Transcript View of Inferior Heart Wall

• List the causes and clinical implications of
various electrolyte abnormalities
• Describe ECG changes in potassium and
calcium
Hypokalemia
• Serum level below 3.5–5.0 mEq/L
• Caused by vomiting, diarrhea, diuretics, gastric
suctioning ,Hypomagnesemia
• Muscle weakness, polyuria
• Digitalis can take advantage and cause Torsades de
pointes
Hypokalemia
• ECG Changes
– ST segment depression
– T waves flatten or join U waves
– U waves get larger than Ts
– QT interval appears to lengthen
– PR interval increases
Hypokalemia
Hypokalemia:
Flat T with K~3
ST depression with prominent T
(actually U) and prolonged QT
when K<2.5-3
Hyperkalemia
• Most common cause is renal failure
• Sinus node can quit at 7.5 mEq/L
• VF or asystole at 10–12 mEq/L
Hyperkalemia:
T wave in hyperkalemia is
typically tall and narrow,
but does not have to be tall
(may be just narrow and
peaked pulling ST segment).
Hyperkalemia
Tall T waves with a
narrow base
QRS widens
•
Sine waves
in severe
cases
Calcium
• Hypercalcemia:
Short QT interval
• Hypocalcemia:
Prolonged QT
interval
Hypocalcemia:
Long QT that is due to a long ST segment, which is different from long
QT due to congenital long QT syndrome, drugs, or hypokalemia. T wave
is not wide, there is no T wave abnormality.
Hypercalcemia: short QTc <390 ms. No significant ST or T wave abnormality
The QT Interval
• Measured from the start of the QRS
complex to the end of the T wave
• Measures the total ventricular activity:
“refractory time”
• QTc is corrected for rate
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The QT/QTc Table
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Prolonged QT Etiologies
• Familial long QT Syndrome
• Congestive Heart Failure
• Myocardial Infarction
• Hypocalcemia
• Hypomagnesemia
• Type I Antiarrhythmic drugs
• Myocarditis
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Shortened QT Etiologies
• Digoxin (Digitalis)
• Hypercalcemia
• Hyperkalemia
• Hypomagnesemia is not associated with
characteristic or specific ECG findings
• It is associated with a non-specific
prolongation of QT and/or QRS intervals,
and is often associated with hypokalemia
and hypocalcemia. Therefore, changes
related to the latter 2 abnormalities may be
seen.
Pathologic Q Waves
I
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Progression of Myocardial
Infarction
• During MI the ECG
often evolves
through three
stages:
– Ischemia
– Injury
– Infarction
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Identification of MI
• Reciprocal
changes
seen on 12lead ECG
may assist
with
distinguishin
g between MI
and
conditions
that mimic it
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View of Inferior Heart Wall
• Leads II, III, aVF
- Looks at inferior heart wall
-Looks from the left leg up
View of Lateral Heart Wall
• Leads I and aVL
– Looks at lateral heart
wall
– Looks from the left arm
toward heart
*Sometimes known as
High Lateral*
View of Lateral Heart Wall
• Leads V5 & V6
– Looks at lateral heart wall
– Looks from the left lateral
chest toward heart
View of Anterior Heart Wall
• Leads V3, V4
– Looks at anterior heart wall
– Looks from the left anterior
chest
View of Septal Heart Wall
• Leads V1, V2
- Looks at septal heart wall
- Looks along sternal borders
Posterior Ischemia, Injury,
Infarction
• Can be identified through leads V7, V8 and
V9
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Right Ventricular Ischemia, Injury,
Infarction
• Can be identified using leads V3R, V4R,
V5R, V6R
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Right Ventricular MI
Anterior MI
Reciprocal ST segment depression
Acute ST segment elevation
Pericarditis
Pericarditis
• Signs and Symptoms
– Chest pain, dyspnea, tachycardia, fever,
weakness, chills
– Chest pain sharp, radiating to back, neck, jaw
– Made worse by lying flat, twisting
– Made better by leaning forward
Pericarditis
• Often pleuritic pain, worse on inhalation
• Pain can last for hours or days
• Pericardial friction rub
– Heard over left lower sternal border
Pericarditis ECG Criteria
• ST segment
elevation
• Concave in all
leads
• T wave elevation
• PR depression
Pericarditis
Pericarditis: Diagnosis
Early Repolarization
ECG Criteria: APE
• Deep S in Lead I
• Abnormal Q in
Lead III
• Inverted T in Lead
III
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The Digitalis Effect
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60% of those on “Dig” have it
ST segment depression
Scooped out appearance
Best seen in inferior/lateral leads
Questions