1 Most episodes of acute lower back pain are caused by muscle strain, such as from lifting a heavy object, a sudden movement or a fall. 2  The low back pain can be very severe and last for several hours, several days or even a few weeks.
3. Characteristics of the Normal ECG. It is important to remember that there is a wide range of normal variability in the 12 lead ECG. The following normal ECG characteristics, therefore, are not absolute. It takes considerable ECG reading experience to discover all the normal variants.
ECG, EKG Cardiology A non-invasive test of the electrical activity of heart's conduction system, which is transformed into recordings on graph paperâan electrocardiograph; in an EKG, electrodesâleads are placed on 12 specific sites of the body: standard limb leadsâI, II, III, augmented limb leadsâaV r , aV l, and aV f, and precordial or chest leadsâV 1 to V 6; EKG tracings consist of 3 major components: the P wave, which indicates atrial depolarization, the QRS complex ...