Cardioactive steroids (CAS) are medically important compounds historically used for conditions like edema and "dropsy." There is literature from the 17th century regarding their therapeutic effects. They are available in several plants including oleander, foxglove, lily of the valley, red squill, dogbane, common milkweed plant, etc. Leaves of Digitalis lanata contain digoxin while seeds of Digitalis purpurea may contain digitalin. Several Chinese herbal medications and aphrodisiacs may also contain cardioactive steroids. Historians believe the selection of yellow contrast in Van Gogh's painting was likely secondary to digitalis toxicity. Digoxin is the most well known cardioactive steroid with application in the treatment of congestive heart failure and for the control of ventricular rate in atrial tachyarrhythmias. It is available in tablet form and liquid filled capsules that can increase its bioavailability. Other less commonly used cardioactive steroids include lanatoside C, digitoxin, ouabain, gitalin, and deslanoside.