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.
Another pattern (ST depression) suggests ischemia - or a lack of blood supply to part of the heart again is suggestive a partial blockage. A resting ECG may be normal despite a blockage. Contrary to popular belief a NORMAL ECG does NOT exclude blockages. The use of excercise (treadmill) or certain medications to increase heart rate (work load on the heart) increase the likelyhood that changes will be found suggesting blockage.