Electrocardiography
A Readily Available and Helpful Tool
Denis A. Ehrich, MD, FACC
For the Family Medicine Refresher Course
March 6, 2015
1
Today’s Agenda
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Bradyarrhythmias
Wide-complex Tachycardias
Narrow Complex Tachycardias
Electrolyte Disturbances
Myocardial Ischemia and Infarction
Miscellaneous ECG patterns
2
BRADYARRHYTHMIAS AND BLOCKS
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85-year-old male without symptoms and on no pertinent cardiac
medications.
a-Atrial tachycardia with AV block
b-Sinus bradycardia (marked) consistent with sick sinus syndrome
c-Sinus rhythm with 2:1 AV block
d-Sinus rhythm with complete (third degree) AV block
e-Sinus rhythm with 3:2 AV Wenckebach
4
Key Considerations
• The tracing shows NSR with 2:1 AV block
– The ventricular rate is about 32/min with non-conducted sinus P
waves alternating with normally conducted P waves
– The sinus (P) wave rate is about 64. The conducted PR intervals
are constant at about 200ms
– It isn’t possible to identify the location of block (nodal vs. infranodal) from this single ECG showing 2:1 AV conduction
• With 2:1 block, involvement of the AV node is favored by a narrow
QRS complex and a prolonged PR interval, or by the presence of
intermittent AV Wenckebach. Block that is infra-nodal (in the HisPurkinje system) would be favored by a concomitant bundle branch
block and/or a PR interval of 160 ms or less
• Pacemaker placement indicated for asymptomatic 2:1 block at any
location and for asymptomatic block below the AV node
5
60-yr-old female with a history of anti-phospholipid syndrome who
presented with chest pain.
a-Atrial fibrillation
b- 2:1 AV nodal block
c-4:3 Mobitz I AV nodal block (Wenkebach)
d-Sino-atrial exit block.
6
Key Considerations
• The tracing shows Mobitz I second degree AV block
in the setting of acute IWMI
– 3 out of every 4 beats are conducted (4:3 Wenckebach)
– Progressive prolongation of the PR intervals and
shortening of the R-R intervals with block of every fourth P
wave
– “Group beating” is present
– Wenckebach and is often associated with high vagal tone
or nodal ischemia in the setting of an inferior wall
myocardial infraction (MI)
– The block is at the level of the AV node
7
85-year-old female with asymptomatic bradycardia.
a Atrial tachycardia with 2:1 block
b- Complete heart block with underlying sinus rhythm
c-Sinus rhythm with 3:1 AV conduction (advanced second degree AV
block)
d- Sinus rhythm with AV Wenckebach
e- Sick sinus syndrome with sino-atrial exit block
8
Key Considerations
• The tracing is consistent with a 3:1 pattern of "advanced"
second degree AV block (Mobitz II block) in which 1 of
every 3 beats is conducted
• Features of this tracing
– Sinus tachycardia (about 115 beats per min) and a ventricular
rate of about 35 per minute
– The conducted PR intervals are constant, which rules out AV
Wenckebach
– Complete heart block is excluded as every 3rd P wave is
conducted
– This pattern is referred to as advanced second degree AV block
• This rhythm is an indication for permanent
pacemaker even without overt symptoms
9
The patient is a 47-yr-old female who is asymptomatic with the following
ECG finding reportedly since birth.
a-Sick sinus syndrome
b-Mobitz I second degree AV block
c- 2:1 AV block
d-Complete heart block
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Key Considerations
• The tracing shows sinus rhythm with complete
heart block and an A-V junctional type escape
rhythm
• The P-P interval surrounding an individual QRS
complex is narrower (shorter) than the P-P
interval between two QRS complexes. Sinus
rate variation with complete heart block is
called ventriculophasic sinus arrhythmia
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Right Bundle Branch Block
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Left Bundle Branch Block
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Left Anterior Fascicular Block
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Left Posterior Fascicular Block
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WIDE COMPLEX TACHYCARDIAS
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a-SVT with RBBB aberrancy
b-Monomorphic VT originating in LV
c-Antidromic AVRT (pre-excitation)
d-Polymorphic VT
e-Torsades de pointes
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Key Considerations
• Ventricular tachycardia (VT) at rate of 170. The right bundle
branch block morphology is an atypical one (monomorphic R,
rather than rSR', in V1), and the R:S ratio is less than 1 in V6, both
suggestive of ventricular tachycardia
• The most common underlying diagnosis in adult North American
patients with sustained monomorphic VT is coronary heart
disease status post myocardial infarction(s)
• This morphology of the VT is suggestive of origin from the left
side of the heart, near the base (right bundle branch block with
inferior/rightward axis)
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57-year-old man with previous ECG showing acute myocardial infarction (MI) with normal
QRS duration. The serum potassium was normal.
