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54 Cards in this Set

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  • Back
rhythm disturbances arising below the AV node
ventricular arrhythmias
the most common of all ventricular arrhythmias
premature ventricular contractions
characterized by a wide and bizarre QRS complex
ventricular beats
True or False:
A retrograde P wave may be seen with PVCs.
True, but not usually.
It is more common to see no P waves.
A PVC is usually followed by a ______.
prolonged pause
True or False:
PVC's are common in normal hearts and rarely require treatment.
True.
True or False:
An isolated PVC in the setting of an AMI is not necessarily cause for concern.
False.
An isolated PVC in the setting of an AMI is an ominous sign because it can trigger a life threatening arrhythmia.
alternating rhythm in which one normal sinus beat is followed by one PVC in a regular pattern
ventricular bigeminy
alternating rhythm in which two normal sinus beats are followed by one PVC in a regular pattern
ventricular trigeminy
Name the set of standards used to determine when one should worry about PVCs.
the rules of malignancy
List the five Rules of Malignancy for identifying situations in which PVCs pose an increased risk.
"Fred Called My Red Head."

(1) Frequent
(2) Consecutive
(3) Multiform
(4) R-on-T
(5) Heart problem/AMI
term for a run of three or more consecutive PVCs
ventricular tachycardia (VT)
usual rate of ventricular tachycardia
100 to 200 beats per minute
True or False:
Unlike PSVT, ventricular tachycardia may be slightly irregular.
True.
But it may take a very fine eye to see this.
True or False:
Sustained VT with a pulse is a relatively stable rhythm.
False.
Sustained VT is an emergency, presaging cardiac arrest and requiring immediate treatment.
In terms of morphology, VT may be ______ or ______.
uniform

polymorphic
What condition is polymorphic VT commonly associated with?
acute myocardial ischemia/infarction
What condition is uniform VT commonly associated with?
Healed infarctions
(scarred myocardium provides substrate for reentrant VT)
chaotic, pulseless, preterminal rhythm seen almost solely in dying hearts
ventricular fibrillation
most frequently encountered rhythm in adults who experience sudden death
ventricular fibrillation
benign ventricular rhythm that is sometimes seen during acute myocardial infarctions
accelerated idioventricular rhythm
True or False:
Accelerated idioventricular is an irregular rhythm.
False.
It is regular.
What is the usual rate of an accelerated idioventricular rhythm?
50 to 100 beats per minute
Ventricular rhythm often characterized by an escape focus that has accelerated to drive the heart
accelerated idioventricular rhythm
ventricular rhythm with a rate of less than 50
idioventricular rhythm
a unique form of V-tach usually seen in patients with prolonged QT intervals
Torsades de Pointes
"twisting of the points" form of V-tach
Torsades de Pointes
four causes of prolonged QT interval
congenital origin
electrolyte disturbances
acute myocardial infarction
pharmocological agents
What are some specific electolyte imbalances that may cause a prolonged QT interval?
hypocalcemia
hypomagnesemia
hypokalemia
What are six pharmocological agents that may cause a prolonged QT interval?
antiarrhythmics
tricyclic antidepressants
phenothiazines
antifungals
antihistamine/antibiotic combos
erythromycin and quinolones
What specific electrical event generally results in a prolonged QT interval?
prolonged ventricular repolarization
(lengthened T wave)
Name a rhythm that may result from a PVC falling on an elongated T wave in a rhythm with prolonged QT intervals.
Torsades de Pointes
True or False:
In the clinical setting, Torsades de Pointes is indistinguishable from standard V-Tach and is treated in exactly the same way.
False.
It is important to distinguish Torsades de Points from standard VT, because they are treated very differently.
True or False:
The prognosis for ventricular arrhythmias is far more ominous than it would be for supraventricular arrhythmias.
True.
Therefore, it is important to be able to distinguish the difference.
In most cases, what is the key difference between supraventricular and ventricular arrhythmias?
the QRS width

