EKG Fundamentals Flashcards
Electrical alternans is an electrocardiographic phenomenon in which the ______ varies between heart beats.
QRS amplitude
Normal PR interval
less than 0.2s (200ms)
Normal QRS
Less than 0.12s (120ms)
3 small boxes
Normal QT interval for men and women
men: less than 0.43s (430ms)
women: less than 0.46 (460ms)
1 large box is how many mm
5mm
1 small box is how many mm and seconds
1mm, 0.04seconds
1 small box is how tall, how many mV
1mm, 0.1mV
Prolonged QT increased risk of?
polymorphic tachycardia
Upward deflection occurs when the flow does what?
- Depolarization - the flow of positive charges Approaches the positive electrode
- Repolarization - the flow of negative charge Approaches the negative electrode
Downward deflection occurs when the flow does what?
the flow of positive charge Moves Away from the positive electrode
Which electrode is considered the eye? Moving away or towards the eye produces what deflection?
Positive Electrode
Moving towards the eye, positive deflection
Moving away from the eye, negative deflection
Describe the position of Lead II and flow movement
RA –> LL
RA: Negative Electrode
LL: Positive Electrode
Describe the position of Lead I and flow movement.
RA –> LA
RA: Negative Electrode
LA: Positive Electrode
Describe the position of Lead III and flow movement.
LA –> LL
LA: Negative Electrode
LL: Positive Electrode
What is the most common lead used in a rhythm strip of the 12-lead EKG
Lead II
Atrial depolarization is what waveform
P wave
AV node depolarization is what waveform
PR segment. No net movement of charge.
What are the two roles of the AV node
- Slow conduction of SA node impulses - holds charge 0.1s (100ms)
- Intrinsic rate of 40-60 beats for second
Q wave is indicative of?
Septal depolarization
What portion of the electrical conduction system depolarizes the interventricular septum
Left Bundle
Depolarization of the apex of the ventricles is what waveform?
R wave
Depolarization of the base of the ventricles is what waveform?
S wave
What occurs during the ST segment in the conduction system?
Ventricles are “stuck” in a depolarized state - no movement of electrical charge.
What waveform is the repolarization of the ventricles?
T wave
Lead I “looks” at what portion of the heart?
High Lateral Wall of LV
Lead II and Lead III “look” at what portion of the heart?
Inferior Wall
The inferior portion of the heart is supplied by?
RCA
Leads V1 and V2 “look” at what portion of the heart? What artery supplies that portion?
Superior Septum
LAD
Leads I, aVL, V5, and V6 “look” at what portion of the heart? What artery supplies that portion?
Lateral Wall
(I and aVL = high lateral. V5 and V6 = low lateral)
Circumflex Artery
When assessing a three-lead ECG, you know that lead III is characterized by?
A neutral lead on the right arm
At standard recording speed, how many millimeters of ECG paper represents one second of time?
25mm (25 small boxes)
5 big boxes
Name two ECG changes associated with hyperkalemia.
peaked T waves
widened QRS
Name two ECG changes associated with hypokalemia.
Flattened T waves
Prominent U waves
During your patient interview in the preoperative area, you noticed that the patient’s chart indicates a diagnosis of right atrial hypertrophy. In lead II of the ECG, which characteristic is consistent with right atrial hypertrophy?
Enlarged P wave
Sinoatrial node depolarization is transmitted from the right atrium to the left atrium via
Bachmann’s bundle
The ST segment is measured from the ___ of the QRS complex to the ___ of the T wave.
end, beginning
Which of the following electrocardiographic leads would be best for monitoring for the transmural injury that could occur during angioplasty procedures?
A. Lead I
B. aVF
C. V3
D. V1
C. V3
Select two common standard leads to analyze or monitor the ST segment.
A. Lead I B. Lead II C. V1 D. V5
B and D
Which of the following 12-lead electrocardiographic changes would be most consistent with subendocardial injury?
A. ST depression in lead II
B. ST elevation in lead II
C. Shortened PR interval in lead I
D. ST elevation in lead I
A
What are the two types of cells within the myocardium?
Nodal Cells (electrical conduction)
Contractile Cells (heart muscle)
Intrinsic heart rates from SA node, AV node, and Bundle of His
SA: 60-100
AV: 40-60
BoH: 20-40
In which precordial lead is the R wave usually smallest?
V1
In which precordial lead is it normal to have a narrow QS or rSR’ ekg pattern?
V1
In normal healthy people, the transition zone, where R and S waves have the same voltage, occurs in which precordial leads?
Commonly V3 and V4,
A normal variant is to have an early transition in V2 or delayed in V5
In which precordial lead is the R wave usually tallest?
V5
V6 is usually blocked a little by the left lung
q wave reflects depolarization of?
Septum - may not always show up on ECG tracing.
Poor R wave progression can indicate?
- Normal Variant
-Cardiac Rotation in the chest, possibly due to lung disease or cardiac enlargement
Which 2 leads do you want to examine when look at the P wave, specifically
Lead II (atrial axis)
V1 - across the atria
A prolonged or broadened P wave longer than 0.11s could indicate?
interatrial conduction delay
Sick Sinus Syndrome
Dual Chamber PM
What is a Sinoatrial Block? How many kinds are there?
The sinus node continues to fire at regular intervals, but some impulses cannot exit from the sinus node or are considerably delayed.
4 types
What is the classic ekg sign of a wandering pacemaker
Three different morphologically different P-waves
usually less than 100bpm and exclude PAC
Should you be alarmed if you identify a Wandering Pacemaker ekg tracing?
No - usually benign, often occurs in young people of athletes because of augmented vagal tone
When assessing for a junctional rhythm, which leads should you look at?
Leads II, III, and aVF because p waves should be upright. (Only negative if the impulse is coming below atria)
How do you determine if primary pacemaker has shifted to the AV node/junction?
Inverted retrograde p waves in the inferior leads and narrow QRS. (p-wave could be absent if no retrograde conduction is occurring)
Rate - 40-60
What is the only difference between VTach and Accelerated Idioventricular Rhythm (AIVR)
The rate. AIVR is a rate around or greater than 40.
VT is a rate greater than 100.
Both are originating in the ventricles
