Abnormalities Caused by Cardiac Pathology

- Abnormalities Caused by Cardiac Pathology (continued) Abn mality Descripti AV heart block The node is diseased and does not conduct the impulse well. There are three types: first degree, in which the PR interval is prolonged; second degree, in which some waves do not pass through to the ventricles; and third degree or complete AV block, in which the atria and ventricles beat independently (Figure 50-17). 1 FIGURE 50-17 > Third-degree heart block. Myocardial infarction There are broad and deep Q waves. (MI) Old injury.- The ST segment is usually depressed below the baseline. Depressed wave below baseline can indicate an old MI or a current MI and is often indicated in patients with coronary arteiy disease. New injury: The ST segment is usually elevated above the baseline, Angina pectoris is the name for the syndrome of pain and oppression in the anterior chest caused by heart tissue being deprived of oxygen. If this pain lasts 2030 minutes, suspect a myocardial infarction in which the heart tissue is actually dying.