a-Sinus rhythm with bifasicular block
b-Complete heart block (CHB) with underlying sinus rhythm
c- Accelerated idioventricular rhythm (AIVR)
d-Ventricular tachycardia (VT)
e-Junctional rhythm with typical right bundle branch block (RBBB)
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Key Considerations
• The tracing shows AIVR, originating from the
left ventricle and therefore accounting for the
atypical RBBB morphology
• ST elevations in the precordial leads are due
to an underlying acute myocardial infarction
• The rate of about (83 per minute) is too slow
for ventricular tachycardia and too fast for
complete heart block
20
Wide complex tachycardia in a 77-year-old man with coronary artery disease.
a-Wolff-Parkinson-White pre-excitation with antidromic conduction during atrio-ventricular
reentrant tachycardia (AVRT)
b- Sinus tachycardia with right bundle branch block aberrancy
c- Ventricular tachycardia with underlying sinus tachycardia and AV dissociation
d- AV nodal reentrant tachycardia with right bundle branch block aberrancy
e- atrial flutter with 2:1 AV conduction and right bundle branch block aberrancy
21
Key Considerations
• Monomorphic ventricular tachycardia
with underlying sinus tachycardia at
about 136/min and AV dissociation,
confirming the diagnosis of ventricular
tachycardia (VT)
– Note the clear sinus P waves, e.g., just after 5th
QRS
22
59-year-old female with sudden palpitations and lightheadedness.
a-Atrial fibrillation with WPW pre-excitation
b-Ventricular tachycardia (monomorphic)
c- Ventricular tachycardia (torsades de pointes)
d-Atrial fibrillation with right bundle branch block aberrancy
e-Tremor artifact with Parkinson's disease
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Key Considerations
• This is a dramatic example of atrial fibrillation with the
Wolff-Parkinson-White (WPW) syndrome and
conduction down the bypass tract
• This rhythm is a wide complex tachycardia with a rate of
about 230 beats/min
• The major clues to atrial fibrillation include the
"irregularly irregular" rhythm and the extremely rapid
rate
• In contrast, VT may be mildy irregular but this degree of
irregularity would be unusual at this very fast rate
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Elderly female with a history coronary artery disease (CAD) and paroxysmal atrial fibrillation
who presented with CHF exacerbation and a recent history of syncope.
a-Dofetilide toxicity and torsade(s) de pointes ventricular tachycardia
b- Digoxin toxicity and bidirectional VT
c- Hyperkalemia with intermittent VT
d-Hypercalcemia and polymorphic VT
e-Acute ST elevation MI with polymorphic VT
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Key Considerations
• The underlying rhythm (Sinus bradycardia) has a long
Q-T interval with bursts of polymorphic ventricular
tachycardia, rate about 190 bpm diagnostic of nonsustained torsade(s) de pointes
• Potential causes of the long QT interval
– Many drugs (check out the list at University of Arizona’s
www.crediblemeds.org
– Electrolyte disturbances such as hypokalemia and
hypomagnesemia
– Bradyarrythmias such as high degree AV heart block
– Long QT syndromes (“channelopathies”)
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NARROW COMPLEX
TACHYCARDIAS
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49-year-old woman with a "rapid heart beat" has the following ECG.
a-Sinus tachycardia
b-AV nodal reentrant tachycardia
c-atrial flutter with 2:1 AV block
d-atrial fibrillation
e-Atrial tachycardia
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Key Considerations
• The ECG shows classic AV nodal reentrant tachycardia
(AVNRT) at rate 150
– P waves can be located at the end of the QRS in lead II (best seen on
the rhythm strip
• Differential diagnosis
– AVNRT
– Ectopic atrial tachycardia
– Orthodromic atrio-ventricular reentrant tachycardia (AVRT), involving
retrograde conduction over a "concealed" bypass tract
– Atrial flutter with 2:1 block
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What is the rhythm?
a-AV nodal re-entrant tachycardia
b-Sinus tachycardia
c-Atrial fibrillation
d-Atrial flutter with 2:1 block
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Key Considerations
• This is atrial flutter with 2:1 conduction
• Don't miss hidden atrial (F) wave just after
QRS
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A middle-aged woman with recent onset palpitations. This arrhythmia is most consistent
with which endocrine disorder?
