Download ECG Interpretation Interactive Case Studies

ECG Interpretation
Interactive Case Studies
Sagar Kalahasti, M.D., F.A.C.C.
Staff Cardiologist, Heart and Vascular Institute
Cleveland Clinic
No relationships to disclose
What Should I Expect on the
Boards?
• ECG tracings with one or two major findings
• Clinical vignette with each tracing
• Questions that are focused as much on the clinical scenario as
the ECG itself
• No trickery
• No coding of all of the abnormalities on the ECG
ECG Interpretation: A Case-Based Review
ECG Fundamentals
•
•
•
•
•
Rate: Fast or slow?
Rhythm: Sinus or not? Narrow complexes or wide?
Intervals: PR and QT normal or prolonged?
P wave: Normal sinus axis? Atrial enlargement?
QRS: Axis shift? Q waves? Ventricular hypertrophy? Bundle branch
block?
• The ST segment: Elevation or depression?
• The T wave: Upright or inverted?
Best approach is to apply the same systematic
approach to each ECG
ECG Interpretation: A Case-Based Review
Heart Rate and Timing
One small box = 0.04 sec = 40 ms
One large box = 0.2 sec = 200 ms
Paper speed 1500 mm/min
One beat per 0.2 sec = 300 bpm
Heart Rate = 1500/RR (mm) OR 300/ # large boxes between two R waves
300 150 100 75
3 seconds between hash marks
ECG Interpretation: A Case-Based Review
ECG Complexes and Intervals
P wave: atrial depolarization (right-left)
QRS: ventricular depolarization (septum-LV-RV)
T wave: ventricular repolarization
PR interval: efficiency of atrial and AV nodal conduction
ST segment: “quiet time” between ventricular depolarization and repolarization
QT interval: efficiency of ventricular depolarization and repolarization
ECG Interpretation: A Case-Based Review
Case 1
A 70 year-old man with a history of hypertension and
paroxysmal atrial fibrillation presents to the
emergency department complaining of episodic
dizziness and palpitations. His medication list
includes “a heart pill and a water pill.”
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 1
All of the following may account for this man’s
presentation except…
A. Hypocalcemia
B. Hypomagnesemia
C. Hyperkalemia
D. An inherited ion channel disorder
E. An adverse drug interaction
ECG Interpretation: A Case-Based Review
The QT Interval
•
•
Normal QT is 0.35 – 0.43 seconds
QTc = QT/√RR in seconds
• Prolonged QTc if ≥ 0.44 sec
• Entire T wave should fall in first half of the RR interval
Normal QT
Prolonged QT
ECG Interpretation: A Case-Based Review
Causes of QT Interval Prolongation
• Medications
–
–
–
–
Class Ia (quinidine, procainamide) and III (sotalol, amiodarone) antiarrhythmics
Tricyclic antidepressants
Non-sedating antihistamines
Ranolazine
• Electrolyte Deficiencies
– Hypomagnesemia
– Hypocalcemia
– Hypokalemia
•
•
•
•
Liquid Protein Diets
Intracranial hemorrhage
Inherited long QT syndromes
Metabolic Derangement
– Myxedema
– Hypothermia (look for shivering artifact)
ECG Interpretation: A Case-Based Review
Case 2
A 44 year-old woman with a murmur since childhood
presents with several months of progressive exertional
dyspnea. Her physical examination is remarkable for a
systolic ejection murmur along the left sternal border,
a split S2 that does not change with respiration and
pitting lower extremity edema.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 2
Her subsequent echocardiogram is most likely to
demonstrate which of the following?
A. Flow across the interatrial septum detected by color
Doppler
B. A calcified aortic valve with a high transvalvular pressure
gradient
C. A large pericardial effusion
D. Severe left ventricular hypertrophy with outflow tract
obstruction in mid systole
E. Normal left and right ventricular size and function
ECG Interpretation: A Case-Based Review
Right Axis Deviation
• QRS axis between 100° and 270°
• May be a normal variant in children and young adults
• Causes
– Pulmonary embolism
– Obstructive pulmonary disease
– Right ventricular hypertrophy left posterior fascicular block
– Lateral wall myocardial infarction
– Ostium secundum ASD
ECG Interpretation: A Case-Based Review
QRS Axis Determination
QRS (+) in I and aVF?
