E. (1) sea shell fossils (2) it is made of old ocean floor that got uplifted during collision. 4. At convergent plate boundaries, the volcanic mountain chains that form are called (1) ________ in an ocean-. ocean setting and (2) __________ in an ocean-continent setting.
Poor R wave progression is a vague term used to describe the transition in voltage in the precordial leads of an electrocardiogram (ECG). It is not a diagnosis but simply describes a pattern frequently noted. In a normal individual there is a progressive increase in the magnitude of the voltage in the leads from V1 to V4.
The T wave is the most labile wave in the ECG. T wave changes including low-amplitude T waves and abnormally inverted T waves may be the result of many cardiac and non-cardiac conditions. The normal T wave is usually in the same direction as the QRS except in the right precordial leads (see V2 below). Also, the normal T wave is asymmetric with the first half moving more slowly than the second half. In the normal ECG (see below) the T wave is always upright in leads I, II, V3-6, and always inverted in lead aVR. The other leads are variable depending on the direction of the QRS and the age of the patient.