Slide 1:12 Lead ECGs: Ischemia, Injury & Infarction EMS Professions Temple College


Ischemia, Injury & Infarction :Ischemia, Injury & Infarction Definitions Injury/Infarct Recognition Localization & Evolution Reciprocal Changes The High Acuity Patient


The Three I’s :The Three I’s Ischemia lack of oxygenation ST segment depression or T wave inversion Injury prolonged ischemia ST segment elevation Infarct death of tissue may or may not show a Q wave


Injury/Infarct Recognition :Injury/Infarct Recognition Epicardial Coronary Artery Lateral Wall of LV Positive Electrode Septum Interior Wall of LV Well Perfused Myocardium


Injury/Infarct Recognition :Injury/Infarct Recognition Normal ECG


Injury/Infarct Recognition :Injury/Infarct Recognition Epicardial Coronary Artery Lateral Wall of LV Septum Interior Wall of LV Ischemia Positive Electrode Left Ventricular Cavity


Injury/Infarct Recognition :Injury/Infarct Recognition Ischemia Inadequate oxygen to tissue Represented by ST depression or T inversion May or may not result in infarct or Q waves


Injury/Infarct Recognition :Injury/Infarct Recognition ST Segment Depression


Injury/Infarct Recognition :Injury/Infarct Recognition Thrombus Ischemia Injury


Injury/Infarct Recognition :Injury/Infarct Recognition Injury Prolonged ischemia Represented by ST elevation referred to as an “injury pattern” Usually results in infarct may or may not develop Q wave


Injury/Infarct Recognition :Injury/Infarct Recognition ST Segment Elevation


Injury/Infarct Recognition :Injury/Infarct Recognition Infarcted Area Electrically Silent Depolarization Infarct


Injury/Infarct Recognition :Injury/Infarct Recognition Infarct Death of tissue Represented by Q wave Not all infarcts develop Q waves


Injury/Infarct Recognition :Injury/Infarct Recognition Q Waves


Injury/Infarct Recognition :Injury/Infarct Recognition Infarcted Area Electrically Silent Thrombus Depolarization Ischemia


Injury/Infarct Recognition :Injury/Infarct Recognition What to Look for: ST segment elevation Present in two or more anatomically contiguous leads


Injury/Infarct Recognition: Practice :Injury/Infarct Recognition: Practice


Localization :Localization Inferior: II, III, AVF Septal: V1, V2 Anterior: V3, V4 Lateral: I, AVL, V5, V6


Localization :Localization I Lateral II Inferior III Inferior aVR aVL Lateral V1 Septal aVF Inferior V2 Septal V3 Anterior V4 Anterior V5 Lateral V6 Lateral Which coronary arteries are most likely associated with each group of contiguous leads?


Localization: Left Coronary Artery :Localization: Left Coronary Artery Left Main Left Circumflex Lateral Wall Anterior Wall of Left Ventricle Septal Wall Right Ventricle Right Coronary Artery Anterior Descending Artery


Localization: Left Coronary Artery (LCA) :Localization: Left Coronary Artery (LCA) Left Main (proximal LCA) occlusion Extensive Anterior injury Left Circumflex (LCX) occlusion Lateral injury Left Anterior Descending (LAD) occlusion Anteroseptal injury


Localization Practice ECG :Localization Practice ECG


Localization Practice ECG :Localization Practice ECG


Localization Practice ECG :Localization Practice ECG


Localization: Extensive Anterior MI :Localization: Extensive Anterior MI Evidence in septal, anterior, and lateral leads Often from proximal LCA lesion “Widow Maker” Complications common Left ventricular failure CHF / Pulmonary Edema Cardiogenic Shock


Localization: Definitive Therapy for Extensive AWMI :Localization: Definitive Therapy for Extensive AWMI Normal blood pressure Thrombolysis may be indicated Signs of shock PTCA CABG


Localization: LCA Occlusions :Localization: LCA Occlusions Other considerations Bundle branches supplied by LCA Serious infranodal heart block may occur


Localization: Right Coronary Artery :Localization: Right Coronary Artery Right Coronary Artery Posterior Descending Artery Inferior Wall of left ventricle Posterior Wall Lateral Wall Left Ventricle Left Coronary Artery


