Original Article: http://www.mayoclinic.com/health/medical/IM02124
- Video: Endovenous thermal ablation
Normally, veins return blood from the rest of your body to your heart, so the blood can be recirculated. To return blood to your heart, the veins in your legs must work against gravity. Varicose veins may be caused by weakened valves (incompetent valves) within the veins that allow blood to pool in your veins instead of traveling to your heart.