Jason Ryan, MD Intern Report How to Read an EKG Jason Ryan, MD Intern Report

How to read an EKG Rate and Rhythm Axis and Intervals Hypertrophy how fast/slow regular/irregular wide/narrow Axis and Intervals PR, QRS, QT Hypertrophy LAE/RAE LVH/RVH ST Changes and Q waves

How to read an EKG Rate 300 100 60 40 150 75 50

How to read an EKG Axis QRS Lead aVF (+) (-) -90o LAD Lead I (-) (+) RAD Normal Axis 90o

How to read an EKG Intervals Correct QT 1. QTc=QT/(RR)1/2 (Bazett) 2. QTC=QT + 0.00175(HR-60) (Hodges) QRS 0.7-011 QTc <0.46 PR 0.14-0.21

How to Read and EKG Atrial Enlargement

How to Read and EKG Ventricular Enlargement

Sinus Rhythm Rate between 60 to 100 P wave before every QRS Smooth contour Either all positive or all negative except V1 <0.12s and <0.2mv Upright P waves in I, II, aVF Negative P wave in aVR

Limb Lead Reversal Right and Left arm reversed P wave positive aVR P wave negative aVL and I Limb leads look normal Right arm and Right leg reversed P wave negative I, L Lead II isoelectric (almost no QRS)

Left Bundle Branch Block Criteria: QRS > 120ms (3 small boxes) Broad, notched, or slurred R waves in I, aVL, and V5-V6 Secondary ST-T changes in I, aVL, and V5-V6 Absence of Q waves in I, V5-V6 R-wave peak time >60ms (1.5 small boxes) V5-V6 Separate criteria for STE AMI

Right Bundle Branch Block Criteria: QRS >120ms (3 small boxes) R’ in the right precordial leads with R’>R Secondary ST-T changes in R precordial leads Supporting findings: Slurred S wave in I, aVL, left precordial leads Usual criteria for STE AMI apply

Left Ventricular Hypertrophy SV1orV2+ RV5orV6>35mm >40 if 30-40yrs old >60 if 16-30yrs old RaVL>11mm RI + SIII >25mm RaVL + SV3 >28mm(men) or 20mm(wmn)

Left Ventricular Hypertrophy Associated ST-T wave abnormalities STD and TWI in V5-V6 Leads where QRS is mainly positive Slight STE with upright T in V1-V2 Leas where QRS is mainly negative

Sinus Tachycardia All sinus rhythm criteria Rate >100 P before every QRS Upright P in I, II, aVF Inverted P aVR Rate >100

T Wave Inversions Indicative of subendocardial or evolving ischemia Can be a normal variant in several leads or in the presence of BBB Can be caused by several other conditions Hypertrophic obstructive cardiomyopathy Intracranial processes (hemorrhage) Medications or electrolyte abnormalities Myocarditis/pericarditis or pulmonary embolism

ST depressions Horizontal ST depressions are strongly suggestive of ischemia in the appropriate clinical setting Don’t necessarily localize Stress testing Reciprocal changes Several other conditions can provoke ST depressions: LVH Medications or electrolytes Bundle Branch Block Pulmonary embolism

ST Elevations Localizes best of all ischemic EKG changes Usually indication of acute myocardial injury (occluded artery) Several conditions can also cause ST elevations: Pericarditis Early repolarization LBBB LVH

Evolution of EKG changes ST Elevation MI Evolution of EKG changes Normal Acute Hours 1-2 Days 3-7 Days > 7 Days

Leads go together Anterior

Leads go together Lateral

Leads go together Inferior