Post on 19-Jan-2016
ECG REVIEW: THE BASICS
Megan Chan, PGY-1
UHCMC 2015
http://thepracticalpsychosomaticist.com/2013/04/01/qtc-interval-prolongation-and-antipsychotics-by-elysha-elson-pharm-d-mph/
THE ECG UNIT
http://cal.vet.upenn.edu/projects/lgcardiac/ecg_tutorial/printerval.htm
THE SYSTEMATIC PROCESS Rate
300/(# large boxes between R—R interval) 300-150-100-75-60-50
Rhythm Regular vs irregular Sinus rhythm?
P before every QRS (easiest to see in leads II and V1) Positive p wave in I & II; negative p in aVR
Axis Normal axis?
Positive QRS sum in I and II (or aVF ) Left deviation?
Up in I, down in II Right deviation?
Down in I, up/down in II
THE SYSTEMATIC PROCESS CONT.
Intervals PR interval: normal 120-200ms (3-5 small
boxes) Short PR interval = WPW Long PR interval = heart block
QRS complex: normal <120ms (≤ 3 small boxes) Long QRS: conduction delays, hyperkalemia,
ventricular rhythm QT interval: normal ≤ 430 in men, ≤ 450 in
females (less than R—R/2) Long QT: MI, myocarditis, hypocalcemia,
hypothyroidism, subarachnoid hemorrhage, drugs—sotolol, amiodarone, hereditary
THE SYSTEMATIC PROCESS CONT.
Conduction Abnormalities AV blocks RBBB LBBB IVCD (interventricular conduction delay) Left Anterior Fascicular Block Left Posterior Fascicular Block
http://healthybeatinghearts.blogspot.com/2011/01/first-week-with-new-pacemaker.html
http://www.zuniv.net/physiology/book/images/11-13.jpg
http://dualibra.com/wp-content/uploads/2012/04/037800~1/Part%209.%20Disorders%20of%20the%20Cardiovascular%20System/Section%202.%20Diagnosis%20of%20Cardiovascular%20Disorders/221.htm
http://www.emedu.org/ecg/crapsanyallans.php
HEMI BLOCKS = LEFT FASCICULAR BLOCKS
http://www.usfca.edu/fac-staff/ritter/Image74.gif
http://aliem.com/wp-content/uploads/2013/08/LAFB.png
http://aliem.com/wp-content/uploads/2013/08/LPFB.png
http://cdn.lifeinthefastlane.com/wp-content/uploads/2011/02/avhisbb.jpg
LAFB
LPFB
HYPERTROPHY
http://dualibra.com/wp-content/uploads/2012/04/037800~1/Part%209.%20Disorders%20of%20the%20Cardiovascular%20System/Section%202.%20Diagnosis%20of%20Cardiovascular%20Disorders/221.htm
THE SYSTEMATIC PROCESS CONT.
Chamber size
RAE LAE RVH LVH
• Tall P > 2.5 mm in lead II
• Large diphasic P with large initial phase in V1
• P> 120ms• Diphasic p
with downward terminal phase > 1mm wide and 1mm deep in V1
• M-shaped P in I, II, or aVL
• R in aVR > 5mm (or R>Q)
• R in V1 > 7mm
• qR in V1• R in V1 + S in
V5/V6 > 10mm
• Deep S in V5/V6 > 7mm
• R in aVL > 11mm
• R in V5/V6 + S in V1/V2 > 35mm
• R in I + S in III > 25 mm
• R in aVF > 20mm
• S in aVR > 14mm
THE SYSTEMATIC PROCESS CONT. Ischemia
What ECG changes do you expect to see? Hyperacute T waves Inverted T waves ST segment
elevation Q waves ST depressions = ???
Subendocardial ischemia ST elevations = ???
Transmural ischemia What are Pathologic Q waves?
1 small box wide and/or >5mm or 1/3 of R wave deep Other changes:
Old septal infarct: No R waves in V1-V3 Old lateral infarct: No R wave progression in V4-V6 RV infarct: ST elevation in V4 & V5 with right sided EKG
THE SYSTEMATIC PROCESS CONT.
