A potential therapeutic pitfall in the treatment of venous reflux due to variant planar anatomy of varicose segments

Introduction

Ultrasonographic evaluation of lower extremity veins has assumed a more pivotal role in planning, executing and monitoring treatment of venous insufficiency as the therapy became more patient-specific with the introduction of novel minimally invasive techniques. In contrast to the standard, and somewhat archaic, surgical treatment of venous insufficiency, which basically is stripping of proximal segment of great saphenous vein (GSV) and surgical ligation at its confluence with common femoral vein, this personalized approach requires meticulous mapping of superficial venous system including both main and accessory components along with all relevant anatomic variations.

Mapping of superficial veins of lower extremity is based on standards established by the International Union of Phlebology/L'Union Internationale de Phlébologie (UIP). By consensus, identification of GSV proper is based on its course within the saphenous compartment, an adipose-filled potential space extending from inguinal ligament to dorsomedial aspect of the foot and bound by saphenous and muscular fasciae. ¹ Ultrasonographic B-mode scan of GSV in transverse plane resembles a crude version of an ancient hieroglyph, the eye of Horus, with saphenous vein being the iris, superficial/saphenous fascia the upper eyelid, and deeper muscular aponeurosis the lower eyelid, hence the names “Egyptian eye,” or simply “the eye sign” (Figure 1). ² By definition, all accessory, communicating, or tributary veins of GSV are located superficial to the saphenous compartment. This facilities identification of variations which are rather common in the GSV territory.^3–6

OPEN IN VIEWER

Figure 1.

Transverse scan of GSV within the saphenous compartment. Arrows denote saphenous fascia, while arrowheads delineate muscular fasciae. On the upper left corner is the Eye of Horus symbol; origin of the term Egyptian Eye.

During routine pre-procedural evaluation and segmental mapping of saphenous system in patients presenting with symptoms of lower extremity venous insufficiency, we observed a rather overlooked variation of GSV. Although closely resembling saphenous vein duplication, this variation is more likely to be a part of the spectrum of segmental hypoplasia and aplasia because it has a prominent extra-compartmental component. The purpose of this study is to elaborate on this variation by delineating its course and evaluating its extent of involvement in a patient population with saphenous vein insufficiency.

Materials and methods

Institutional review board approval was obtained before commencement of this prospective single-center study. Patient recruitment was from June 2013 through June 2014 at the interventional radiology clinic of a tertiary referral hospital. Adult patients presenting with symptoms of lower extremity venous insufficiency to outpatient clinic were enrolled after giving written informed consent. History of any prior venous intervention, any major trauma and operation of limb, thrombophlebitis or venous thrombosis comprised exclusion criteria.

A dedicated ultrasound device (Acuson Antares, Siemens Healthcare) with a 9–13 MHz linear transducer was used; a wide FOV and a frame rate of 30 frames/s was employed. Whole thigh and leg regions were scanned while the patients were standing upright. All examinations were performed by a single radiologist with more than 10 years of experience in venous Doppler imaging.

GSV anatomy, along with its tributaries, was mapped with detailed recording of its diameter, patency, course in relation to fascial anatomy and presence of venous reflux. During work up, we observed a peculiar variation of GSV comprising one GSV proper coursing throughout saphenous compartment without interruption and one extra-compartmental venous arch of similar caliber originating distally from and then proximally fusing with the intra-compartmental GSV. Extra-compartmental vein always left the saphenous compartment immediately after take-off, followed an arch-shaped course proximally and superficially, and then re-entered the compartment just before fusing with the GSV (Figure 2). This variation has not yet been given a specific name by UIP; thus, for the sake of brevity, we referred to it as “saphenous bow” throughout the manuscript.

OPEN IN VIEWER

Figure 2.

Transverse scan of GSV with saphenous bow variation. Saphenous compartment delineated with dashed lines and veins outlined as dotted lines. (a) Re-entry point of extra-compartmental arch into GSV proper. (b) Intra- and extra-compartmental components course parallel to each other. (c) Extra-compartmental arch takes-off from GSV proper. T and G, respectively, denote tibia and medial gastrocnemius of the tibio-gastrocnemial angle. Dashed lines delineate paratibial saphenous space.

