ST Segment Elevation cont.. Other Causes Coronary vasospasm Acute Pericarditis Ventricular Aneurysm Hyperkalemia Early Depolarization Current of Injury- I nability to maintain a normal resting potential. Resting membrane drops from –90 to –70. Outside of injured cell is more negative, compared to a normal cell, because of leakage of ions resulting in a abnormal baseline.Gives appearance of ST Elevation.

ST Segment Depression ST depression is an ECG sign of subendocardial ischemia and injury. ST depression is > 1 mm below the baseline, measured.04 second after the J point of the QRS. ST depression appears within minutes after the onset of subendocardial non-Q-wave MI, during an anginal attack, or after exercise. ST depression quickly reverts to normal after and anginal attack or after exercise as myocardial ischemia is corrected.

ST Segment Depression cont.. Other causes: Left & Right Ventricular Hypertrophy Left & Right Right Bundle Branch Blocks Digitalis in Therapeutic and Toxic doses.

Q wave Normal result from the depolarization of the IS from left to right. Abnormal Q waves are signs of irreversible myocardial necrosis in the evolution of an acute MI. Considered abnormal if it is.04 second wide and depth of > 25% of the height of the succeeding R wave. Appear in about 2 hours or on the average of 8 to 12 hours after the onset of the MI reaching max in about 24 to 48 hours.

Complications of Acute MI Myocardial Dysfunction secondary to myocardial damage resulting in right & left ventricular failure. The disruption of the electrical conduction system, resulting in various arrhythmias.

THE END OF CHAPTER 15 Hauszar Robert, Basic Dysrhythmias, Interpretation & Management, Third Edition, Mosby, Inc. 2002, pp