ZEPHYR / SCIENCE PHOTO LIBRARY ZEPHYR / SCIENCE PHOTO LIBRARY
Heart pacemaker. Coloured chest X-ray showing a surgically-implanted heart pacemaker (blue, round, upper left). The pacemaker supplies electrical impulses, along wires that lead to the heart (pale bulge, lower right), 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).
Model release not required. Property release not required.