QRS (+) in I and (-) in AVF?
RExtreme Axis
Extreme Axis
Look at II…
xxiiss
A
A
t
LLeefft
L
If (+) in II
+
If (-) in II
QRS (-) in I and (+) in aVF?
QRS (-) in I and (-) in aVF?
Lead I (0°)
Normal
Normal Axis
Axis
Right
Right Axis
Axis
Normal
Normal Axis
Axis
III
+
+
Lead II (60°)
Lead aVF (90°)
ECG Interpretation: A Case-Based Review
Right Atrial Enlargement
• Causes of Right Atrial Enlargement
– COPD
– Pulmonary Hypertension
– Congenital Heart Disease
– ASD
– Pulmonic stenosis
– Eisenmenger’s
– Normal variant in thin patients
ECG Interpretation: A Case-Based Review
P Wave Morphology
Left Atrial Enlargement
P wave duration > 0.12 sec in II, III, aVF
P wave notched in II, III, aVF
V1 terminal P deflection > 1mm
V1 terminal P deflection > 0.04 sec
Right Atrial Enlargement
P wave amplitude > 2.5 mm in II, III, aVF
P wave peaked in II, III, aVF
P wave axis ≥ 70°
V1 initial P deflection > 1.5 mm
ECG Interpretation: A Case-Based Review
Right Ventricular Hypertrophy
• Diagnostic Criteria
– Right axis deviation
– R/S ratio in V1 > 1 or R/S ratio in V5 or V6 ≤ 1
– R wave in V 1 ≥ 7 mm
– R wave in V1 + S wave in V5 or V6 ≥ 10.5 mm
– qR complex in V1
– ST depression or T wave inversion in right precordial leads
– Onset of intrinsicoid deflection in V1 < 0.05 sec
• Common Causes
– Pulmonary Hypertension
– Pulmonic Stenosis
– COPD
ECG Interpretation: A Case-Based Review
Case 3
An 83 year-old man with paroxysmal atrial fibrillation,
diabetes and stage II chronic kidney disease presents
to your office complaining of lethargy for one week.
Two weeks ago he twisted his left ankle while walking
his dog. He developed subsequent left ankle pain and
swelling that improved with an over-the counter oral
analgesic.
Examination reveals a well appearing man in no
distress. Blood pressure is 110/65 mmHg. His
cardiovascular exam is remarkable for a regular
bradycardia and occasional prominent jugular venous
a waves.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 3
The most likely culprit for this man’s presentation is which of
the following?
A.
B.
C.
D.
E.
Advanced age.
Coronary artery disease.
Digoxin.
A tick bite.
Dental therapy without amoxicillin prophylaxis.
ECG Interpretation: A Case-Based Review
Complete (3rd degree) AV Block
• Criteria
– Atrial and ventricular impulses occur independent of each other
– Atrial rate is usually faster than ventricular rate
– PR interval varies
– PP and RR interval are constant
• Causes
– Digitalis toxicity
– Myocardial infarction
– Inferior – better prognosis
– Anterior – usually requires permanent pacing
– Degeneration of the conduction system
– Endocarditis
– Lyme Disease
ECG Interpretation: A Case-Based Review
AV Conduction Delays
• Second Degree AV Block
– Mobitz Type 1
– Progressive PR prolongation until P does not conduct
– RR containing the dropped P is < 2 x PP interval
– Normal QRS duration (usually)
– Consider myocardial infarction (inferior in particular)
– Mobitz Type 2
– Intermittent non-conduction of P wave
– PR interval constant
– RR containing the dropped P is = 2 x PP interval
– Widened QRS
ECG Interpretation: A Case-Based Review
2:1 AV Block
* Regular atrial rhythm with two P waves for each QRS
* Can be Mobitz I or Mobitz II
• Favors Mobitz I
• Narrow QRS
• Block improves with
atropine
• Block worsens with vagal
maneuvers
• Inferior MI setting
• Favors Mobitz 2
• Widened QRS
• Block worsens with
atropine
• Block improves with vagal
maneuvers
• Anterior MI setting
ECG Interpretation: A Case-Based Review
Digitalis and the ECG
• Digitalis can cause practically any ECG abnormality
• Digitalis Effect
– PR prolongation and QT shortening
– Sagging “hockey stick” ST segments
– Flat, biphasic or inverted T waves
• Digitalis Toxicity
– Second or third degree AV block
– Atrial fibrillation or atrial tachycardia with third degree AV block
– Bidirectional ventricular tachycardia
ECG Interpretation: A Case-Based Review
Case 4
A 64 year-old woman presents to an urgent care
center complaining of nausea, vomiting and
diaphoresis that began two hours ago. She was
previously well and does not see a doctor on a regular
basis. Her vital signs include a blood pressure of
110/70 mmHg and heart rate of 75 bpm. Examination
reveals a pale, diaphoretic woman who looks
uncomfortable and in mild respiratory distress.