a-Hyperthyroidism
b-Hypothyroidism
c-Hyperparathyroidism
d-Addison’s Disease
e-Cushing’s disease
Key Considerations
• The rhythm is atrial fibrillation with a rapid
ventricular response
• The patient was markedly hyperthyroid
• An estimated 5-15% of patients with
hyperthyroidism (especially older ones) will
develop atrial fibrillation
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54-year-old man with chronic heart failure. What is the rhythm (most likely recorded at
rest)?
a-Atrial flutter with variable block
b-Sinus tachycardia with variable AV block
c-Sinus tachycardia with complete heart block
d-(Ectopic) atrial tachycrdia with variable AV block
e-(Ectopic) atrial tachycardia with complete heart block
Key Considerations
• Atrial tachycardia (rate about 220) with
variable AV block
–Note the varying degrees of 1st degree
and of second degree block that are
present (usually 2:1)
• Always consider digoxin excess in cases
of atrial tachycardia with block
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51-year-old female with palpitations.
a-Atrioventricular re-entrant tachycardia
b-Atrial fibrillation
c-Atrial flutter
d-Sinus tachycardia with long first degree AV
block
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Key Considerations
• This is atrioventricular reentrant tachycardia
(AVRT).
• This also known as orthodromic tachycardia
and occurs in patients with WPW syndrome
• The inverted P waves in leads II, III, and F, with
upright P waves in aVR are consistent with
retrograde activation of the atria via the
accessory pathway. The descending limb is
down the AV node and His-Purkinje system
• There is no delta wave during this arrhythmia
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An Example of Pre-Excitation
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a-Atrial flutter with variable block
b-atrial fibrillation
c-Wandering atrial pacemaker
d-Atrio-ventricular reentrant tachycardia
e-Multifocal atrial tachycardia
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Key Considerations
• In MAT there are 3 or more consecutive
ectopic (non-sinus) P waves are present at a
rate > 100
• Seen in decompensated COPD or
theophylline toxicity
• At rates of <100 beats/min it is called
multifocal atrial rhythm or wandering atrial
pacemaker
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ELECTROLYTE DISTURBANCES
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Elderly female admitted with obtundation.
a-Hyponatremia
b-Hypernatremia
c- Hyperkalemia
d- Hypokalemia
e-Hypercalcemia
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Key Considerations
• The ECG findings of hyperkalemia
– Symmetrically peaked ("tented") T waves associated with potassium
levels in excess of 6 mEq/L
– Broad and flattened sinus P waves that may precede frank sinoventricular conduction seen with severe hyperkalemia (i.e.,
conduction from the sinus node to the ventricles through specialized
inter-nodal tissue without atrial depolarization). This conduction
pattern may simulate a junctional rhythm.
• The narrow QRS complex in this tracing is somewhat atypical
for severe hyperkalemia
• T wave peaking with hyperkalemia is a relative finding: the
absolute magnitude of the T waves cannot be used to rule in
or rule out hyperkalemia
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A More Typical QRS Duration in
Hyperkalemia
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This is the admitting ECG of a previously healthy 49-year-old man who presented
with progressive muscle weakness and constipation. He had no chest pain or
dyspnea.
a-Hypokalemia
b-Hyperkalemia
c-Hypocalcemia
d-Hypercalcemia
e-Hypothyroidism
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Key Considerations
•
Key finding in hypercalcemia
– A very short ST segment with a consequently short QT interval (about 300 msec here).
•
Differential diagnosis of a short QT interval (lower limits are not welldefined)
– Digoxin therapy (associated with characteristic "scooping" of the ST-T complex).
– “Channelopathy"-related (may be associated with ventricular arrhythmia and sudden
cardiac arrest
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Cardiac arrhythmias, however, are unusual with hypercalcemia
AV block, sinus arrest, sino-atrial block, ventricular tachycardia, and
cardiac arrest have been reported, usually in patients receiving rapid IV
injections of calcium
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A 38-yr-old woman with weakness. Previous ECG was normal and she was on
no medications.
a-Hypercalcemia
b-Hypernatremia
c-Hypokalemia
d-Hypocalcemia
e-Hyponatremia
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Key Considerations
•Findings of hypokalemia
– Diffuse T wave flattening or inversions
– Markedly prominent U waves. These are best seen in leads V2 and V3,
but are essentially invisible in lead aVL.
•Differential diagnosis
– Hypokalemia (K+ here was 2.4 mEq/L) and
– Drugs, especially the class 1A antiarrhythmic (like quinidine,
procainamide, disopyramide) and related agents (like the
phenothiazines and tricyclics), etc.
– Patients with hereditary (congenital) long QT syndromes due to
"channelopathies" may show a similar finding.
