Anatomic response of canine hindlimb vasculature to chronic venous occlusion.

Total limb (iliac) flow, small-vein pressure, and total small-vessel and venous resistances were measured in the fully dilated bed 2 h, 2 wk, and 8 wk after extensive ligation of veins. Values were compared to similar measurements in the contralateral unoccluded extremity. Wall thickness, lumen size and distensibility of noncollateral veins, and enlargement of collateral veins were evaluated 8 wk after venous ligation. Two hours after ligation, anatomic vascular resistance was twice normal, and venous resistance was increased sevenfold. Eight weeks later, total limb anatomic resistance had decreased to a value slightly less than normal, suggesting an "overcompensation" in anatomic resistance. Wall thickness of noncollateral veins was greater than normal at 8 wk postligation, and lumen size and distensibility were less than normal in spite of a return of supine venous pressure to normal levels.