Heart pacemaker. Coloured chest X-ray showing a surgically-implanted heart pacemaker (round,lower left). The pacemaker supplies electrical impulses,along wires that lead to the heart (blue bulge,lower centre),to keep it beating regularly. This pacemaker is preventing an irregular heartbeat,cardiac arrhythmia. This condition arises when the sinoatrial node,the heart area that initiates the heartbeat,malfunctions,or when its impulses are being blocked (heart block). The upper abdominal organs (across bottom),neck (top centre),lung cavities (white,each side of the heart),and the right upper arm bone (down left),are also seen |