Pacemaker cells in the SA node are located:
at the junction between the vena cava and right atrium
primarily in the right atrium
at the junction between the right atrium and the right ventricle
near the coronary sinus
The wave of depolarization in the heart moves from the SA node to the RA, interatrial septum and left atrium at a rate of 0.4 m/sec.
Which of the following is a result of atrial depolarization?
QRS complex
P wave
T wave
V wave
The rate of depolarization slows down as the wave reaches the small AV node cells.
The wave of depolarization after the AV node:
spreads rapidly at a rate of 2-4 m/sec
spreads rapidly at a rate of 3-5 m/sec
travels through the bundle of His and then to the bundle branches
is slowed at the bundle of His
The QRS complex P wave PR interval( QRS complex, P wave, PR interval ) seen in an EKG is due to depolarization of the ventricles.
Which of the following cells is/are capable of generating spontaneous pacemaker activity?
AV node
SA node
Bundle cells
Purkinje fibers
Without any neural modulation SA node cells would fire at a rate of 100-120 bpm.
Atrial fibrillation occurs when the atrial muscle depolarizes so frequently (rates up to 500/min) that the atrial contraction is ineffective and the QRS complex is replaced by small oscillations.
Standard limb lead I compares voltage between:
right arm and left leg
right arm and left arm
left arm and left leg
Standard limb lead II compares voltage between the right arm and left leg.
Augmented lead aVL averages negative leads on the right arm and ❌ to compare to a positive lead on the left arm.
Augmented lead _____ has negative leads averaged between the left arm and left leg, with the positive lead on the right arm.
aVR
AVL
aVF
Augmented lead aVF averages negative leads on both feet and compares voltage to a positive lead on the left arm.
Which of the following are components of standard limb lead III?
negative lead on the left arm
negative lead on the right arm
positive lead on the left leg
positive lead on the right leg
What abnormality is portrayed in the EKG tracing?
1st degree heart block
2nd degree heart block, Mobitz Type II
ST elevation
2nd degree heart block, Mobitz Type I
The portrayed EKG tracing demonstrates 2nd degree, Mobitz Type II heart block.
This EKG tracing demonstrates 3rd degree heart block. Which of the following are characteristics of this abnormality?
Complete A-V disassociation (dissociated P waves)
consistent QRS complex
3rd degree burns
Absent PR interval (atria & ventricles beat independently)
Absent P waves
Ventricular bradycardia
What abnormality is demonstrated by the EKG tracing?
Ventricular fibrillation
Atrial fibrillation
Auricular fibrillation
Defibrillation
(as shown in this tracing) is characterized by a heart rate greater than bpm and wide interval.
This EKG tracing demonstrates sinus bradycardia.
What abnormality is demonstrated here?
Atrial flutter
The pictured abnormality demonstrates atrial flutter. How does this differ from atrial fibrillation?
Electrical activity is coordinated in flutter, but not in fibrillation
Electrical activity is coordinated in fibrillation, but not in flutter
Characteristic "sawtooth" P waves are present
QRS is grossly abnormal.
This EKG tracing demonstrates which of the following?
Sinus bradycardia
Sinus tachycardia
Sinus arrhythmia
Sinus pressure
Which is the most common cause of sudden death?
Abetalipoproteinemia
PA students suddenly transitioning to a sedentary lifestyle and questionable dietary habits
Darth Proteus + a bottle of Don Julio 70
Where does standard limb lead III record differences in potential?
Left arm (-) and left leg (+)
Right arm (-) and left leg (+)
Right arm (+) and right leg (+)
You're performing an EKG on a patient and focusing on limb lead II. In terms of deflection, what do you expect to see on the tracing upon atrial depolarization?
positive (upward) deflection forming the P wave
negative (downward) deflection forming the P wave
formation of the QRS complex
formation of the Z wave
With respect to limb lead II, what do you expect to observe on an EKG upon the FIRST stage of ventricular depolarization?
a slight positive deflection at the beginning of the QRS complex
a slight negative deflection at the beginning of the QRS complex
no measurable deflection
a large negative deflection at the beginning of the QRS complex
With respect to aVR, you expect to see a negative (downward) deflection upon the SECOND stage of ventricular depolarization.
All of the following are terms that describe abnormal pathways of depolarization in cardiac muscle except:
re-entry
circus movement
reciprocating tachycardia
fibrillation
refractory repolarization
Regarding the QRS axis of the heart, if the QRS is positive (upright) in lead I and positive (upright) in lead aVF, then you have a normal axis.
If the QRS axis (vector) is negative in lead I and negative in lead aVF, then:
You are in the NW axis (can be seen in patients with v-tach; relatively rare)
This confirms a left axis deviation (LAD) usually seen with left ventricular hypertrophy or right ventricle damage
This confirms a right axis deviation (RAD) usually seen with right ventricular hypertrophy or left ventricle damage
I need to watch the video provided in the explanation to understand more
The normal QRS axis of the heart comprises a vector between +90 and -50 degrees
A normal PR interval is between
0.12 and 0.2 sec
0.2 - 0.3 sec
0.06 - 0.1 sec
0.35 - 0.4 sec
You are a 2nd year student and your internal medicine preceptor asks you the following question regarding an EKG trace: "How many seconds are represented by 1 big box?". Your answer is:
1 second
0.2 seconds
0.5 mV
0.4 seconds
The best immediate treatment for ventricular fibrillation would be blocking the
I (f) channel
TEA-type K channel
Na+ channel
None of the above
Which of the leads is depicted in this image?
aVL
Limb lead II
Limb lead III
Precordial lead
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