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.
A resting electrocardiogram (ECG) revealed sinus tachycardia with a rate of 126 beats/min, normal QRS axis, widespread ST-segment depression in the limb and precordial leads, with ST-segment elevation in the augmented unipolar limb lead (right arm) 0 aVR.