Rhythms Flashcards
What are the general concepts to keep in mind when approaching an arrhythmia?
Is the rhythm fast or slow?
Is the rhythm regular or irregular? If it is irregular, is it regularly irregular or irregularly irregular?
What are the P wave concepts to keep in mind when approaching an arrhythmia?
Do you see any P wave?
Are all of the P waves the same?
Does each QRS complex have a P wave?
Is the PR interval constant?
What are the QRS complex concepts to keep in mind when approaching an arrhythmia?
Are the P waves and QRS complexes associated with one another?
Are the QRS complexes narrow or wide?
Are the QRS complexes grouped or not grouped?
Are there any dropped beats?
Tachycardia Rhythm
> 100 BPM
Bradycardia Rhythm
< 60 BPM
What are the 3 instances of irregularly irregular rhythms?
Atrial fib
Wandering atrail pacemaker
multifocal atrail tachycardia
What does the presence of a P wave tell you?
The rhythm in question has so atrial or supraventricular component
What do we consider if the P waves are not all the same?
There is another pacemaker cell firing OR there is some other component of the complex superimposed on the P wave, such as a T wave occurring at the same time as the P wave.
What does the presence of 3 or more different P wave morphologies with different PR intervals define?
Either a wandering atrial pacemaker or multifocal atrial tachycardia
If you have an abnormal number of P waves in comparisson to QRS complexes, what are you dealing with?
Some sort of AV nodal block
What do wide QRS complexes indicate?
The impulses did not follow the normal electrical conduction system, and instead were transmitted by direct cell-cell contact at some point in their travels through the heart
When do we find wide QRS complexes?
Ventricular premature contractions (VPCs)
Aberrantly conducted beats
Ventricular tachycardia
Bundle branch blocks
Trigeminy
A repeating pattern of two normal complexes followed by a premature complex
When do dropped beats occur?
AV nodal blocks
Sinus arrest
Normal Sinus Rhythym
Rate 60-100 bpm Regularity Regular P wave Present P:QRS ratio 1:1 PR interval Normal QRS width Normal Grouping None Dropped Beats None
Sinus Arrhythmia
Rate 60-100 bpm Regularity Varies with respiration P wave Normal P:QRS ratio 1:1 PR interval Normal QRS width Normal Grouping None Dropped Beats None
Why does a sinus arrhythmia occur?
Normal respiratory variation becoming slower during exhalation and faster upon inhalation (inhalation increases venous return by lowering intrathoracic pressure)
Sinus Bradycardia
Rate less than 60 Regularity Regular P wave Present P:QRS ratio 1:1 PR interval Normal; slightly prolonged QRS width Normal; slightly prolonged Grouping None Dropped Beats None
Sinus Tachycardia
Rate greater than 100 bpm Regularity Regular P wave Present P:QRS ratio 1:1 PR interval Normal; slightly shortened QRS width Normal; slightly shortened Grouping None Dropped Beats None
Sinus Pause/Arrest
Rate Varies Regularity irregular P wave Present except in areas of pause or arrest P:QRS ratio 1:1 PR interval Normal QRS width Normal Grouping None Dropped Beats Yes
What is a sinus pause?
A variable time period during which there is no sinus pacemaker working
What is a sinus arrest?
A longer pause, though there is no clear cut criterion for how long a pause has to last before it is called an arrest
Sinoatrial Block
Rate varies Regularity irregular P wave Present, except in areas with dropped beats P:QRS ratio 1:1 PR interval Normal QRS width Normal Grouping None Dropped Beats Yes
What is a sinoatrial block?
occurs in some multiple of the P-P interval, after the dropped beat, the cycle continues on time as scheduled. The pathology involved is a non-conducted best from the normal pacemaker.
