Planning endovascular vein valve implantation: significance of vein size variability

Endovascular placement of prosthetic valves is currently in clinical trials as treatment for lower extremity venous hypertension caused by valvular insufficiency. Femoropopliteal vein sizing is a critical factor in treatment planning. A wide diameter range could influence selection of an endoprosthesis. Quantitative data describing intrasubject vein diameter variation are scant. We measured vein diameters with ultrasound imaging to assess minimum-maximum diameter range under forced conditions of venoconstriction and venodilatation.

Diameter of the common femoral vein (CFV), proximal femoral vein (PFV), mid-femoral vein (MFV), and distal femoral vein (DFV) in the thigh and the popliteal vein (PV) was measured in the morning under conditions of minimal venodilation and in the afternoon under conditions of stressed venodilatation that included activities of daily living and a 5-minute treadmill walk. Measurements were obtained twice on two different days in both extremities in 20 subjects with CEAP clinical classification C(0) (n = 10), C(3) (n = 7), C(4) (n = 1), or C(5) (n = 2).

Average vein diameter increased, from 11.2 +/- 2.5 (SD) mm to 14.5 +/- 2.3 mm at the CFV, from 6.9 +/- 1.8 mm to 9.4 +/- 1.9 mm at the PFV, from 6.9 +/- 1.6 mm to 9.0 +/- 1.8 mm at the MFV, from 7.3 +/- 1.7 mm to 9.1 +/- 1.5 mm at the DFV, and from 8.4 +/- 1.4 mm to 9.7 +/- 1.8 mm at the PV (P <.001 for all differences). Maximum diameter change was 8.2 mm at the CFV, 7.0 mm at the PFV, 6.6 mm at the MFV, 6.0 mm at the DFV, and 5.1 mm at the PV. Dilatation of 4 mm or greater occurred in 43% of CFV, 15% of PFV, 11% of MFV, 3% of DFV, and 1% of PV. Minimum vein diameter was found at PFV in 41%, MFV in 34%, and DFV in 23% of morning measurements and at PFV in 21%, MFV in 38%, DFV in 28%, and PV in 16% of afternoon measurements.

Femoropopliteal veins demonstrated a wide range of diameters, and significant diameter changes were detected in all vein segments. Variations in vein diameter must be evaluated in candidates for endovascular venous valve prostheses. Such devices must adapt to a wide range in vein diameter.