Abstract: The disclosed invention is directed to devices, therapeutics and methods of diagnosing and treating cardio vascular disease in a patient comprising measuring plasma levels of one of free sulfide, acid labile sulfide (ALS), bound sulfane sulfur (BSS), total sulfide metabolites, and some combination thereof, diagnosing, based on plasma levels, the patient with cardio vascular disease, and administering a therapeutically effective dose of a pharmaceutical composition to the patient. According to a further embodiment, the patient is diagnosed with cardio vascular disease if the patient has a polymorphism in a cystathionine gamma-lyase gene but not a cystathionine-beta-synthase gene. According to a further embodiment, the patient is diagnosed with peripheral atrial disease if the patient is African American and the plasma BSS level is significantly lower than an average control plasma BSS level.