Revision of 12 lead EKG and cardiac surgeries Ambreen Gowani Acknowledgement: Saleema Allana
2 • When the coronary blood supply to the heart muscle is actually compromised, three ECG changes may be recorded: • Ischemia (T wave change) • Injury (ST segment change) • Infraction (QRS change) Changes In the ECG
5 Myocardial Injury • Myocardial injury (ST segment change) denotes as acute reduction in the coronary blood supply causing injury to ventricular heart muscle.
6 Myocardial Infarction • Myocardial infarction denotes death or necrosis of ventricular heart muscle when the compromised coronary blood supply is not reestablished. • The heart muscle cells do not recover or regenerate; instead, a scar forms in the area of infarction.
“ Primary ” ST-T Wave changes • Drug effects (e.g., digoxin, quinidine, etc) • Electrolyte abnormalities (e.g., hypokalemia) • Ischemia, infarction, inflammation, etc • Neurogenic effects (e.g., subarrachnoid hemorrhage causing long QT)
"Secondary" ST-T Wave changes ST-T changes seen in bundle branch blocks ST-T changes seen in nonspecific Intra Ventricular Conduction Delay ST-T changes in PVCs, ventricular arrhythmias
9 • Myocardial infarction is depicted by the appearance of Q waves. • Insignificant Q waves < 0.04 second are normally present in ECG leads I, aVL, V5, and V6 • Significant Q waves of myocardial infarction are > 0.04 second and >2mm deep. Old MI
ST Elevation and non-ST Elevation MIs
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- Fall '19