast treatment of their leg veins. They categorized perforating veins into direct, which connected superficial veins to deep axial veins and indirect, which connected superficial veins to muscular veins and are more variable in distribution The Mayo study confirmed four groups of direct perforating veins; of which the lower three groups correspond to the older nomenclature of the Cockett 2 and 3 perforators.

Anatomic location of ICPVs

Figure 1 compares data from several studies including our own that examined the anatomic location of pathologic perforating veins, ICPVs, as observed directly at surgery. Forty-five percent of ICPVs were located in an area 10–15 cm above the medial malleolus, the typical Cockett 2/3 area,⁵ but due to the anatomy of the subfascial compartments only 32% of Cockett 2, 74% of Cockett 3 and 40% of the Cockett 4 perforators would be available in the superficial posterior compartment alone for their interruption via a SEPS procedure. As shown in Figure 2, to access the remainder of the Cockett 2/3 perforators the lamina profunda fascia of the deep posterior compartment must be incised through a paratibial fasciotomy and in addition the intramuscular septum must be incised and dissected to achieve exposure of the remaining Cockett 2/3 veins.^5,8

Figure 1

Anatomic location of incompetent perforators. The proportion of incompetent perforators at the lower, middle and upper calf regions are displayed with the highest proportion found at the middle location (Cockett III). At this level, the majority of ICPVs are accessible in the superficial posterior compartment in contrast to the two other sites⁵

Figure 2

Paratibial fasciotomy. To access ICPVs in the deep posterior compartment, a paratibial fasciotomy must be made to expose perforators restricted to this compartment

Pathophysiology

Invasive venous pressures studies by Warren and his associates¹⁶ demonstrated that ambulatory venous pressures failed to reduce in limbs with CVI, which produced ambulatory venous hypertension. Linton¹⁷ outlined the pathophysiological sequence of events as follows: recanalization of the deep system leads to valvular destruction and increased deep venous pressure, so that these veins (perforators), particularly on the ‘inner side of the lower leg above the ankle, become dilated and the valves become incompetent’. The high ambulatory deep venous pressure is transmitted through these ICPVs to the superficial venous system.

Effect of surgery on venous haemodynamics

Several studies have examined the role of ICPV ablation, as assessed by haemodynamic studies^18–21 and are summarized in Table 1. The purpose of these studies was to isolate the haemodynamic effect of ICPV treatment from that of that of the great saphenous vein (GSV) and these studies are detailed in a recent publication.²² These series of physiologic studies question whether interruption of the ICPVs alone is associated with any noticeable haemodynamic benefit, a surrogate endpoint. Whether treatment of ICPVs is important for ulcer healing or to prevent recurrence in complimenting GSV ablation for advanced CVI is unsettled and will require a randomized controlled trial (RCT) with clinical outcomes. Finally, it is important to note that irrespective of the procedure on the superficial venous system, no beneficial haemodynamic changes were observed in the presence of post-thrombotic changes in the deep venous system.²²

Table 1

Effect of ICPV ablation on haemodynamics

Author	Hem. technique	Manoeuvre	Findings
Bjordal (14)	AVP Flow measurement	Occ. of GSV → ICPV————— →	AVP normalized No change
St Thomas' (15)	AVP	L & S of GSV → Subfascial lig. →	AVP normalized No significant change in AVP even with normal deep
Akesson (16)	Foot volume Occ pleth AVP	L & S → Subfascial (3 months) →	82 → 69 mmHg No change
Rhodes (17)	Strain gauge plethsymography	SEPS/L & S SEPS only →	Improved No improvement

AVP = Ambulatory venous pressure; Occ = occlusion; Pleth = plethysmography

Clinical outcomes following ICPV ablation

In the absence of any available RCTs at the time we carried out a systematic analysis of SEPS, which reviewed 22 case series for efficacy and safety.⁹ Approximately half the limbs had an open ulcer and these C6 limbs demonstrated a 90% ulcer healing rate, while the combined series (C5/6 limbs) showed a low 10% ulcer recurrence rate. SEPS was safe with a low 1% rate of DVT and no pulmonary emboli or deaths were identified. Besides the inclusion of many limbs that had combined GSV and ICPV ablation, further bias was introduced by the lack of a comparator arm, such as compression and wound care, to which the surgical arm could be compared.

Effect of ICPV interruption on ulcer healing and/or recurrence

To address the problems in the previous systematic review of ICPV ablation, we recently limited our search to RCTs on superficial venous surgery for venous ulcer. The purpose of this systematic review was to ascertain whether treating ICPVs makes a difference in the healing/recurrence of venous ulcers.²² In this review we used evidence-based methods to analyse the evidentiary quality of study design and outcomes for the various studies surrounding a treatment choice.

