The action potential propagates as a wave of depolarization through the conduction system myocardium. This wave is the electrical signal that triggers myocardial contraction.
Which of the following is FALSE regarding electrocardiography?
It provides information about cardiac size (hypertrophy) and the mean vector (direction) of ventricular or atrial activation (mean electrical axis-MEA)
Is indicated when the heart rate is too high, too slow, or the rhythm is inappropriately irregular
A wave of depolarization directed towards the positive electrode of a lead results in a positive deflection on the EKG
The normal heart depolarizes from left to right, cranial to caudal, and dorsal to ventral
Which of the following are correctly paired? Check all that apply.
Atrial depolarization- P wave
Atrial depolarization- QRS complex
Atrial depolarization- T wave
Ventricular depolarization- QRS complex
Ventricular depolarization- P wave
Ventricular depolarization- T wave
Ventricular repolarization- T wave
Ventricular repolarization- QRS complex
Ventricular repolarization- P wave
MEA (mean electrical axis) is the dominant direction of atrial activation.
What is the origin of a narrow QRS?
Supraventricular
The ventricles
Intraventricular conduction delay
Which of the following is FALSE regarding arrhythmias?
Develop when the conduction system prevents initiation or propagation of the wave front
They are clinically important because they can be responsible for clinical signs including syncope, low cardiac output, and sudden cardiac death
Tachyarrhythmias develop with high vagal tone
Bradyarrhythmias develop when disease of the conduction system slows the rate of depolarization or "blocks" conduction
What type of arrhythmia does this image represent? Note: this is on 25 mm/sec paper.
Sinus arrhythmia
Sinus tachycardia
Sinus bradycardia
Sinus arrest
What does this image demonstrate?
Supreventricular Tachycardia (SVT)
Supraventricular Tachyarrhythmia (SVTA)
Sinus Tachycardia
Atrial fibrillation
What does this image depict?
Supraventricular tachyarrhythmia
Supraventricular tachycardia
What is this?
Ventricular fibrillation
Ventricular tachycardia
How are AV blocks resolved?
They aren't, the patient just lives with it
Administration of atropine
Exercise
They resolve on their own
Which of the following is CORRECT?
1st degree AV block: PR prolongation 2nd degree AV block: complete failure of AV conduction 3rd degree AV block: intermittent failure of AV conduction
1st degree AV block: complete failure of AV conduction 2nd degree AV block: intermittent failure of AV conduction 3rd degree AV block: PR prolongation
1st degree AV block: PR prolongation 2nd degree AV block: intermittent failure of AV conduction 3rd degree AV block: complete failure of AV conduciton
1st degree AV block: complete failure of AV conduction 2nd degree AV block: PR prolongation 3rd degree AV block: intermittent failure of AV conduction
Which AV block is this?
1st degree
2nd degree
3rd degree
Which AV Block is this?
What is going on in this EKG?
Sick sinus syndrome
Hyperkalemic rhythm
1st degree AV block
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