Comment to: Great saphenous vein diameter at the saphenofemoral junction and proximal thigh as parameters of venous disease class by Mendoza E, Blättler W, Amsler F. Eur J Vasc Endovasc Surg 2013;45:76-83.

Stefano Ricci

Abstract

The aim of this study was to investigate a possible correlation of GSV diameters measured at the SFJ and the proximal thigh (PT) with the importance of the venous disorder. Between October and December 2009. 844 legs were screened and 182 legs included in the survey (CEAP C1-C5). The criterion for patient inclusion was the presence of a GSV reflux beginning at the terminal or the preterminal valve and escaping through a mid-thigh branch vein (above knee reflux, -51 legs- group II) or escaping through a lower leg branch vein (above and below knee reflux-71 legs-, group III). Legs with varices but no GSV were recruited as controls (-60 legs- group I).
Vein diameters were measured holding the probe transversely with no pressure at the SFJ distal to the terminal valve and 15 cm below the junction. Measurement of GSV vein diameter at the SFJ is challenging for the curvature of the inguinal GSV, the presence of epigastric, pudendal and accessory veins and eventual aneurysmatic dilatations. The PT site 15 cm below the SFJ, chosen by CHIVA Group members, is located in the truncal portion of GSV where the vein is cylindrical and largely devoid of joining branches, so well accessible, and diameter measurements can be taken reliably.
GSV diameters in all groups, measured at both sites, were not related with patients’ age and sex or calf muscle-pump function. Modest correlations were found with body weight and BMI but not with height. GSV diameters in controls (group I) measured 7.5 mm (±1.8) at the SFJ and 3.7 mm (±0.9) at the PT. In patients with GSV reflux (groups II and III), they measured 10.9 mm (±3.9) at the SFJ and 6.3 mm (±1.9) at the PT, respectively. Vein diameters were larger in the presence of reflux, compared with its absence, by an average of 3.4 mm at the SFJ and 2.6 mm at the PT. No difference in diameters was found between group II and group III. Thus, the degree of vein dilatation was independent of the length of reflux above knee only versus above and below knee.
A GSV diameter above the 2 SD margin of group I legs was found in 2% in group I at either point of measurement. In groups II and III, a significantly different prevalence was observed when measurements made at the SFJ and PT, respectively. The 2 SD margin was exceeded by 43% of patients when measured at the SFJ and by 62% when measured at the PT. A mathematical formula was developed to mutually convert measurements taken at the SFJ and the PT, used to revise published data.

Conversion PT to SFJ (95% CI 1.698–1.836): diameter SFJ (mm) = 1.767 × diameter PT (mm)

Conversion SFJ to PT (95% CI 0.544–0.548): diameter PT (mm) = 0.566 × diameter SFJ (mm)

Measurement at the PT as compared to measurement at the SFJ demonstrated higher accuracy and both higher sensitivity and specificity for venous disease class as well as for prediction of reflux. GSV diameter, venous hemodynamic (PPG refilling times) and clinical disease class did not differ whether reflux was above knee only or above and below knee. Diameter assessment at the PT seems suitable for stratification of patients allocated to future interventional trials as well as for outcome evaluation.

Comment by Stefano Ricci

Obtaining the greatest result with the lowest effort is the ideal research objective. This paper could be a good example of this concept. As nothing simpler than GSV diameter measurement may be done during ultrasound examination, this measurement reveals indirectly the presence of pathology, being a possible outcome evaluation method, and (in the future, as said by the authors) becoming an argument in the discussion of treatment options. Although the diameter measurement is a simple measurement, no consensus exists on where the measurement should be done. The authors suggest studying the proximal thigh (15 cm below the junction) following the experience of CHIVA Group members, as this GSV tract is the more constant, the more involved, and usually free from tributaries. According to the study results, a diameter of 3.7 mm (from 2.8 to 4.6 mm) indicate reflux absence, a diameter of 6.3 (from 4.4 to 8.2) means reflux present. If this observation will be confirmed by other studies, a great diagnostic contribution will be offered.

However some details may be discussed:

i) Although simple, the diameter measurement should be described in details, because inter-observer differences are common; considering that 2 mm of difference may change the score, a precise measuring method should be created, for example performing multiple observations, using multiple observers, using maximal magnification, choosing the diameter orientation when the section is not circular, considering time of day, patient positioning, room temperature, etc.;

ii) The caliber of the GSV, when incontinent, is related to the flow in the diastolic phase, particularly to reflux velocity; when the SFJ terminal valve is incompetent, the reflux volume is much more important than in cases in whom the terminal valve is competent, like demonstrated by Cappelli in a paper of paramount importance.1 This author, using the same PT measurement, showed that in incompetent GSV, diameters below 5 mm belong in 70% of cases to competent terminal valve legs; while diameters over 6 mm belong in 70% of cases to incompetent terminal valve legs, showing an interesting diameter difference related to the terminal valve. Why did you choose to ignore this important criterion, giving more importance to the length of the GSV reflux?

iii) Reflux in GSV of small caliber (3-4mm) is not so rare in every day experience, and in papers reports. How do you explain so few cases in your observation? US machine setting? Patients’ selection? What else?

Reply by the Author (Mendoza)

Thank you for your comments and the opportunity to reply.

i) Diameter measurement point: The locations of the sites of measurement used in this survey are shown in Figure 1. We agree that intra- and inter-observer comparisons have to be carried out - as for any diagnostic test. This, however, was not our aim. The study argues for the 15 cm proximal thigh site because of its good correlation with clinical findings. Thus, the required assessment of accuracy can be limited to this site;

ii) Caliber of refluxive veins in relation to competent or incompetent terminal valve (Cappelli): Our paper compared diameters with clinical findings and examined its potential use for decision-making. We assessed the criteria published by Cappelli as well: 30% of patients had a competent and 70% an incompetent terminal valve. Correlation between diameter and competence of terminal valves in refluxive GSV was high (Pearson’s r 0.594, P<0.0001), diameters ranged in the same margins;

iii) The extension of GSV reflux down the leg was studied because the criterion is attributed a high predictive value for clinical disease severity in Germany;

iv) Prevalence of small GSV diameters: 5% of our patients had a diameter <5 mm. There may be a selection bias in the sense that our study center is particularly known for a critical assessment of surgical indications and for regularly offering a wait and see strategy. Therefore, we may see fewer subjects with less severe disease than other centers.

References

1. Cappelli M, Molino Lova R, Ermini S, Zamboni P. Hemodynamics of the sapheno-femoral junction. Patterns of reflux and their clinical implications. Int Angiol 2004;23:25-8.[Abstract][PubMed]

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