Figure 1: (a) Balloon angioplasty of the left internal jugular valve; impression on the balloon indicates the location of restricting annulus. (b) Post-balloon venography of the left internal jugular vein: satisfactory outflow from the vein; stenosis that was previously seen during angioplasty (thick white arrow) disappeared, there is, however, still collateral outflow through the external jugular vein (thin black arrows) and the thyroid veins (thin white arrow); thick grey arrow points the area of compression by omohyoid muscle (revealed by means of sonography at followup): this compression does not show up at venography.