Am looking for a varicose vein medical specialist with the highest credentials. would that be a cardiologist, vascular surgeon, dermatologist or ?

Ask that doctor. : There is no "highest" credential. Expertise depends on the specific training and interest of the individual physician. Some physicians also only offer treatment for part of the problem. Ask the doctor if they do ablation, phlebectomy, and sclerotherapy and how many of each of these they have performed in total and how many currently each month. I would suggest 200 ; 10 as absolute minimums.

Vascular Surgeons: A specialist that is best qualified to treat varicose veins & other vein diseases is a board-certified vascular surgeon. They are the only vein specialist that has formal fellowship training in vein surgery & vein interventions. They have undergone 7 years of university surgery training. Any other doctor is not recognized by the American Board of Medical Specialties as a certified vein surgeon.

Varicose veins: I would recommend been evaluated by a vascular surgeon