Results

Ultrasonographic evaluation of 318 consecutive eligible patients, 216 women and 102 men, had positive findings related to GSV territory in a total of 568 limbs. Patients’ ages ranged from 18 to 83 years with a mean age 44.6 ± 11.7 years.

A saphenous bow was observed in 5.1% of GSVs (n = 29). We observed three subtypes based on points of take-off and re-entry of the extra-compartmental constituent (Figure 3). Of the 29 cases with saphenous bow, 14 were type 1 (48.3%), 7 were type 2 (24.1%), and 8 were type 3 (27.6%).

OPEN IN VIEWER

Figure 3.

Types of saphenous bow variation based on take-off and re-entry points of extra-compartmental arch. Type 1, take-off from leg level and re-entry in thigh level. Type 2, both take-off and re-entry points are below the knee level. Type 3, both take-off and re-entry points are above the knee level.

Duration of venous insufficiency symptoms ranged from 2 to 58 months with mean duration of 26 ± 4 months. Clinical spectrum of venous insufficiency signs was classified using the “C” component of the updated version of Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification (Table 1). ⁷

OPEN IN VIEWER

Table 1.

Clinical signs of chronic venous insufficiency classified based on the “C” component of CEAP classification.

CEAP	Right limb (n)	Left limb (n)
C1	110	105
C2	113	119
C3	36	42
C4	17	14
C5	5	3
C6	3	1
Total	284	284

Sufficiency or insufficiency of the GSV and the saphenous bow was observed in three patterns. Either only the intra-compartmental vein (n = 4, 13.8%) or only the extra-compartmental arch (n = 3, 10.3%) demonstrated reflux; or both intra- and extra-compartmental components were insufficient (n = 22, 75.9%) (Figure 4). In total, 25 out of 29 cases (%86.2) had insufficiency involving the extra-compartmental arch, either alone or together with insufficiency of GSV proper. All patients with saphenous bow variation had CEAP scores ≥2. However, there was not a statistically significant association between the presence of this variation and higher CEAP scores (p = 0.348).

OPEN IN VIEWER

Figure 4.

Patterns of distribution of insufficient segments in patients with saphenous bow variation. Dashed lines denote presence of venous reflux. (a) Only the intra-compartmental vein has reflux (n = 4, 13.8%). (b) Only the extra-compartmental arch has reflux (n = 3, 10.3%). (c) Both intra- and extra-compartmental components have reflux (n = 22, 75.9%).

Discussion

This study demonstrates an often overlooked variation of GSV. This variant was observed in 5.1% of GSV with positive signs for venous insufficiency. Of particular concern is that 10.3% of saphenous bow variation had insufficient extra-compartmental arch with a competent GSV proper. Thus, it may be inferred that commencing with ablation of GSV proper and failing to identify saphenous bow variation before treatment has a 10% inherent risk of ablating a totally functional GSV proper while leaving the refluxing variant segment untouched.

According to new nomenclature, an accessory saphenous vein is any extra-compartmental venous structure ascending parallel to GSV. Anterior and posterior accessory GSV are the most frequently observed, and thus best defined, of such accessory veins.^1,2 Segmental hypoplasia or aplasia, on the other hand, does not fit into definition of accessory vein because in segmental hypoplasia/aplasia, there is an extra-compartmental vein that connects distal and proximal normal caliber segments of GSV, therefore by-passing the hypoplastic/aplastic intra-compartmental segment; thus, have been regarded as a different entity. ⁸