narrow QRS = supraventricular
wide QRS = ventricular
What is the one circumstance that may cause a supraventricular rhythm to look like ventricular rhythm?
when a supraventricular beat is conducted aberrantly through the ventricles
True or False:
An aberrantly conducted supraventricular beat may be indistinguishable from a ventricular beat.
True.
What type of beat often precipitates an aberrantly conducted supraventricular beat?
atrial premature beats
What ventricular conduction situation may by present in cases of premature atrial contractions that occur very early?
The right bundle branch has a tendency to sluggishly repolarize at the Purkinje fibers, so a very early PAC may find half of the ventricular conduction system refractory and unable to depolarize, causing the beat to be aberrantly conducted through the ventricles
Name the two possible causes of a wide QRS complex.
(1) ventricular beat
(2) supraventricular beat conducted aberrantly
How can you tell a single aberrantly conducted atrial beat from a ventricular beat?
Only in the case of the atrial beat will a P-wave precede the wide QRS complex, possibly buried within a preceding T wave.
What two clinical clues may help tell a sustained aberrantly conducted supraventricular rhythm from a sustained ventricular rhythm?
CAROTID MASSAGE
Carotid massage may terminate PSVT but not VT

P-WAVES/CANNON A-WAVES
More that 75% of VT are accompanied by AV dissociation. Although the QRS complexes usually hide the underlying P-waves, Cannon A Waves may be detectible in VT (whereas they would not be present in PSVT)
What three electrocardiographic clues may help tell a sustained aberrantly conducted supraventricular rhythm from a sustained ventricular rhythm?
P-WAVES
AV dissociation P-waves can sometimes be seen on EKG in cases of VT, whereas PSVT will typically show retrograde P-waves, if any. On very rare occasions, VT may also produce retrograde P-waves, but this is not normally the case.

FUSION BEATS
Fusion beats (or capture beats) may be seen in VT only, as they result from a normally conducted supraventricular impulse that was allowed to slip through the AV juntion to collide with a simultaneous ventricular beat.

INITIAL QRS DEFLECTION
In aberrant PSVT, the initial QRS deflection is typically in the same direction of the normal QRS; in VT, the initial deflection is often in the opposite direction.
True or False:
On EKG, it may be impossible to tell the difference between VT and an aberrantly conducted PSVT.
True.
The distinction can be difficult or impossible to make.
The Ashman phenomenon is commonly seen in patients with what arrhythmia?
atrial fibrillation
Condition characterized by a wide, aberrantly conducted supraventricular beat occurring after a QRS complex that is preceded by a long pause
the Ashman phenomenon
Describe what causes the Ashman phenomenon.
refractory bundle branches due to a lengthy pause after the preceding beat

(bundle branches tend to repolarize much more slowly following a delayed beat)
Why is the Ashman phenomenon common during A-fib?
The irregularly timed ventricular responses typical of A-fib sets the stage for:

(1) short beats followed by long beats

(2) delayed repolarization of the bundle branches following the short/long beat sequence

(3) premature beats aberrantly conducted during the relative refractory period of the bundle branches
True or False:
A narrow QRS complex virtually always implies a supraventricular rhythm.
True.
Invasive procedure in which the exact source of an arrhythmia can be mapped to determine the most appropriate therapy.
Programmed Electrical Stimulation

(aka: Electrophysiologic Studies or "EPS")
surgical procedure that intentionally damages a reentrant pathway to cure an arrhythmia
catheder ablation
small device implanted under the skin below the shoulder that monitors and corrects dangerous arrhythmias with a shock to the right ventricle through an implanted electrode
implantable cardioverter-defibrillator
small portable devices that require minimal training and are capable of detecting and correcting ventricular fibrillation in collapsed individuals
automatic external defibrillators (AED)
An aberrant-looking beat that occurs at the regular R-R interval may be a ______.
fusion beat

(capture beat)