Figure 12b. Three-lead pacemaker and biomechanical prosthetic mitral heart valve. Posteroanterior (a) and lateral (b) radiographs of the chest show a three-lead pacemaker (Carbomedics) placed via the left subclavian vein with the electrodes in the right ventricle (lower arrow), in the right atrium (upper arrow), and in the right superior vena cava–right atrial junction (not marked). A biomechanical prosthetic mitral heart valve is also seen.