EKG book...arrhythmias Flashcards
Any disturbance in the rate, regularity, site of origin or conduction of the cardiac electrical impulse
Arrhythmia
HR as low as 35-40 bomb are common and quite normal in…
Well trained athletes
- Palpitations
- Light headedness/syncope
- Sudden death
Clinical manifestations of arrhythmias
HIS DEBS mnemonic…arrhythmogenic factors that should be considered in patients w arrhythmias
Hypoxia
Ischemia/irritability
Sympathetic stimulation
Drugs
Electrolyte disturbances
Bradycardia
Stretch
In order to ID arrhythmias correctly, what must be examined?
Rhythm strip
Reentry loops represent a disorder of….
Impulse transmission
With junctional escape, depolarization originates near the AV node, and the usual pattern of atrial depolarization does not occur. As a result, a normal what is not seen?
P wave
What does an EKG of sinus arrest or sinus block look like?
Normal sinus rhythm followed by flat line
What does an EKG of junctional escape look like?
Normal sinus rhythm, followed by a longer than normal pause, then QRS complexes (further apart) with no p wave before
Ectopic rhythms and reetrant rhythms are the 2 major causes of
Nonsinus arrhythmias
These can be limited within a single anatomic site (i.e. the AV node), can occur through an entire chamber or they can even involve both an atrium and ventricle
Reentrant loops
- Are normal P waves present?
- Are the QRS complexes narrow (0.12 seconds)
- What is the relationship between the P waves and the QRS complexes
- Is the rhythm regular or irregular?
The 4 questions you must ask when looking at an arrhythmia EKG
If there are normal appearing P-waves with a normal axis, then the origin of the arrhythmia is most likely within the…
Atria
a normal P wave axis is a pretty good indication the rhythm originates above the AV node
A QRS complex of less than 0.12 seconds in duration…
Narrow
A QRS complex of greater than 0.12 seconds in duration…
Wide
A narrow QRS complex implies that ventricular depolarization is proceeding along which pathway?
The usual pathway! (AV node to Bundle of His to bundle branches to Purkinje cells)
*this is the most efficient means of conduction, which is why the QRS complex appears narrow
A narrow QRS complex indicates that the origin of the rhythm must be at or above the…
AV node
A wide QRS complex usually implies that the origin of depolarization is within…
The ventricles
What does the QRS complex look like when depolarization is initiated within the ventricular myocardium, not the conduction system
Wide QRS
If the P wave and QRS complexes correlate in a 1:1 fashion, with a single P wave preceding each QRS complex, then the rhythm almost certainly has a ______ origin
Sinus or other atrial
Single ectopic supra ventricular beats that originate in atria
Atrial premature beats
Single ectopic supra ventricular beats that originate in the vicinity of the AV node
Junctional premature beats
If the P wave contour of the premature beat differs from that of the normal sinus beat…
Atrial premature beat
If there is no P wave preceding the premature QRS complex..
Junctional premature beat
What is the difference between a junctional premature beat and a junctional escape beat?
Junctional premature occurs EARLY, prematurely interposing itself into the normal sinus rhythm
An escape beat occurs LATE, following a pause when the sinus node has failed to fire
A premature junctional beat has no..
P wave preceding the QRS complex
The QRS complex in both atrial and junctional premature beats..
Normal! …conduction occurs normally to the ventricles
Common arrhythmia with abrupt onset, initiated by a premature supra ventricular beat, with a quick termination. Rate is usually between 150-220 bpm
Paroxysmal supraventricular tachycardia (PSVT)
Regular, narrow QRS tachycardia
P waves usually not seen
Paroxysmal supraventricular tachycardia (PSVT)
Most common cause of Paroxysmal supra ventricular tachycardia (PSVT)
AV nodal reentry
What can be done to help diagnose and terminate an episode of paroxysmal supra ventricular tachycardia (PSVT)
Carotid massage
vagal stimulation slows conduction through AV node
Can interrupt the reentrant circuit and thereby terminate the PSVT arrhythmia OR can at least..
Slow the PSVT arrhythmia so that the presence or absence of P waves can be more easily determined and the arrhythmia diagnosed
Carotid Massage
The carotid sinus contins baroreceptors that influence vagal input to the heart, primarily affecting the…
SA and AV nodes
What must you check for before performing a carotid massage?
Carotid bruit
With the pt lying flat, extend the neck and rotate the head away from you. Palpate the carotid artery at the angle of the jaw and apply pressure for….