Two RCTs examined the effect of ICPV ligation on ulcer recurrence in C5 patients, where treatment with surgery (ablation of the ICPVs ± GSV) and elastic compression (EC) was compared with EC alone. In a small study by Stacey et al. ²³ oriented to haemodynamic outcomes, a risk reduction analysis showed no advantage for the surgical group in preventing ulcer recurrence (Figure 3).

Figure 3

Individual risk ratios (RRs) for the four randomized controlled trials (RCTs) for reducing ulcer recurrence: The vertical line in the centre represents an RR of 1, where there is no difference between the surgical and the compression group if the horizontal line (95%) confidence interval crosses this line. Neither the Stacey nor the Dutch RCTs achieved significance in favour of the surgical arm²²

The second RCT, the large Dutch Ulcer trial, was based on 200 C6 limbs, which were randomized into either treatment with EC alone or SEPS (±GSV treatment) with EC.²⁴ The ulcer-free period was employed as the primary outcome, while the secondary endpoints included: ulcer healing, ulcer recurrence, quality of life and cost-effectiveness. Over a median study follow-up length of nearly two years, there was no difference in the ulcer-free period between the SEPS group (72%) and the EC group (53%). A risk reduction analysis of the data for ulcer recurrence (Figure 3) confirms no advantage for the SEPS-treated patients, while actual ulcer healing and ulcer recurrence were comparable in the two groups. An apparent stratification as well as a post hoc analysis with its known limitations, however, identified certain factors, which were in favour of the SEPS arm for ulcer-free survival: (1) recurrent ulcer; (2) medially located ulcer; and (3) surgery carried out in a specialized centre.

Unfortunately, the Dutch Ulcer Trial had several problems: (1) A recurring source of bias in this RCT as well as in earlier studies – concomitant treatment of the GSV along with SEPS, which was carried out in over half of the limbs (54%) in this RCT. This design flaw blurs whether the clinical results were due to treatment of the GSV, ICPVs alone or both. (2) The primary outcome for which the RCT was powered was neither ulcer healing nor recurrence, but rather a combination of those endpoints – ulcer-free survival. The secondary outcomes, such as ulcer healing, were comparable between the EC group (73%) and the surgical group (83%) and ulcer recurrence was also similar between the two groups, as was the risk reduction analysis (Figure 3). (3) Finally, a honest and important follow-up duplex evaluation by the investigators showed a relatively high number of ‘missed’ ICPVs on postoperative follow-up duplex scans, i.e. patients were not receiving the full benefit of the surgical intervention and this may adversely influence results. In summary, the major flaw of these two RCTs suggest that the ideal study should limit treatment to ICPVs only or compare treatment of the GSV in one arm to treatment of both the ICPVs and the GSV in the other.²²

The effect of treating GSV incompetence alone on ulcer healing/recurrence

Indirect evidence that diminishes the curative role of ICPV ablation alone for venous ulcer is provided by two RCTs, where the GSV alone was treated and ulcer recurrence was lowered. The relevance of these two studies, a small RCT by Zamboni et al. ²⁵ and a larger RCT, the ESCHAR Study,²⁶ is that they cast doubt on those series where both the ICPVs and GSV were treated concomitantly. If ulcers heal and/or ulcer recurrence is prevented with treatment of the GSV alone, is ICPV ablation really needed?²²

Newer techniques for ablation of ICPVs

Sclerotherapy

Ultrasound-guided sclerotherapy (UGS) with liquid or foam can provide direct treatment of ICPVs, while using a relatively small needle to gain access to the ICPV or its tributary. No incisions are required and UGS is relatively painless. Masuda et al. ²⁷ treated 80 limbs in 68 patients by UGS with liquid sodium morrhuate with a mean of 3 ICPVs/limb. While initially 90% of ICPVs were occluded, this figure dropped to 70% at a mean follow-up of 20.1 months and new or recurrent ICPVs occurred in 35. There were no instances of DVT, but one limb developed skin necrosis, when one of the small accompanying arteries was injected.

To avoid DVT in the posterior tibial veins, Coleridge-Smith²⁸ recommended liquid sclerosant for the lower calf ICPVs and reserved foam sclerotherapy for the higher ICPVs. He points out that the tributary of the ICPV can be cannulated and the sclerosant infused into the ICPV by this route.

Endovenous ablation

Percutaneous endovenous thermal ablation of ICPVs (PAPS) can be carried out with a small incision or puncture site in the calf, but this entry site is made in the compromised skin directly over the ICPV.¹² In a sense PAPS violates the fundamental principle of a minimally invasive technique for ICPVs-avoiding access through the damaged dermal and subcutaneous tissue associated with advanced CVI. The larger probe used in radiofrequency ablation of ICPVs can be more traumatic to the skin and subcutaneous tissue than a micro needle and a small laser fibre. Both techniques may experience difficulty in dealing with the heavily fibrotic tissue or calcification found in the lipodermatosclerotic medial calf, encountered in many cases.²⁹