Atrial Premature Contraction
Rate Depends on the underlying sinus rate
Regularity irregular
P wave Present; in the APC, may be a different shape
P:QRS ratio 1:1
PR interval varies in the APC otherwise normal
QRS width Normal
Grouping Sometimes
Dropped Beats None
What is an APC
Occurs when some other pacemaker cell in the atria fires at a faster rate than that of the SA node. The result is a complex that comes sooner than expected. The premature beat “resets” the SA node, and the pause after the APC is not compensated; the underlying rhythm is distributed and does not proceed at the same pace. This non-compensatory pause is less than twice the underlying normal P-P interval
Ectopic Atrial Tachycardia
Rate 100-180 bpm
Regularity Regular
P wave Morphology of ectopic focus is different
P:QRS ratio 1:1
PR interval Ectopic focus has a different interval
QRS width Normal, but can be aberrant at times
Grouping None
Dropped Beats None
What is an ectopic atrial tachycardia?
Occurs when an ectopic atrial focus fires more quickly than the underlying sinus rate. The P waves and the PR intervals are different because the rhythm is caused by an ectopic atrial pacemaker (a pacemaker outside of the normal SA node). The episodes are usually not sustained for an extended period. Because of the accelerated rate, some ST- and T-wave abnormalites may be present transiently
Wandering Atrial Pacemaker (WAP)
Rate 100 bpm Regularity irregularly irregular P wave At least 3 different morphologies P:QRS ratio 1:1 PR interval Variable depending on focus QRS width Normal Grouping None Dropped Beats None
What is a wandering atrial pacemaker?
Created by multiple atrial pacemakers each firing at its own pace The result is an ECG with at least three different P wave morphologies with their own intrinsic PR intervals. Think of each pacer firing from a different distance with a different P wave axis. The longer the distance, the longer the PR interval. The varying P wave axis causes differences in the morphology of the P waves.
Multifocal Atrial Tachycardia (MAT)
Rate greater than 100 bpm Regularity irregularly irregular P wave At least 3 different morphologies P:QRS ratio 1:1 PR interval Variable QRS width Normal Grouping None Dropped Beats None
What is MAT?
Multifocal atrial tachycardia is merely tachycardic WAP. Both MAT and WAP are commonly found in patients with severe lung disease. The tachycardia can cause cardiovascular instability at times and should be treated. Treatment is difficult, and should be aimed at correcting the underlying problem.
Atrial Flutter
Rate Atrial rate commonly: 250-350 BPM; Ventricular rate commonly 125-175 BPM Regularity Regular, but may be variable P wave Saw toothed appearance, "F waves" P:QRS ratio Variable, most commonly 2:1 PR interval Variable QRS width Normal Grouping None Dropped Beats None
What is atrial flutter?
The P waves appear in a saw toothed pattern, the QRS rate is usually regular and the complexes appear at some multiple of the P-P interval. The usual QRS is 2:1 (meaning 2 Ps for each Q). The ratios vary depending on the rhythm.
Rarely will you have a truly variable ventricular response that does not fall on any multiple of P-P interval.
Some of the P waves are blocked and do not cause a ventricular response. The ventricular response can also occur slower at rates of 3:1 or 4:1, or higher. Sometimes the ventricular response will be irregular.
When you see a ventricular rate of 150 BPM, look for buried P waves of an atrial flutter with 2:1 block
Remember this
Atrial Fibrillation
Rate Variable, ventricular response can be slow or fast Regularity Irregularly irregular P wave None; chaotic atrial activity P:QRS ratio None PR interval None QRS width Normal Grouping None Dropped Beats None
What is Atrial Fib?
Atrial fib is the chaotic firing of numerous pacemaker cells in the atria in a totally haphazard fashion. The result is that there are no discernible P waves, and the QRS complexes are innervated haphazardly in an irregular pattern. The ventricular rate is completely guided by occasional activation from one of the pacemaking sources. Because the ventricles are not paced by any one site, the intervals are completely random.