Cardiopulmonary auscultation is unremarkable.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 4
Which of the following will not provide a long term
survival benefit for this patient?
A. Aspirin
B. Atorvastatin
C. Isosorbide Dinitrate
D. Ramipril
E. Metoprolol
ECG Interpretation: A Case-Based Review
Coronary Disease and the ECG
• Myocardial Ischemia
– Horizontal or downsloping ST segment depression
– Symmetric T wave inversion
• Myocardial Infarction
– ST elevation often preceded by increased T wave amplitude
– Horizontal or upwardly convex ST segment elevation of ≥ 1 mm
in two contiguous limb leads
– Horizontal or upwardly convex ST segment elevation of ≥ 2 mm
in two contiguous precordial leads
– Associated ST depression in non-infarct leads
– Q waves, indicative of completed infarction
– Q ≥ 0.03 sec and > 1 mm deep in I, II, avL, aVF, V4-6
– Q of any size in V1-3
ECG Interpretation: A Case-Based Review
Infarct Localization
• Left Anterior Descending (LAD)
– Septum: V1 and V2
– Anterior: V3 and V4
– Anterolateral (diagonal branches): 1, aVL, V3-6
– Apical: V1-4 and II, III, aVL
• Circumflex
– High Lateral: I, aVL
– Lateral: V4-6
– Anterolateral: I, aVL, V3-6
• Right Coronary Artery (RCA)
– Inferior: II, III, aVF
– Posterior: tall R or ST depression in V1 and V2
– RV: V4R – V6R
ECG Interpretation: A Case-Based Review
Case 5
A 53 year-old man with a history of hypertension,
COPD and remote myocardial infarction presents to
the emergency department complaining of intermittent
palpitations for the past few days. He denies any
recent chest pain, dizziness or syncope. He appears
well and is in no obvious distress. The intake nurse
measures his blood pressure with an automated cuff
and gets a reading of 116/65 mmHg but states that the
pulse reading “can’t be right”. You come over to
investigate and perform an ECG.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 5
The most appropriate next step would be to…
A. Give adenosine 6 mg IV push.
B. Give diltiazem 20 mg IV bolus followed by a drip at 5
mg/hour.
C. Give digoxin 0.5 mg IV push.
D. Deliver a 360 Joule unsynchronized shock immediately.
E. Give amiodarone 150 mg IV bolus followed by a drip at 1.0
mg/min.
ECG Interpretation: A Case-Based Review
Wide Complex Tachycardia
• Favors VT
•
•
•
•
•
•
AV dissociation
Fusion beats
Very wide QRS (>0.14 s)
Precordial concordance
Extreme or left axis
Absence of RS complex in
all precordial leads
• Any precordial RS interval
> 0.1 sec
• Favors Aberrant SVT
•
•
•
•
•
•
•
No AV dissociation
No fusion beats
QRS < 0.14 s
Precordial discordance
Relatively normal axis
Any precordial RS complex
All precordial RS intervals <
0.1 sec
ECG Interpretation: A Case-Based Review
Case 6
A 23 year-old woman with no significant medical history
presents to your office complaining of chest pain for the past
three days preceded by malaise and a cough productive of
yellow sputum. The chest pain has been constant since
onset but waxes and wanes in intensity. She denies any
dyspnea, palpitations or syncope. Vital signs include a
pulse of 100 bpm, BP 138/80 mmHg and a temperature of
38.1° C. Exam reveals an uncomfortable young woman in
no distress. Conjunctival injection is present but her
cardiovascular exam is unremarkable except for regular
tachycardia. Her lungs are clear.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 6
All of the following are appropriate therapeutic agents
for this patient except…
A. Indomethacin
B. Colchicine
C. Aspirin
D. Clopidogrel
E. Ibuprofen
ECG Interpretation: A Case-Based Review
Acute Pericarditis
• Stages
– 1: concave up ST elevation in all leads (except aVR)
– 2: ST point normalizes, T wave amplitude increases
– 3: T wave inversion
– 4: Normalization
• Other Clues
– Sinus tachycardia
– PR depression
– Low voltage or electrical alternans (if effusion)
– Symptoms are important
• Differential diagnosis
– Myocardial Infarction – usually focal, look for reciprocal changes
– Early repolarization – normal variant, young, asymptomatic patients
ECG Interpretation: A Case-Based Review
Case 7
A 58 year-old woman comes to you for preoperative risk
assessment prior to an elective abdominal hysterectomy.