Localization: Right Coronary Artery (RCA) :Localization: Right Coronary Artery (RCA) Proximal RCA occlusion Right Ventricle injured Posterior wall of left ventricle injured Inferior wall of left ventricle injured Posterior descending artery (PDA) occlusion Inferior wall of right ventricle injured


Localization Practice ECG :Localization Practice ECG


Localization: Proximal RCA Occlusion :Localization: Proximal RCA Occlusion Right Ventricular Infarct (RVI) 12-lead ECG does not view right ventricle Use additional leads V3R - V6R V4R Right precordial leads same anatomical landmarks as on left for V3 - V6 but placed on the right side


Localization Practice ECG :Localization Practice ECG Note: “R” designation manually placed on this ECG for teaching purposes


Localization: ECG Evidence of RVI :Localization: ECG Evidence of RVI Inferior MI (always suspect RVI) Look for ST elevation in right-sided V leads (V3-V6)


Localization: Physical Evidence of RVI :Localization: Physical Evidence of RVI Dyspnea with clear lungs Jugular vein distension Hypotension Relative or absolute


Localization: Treatment for RVI :Localization: Treatment for RVI Use caution with vasodilators Small incremental doses of MS NTG by drip Treat hypotension with fluid One to two liters may be required Large bore IV lines


Localization: Posterior Wall MI (PWMI) :Localization: Posterior Wall MI (PWMI) Usually extension of an inferior or lateral MI Posterior wall receives blood from RCA & LCA Common with proximal RCA occlusions Occurs with LCX occlusions Identified by reciprocal changes in V1-V4 May also use Posterior leads to identify V7: posterior axillary line level with V6 V8: mid-scapular line level with V6 V9: left para-vertebral level with V6


Localization Practice ECG :Localization Practice ECG


Localization: Left Coronary Dominance :Localization: Left Coronary Dominance Approximately 10% of population LCX connects to posterior descending artery and dominates inferior wall perfusion In these cases when LCX is occluded, lateral and inferior walls infarct Inferolateral MI


Localization Practice ECG :Localization Practice ECG


Localization Summary :Localization Summary Left Coronary Artery Septal Anterior Lateral Possibly Inferior Right Coronary Artery Inferior Right Ventricular Infarct Posterior


Evolution of AMI :Evolution of AMI Hyperacute Early change suggestive of AMI Tall & Peaked May precede clinical symptoms Only seen in leads looking at infarcting area Not used as a diagnostic finding


Evolution of AMI :Evolution of AMI Acute ST segment elevation Implies myocardial injury occurring Elevated ST segment presumed acute rather than old


Evolution of AMI :Evolution of AMI Acute ST segment Elevated Q wave at least 40 ms wide = pathologic Q wave associated with some cellular necrosis


Evolution of AMI :Evolution of AMI Age Undetermined Wide (pathologic) Q wave No ST segment elevation Old or “age undetermined” MI


AMI Recognition :AMI Recognition A normal 12-lead ECG DOES NOT mean the patient is not having acute ischemia, injury or infarction!!!


Practice :Practice


Practice :Practice


Practice :Practice


Reciprocal Changes :Reciprocal Changes


Reciprocal Changes :Reciprocal Changes II, III, aVF I, aVL, V leads


Reciprocal Changes: Practice :Reciprocal Changes: Practice


Reciprocal Changes: Practice :Reciprocal Changes: Practice


AMI Recognition :AMI Recognition Reciprocal changes Not necessary to presume infarction Strong confirming evidence when present Not all AMIs result in reciprocal changes


Summary :Summary ST segment elevation is presumptive evidence for AMI Other conditions may also cause ST elevation Known as Imposters


Practice Case 1 :Practice Case 1 48 year old male Dull central CP 2/10, began at rest Pale and wet Overweight, smoker Vital signs: RR 18, P 80, BP 180/110, Sa02 94% on room air


Practice Case 1 :Practice Case 1


Practice Case 2 :Practice Case 2 68 year old female Sudden onset of anxiety and restlessness, States she “can’t catch her breath” Denies chest pain or other discomfort History of IDDM and hypertension RR 22, P 110, BP 190/90, Sa02 88% on NC at 4 lpm


Practice Case 2 :Practice Case 2


Practice Case Summary :Practice Case Summary Must take into Account Story Risk factors ECG Treatment