10-15 seconds
Which side should you try first when doing a carotid massage because the rate of success is higher
Right!
Regular and rapid arrhythmia
P waves appear at a rate of 250-350 bpm
Usually generated by a reentrant circuit that runs largely around the annulus of the TRICUSPID valve
Atrial flutter
Atrial depolarization occurs at such a rapid rate that discrete P waves separated by a flat baseline are not seen. Instead, the baseline continually rises and falls
Atrial flutter
In some leads, especially leads II and III, may see a “saw toothed pattern”
Atrial flutter
The AV node cannot handle all of the atrial impulses in atrial flutter, so not all of the atrial impulses pass through the AV node to generate QRS complexes..some just bump into a refractory node. This is known as…
AV block
Which type of AV block is most common?
2:1
For every 2 visible flutter waves, one passes through the AV node to generate a QRS complex and one does not
2:1 AV block
What can increase the degree of a block (i.e. changing a 2:1 block to a 4:1 block), making it easier to identify the saw toothed pattern
Carotid massage
Will carotid massage stop atrial flutter?
No! Because atrial flutter originates above the AV node
Will the saw tooth pattern be negative or positive if the reentrant circuit of atrial flutter is rotating COUNTERCLOCKWISE
Negative
Will the saw tooth patter be negative or positive if the reentrant circuit of atrial flutter is CLOCKWISE around the tricuspid valve
Positive
- at least 2 conduction pathways
2. variable block in one of the pathways
Criteria for reentry
Although atrial flutter is rarely life threatening, the rapid ventricular response may cause…
SOB
Angina
Precipitate or worsen CHF
In those that are hemodynamically stable, what is the first method of choice to return patients from atrial flutter back to normal sinus rhythm
Pharmacologic cardioversion
During this type of arrhythmia, the AV node may be bombarded with more than 500 impulses per minute!!
Atrial Fibrillation
Multiple reentrant circuits whirl around in unpredictable fashion. No true P wave seen
*baseline appears flat or undulates slightly
Atrial Fibrillation
The AV node, faced with a blitz of atrial impulses, allows only occasional impulses to pass through at variable intervals, generating an IRREGULARLY IRREGULAR VENTRICULAR RATE usually between 120-180 bpm
Atrial fibrillation
The irregularly irregular appearance of QRS complexes in the absence of discrete P waves is the key** to identifying…
Atrial fibrillation
Irregularly irregular supra ventricular (narrow QRS) rhythm
Atrial fibrillation
Multiple re-entrant circuits in the atria..chaotic atrial activity generates 400-600 atrial depolarizations per minute, most of which are blocked because AV node in refractory period
Atrial fibrillation
Ventricular rate is usually 120-180 bp
No reproducible P waves; undulating baseline
*initial goal=slow rate with meds!!!
Atrial fibrillation
Patients with atrial fibrillation are at risk of…
Clot/stroke
lots of stagnant blood
Most common sustained arrhythmia in the general popular
A fib
- Slow down HR
- fully anticoagulate
Tx for…
A fib
Palpitations, chest pain, SOB, dizziness may occur in..
A fib
How do you determine ratio in atrial flutter?
Count downward deflections!
Which lead will have positive/upward flutter waves?
V1
When a reentry loops causes regular, narrow QRS with VERY fast rate!!! No P waves
PSVT
Very abrupt start, very abrupt termination. Can tell to the second the beginning and end of.
PSVT
Reentrant supraventricular tachycardia with regular fast QRS complexes, 150-220 bpm
PSVT
Escape rhythm as a result of sinus slowing or sinus arrest. May occur normally in sleep due to increased vagal tone.
Narrow QRS
P waves usually not seen
Typical rate is 40-60 bpm.
Junctional escape rhythm
minimally symptomatic
DOC for PSVT?
Adenosine
If the QRS is wide, where did the arrhythmia originate?
Ventricles
An early beat with a wide QRS complex..
Premature ventricular contraction (PVC)
Every third beat is a PVC
Ventricular trigeminy
2 PVCs back to back
Ventricular couplet
3 PVCs in a row and a rate GREATER than 100
Ventricular tachycardia
“Twisting of the points” or “Fringe of pointed/twisting tips”
Polymorphic VT, very fast and dangerous.
Associated with prolongation of QT interval.
Difficult to treat and often deteriorates into ventricular fibrillation (VF).
Torsade de Points
Fairly common (1/200 incidence) during invasive cardiac procedures including coronary angiography.
Ventricular fibrillation
