Scott Hubbell, MHSc, RRT-NPS, C-NPT, CCT Clinical Education Coordinator/Flight RRT EagleMed

Identify the 12-Lead Views Explain the vessels of occlusion Describe the three I s Basic Interpretation of 12-Lead ECG s

Normal limb lead placement should be on wrists and ankles. Circumstance/Standing Orders/Protocol sometimes prevents that. Consistency is the key for a diagnostic ECG. Misplacement by 1 rib can mask a MI or make a normal ECG appear as if there is an MI.

Limb Lead Placement

avr should be a negative deflection If avr is a positive deflection, check for reversed limb leads

Look for: Negative avr One complete cardiac cycle in each lead Diagnostic frequency response Proper calibration Appropriate speed

Paper Speed

Know what to look for ST elevation > 1mm (some say 2mm) Two contiguous leads Know where you are looking Use ACLS ACS chart as a reference (last slide) You will soon have this memorized

I Lateral avr V1 Septal V4 Anterior II Inferior avl Lateral V2 Septal V5 Lateral III Inferior avf Inferior V3 Anterior V6 Lateral

I avr V1 V4 II avl V2 V5 III avf V3 V6

Inferior Wall II, III, avf Left Leg I avr V1 V4 II avl V2 V5 III avf V3 V6

Inferior Wall I avr V1 V4 II avl V2 V5 III avf V3 V6 Inferior Wall

Lateral Wall I and avl Left Arm I avr V1 V4 II avl V2 V5 III avf V3 V6

Lateral Wall V5 and V6 Left lateral chest I avr V1 V4 II avl V2 V5 III avf V3 V6

Lateral Wall I, avl, V5, V6 Lateral Wall I avr V1 V4 II avl V2 V5 III avf V3 V6

Septal Wall V1, V2 Along sternal borders I avr V1 V4 II avl V2 V5 III avf V3 V6

Septal Wall V1,V2 I avr V1 V4 II avl V2 V5 III avf V3 V6

Anterior Wall V3, V4 Left anterior chest I avr V1 V4 II avl V2 V5 III avf V3 V6

Anterior Wall V3, V4 I avr V1 V4 II avl V2 V5 III avf V3 V6

Normal ECG

Practice

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

Well Perfused Myocardium Epicardial Coronary Artery Septum Left Ventricular Cavity Lateral Wall of LV Positive Electrode Interior Wall of LV

Ischemia Epicardial Coronary Artery Septum Left Ventricular Cavity Lateral Wall of LV Interior Wall of LV Positive Electrode

Ischemia Inadequate oxygen to tissue Subendocardial Represented by ST depression or T inversion May or may not result in infarct

ST depression

Injury Thrombus Ischemia

Injury Prolonged ischemia Transmural Represented by ST elevation Usually results in infarct

ST elevation

Infarction Death of tissue Represented by Q wave Not all infarcts develop Q waves

Infarction Infarcted Area Electrically Silent Depolarization Many infarcts do not develop Q waves

Thrombus Infarcted Area Electrically Silent Ischemia Depolarization

Q Waves

Anatomy Revisited RCA right ventricle inferior wall of LV posterior wall of LV (75%) SA Node (60%) AV Node (>80%) LCA septal wall of LV anterior wall of LV lateral wall of LV posterior wall of LV (10%)

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

Left Coronary Artery (LCA) Left Main (proximal LCA) Left Circumflex (LCX) Left Anterior Descending (LAD)

Distribution LAD = anteroseptal LCX = lateral Proximal LCA = extensive anterior

Practice ECG

Extensive Anterior MI Evidence in septal, anterior, and lateral leads Often from proximal LCA lesion Widow Maker Complications common

Definitive Therapy for Extensive AWMI Normal blood pressure Thrombolysis Signs of shock PTCA CABG

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

Right Coronary Artery Left Coronary Artery Lateral Wall Left Ventricle Right Coronary Artery Posterior Descending Artery Posterior Wall Inferior Wall

Right Coronary Artery (RCA) Proximal RCA Posterior descending artery (PDA)

RCA Distribution Proximal RCA Right ventricle Posterior wall Inferior wall PDA Inferior wall

Practice ECG

Proximal RCA Occlusion Right Ventricular Infarct (RVI) 12-lead ECG does not view right ventricle Use additional leads V3R - V6R V4R

Right Precordial Leads (Right sided ECG) On right side of chest Same anatomical landmarks as V3 - V6

Practice ECG

ECG Evidence of RVI Inferior MI (always suspect RVI) ST elevation right V leads

Cardiac Blood Flow To Lungs From Lungs To Body From Body

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

Treatment for RVI Use caution with vasodilators Small incremental doses of MS NTG by drip

Fluid for Hypotension One to two liters may be required Large bore lines suitable here

Posterior Wall MI (PWMI) Usually an extension of an inferior or lateral MI Common with proximal RCA occlusions Occurs with LCX occlusions

PWMI Reciprocal changes V1 - V4 Indicative changes V7, V8, V9

Posterior Leads V7 Posterior axillary line Level with V6 V8 Mid-scapular line Level with V6 V9 Left para-vertebral Level with V6

Indicative Leads ST Infarcted Tissue Q Posterior Wall Ischemic Tissue LV RV Reciprocal Leads R ST

PWMI Best to identify with direct leads V7, V8, V9 ST elevation in posterior leads is evidence of posterior MI

Practice ECG