ECG questions and answers| (164 questions) Graded A
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Course
ECG
Institution
ECG
Normal ECG Conduction Correct Answer:
Frontal and Horizontal Plane (image) Correct Answer:
Frontal Plane Correct Answer: 6 limb leads: look at the heart @ a different 30 degree interval
the limb leads: BIPOLAR I< II< III
Unipolar limb leads aVR>aVL>aVF
-reference point ...
ECG questions and answers|
(164 questions) Graded A
Normal ECG Conduction Correct Answer:
Frontal and Horizontal Plane (image) Correct Answer:
Frontal Plane Correct Answer: 6 limb leads: look at the heart @ a different 30 degree interval
the limb leads: BIPOLAR I< II< III
Unipolar limb leads aVR>aVL>aVF
-reference point is in the centre of the Δ
Horizontal Plane Correct Answer: CHEST Leads
V1-V6 unipolar leads looking into the heart
What does an ECG mean?
-cellular level Correct Answer: -sum of all the electrical activity of all the cardiomyocytes
What does the ECG mean?
-myocardial level Correct Answer:
P wave Correct Answer: atrial depolarization
-Abnormal axis
indicates ectopic atrial
pacemaker
-
Abnormal
morphology or
duration indicate RA
or LA pathology
PR interval Correct Answer: The PR interval represents the time from the start of atrial depolarization to
the start of ventricular depolarization. It includes the delay in conduction that occurs at the AV node.
The PR interval
P.50
normally lasts from 0.12 to 0.2 seconds
-Short PR interval
indicates accessory AV
pathway
,-
Long pathway indicates
conducting tissue
disease (AV node/His)
FLAT LINE: but really its not flat but because we cant reach the AV node with electrodes (small structure)
Q wave Correct Answer: septal depolarization left-right direction
-Pathological
(large) q wave
indicates
myocardial
damage - usually
old infarct
Septal Depolarisation Correct Answer: Usually from left side to right side that's why the Q wave is
negative
R wave Correct Answer: Ventricular Depolarization
Too large, or
wrong axis: may
indicate
hypertrophy.
Too small: may
indicate damage
Big R wave as the impulse moves from the back to the front of the heart (towards electrodes)
The amplitude of the QRS complex is much greater than that of the P wave because the ventricles,
having so much more muscle mass than the atria, can generate a much greater electrical potential.
S wave Correct Answer: remaining
ventricular
depolarization
Prolongation of QRS
complex indicates
delay in conduction
within ventricle,
including bundle
branch block
ST segment Correct Answer: ventricular systole: usually horizontal or gently up-sloping in all leads. It
represents the time from the end of ventricular depolarization to the start of ventricular repolarization
, ST elevation may
indicate myocardial
infarction or
pericarditis.
ST depression may
indicate ischaemia.
T wave Correct Answer: ventricular repolarisation: Unlike depolarization, which is largely passive,
repolarization requires the expenditure of a great deal of cellular energy the membrane pump)
Twave is highly susceptible to all kinds of influences, both cardiac and noncardiac (e.g., hormonal,
neurologic), and is therefore variable in its appearance.
The amplitude, or height, of a normal T wave is one third to two thirds that of the corresponding R
wave.
Inverted T wave seen in
myocardial infarction
and ischaemia.
Prolonged T wave
indicates delayed
repolarization
Local Electrograms VS Surface ECG Correct Answer:
U wave Correct Answer: a wave on the cardiac cycle that indicates an immature cardiovascular system
or an electrolyte imbalance
little blip
Interval Times Correct Answer: PR: from P to Q (some machines dont have a Q wave)
Systematic Approach to Interpreting 12 Lead ECG Correct Answer: 1. Rate
2. QRS axis (I, aVF)
3. Rhythm: PR relationship
4. QRS width (BBB), voltage (LVH)
5. Ischaemia: Q, ST, TWI
6. QT interval
7. Previous ECG fro comparison
ECG Graph paper Correct Answer: 1. Amplitude (1mV/cm)
2. Time 25mm/sec
3. Small boxes= 40msec X 0.1mV
4. Large box= 0.2sec x 0.5mV
1. RATE Correct Answer: HR= 300/(# of large boxes"
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