Saphenous bow variation appears to be a part of the segmental aplasia/hypoplasia continuum which starts with the most common form of GSV observed: A single and patent GSV coursing within the saphenous compartment, from dorsum of the foot to the saphenofemoral junction in the groin, without interruption. ⁹ Then comes the segmental aplasia, in which GSV leaves the saphenous compartment at the distal intra-compartmental aplastic segment, ascends cranially and parallel to the compartment, and re-enters the compartment where aplasia ends. Although often ignored, segmental aplasia has been reported in approximately one-third of patients with CEAP scores ≥1. ⁸ Next is the segmental hypoplasia which is very much like its aplastic counterpart, but this time there is a hypoplastic vein of <1.0 mm diameter coursing within the saphenous compartment in between the take-off and re-entry points. In a large ultrasonography series, segmental hypoplasia was reported in 12% of normal subjects and in 25% of patients with venous insufficiency. ¹⁰ On one end of this continuum is the saphenous bow variation we described. What makes this a unique entity is that both intra- and extra-compartmental segments of the veins have normal shapes and diameters ≥1.0 mm (Figure 5).

OPEN IN VIEWER

Figure 5.

Segmental aplasia/hypoplasia continuum. Saphenous compartment delineated with dashed lines. (a) A single and patent GSV coursing within saphenous compartment. (b) Segmental aplasia. GSV leaves saphenous compartment at distal intra-compartmental aplastic segment, ascends cranially and parallel to the compartment, and re-enters compartment where aplasia ends. (c) Segmental hypoplasia. Similar to its aplastic counterpart, but this time there is a hypoplastic vein (diameter <1.0 mm) within saphenous compartment. (d) Saphenous bow variation. Both intra- and extra-compartmental segments of GSV have calibers ≥1.0 mm.

Whether having an extra-compartmental origin is a definite criterion for naming accessory veins is still ambiguous in the new UIP nomenclature.^2,3 In this perspective, since the extra-compartmental component of saphenous bow originates from the GSV proper and leaves the compartment immediately after, it cannot be regarded as an accessory vein. Saphenous bow is not a duplication either. Because in a true duplication, reported to be <1% in recent Doppler ultrasonography series, two venous trunks of GSV course within the same saphenous compartment. Unlike saphenous arch, duplicated segment is usually short and is almost always above the knee level.^1,4

Variations of GSV do not require further testing for other congenital anomalies; but, they are of great significance in one context: Planning of treatment of venous insufficiency. A thorough mapping of GSV territory prior to commencement of endovascular therapy or surgery is good clinical practice.^3,11 Reporting radiologist must be familiar with spectrum of GSV variations and meticulously report extent of insufficiency in variant segments in order to prevent unnecessary, and clinically futile, procedures involving ablation of competent veins, while the real culprit goes undetected by the operator. Documenting any anatomic variations before therapy is especially important in settings where the diagnosing and treating parties are different. In our clinical practice, we aim to treat only the segment that is proven to have reflux, whether it be the arch or the GSV proper. In cases with insufficiency of both intra- and extra-compartmental veins, we prefer treatment with thermal ablation of both components. In select cases, however, thermal ablation of intra-compartmental GSV and foam sclerotherapy of extra-compartmental arch are more feasible. Recurrence of symptoms is more likely to be encountered in patients with variant anatomy. Unknown or undocumented venous variations may contribute to recurrence of reflux post-treatment. Since variations in superficial venous system of lower extremity are relatively common, we prefer endovascular treatment under sonographic guidance in this subgroup of patients.

A limitation of this study is that there was no control group of healthy subjects among our sample. This hinders extrapolation of our findings on general population; and based on our data, there seems to be no statistically significant association between this variation and severity of venous insufficiency. Furthermore, whether saphenous bow variation has any clinical implications on venous insufficiency and pathogenesis of varicose veins remains unclear.

Conclusions

In this series, we present a rather overlooked variation of GSV comprising two components; one GSV proper coursing throughout saphenous compartment without interruption and one extra-compartmental venous arch of similar caliber originating distally from and then proximally fusing with the intra-compartmental GSV. This variation appears to be a part of the segmental aplasia/hypoplasia continuum and Doppler scans demonstrated reflux in the extra-compartmental arch in great majority, i.e. 86.2%, of cases with this particular variant. This emphasizes the importance of accurate detailed mapping of the venous system and knowledge of venous variations prior to intervention for optimal treatment outcomes.