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76 Cards in this Set
- Front
- Back
term for arrhythmias that originate in the atria or the AV node
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supraventricular arrhythmias
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single ectopic supraventricular beats that originate in the atria
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atrial premature beats
(premature atrial contractions or PACs) |
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single ectopic supraventricular beats that originate in the vicinity of the AV node
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junctional premature beats
(premature junctional contractions or PJCs) |
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True or False:
Premature atrial and junctional beats generally indicate underlying cardiac disease. |
False.
Premature atrial and junctional beats are common phenomena that neither indicate underlying disease nor require treatment. |
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True or False:
Premature atrial and junctional beats can initiate more sustained arrhythmias. |
True.
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What are two ways an atrial premature beat can be distinguished from a normal sinus beat.
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contour of P-wave and timing
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True or False:
Sinus P-waves and Atrial P-waves are essentially of the same morphology. |
False.
When atrial depolarization does not occur in the normal matter, the configuration of the resultant P-wave differs from a normal sinus wave. |
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If the site of origin of an atrial beat is far from the sinus node, what prominent EKG finding would you expect to find?
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atrial axis deviation
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True or False:
An atrial premature beat comes too early, intruding itself before the next anticipated sinus wave. |
True.
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abnormal p-waves sometimes seen in junctional premature beats
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retrograde P-waves
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What is the usual configuration of P-waves in most junctional beats?
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Invisible. Most junctional beats do not have detectible P-waves; a few have visible retrograde P-waves.
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What is the difference between a junctional escape beat and a junctional premature beat?
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Timing.
The escape beat occurs after a long pause; the premature beat occurs early (prematurely). |
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True or False:
Both atrial and junctional premature beats result in wide QRS complexes. |
False.
Atrial and junctional premature beats are usually conducted normally through the ventricles. |
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What are the five types of sustained supraventricular arrhythmias?
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(1) Paroxysmal Supraventricular Tachycardia (PSVT)
aka: AV Nodal Tachycardia (2) Atrial Flutter (3) Atrial Fibrillation (4) Multifocal Atrial Tachycardia (MAT) (5) Paroxysmal Atrial Tachycardia (PAT) aka: Ectopic Atrial Tachycardia |
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Name a very common supraventricular arrythmia of sudden onset, usually initiated by a premature atrial or junctional beat, that often terminates as abruptly as it started.
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PSVT
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What is meant by Paroxysmal?
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Sudden (or violent) onset
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True or False:
PSVT can occur in perfectly normal, disease-free hearts as a result of alcohol, coffee, or sheer excitement. |
True.
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Is PSVT regular or irregular?
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PSVT is an absolutely regular rhythm.
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What is the usual rate of PSVT?
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between 150 and 250 beats per minute
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What is the most common form of PSVT driven by?
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reentrant circuit looping within the AV node
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True or False:
All PSVTs are essentially from exactly the same source. |
False.
There are several types of PSVT. |
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True or False:
PSVT may produce retrograde P waves. |
True.
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If retrograde P-waves were present in PSVT, in which leads would you expect to see them?
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Leads II or III,
"psuedo R-prime" in V1 |
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What is a psuedo R-prime?
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a little blip in the QRS complex that represents a superimposed P wave
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True or False:
In most cases of PSVT, P-waves are readily seen. |
False.
In most cases of PSVT, P waves are so buried in the QRS complexes that they cannot be identified with any confidence. |
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Would you typically expect to see a wide or narrow QRS complex in cases of PSVT?
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narrow
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What is the purpose of the carotid massage?
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It is typically used to help diagnose or terminate an episode of PSVT.
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receptors located at the angle of the jaw at the carotid bifurcation that sense changes in blood pressure
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baroreceptors
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How do baroreceptors regulate cardiac output?
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When a rise in pressure is detected, reflex responses are sent from the brain along the vagus nerve to the heart.
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What two effects does vagal input have on the heart?
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(1) slows conduction through the AV node (very important)
(2) decreases sinus rate |
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How can baroreceptors be fooled into thinking that blood pressure is rising?
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gentle pressure applied externally to the carotid artery
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Why does the bearing down or squatting tend to slow cardiac function?
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Both maneuvers cause a temporary rise in blood pressure that stimulates vagal input to the heart.
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Which is the simplest and most widely used maneuver for stimulating vagal input to the heart?
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carotid massage
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Why is carotid massage particularly effective on PSVT?
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Carotid massage slows conduction through the AV node. In most cases, the underlying mechanism of PSVT is a reentrant circuit in the AV node.
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What two effects might carotid massage have on PSVT?
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(1) Interrupt the reentrant circuit and thereby terminate the arrhythmia
(2) At the very least, slow the arrhythmia so that the presence or absence of P waves can be more easily determined and the arrhythmia diagnosed |
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True or False:
Carotid massage may induce sinus arrest. |
True.
