DENNIS POTOKAR / SCIENCE PHOTO LIBRARY DENNIS POTOKAR / SCIENCE PHOTO LIBRARY
Healthy ECG heart printout. Electrocardiogram (ECG) printout of a healthy heartbeat. The heart is a hollow muscle that pumps blood around the body. ECG traces measure the beating of the heart as a series of waves of various sizes. These waves correspond to the electrical activity of the heart muscle just before it contracts. The tall wave corresponds to contraction of the heart's lower chambers, the ventricles. A small wave just before this peak (not clear) shows the contraction of the upper chambers, the atria. The medium wave occurs as the heart's electrical potential returns to normal. An ECG is an important means of monito- ring the heart and diagnosing heart diseases.
Model release not required. Property release not required.