12 Lead ECGs Ischemia Injury Infarction Terry White

12 Lead ECGs: Ischemia, Injury & Infarction Terry White, RN, EMT-P

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

The Three I’s H Ischemia Flack of oxygenation FST segment depression or T wave inversion H Injury Fprolonged ischemia FST segment elevation H Infarct Fdeath of tissue Fmay or may not show a Q wave

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

Injury/Infarct Recognition Normal ECG

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

Injury/Infarct Recognition H Ischemia FInadequate oxygen to tissue FRepresented by ST depression or T inversion FMay or may not result in infarct or Q waves

Injury/Infarct Recognition ST Segment Depression

Injury/Infarct Recognition Injury Thrombus Ischemia

Injury/Infarct Recognition H Injury FProlonged ischemia FRepresented by ST elevation W referred to as an “injury pattern” FUsually results in infarct W may or may not develop Q wave

Injury/Infarct Recognition ST Segment Elevation

Injury/Infarct Recognition Infarcted Area Electrically Silent Depolarization

Injury/Infarct Recognition H Infarct FDeath of tissue FRepresented by Q wave FNot all infarcts develop Q waves

Injury/Infarct Recognition Q Waves

Injury/Infarct Recognition Thrombus Infarcted Area Electrically Silent Ischemia Depolarization

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

Injury/Infarct Recognition: Practice

Localization I a. VR V 1 V 4 II a. VL V 2 V 5 III a. VF V 3 V 6 Inferior: II, III, AVF Septal: V 1, V 2 Anterior: V 3, V 4 Lateral: I, AVL, V 5, V 6

Localization Which coronary arteries are most likely associated with each group of contiguous leads? I Lateral a. VR II Inferior a. VL Lateral III Inferior a. VF Inferior V 1 Septal V 4 Anterior V 2 Septal V 5 Lateral V 3 Anterior V 6 Lateral

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

Localization: Left Coronary Artery (LCA) H Left Main (proximal LCA) occlusion FExtensive Anterior injury H Left Circumflex (LCX) occlusion FLateral injury H Left Anterior Descending (LAD) occlusion FAnteroseptal injury

Localization Practice ECG

Localization Practice ECG

Localization Practice ECG

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

Localization: Definitive Therapy for Extensive AWMI H Normal blood pressure FThrombolysis may be indicated H Signs of shock FPTCA FCABG

Localization: LCA Occlusions H Other considerations FBundle branches supplied by LCA FSerious infranodal heart block may occur

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

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

Localization Practice ECG

Localization: Proximal RCA Occlusion H Right Ventricular Infarct (RVI) F 12 -lead ECG does not view right ventricle FUse additional leads V 3 R - V 6 R W V 4 R W FRight precordial leads W same anatomical landmarks as on left for V 3 V 6 but placed on the right side

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

Localization: ECG Evidence of RVI H Inferior MI (always suspect RVI) H Look for ST elevation in right-sided V leads (V 3 -V 6)

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

Localization: Treatment for RVI H Use caution with vasodilators FSmall incremental doses of MS FNTG by drip H Treat hypotension with fluid FOne to two liters may be required FLarge bore IV lines

Localization: Posterior Wall MI (PWMI) H Usually extension of an inferior or lateral MI FPosterior wall receives blood from RCA & LCA H Common with proximal RCA occlusions H Occurs with LCX occlusions H Identified by reciprocal changes in V 1 -V 4 FMay also use Posterior leads to identify W V 7: posterior axillary line level with V 6 W V 8: mid-scapular line level with V 6 W V 9: left para-vertebral level with V 6

Localization Practice ECG

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

Localization Practice ECG

Localization Summary H Left Coronary Artery FSeptal FAnterior FLateral FPossibly Inferior H Right Coronary Artery FInferior FRight Ventricular Infarct FPosterior

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

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

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

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

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

Practice

Practice

Practice

Reciprocal Changes

Reciprocal Changes II, III, a. VF I, a. VL, V leads

Reciprocal Changes: Practice

Reciprocal Changes: Practice

AMI Recognition H Reciprocal changes FNot necessary to presume infarction FStrong confirming evidence when present FNot all AMIs result in reciprocal changes

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

Practice Case 1 H 48 year old male F Dull central CP 2/10, began at rest H Pale and wet H Overweight, smoker H Vital signs: RR 18, P 80, BP 180/110, Sa 02 94% on room air

Practice Case 1

Practice Case 2 H 68 year old female F Sudden onset of anxiety and restlessness, F States she “can’t catch her breath” F Denies chest pain or other discomfort H History of IDDM and hypertension H RR 22, P 110, BP 190/90, Sa 02 88% on NC at 4 lpm

Practice Case 2

Practice Case Summary H Must take into Account FStory FRisk factors FECG FTreatment