Her medical history is significant only for bleeding uterine
fibroids. She denies any concerning symptoms and
exercises regularly without limitations or symptoms. Her
physical examination is completely within normal limits and
her ECG is shown.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 7
Which of the following statements regarding this patient
is false?
A. She will likely remain asymptomatic.
B. Radiofrequency ablation is appropriate therapy if she
develops palpitations.
C. Procainamide is appropriate therapy if she develops
rapid atrial fibrillation.
D. Verapamil is appropriate therapy if she develops rapid
atrial fibrillation.
E. Cardioversion is appropriate therapy if she develops
rapid atrial fibrillation
ECG Interpretation: A Case-Based Review
Wolff-Parkinson White (WPW)
• Criteria
– PR interval < 0.12 seconds
– QRS widening with ventricular pre-excitation “delta” wave
• Presentation
– Narrow complex tachycardia
– Wide complex tachycardia
– Atrial fibrillation
– AVOID AV nodal blocking drugs
• Management
– Antiarrhythmic therapy
– Cardioversion
– Radiofrequency Ablation
ECG Interpretation: A Case-Based Review
Case 8
A 62 year-old man with a history of diabetes and
hypertension presents to the emergency department with
two days of lethargy and malaise. He was seen in the
emergency department four days ago for left flank pain and
hematuria. A contrast enhanced CT scan was negative for
kidney stones or other abdominal or pelvic pathology. His
pain resolved with IV morphine and toradol and he was sent
home with oral percocet and instructions to strain his urine.
His flank pain and hematuria have since resolved. His
physical examination is unremarkable.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 8
All of the following interventions are appropriate at
this time except…
A. intravenous calcium chloride
B. intravenous glucose and regular insulin
C. nebulized albuterol
D. oral polystyrene sulfonate
E. intravenous magnesium sulfate
ECG Interpretation: A Case-Based Review
Potassium and the ECG
• Hyperkalemia
• Mild (K 5.5-6.5 mEq/L)
– Peaked T waves
– > 10 mm in precordial leads
– > 6 mm in limb leads
– Shortened QT
• Moderate (K 6.6-7.5 mEq/L)
–
–
–
First degree AV block
Wide P with low amplitude
QRS prolongation
• Severe (K > 7.5 mEq/L)
–
–
–
–
–
• Hypokalemia
• Prominent U waves
• ST depression, flattened T
waves (K usually < 2.5 mEq/L)
•
•
•
•
Increased P amplitude
Prolonged QT
All degrees of AVB
Ventricular arrhythmias
Sinus arrest
Left or right bundle branch pattern
Marked QRS widening (sine wave)
ST elevation
Ventricular arrhythmia and asystole
ECG Interpretation: A Case-Based Review
Case 9
A 19 year-old male college student with no known
medical history presents to the university student
health clinic complaining of episodic dizzy spells for the
past two weeks. He describes episodes of
lightheadedness and palpitations that occur for a few
minutes and then spontaneously resolve. He
attributed these to “finals week jitters” but he is now on
summer break and the symptoms have continued. He
tells you “I’m feeling dizzy right now”.