To evaluate the present status of PAPS we conducted a systematic review, which consisted of: (1) the five current series on PAPS, which were published in peer-reviewed journals^30–34; (2) seven presentations at medical meetings;^35–41 and (3) two series contained within two review papers (with the same senior author). Including the abstracts, 1573 ICPVs treated by PAPS were available for analysis. Table 2 summarizes the patient characteristics and outcomes of the five published series – all observational case series.^26–30 An analysis of these five studies shows major flaws: (1) the studies are small in patient number – only one of five had greater than 50 subjects; (2) there is little description of the pretreatment clinical characteristics and the majority of the studies (3/5) treated mild disease (C2, C3); (3) the duplex criteria for incompetence is not stated or is variable; (4) there is a limited length of follow-up with only one study greater than four months; (5) three of five series had concomitant procedures performed; (6) surrogate outcomes measures, such as ICPV occlusion, predominate – not important clinical or functional endpoints. Complications included parathesias in two trials and a gastrocnemius DVT in a third. Two series reported no complications.

Table 2

Characteristics of the five published series for percutaneous thermal ablation of perforators

	Proebstle	Marks	Bacon	Van den Bos	Hingorani
Factor
Patients/ICPVs (#)	60/67	18/25	37/125	12/14	38/48
ICPV (Diam., mm)	3.3	4	NS	4	4
Other Rx	50% GSV	6% GSV	>90% GSV	None	None
Outcomes
Follow-up (mos.)	3	0.25	60	3	1
Occluded (%)	99	92	81	64	88
Complications	+	0	+	+	0

Combined series

Figure 4 combines the characteristics of the five published case series with the nine other series. The mean number of patients was less than 50 and the length of follow-up averaged less than two months. While over 80% of the ICPVs were occluded, only four series included C4–6 disease. The occlusion rates for ablation of ICPVs by PAPS for the individual series are portrayed in Figure 5 and all but two were greater than 80%. Complications described in the nine additional series included: tibial vein DVT in three series, foot drop in one and skin burns in one. Finally, the technical problems encountered in these series can be summarized as follows: (1) large catheter size may lead to tissue damage in C5/6 limbs; (2) difficulty in penetrating dense lipodermatosclerotic tissue; (3) parasthesias; (4) difficulty in occluding large-diameter, high flow ICPVs; and (5) an appreciable learning curve – PAPS appears more difficult than endovenous ablation of the GSV. This review of PAPS suggests that future technological refinements are required and better trials with clinical outcomes are needed.

Figure 4

Characteristics of the combined published and presented series. Small patient numbers, short follow-up periods and high proportion of mild disease (C2/3) are evident in this compilation

Figure 5

Occlusion rates of incompetent perforating veins by PAPS for the combined published and presented series. Only two series had less than an 80% short-term occlusion rate

Current approach

Selection

Two RCTs showed that ICPV ablation had no haemodynamic or clinical advantages over GSV ablation alone for patients with mild CVI (CEAP Clinical Class 2, 3),^42,43 so that ICPV ablation should be reserved for more advanced cases of CVI. Patients with active ulcers, who have failed a four- to six-month course of wound care (including advanced products) and compression – the ‘stalled wound’ or ideally patients with healed ulcers, are candidates for ICPV ablation. The procedure can be either combined with or follow endovenous ablation of the GSV, because the latter can be performed under local and tumescent anaesthesia in most patients. Limbs with large, long-standing medially-located ulcers or those with recurrent ulcers after GSV ablation may benefit the most from treatment of the ICPVs. The duplex criteria for diagnosing ICPVs are extremely important in the selection process and influence our decision to ablate ICPVs concomitant with the GSV. An enlarged ICPV diameter at the fascia of >3.5 mm as well as duplex evidence of high volume and prolonged outward flow may indicate an ICPV with significant pathophysiology. The technique of ICPV ablation is dictated by the anatomy, the patient's risk and the operator's technical experience. We prefer SEPS for limbs with multiple ICPVs, dense lipodermatosclerosis and/or paratibial location. Despite the lowering of wound morbidity, SEPS has several disadvantages: (1) regional or general anaesthesia is required; (2) the peri/inframalleolar ICPVs are difficult to access for treatment; and (3) a significant learning curve is required to become proficient at the technique.

Currently, PAPS is employed in poor surgical candidates, limbs with few ICPVs and paramalleloar ICPVs de novo or those missed at SEPS. We currently reserve sclerotherapy for failure of other techniques.

Summary

The systematic review questions the current evidence for treatment of ICPVs, which can only be answered by a properly done RCT. In the absence of such evidence our initial approach should be toward eliminating saphenous reflux. Large diameter (>3.5 mm) ICPVs with high volume reversal of flow can be treated and if multiple they may be best eliminated by SEPS. PAPS is a potentially helpful technique for poor risk candidates with a solitary or only a few ICPVs, but with technological improvements may be used more widely. These findings may place the future role of ICPV treatment as an additive effect – for improving the results of patients treated with GSV ablation alone and for segmental deep venous reflux.

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