ECG REVIEW: THE BASICS
Megan Chan, PGY-1
UHCMC 2015
http://thepracticalpsychosomaticist.com/2013/04/01/qtc-interval-prolongation-andantipsychotics-by-elysha-elson-pharm-d-mph/
THE BASICS
http://flylib.com/books/en/2.569.1.27/1/
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?


Left deviation?


Positive QRS sum in I and II (or aVF )
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.blogsp
ot.com/2011/01/first-week-withnew-pacemaker.html
http://www.zuniv.net/physiology/book/images/11-13.jpg
http://dualibra.com/wpcontent/uploads/2012/04/037800~1/Part%209.%20Disorders%20of%20the
%20Cardiovascular%20System/Section%202.%20Diagnosis%20of%20Car
diovascular%20Disorders/221.htm
http://www.emedu.org/ecg/crapsanyallans.php
HEMI BLOCKS = LEFT FASCICULAR BLOCKS
http://www.usfca.edu/fac-staff/ritter/Image74.gif
LAFB
LPFB
http://aliem.com/wp-content/uploads/2013/08/LAFB.png
http://cdn.lifeinthefastlane.com/wpcontent/uploads/2011/02/avhisbb.jpg
http://aliem.com/wp-content/uploads/2013/08/LPFB.png
HYPERTROPHY
http://dualibra.com/wpcontent/uploads/2012/04/037800~1/Part%209.%20Disorders%20of%20the
%20Cardiovascular%20System/Section%202.%20Diagnosis%20of%20Car
diovascular%20Disorders/221.htm
THE SYSTEMATIC PROCESS CONT.

Chamber size
RAE
LAE
• Tall P > 2.5
• P> 120ms
mm in lead II • Diphasic p
• Large diphasic
with
P with large
downward
initial phase
terminal
in V1
phase > 1mm
wide and 1mm
deep in V1
• M-shaped P in
I, II, or aVL
RVH
LVH
• 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


Pericarditis


Low voltage (R waves < 5mm in limb leads, <10mm in
precordial leads)
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-86d882d3ca7d0120.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
HOW TO DRAW A NORMAL ECG
aVR
I
Same as
aVR but T &
P waves can
be + or –
Same as II
Inverted II
aVL
II
V4
V1
V2
Similar to
V3 but less
QRS voltage
Similar to V3
with smaller
S, taller R
V5
Similar to V3
with larger S,
smaller R
Similar to V4
with smaller S,
taller R
(R wave progression)
aVF
III
Same as II
V3
V6
Same as II
Same as II
Biphasic QRS
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/Ser
ver_442934/Image/1.1/residentguides/final/icuguidebo
ok.pdf. Accessed December 1, 2014.