EU Post Market Clinical Follow-Up Study of the Venclose System for Saphenous Vein Incompetence

Inclusion Criteria: * Subject is male or female and 18 to 80 years old (inclusive) at time of enrollment (signing of consent). * Subject has significant venous reflux by Duplex Ultrasound (DUS), defined as reverse flow with reflux duration greater than 0.5 seconds after the Valsalva maneuver or distal augmentation while the patient is standing or in reverse Trendelenburg position. * Subject is eligible for endovascular treatment, as determined by the treating investigator. * Subject's general physical condition allows for a significant amount of ambulation after the procedure, as determined by the treating investigator. * Subject is willing and able to complete study requirements, including all follow-up visits and assessments. * Subject voluntarily provides written informed consent to participate in this study. Exclusion Criteria: * There is evidence of old or fresh thrombus in the subject's diseased vein segment to be treated, as determined by Duplex Ultrasound (DUS) within 2 weeks prior to the index procedure. * In the judgment of the treating investigator heat energy delivery to the subject would be contraindicated. * Subject is concurrently participating in another interventional clinical trial. * Subject is pregnant or plans to be pregnant or lactating at the time of the treatment procedure. * Subject has known or suspected allergies or contraindications to any general or local anesthetic agents and/or any antibiotic medication that cannot be adequately pre-treated.