– This ventricular repolarization prolongation pattern is of great
importance because it identifies patients at high risk of torsade de
pointes type of polymorphic ventricular tachycardia.
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If you could do only one serum lab test, what would it be in this case?
a-Calcium
b-Potassium
c-Sodium
d-Digoxin Level
e-Troponin
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Key Considerations
• ECG shows subtle QTc
prolongation.
• The QT is long in this case because
the ST segment is somewhat
prolonged. This relates to
prolongation of the plateau phase
of action potential which is
prolonged with hypocalcemia.
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MYOCARDIAL
ISCHEMIA/INFARCTION
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51-year-old male with bicuspid aortic valve, aortic insufficiency and hypertension had
an episode of chest pain 2 days prior to this tracing.
a-Antero-lateral myocardial ischemia
b-Hyperkalemia
c-Hypothermia
d-Hyperthyroidism
e-Severe hypokalemia
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Key Considerations
• Findings sinus rhythm at about 65 beats/min with diffuse,
prominent anterior T wave inversions consistent with
probable ischemia/non-Q wave myocardial infarction
• Differential diagnosis
– CNS disease (intracranial hemorrhage, head injury, tumor)
– Apical hypertrophic cardiomyopathy (usually most
marked in the mid-lateral precordial leads
– Intermittent right ventricular pacing or intermittent LBBB
("memory T waves"; however this syndrome is usually
associated with upright T waves in I and aVL
– Takotsubo (stress) cardiomyopathy (left ventricular apical
"ballooning" pattern on angiogram)
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The patient is an elderly female with a known history of left bundle branch block who
presented to the emergency ward with shortness of breath.
Can you read ischemia or infarction in the face of a LBBB
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Key Considerations
• The ECG demonstrates LBBB with biphasic and
inverted T waves in leads 2, 3 and F.
– Uncomplicated bundle branch blocks should have
"secondary" ST-T wave changes opposite in
direction to the major vector of the QRS complex
– The T waves here are inverted rather than the
expected upright direction suggesting that an
ischemic process is evolving in the inferior wall
– See the “Sgarbossa Criteria” (N Engl J Med 1996;
334:481-487February 22, 1996)
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60-yr-old female with a history of anti-phospholipid syndrome who presented with
chest pain.
a-Acute anterior myocardial infarction
b-Acute lateral wall myocardial infarction
c-Loculated pericarditis
e-Acute inferior wall myocardial infarction
d-Normal variant early repolarization
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Key Considerations
• Sinus rhythm with AV Wenckebach with 4:3
conduction in the setting of an acute inferior wall
infarction.
• The ECG demonstrates Q waves and ST elevation in
leads 2, 3, and aVF. There are also reciprocal ST
segment depressions in leads 1, aVL and V2-3.
• The rhythm is Wenckebach showing progressive
prolongation of the PR intervals, shortening of the R-R
intervals and block of every fourth P wave.
• The presence of "group" beating is easily recognized
and characteristic of Wenckebach. The block is at the
level of the AV node.
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This ECG from a 58-yr-old man shows evidence of WHICH one of the following
groups of diagnoses?
a)
b)
c)
d)
e)
Brugada pattern
Left bundle branch block
RIght bundle branch block with acute anteroseptal MI
Hyperkalemia
RIght ventricular hypertrophy
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Key Considerations
• The ECG reveals an acute anteroseptal myocardial infarction
in the setting of a (preexisting) right bundle branch block.
– The anterior precordial leads reveal a qR pattern (analogous to an
RSR' with the R replaced by a pathologic Q), marked ST elevation, and
upright T waves.
•
Three points with regard to a RBBB:
– Secondary T wave inversions are typically seen in the right
precordial leads (only in those leads with a terminal R').
– Upright T waves in such leads might indicate ischemia, etc.
– T wave inversions in leads with no terminal R' might also
be ischemic.
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A 52-year-old man. What is his chief complaint? What is the rhythm disturbance? Look
carefully at both ends of strip.
a-Acute inferior myocardial infarction
b-Acute infero-lateral infarction
c-Acute infero-lateral and posterior myocardial infarction
d-Acute anterior myocardial infarction
e-Acute lateral myocardial infarction
Key Considerations
• Acute infero-lateral and probably posterior myocardial
infarction
– Inferior Q waves and hyper-acute ST-T complexes inferiorly and
laterally with reciprocal ST depressions V1-V3. The initial R waves in
V1 are tall in setting of a pre-existent RBBB
– There is also second degree AV block with 2:1 block initially and then
3:2 AV Wenckebach
• In an inferior infarct, the block is in the AV node usually due
to ischemia and increased vagal tone.
