Transcript EKG - Georgetown University

EKG 101
Deborah Goldstein
Georgetown University
Department of Internal Medicine
Steps to Interpreting an EKG
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Rate
Rhythm
Axis
Intervals (PR, QRS, QTc)
Hypertrophy
ST segments
T waves
Q waves
Rate
Naming stuff
Normal Sinus Rhythm
• P before every QRS
– Best places to look: II, V1
• QRS after each P
Axis
1. The direction of the mean electrical vector,
representing the average of current flow in the frontal
plane.
2. Normal axis: –30 to +90 degrees.
Axis
Axis
• Look at lead I and aVF.
• Then find the isoelectric lead (where the QRS
complex is most nearly biphasic).
• Then go 90 degrees perpendicular to the isoelectric
lead.
Axis
Axis
Rate, Rhythm, Axis
Rate, Rhythm, Axis
Rate, Rhythm, Axis
Ddx of Axis Deviation
LAD
• Left ventricular hypertrophy, Left anterior fascicular
block, LBBB, Inferior wall MI
• Pregnant, ascites, short/fat
RAD
• Right ventricular hypertrophy, Left posterior
fascicular block, RBBB, lateral wall MI
• PE
PR Interval
• Normal PR = 0.12 – 0.20 seconds (3-5 little
boxes)
• Long PR >0.20 seconds (>5 little boxes)
=Delayed conduction from atria to ventricles
• First-degree AV block
– PR>0.20 seconds
– NO dropped QRS
Second Degree AV Block
• Wenckebach (Type 1)
=block within AV node
– PR interval progressively lengthens...then dropped
QRS
• Mobitz (Type 2)
=block within His-Purkinje system
– Fixed PR with dropped QRS
– WORSE!
– Sarcoid, Lyme....
– Pacemaker!
Third Degree AV Block
=Failure of conduction of any atrial impulses to get to
the ventricles
=Complete AV block
Causes of Acute AV Block:
• Calcium channel blockers
• Acute RCA occlusion
• Digoxin toxicity
What kind of AV Block?
What kind of AV Block?
What kind of AV Block?
What kind of AV Block?
QRS Interval
Normal = 0.06-0.10 seconds
Wide QRS = >0.12 seconds (>3 little boxes)
• PVC...if >3 in a row or >6/min=VTach
• RBBB, LBBB
• Left fascicular hemiblock
• Hyperkalemia
Narrow QRS= <0.06 sec
• SVT (150-250 bpm)
• Idiojunctional rhythm (40-60 bpm)
• Premature junctional complex
Chest Leads
V1
V6
Bundle Branch Block
V1-V2 = Right precordial leads
V5-V6 = Left precordial leads
LBBB
• Rabbit ears in V6 represent delay between
depolarization from the septum  to the LV
RBBB
• Rabbit ears in V1 represent delay between
depolarization from the septum to the RV
V1
V6
Normal:
V1: rS complex
V6: qR complex
RBBB:
V1: Rabbit Ears (rSR)
V6: qRS complex
LBBB:
V1: wide QS complex
V6: Rabbit Ears
Wide QRS—Why?
Wide QRS—Why?
QT Interval
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Should be < ½ (R-R’ interval)
Measure from the start of the QRS to end of T wave
Varies with heart rate, so correct for RR interval
Normal QTc: women=0.44, men=0.42
QTc = QT (#of small squares) x 0.04
√RR
• Long QT can lead to ‘R on T’Death
Causes of Long QT
**Think ‘Lytes and Meds first!
• Low K, Low Ca, Low Mg
• Macrolides, Quinolones
• All Antipsychotics (Haldol worst, Geodon
least)
• SSRIs
• Sotalol, Quinidine, Ondansetron, Amio, TCAs
• Pts w/LVH or CHF are predisposed to medicationrelated lengthening of QT interval!
– Avoid Macrolides, Quinolones in them!