Case 9
All of the following statements regarding this patient are
true except …
A. Carotid sinus massage may terminate this rhythm
B. Intravenous adenosine may terminate this rhythm
C. This rhythm may be amenable to cure with radiofrequency
ablation
D. This rhythm may not be amenable to cure with
radiofrequency ablation
E. This patient will require anticoagulation to prevent stroke.
Supraventricular Tachycardias
• Criteria
– Regular rhythm
– Narrow QRS complexes (unless pre-existing bundle
branch block or aberrancy is present)
– Rate > 100 bpm
– Atrial waveform absent or appears retrograde
• Differential Diagnosis
– AV nodal reentry (most common by far)
– Atypical AV nodal reentry
– AV reentry
A-V Reentry
Case 10
A 42 year-old man with no medical history presents to an
urgent care center with several hours of palpitations and a
“rapid heart rate”. He tells you that he’s experienced two
similar episodes over the past year but “they always went
away before I could get to a doctor”. He denies any other
symptoms and his current vital signs are BP 120/80 mmHg,
HR 150 bpm, RR 14. He looks well and his exam is
remarkable only for tachycardia. Last month the patient
established care with a new primary care physician who, in
view of his history of palpitations, arranged for a 48 hour
Holter monitor and a surface echocardiogram. Both were
completely normal.
ECG Interpretation: A Case-Based Review
Case 10
Which of the following statements regarding this patient is
true?
A. He requires long-term coumadin therapy to prevent stroke.
B. He requires hospitalization for intravenous heparin and
TEE-guided cardioversion.
C. Catheter-based treatment of his arrhythmia has a high
success rate.
D. The antiarrhythmic drug of choice for this patient is
amiodarone.
E. His arrhythmia is not likely to reoccur following
cardioversion.
Atrial Tachyarrhythmias
• Atrial Flutter
– Sawtooth “F waves”, typically at 240-340 bpm
– Typical flutter has negative F waves in inferior leads
– F waves lack an isoelectric baseline
• Atrial Fibrillation
– Absent P waves or coarse, variable atrial “wavelets”
– Irregularly irregular QRS pattern
• Multifocal Atrial Tachycardia
– Atrial rate > 100 bpm
– Atrial waveforms with ≥ 3 morphologies
– Variable PP and PR intervals
– Seen often in patients with pulmonary disease
ECG Interpretation: A Case-Based Review
Case 11
A 65 year-old woman with type 2 diabetes,
hypertension and hypothyroidism recently moved to
your town and is seeing you today to establish care
with a new internist. She presently voices no
complaints and states that her blood pressures and
blood sugars have been well controlled with HCTZ,
lisinopril and metformin. She maintains an active
lifestyle that includes walking, biking and swimming
almost daily. Her ECG is shown.
ECG Interpretation: A Case-Based Review
ECG Interpretation: A Case-Based Review
Case 11
All of the following are true about this patient except…
A. Her ECG may represent a variant of normal.
B. Her ECG may represent a prior myocardial infarction.
C. Her ECG may represent age-related degeneration of the
conduction system.
D. Her ECG may represent structural heart disease.
E. Her ECG may make the future diagnosis of myocardial
infarction difficult.
ECG Interpretation: A Case-Based Review
Left Bundle Branch Block
• Criteria
– QRS duration ≥ 0.12 seconds
– Broad, monophasic R waves in I, V5 and V6
– rS or QS in V1
– QRS-peak R wave duration >0.05 seconds
• Seen in…
– LVH
– Myocardial infarction
– Structural heart disease
– Conduction system degeneration
– Congenital heart disease
– Almost never occurs in normals
ECG Interpretation: A Case-Based Review
Right Bundle Branch Block
Criteria
- QRS ≥ 0.12 seconds
- rsR’ or rSR’ in V1 and/or V2
- QRS-peak R duration > 0.05 seconds in V1 and V2
- Wide, slurred S waves in I, V5 and V6
Seen in normals, hypertension, rheumatic heart disease, cor
pulmonale, degenerative conduction disease, Ebstein’s anomaly.
ECG Interpretation: A Case-Based Review
What Should I Focus On?
• ECG manifestations of systemic and non-cardiac illnesses
– Thyroid disease
– Pulmonary Disease
• ECG manifestations of electrolyte disturbances
– Potassium
– Calcium
• Relationship between the surface ECG and coronary artery
distribution
• ECG manifestations of structural heart diseases and their
corresponding physical exam findings
– Secundum ASD
– Mitral Stenosis
ECG Interpretation: A Case-Based Review
Good Luck!
Acknowledgement
Dr. Michael Faulx, MD,FACC