The side lengths of a right triangle form a so-called Pythagorean triple. A triangle that is not a right triangle is sometimes called an oblique triangle. Special cases of the right triangle include the isosceles right triangle (middle figure) and 30-60-90 triangle (right figure).
The first pacemaker was implanted on 8th October 1958 in a 43 year old man called Arne Larsson with complete heart block and Stokes-Adams attacks. Technological innovations between 1973 and 1980 rendered obsolete the reliable pacemaker of 1970.
A pacemaker is implanted under the skin, usually on the left side of the chest below the collarbone. The procedure takes about an hour, and most patients go home within a day. Types of pacemakers vary; some correct a slow heartbeat, while others stop an irregular heartbeat or stop severe heart failure.