Long QT: Less common causes
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Hypothyroid
Hypothermia
AV Block
MI
CVA
Head injury
Congenital long QT
Atrial Enlargement
RAE
• P wave is tall and peaked (>2.5mm high)
• OR Biphasic P wave with initial positive inflection
• Ddx: Pulmonary HTN, COPD, PE
LAE
• P wave is wide (>0.12 sec) and notched in the middle
“M”
• OR Biphasic P wave with terminal negative inflection
• Ddx: Systemic HTN, Aortic Insufficiency, Mitral
Stenosis
Which Atria is Enlarged?
Which Atria is Enlarged?
II
V1
LVH Criteria
• Sokolow + Lyon
– S V1+ R V5 or V6 > 35 mm
• Cornell criteria (Circulation, 1987;3: 565-72)
– S V3 + R avl > 28 mm in men
– S V3 + R avl > 20 mm in women
• Framingham criteria (Circulation,1990; 81:815-820)
– R avl > 11mm, R V4-6 > 25mm
– S V1-3 > 25 mm, S V1 or V2 +
– R V5 or V6 > 35 mm, R I + S III > 25 mm
• Romhilt + Estes (Am Heart J, 1986:75:752-58)
– Point score system
(Am Heart J, 1999;37:161)
LVH “S V1+ R V5 or V6 > 35mm”
ST changes: axis + anatomy
• Lateral:
– I, aVL
– LCA, CFX
• Anterior:
– V1, V2, V3, V4
– LAD
Inferior:
-II, III and aVF
-RCA (or LCA)
Memorize this slide
Q waves
• Normal Q wave:
– Small septal Qs in I, aVL, V5, V6
– Isolated Qs in III, V1
• Pathologic Q wave:
– wider than 1 small box (0.04 sec)
– OR >25% height of the R wave in that complex
Normal Q waves
Abnormal Q Waves
Non-ST Elevation MI
=Severe subendocardial ischemia
• Marked, diffuse ST depressions in I, II, III, aVL ,
aVF , V2-V6
2 EKGs, several hours apart
Acute ST Elevation MI
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5.
6.
Normal
Hyperacute
• T wave Elevation
Acute
• ST Elevation
Hours Later
• ST Elev, Q begins to form, T wave inverts
Days Later
• Q wave, T wave inversion
Weeks Later
• Q wave
A 55 year old man with 4 hours of "crushing" chest pain.
Acute Inferior Wall MI
• ST elev in II, III, AVF
• Reciprocal ST depression in anterior leads (V2-V4)
=RCA occlusion (some LCx)
A 53 year old man with Ischemic Heart disease
Old Inferior Wall MI
• Pathologic Q wave in II, III, AVF:
– wider than 1 small box (0.04 sec)
– OR >25% height of the R wave in that complex
An 83 year old man with aortic stenosis.
LVH, LAE
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Romhilt-Estes LVH Point System:
3 points for Left Atrial Enlargement
– M shaped P wave in II
– P has prominent terminal negative component in
V1
• 3 points for:
– R wave in V5 or V6 >30mm
– or S wave in V1 or V2 >30mm
– or R or S in limb leads>20mm
• >5 points: definite LVH
A 76 year old man with breathlessness.
Afib with RVR
• Irregularly irregular ventricular rhythm.
• Must look carefully to see it is NOT regular
A 72 year old man on routine office visit
Ventricular Pacemaker
•Pacer spikes—hard to see!
•Wide QRS complexes
•Pacemaker starts after a long R - R interval following
a blocked atrial premature beat...then NSR
A 58 year old man on hemodialysis presents with
profound weakness after a weekend fishing trip.
Hyperkalemia
K >8.0
• Wide, tall and tented T waves
• Wide QRS
• Small or absent P waves
• Atrial fibrillation
• Shortened or absent ST segment
• Ventricular fibrillation
Atrial Flutter
• Saw tooth baseline with rate of 250-300
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Ischemic heart disease
Hypertension
Mitral valve disease
Thyrotoxicosis
Cardiomyopathy
Pericarditis
Evolves over hours-weeks
1. PR depression, ST elevation (concave up)
in same leads, upright T
2. Normal P, normal ST, flat T
3. Normal P, normal ST, T Wave inversion
4. normal P, normal ST, upright T
Hypocalcemia
• Long QT
• Inverted T waves