Everything Else Pericardial Effusion
Low voltage (R waves < 5mm in limb leads, <10mm in precordial leads)
Pericarditis Diffuse ST elevations and PR depressions
Pulmonary Embolism “S1Q3T3”:S wave in I, Q wave in III, T wave inversion
in III
Location Leads Occluded Vessel
Anterior V2-V4 LAD
Anteroseptal V1-V4 LAD
Anterolateral V1-V6, I, aVL LAD, diagonal
Lateral V5-V6, I, aVL Circumflex, diagonal
Inferior II, III, aVF RCA, circumflex
Posterior Tall R in V1-V3, ST depression in V1-V2
RCA
http://www.edoctoronline.com/media/19/photos_245a975b-66ad-4f7e-86d8-82d3ca7d0120.jpg
http://dotwordpressdotcom.wordpress.com/med-school/clinical-skills/ecgs/
THE DR. ORTIZ METHOD 4 step method to interpreting 80% of ECGs in 1
minute What are the most important ECG leads?
II— best axis, dx inferior wall MI, most studied V1—best p wave, dx anterior wall MI & RBBB V5—dx lateral wall MI, LBBB, & LVH
What 2 leads are best for determining axis? I & II
100% sensitive & specific w/ zero false + Normal axis is -30 to 90 aVF was used > 100 years ago
Special thanks to Dr. Jose Ortiz!
THE DR. ORTIZ METHOD Step 1: Demographics
Verifying pt name and calibration of ECG Step 2: Two second look at lead II
Regularity of the tracing. Any funny beats? P waves
Upright sinus “M” shape LAE Mountain peaks RAE
Axis: QRS positive 50% chance of normal axis Intervals
Normal QRS <3 boxes >3 boxes BBB
Q waves –75% risk for inferior MI
THE DR. ORTIZ METHOD Step 3: Study three things about the
QRS Axis: normal vs L deviation vs R deviation
Confirm suspected axis by looking at lead I Width: normal vs RBBB vs LBBB
> 3 boxes wide = abnormal Look at V1 If RSR’ then RBBB; If large S then LBBB.
Height: normal vs low voltage vs LVH Remember “14-12-35” for LVH
Lead I: R > 14 Lead aVL: R > 12 S in V1 + R in V5/V6 > 35
THE DR. ORTIZ METHOD
Step 4: Rate, ST segments, T waves, Infarcts Anterior/Septal infarct: V1-V4 Inferior infarct: II, III, aVF Lateral infarct: aVL, I, V5, V6
DRAW A NORMAL ECG
http://www.lysosomalstorageresearch.ca/Fabry_eClinic/electrocardiography-ecg.html
I
II
III
aVR
V1 V4
aVL V2 V5
aVF V3 V6
Same as II
Same as II
Same as II Same as II
Inverted II
Same as aVR but T & P waves can be + or –
Biphasic QRS
Similar to V3 but less QRS voltage
Similar to V3 with larger S, smaller R
HOW TO DRAW A NORMAL ECG
Similar to V3 with smaller
S, taller R
Similar to V4 with smaller S,
taller R(R wave
progression)
REFERNCES
Agabegi SS, Agabegi ED. Step up to Medicine, 3rd ed. 2013. Lippincott Williams & Wilkins. Philadelphia, PA.
Gomella LG, Haist SA. Basic EKG reading. In: Clinician’s Pocket Reference. McGraw-Hill; 2007. http://flylib.com/books/en/2.569.1.27/1/. Accessed Nov 18, 2014.
Longo DL, Fauci AS, Kasper DL, et al. Electrocardiography. In: Harrison’s Principles of Internal Medicine, 18th ed. 2012. McGraw Hill. New York, NY.
University of Illinois at Chicago. Online ICU Guidebook. 2013. http://chicago.medicine.uic.edu/UserFiles/Servers/Server_442934/Image/1.1/residentguides/final/icuguidebook.pdf. Accessed December 1, 2014.