Medical device for constricting a body passage and a method thereof

A medical device, comprising:

• a plurality of rectangular plates configured to surround a body passage so that each rectangular plate contacts the body passage for constricting at least a portion of the body passage, wherein the plurality of rectangular plates are elastically connected to one another by a spring, and, together with the spring, form an annular prosthesis to enclose a space therebetween;
• a pressure sensor to sense a pressure on a bladder;
• a computer electrically connected to the pressure sensor and the plurality of rectangular plates, wherein the computer controls an electrical current that affects a magnetic force that affects a size of the space in response to signals from the pressure sensor;
• wherein each of the plurality of rectangular plates comprises a curve configured to accommodate a curved surface of the body passage;
• wherein each rectangular plate has a chord, measured as a straight line distance between opposing ends of the curve, of 0.2 to 1.5 mm;
• and
• wherein each rectangular plate has a curve depth, measured as a shortest distance between the chord and a highest point of the curve, of more than 0.1 mm and up to 0.3 mm.