Always have a rhythm strip running as well as equipment for resuscitation on standby. |
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True or False:
Atrial Flutter is more common than PSVT. |
False.
Atrial Flutter is less common than PSVT. |
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What is the typical rate of P waves in atrial flutter?
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250 to 350 beats per minute
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What is atrial flutter generated by in its most common form?
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a reentrant circuit around the annulus of the tricuspid valve
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the rising and falling baseline waves associated with atrial flutter
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flutter waves
(saw-toothed pattern) |
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In which leads is the saw-toothed pattern commonly associated with atrial flutter most likely to be clearly visible?
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Leads II and III
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Why aren't all atrial flutter waves allowed to proceed through the AV node?
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The AV node does not have sufficient time to repolarize between each wave
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phenomenon in A-flutter characterized by intermittent depolarization of the AV node by flutter waves
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AV block
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Most common AV block ratio in Atrial Flutter?
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2:1 is most common
(3:1 and 4:1 also frequently seen) |
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True or False:
Carotid massage is effective for terminating Atrial Flutter. |
False.
Because atrial flutter originates above the AV node, carotid massage will not result in termination of the rhythm. |
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Rhythm characterized by chaotic atrial activity and AV nodal bombardment of more than 500 atrial impulses per minute.
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atrial fibrillation
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Describe baseline appearance in atrial fibrillation.
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flat or slightly undulating,
no true P waves visible |
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True or False:
In atrial fib, the AV node regularly responds to atrial impulses. |
False.
The AV node, faced with an extraordinary blitz of atrial impulses, allows only occasional impulses to pass through at irregular intervals. |
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How would the regularity of the ventricular rhythm in atrial fibrillation be characterized?
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"irregularly irregular"
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Most commonly, the ventricular rate of atrial fibrillation falls within this range.
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120 to 180 beats per minute
(however slower and faster rates are often seen) |
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What is the key to identifying atrial fibrillation.
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irregularly irregular QRS complexes
in the absence of discrete P waves |
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wavelike forms often seen on close inspection of atrial fib baseline
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fibrillation waves
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Describe the effect of carotid massage on atrial fibrillation.
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may slow the ventricular rate, but it is rarely used because the diagnosis of a-fib is usually obvious
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True or False:
A-flutter is more common that A-fib. |
False.
A-fib is much more common than A-flutter. |
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True or False:
Atrial fib does not generally reflect any underlying cardiac pathology. |
False.
Underlying cardiac pathology is often present, especially mitral valve disease or coronary artery disease. (Differential diagnosis include hyperthyroidism, pulmonary emboli, and pericarditis.) |
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True or False:
Multifocal Atrial Tachycardia is an irregular rhythm. |
True.
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What is the usual rate seen in Multifocal Atrial Tachycardia?
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100 to 200 beats per minute
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Define the probable source of MAT.
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random firing of several different ectopic atrial foci
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Which type of disease is most commonly associated with MAT?
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Severe lung disease
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What is the most frequently required treatment for MAT?
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MAT rarely requires any treatment.
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What is the effect of carotid massage on MAT?
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Carotid massage has no effect on MAT.
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Name the rhythm that is similar to MAT, but with a rate of less than 100 beats per minute.
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wandering atrial pacemaker
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True or False:
A wandering atrial pacemaker can be seen in normal, healthy hearts. |
True.
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How is MAT distinguished from atrial fibrillation?
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MAT is characterized by easily identifiable, variable contour P waves occuring before each QRS complex.
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True or False:
In MAT, the intervals between different P waves and the QRS complex generally remains constant. |
False.
The intervals are variable. |
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What is a necessary finding to diagnose MAT?
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at least three different P wave morphologies
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True or False:
Paroxysmal Atrial Tachycardia is an irregular rhythm. |
False.
PAT is regular. |
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What is the usual rate for PAT?
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100 to 200 beats per minute
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What are to two possible origins of a PAT rhythm?
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(1) enhanced automaticity of an ectopic atrial focus
(2) reentrant circuit within the atria |
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Of the automatic and reentry forms of PAT, which form is more common?
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Automatic.
(increased automaticity of an ectopic focus) |
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What are the typical signs of automatic type PAT?
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"warm-up period" start-up, characterized by rhythm irregularity during this period; similar "cool-down period" upon termination
PAT itself is regular when sustained. |
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What are the typical signs of reentrant type PAT?
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abrupt startup with an atrial premature beat
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What is another term used for reentrant type PAT?
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atypical atrial flutter
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What is the most common underlying cause of PAT?
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digitalis toxicity
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How can you tell PAT from PSVT?
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Many times you can't. However, look for a warm-up or cool-down period. Carotid massage can also be helful, as it will generally terminate PSVT but not PAT.
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What is the effect of carotid massage on PAT.
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Carotid massage has no effect on PAT.
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