Junctional Premature Contraction
Rate Depends on underlying rhythm
Regularity irregular
P wave Variable (none, antegrade, or retrograde)
P:QRS ratio None or 1:1 if antegrade or retro grade
PR interval None, short, or retrograde; if present does not represent atrial stimulation of the ventricles
QRS width Normal
Grouping None, but can occur
Dropped Beats None
What is JCP
A beat that originates prematurely in the AV node. Because it travels down the normal electrical conduction system of the ventricles, the QRS complex is identical to the underlying QRS. JCPs usually appear sporadically, but can occur in a regular, grouped pattern such as supraventricular bigeminy or trigeminy. There may be an antegrade or retrograde P wave associated with the complex. Antegrade is one that appears before the QRS complex. The PR intervals are very short in these cases and P-wave access will be abnormal (inverted leads II, III, aVF.
Junctional Escape Beat
Rate Depends on underlying rhythm
Regularity Irregular
P wave Variable (none, antegrade, or retrograde)
P:QRS ratio none; 1:1 if antegrade or retrograde
PR interval None, short, or retrograde; if present, does not represent atrial stimulation of the ventricles
QRS width Normal
Grouping None
Dropped Beats Yes
What is a junctional escape beat?
Occurs when the normal pacemaker fails to fire and the next available pacemaker in the conductive system fires in its place. The AV node sense the normal pacemaker did not fire. So when its turn comes up and it reaches its threshold potential, it fires. The distance of the escape beat from the preceding complex is always longer than the normal P-P interval.
Junctional Rhythym
Rate 40-60 bpm
Regularity Regular
P wave Variable (none, antegrade, or retrograde)
P:QRS ratio None, or 1:1 if antegrade or retrograde
PR interval None, short or retro grade; if present, does not represent atrial stimulation of the ventricles
QRS width Normal
Grouping None
Dropped Beats None
What is a junctional rhythm?
Arises as an escape rhythm when the normal pacemaking function of the atria and SA node is absent. It can also occur in the case of AV dissociation of 3rd degree AV block.
Accelerated Junctional Rhythm
Rate 60-100 bpm
Regularity Regular
P wave Variable (none, antegrade, or retrograde)
P:QRS ratio None, or 1:1 if antegrade or retrograde
PR interval None, short or retro grade; if present, does not represent atrial stimulation of the ventricles
QRS width Normal
Grouping None
Dropped Beats None
What is accelerated junctional rhythm?
Originates in a junctional pacemaker that, because it is firing faster than the normal pacemaker, takes over the pacing function. It is faster than expected for a normal junctional rhythm, pacing at a range of 60-100 BPM. If it exceeds 100, it is known as a junctional tachycardia. As with other junctional pacemakers, the P waves can be absent or condicted in an antegrade or retrograde fashion.
Ventricular Premature Contraction
Rate Depends on underlying rhythm Regularity Irregular P wave Not present on the VPC P:QRS ratio No P waves on the VPC PR interval None QRS width Wide (.12 sec), bizarre appearance Grouping Usually not present Dropped Beats None
What is a VPC?
Caused by a premature firing of a ventricular cell. The ventricular pace maker fires before the normal SA node or supraventricular pacer, which causes the ventricles to be in a refractory state (not yet repolarized and unavailable to fire again) when the normal pacemaker fires, Hence, ventricles do not contract at their normal time. However, underlying pacing schedule is not altered, so the beat following the VPC will arrive on time. This is called a compensatory pulse.
Ventricular escape beat
Rate depends on underlying rhythm Regularity Irregular P wave None in the VPC P:QRS ratio None in the VPC PR interval None QRS width Wide (0.12 sec), bizzare appearance Grouping None Dropped Beats None
What is a ventricular escape beat?
Similar to a junctional escape beat, but the focus is in the ventricles. The pause in non-compensatory in this case because the normal pacemaker did not fire. (This is what led to the ventricular escape beat) The pacer then resets itself on a new timing cycle, and may even have a different rate
Idioventricular Rhythym
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