– In acute ASMI, new RBBB with left axis deviation is a Type
II block caused by severe involvement of His-Purkinje
system and carries ominous prognosis with high risk of
complete heart block with slow (or no) escape rhythm.
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A 67-year-old man. What is the QRS duration? What is going on?
a-LBBB
b-Monomorphic ventricular tachycardia
c-Long QT syndrome
d-Polymorphic ventricular tachycardia
e-Hyper-acute anteroseptal myocardial infarction
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Key Considerations
• The QRS duration is normal
• What may appear to be a wide QRS in leads V2-V6 is
actually massive ST elevation due to acute transmural
anterior ischemia/myocardial infarction MI
• Q waves are starting to appear in the precordial leads
• This ST pattern, called "tombstones" is more
technically known as a "monophasic current of injury."
– This is also the pattern you see if you touch the
epicardium of the heart with a needle (e.g. during
pericardiocentesis)
• This pattern can be mistaken for a bundle branch block
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MISCELLANEOUS ECG PATTERNS
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This ECG from a 49-year-old man is most consistent with which clinical scenario?
a) Crushing substernal chest pain; markedly elevated
total creatine kinase (CK) and CK-MB
b) Pleuritic chest pain with normal troponin and CK-MB
c) Asymptomatic; routine preoperative ECG
d) Severe dyspnea with perfusion defects on pulmonary
V/Q scan
e) Recurrent episodes of syncope
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Key Considerations
• The ECG shows acute pericarditis
• Diffuse ST segment elevations (I, II aVF, V2-V6)
• Subtle PR segment deviations (elevated in aVR
and depressed in the infero-lateral leads).
• The ST elevations are due to a ventricular current of
injury from the pericardial inflammation.
• The PR changes are due to an associated atrial current
of injury.
• Resting sinus tachycardia is noted. The patient had a
fever but no pericardial effusion.
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A 43 year-old man is found unresponsive. What is the most likely diagnosis?
a)
b)
c)
d)
e)
Hyponatremia
Brugada pattern
Tricyclic antidepressant overdose
Systemic hypothermia
Myxedema
67
Key Considerations
• The findings on this tracing are consistent
with hypothermia
• The rhythm is sinus bradycardia at a rate
of about 46 bpm
• There are prominent “J” (Osborn) waves
in leads V4-V6 and marked QT
prolongation (620 msec).
• The baseline noise in this context is
consistent with shiver-related artifact.
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55 year-old African-American male with hypercholesterolemia and multiple complaints,
including anginal sounding chest pain, as well as more atypical symptoms. This resting
ECG was unchanged from previous. The ECG findings of ST elevation and tall T waves
here are most consistent with which ONE of the following?
a) Acute pericarditis
b) Brugada pattern
c) Benign early repolarization variant
d) Acute anterior ST elevation MI (STEMI)
e) Hyperkalemia
Key Considerations
• Distinguishing normal variant ST early
repolarization from pericarditis and
myocardial injury
• J point elevation (V2-V5)
• Distinctive J point notching
• Absence of PR segment deviations
• Absence of reciprocal changes
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39-year-old man with acute dyspnea and "muscle strain" in left leg.
71
Key Considerations
• The tracing reveals
• Sinus tachycardia with an indeterminate axis
• P- pulmonale
• Prominent T wave inversions in V1-V4 consistent with
acute RV pressure overload
• Evidence for acute RV dilatation
• Delayed precordial transition zone (R=S in V6)
• Q3-T3-S1-S2 pattern simulating inferior myocardial
infarction
• RV conduction delays
• Right axis shift.
• Most of the time the ECG in pulmonary embolism is nonspecific; although, with a large PE, sinus tachycardia is usual.
72
This ECG is from an asymptomatic 61-year-old male is consistent with syncopal
episodes and a cardiac arrest of the following
73
Key Considerations
• The tracing is consistent with the Brugada Syndrome
• ST elevations in leads V1-V3 with a “coved” appearance in V1V2, associated with slight T wave inversion.
• These findings are called the “Brugada pattern,”
• May be associated with increased risk of ventricular
tachyarrhythmias and even sudden cardiac death (Brugada
syndrome).
• There is a “pseudo” RBBB pattern-prominent S waves are not
present with the Brugada pattern in V5-V6
• The Brugada pattern can also be simulated by a normal
variant (early repolarization pattern) in the right chest leads
(usually with a “saddle-back” ST appearance). The distinction
between normal variants and an actual Brugada abnormality
can be difficult.
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