4 Atrial and Ventricular Dysrhythmias Flashcards
(126 cards)
1
Q
Sinus rhythms originate from…
A
The sinoatrial (SA) node
2
Q
During normal heart activity, the _____ acts as the primary pacemaker
A
SA node
3
Q
NSR is ____ dependent
A
Age
4
Q
NSR for newborns
A
110-150 bpm
5
Q
NSR for 2 year olds
A
85-125 bpm
6
Q
NSR for 4 year olds
A
75-115 bpm
7
Q
NSR for 6+ year olds
A
60-100 bpm
8
Q
Describe sinus bradycardia
A
HR < 60bpm
Rhythm is regular
P waves normal and homogenous
QRS complexes are normal and homogenous
PR intervals are normal
9
Q
Examples of causes of sinus bradycardia
A
Cardiac diseases
Use of certain drugs (ie Digoxin, beta blockers, CCBs, Li, Amiodarone, propafenone, quinidine)
Excessive vagal tone or decreased sympathetic stimulation
Noncardiac disorders
10
Q
_____ can result if the heart rate slows to the point where cardiac output drops significantly
A
Hypotension
11
Q
Patients are less tolerant to bradycardia if HR < _____
A
45bpm
12
Q
Describe Sinus Tachycardia
A
Rate is between 100 and 160 bpm
Rhythm is regular
P waves normal and all look alike (one precedes each QRS)
QRS complexes are normal and all look alike
PR intervals are normal
13
Q
Examples of causes of Sinus Tachycardia
A
Cardiac Diseases (CHF, cardiogenic shock, pericarditis)
Use of certain drugs (sympathomimetics, dopamine, dobutamine, vagolytic drugs like atropine, caffeine, nicotine, amphetamines)
Increased sympathetic stimulation
14
Q
Sinus tachycardia can increase….
A
Myocardial oxygen consumption —> aggravation of ischemia (bringing on CP) and infarction, particularly in those with CVD
15
Q
Sinus Dysrhythmia is also known as…
A
Sinus arrhythmia
16
Q
Sinus dysrhythmia is the same as NSR except…
A
There is a patterned irregularity
Cycle of slowing, then speeding up, then slowing again
17
Q
What does respiration have to do with sinus dysrhythmia?
A
The beat-to-beat variation produced by irregular firing of the SA node usually corresponds with the respiratory cycle and changes in intrathoracic pressure
HR increases during inspiration and decreases during expiration
18
Q
Sinus dysrhythmia can occur naturally in…
A
Athletes
Children
Older adults
19
Q
Pathological conditions —> sinus dysrhythmia
A
Patients with heart disease or inferior wall MI
Individuals receiving certain drugs (digitalis and morphine)
Conditions in which there is increased intracranial pressure
20
Q
Sinus dysrhythmia is usually of no clinical significance and produces no symptoms, but in some patients…
A
It may be associated with palpitations, dizziness, and syncope
21
Q
Sinus pause/arrest occurs when…
A
The SA node transiently stops firing —> short periods of cardiac standstill until a lower-level pacemaker discharges or the SA node resumes its normal function
22
Q
Sinus pause is when _____ beats are dropped, where as Sinus arrest is ______ beats dropped
A
1-2
3+
23
Q
Most prominent characteristic of sinus pause/arrest on ECG
A
A flatline
Pause —> irregularity
Rhythm typically resumes its normal appearance after pause, unless an escape pacemaker resumes the rhythm
24
Q
Describe sinus arrest
A
Rate typically between 60-100 bpm
Rhythm irregular
P waves are normal but are absent where there is a pause in rhythm
QRS complexes are normal and all look alike but are absent where there is a pause in rhythm
PR intervals are normal but absent where there is a pause in rhythm
25
Causes of sinus arrest
SA disease (fibrosis, degeneration)
Cardiac disorders (chronic CAD, MI, acute myocarditis, CM)
Use of certain drugs (digoxin, Procainamide, quinidine, salicylates, excessive doses of beta blockers or CCBs)
Increased vagal tone (valsalva, carotid sinus massage, vomiting)
Hyperkalemia
Hypoxia
26
What are some other names for Sinus Node Dysfunction?
Sick Sinus Syndrome
Brady-tachy syndrome
27
Sick Sinus Syndrome is primarily a disease of the ______ due to ________
Elderly
Degenerative disease of the SA node
(But it can occur in younger people too)
28
Sick Sinus Syndrome is characterized by ...
Periods of bradycardia, tachycardia, prolonged pauses or alternating bradycardia and tachycardia
29
Treatment for Sick Sinus Syndrome
May require a pacemaker for the slow rhythms and medication for the fast rhythms
30
Atrial dysrhythmias originate in ...
The atrial tissue or in the internodal pathways
Believed to be caused by three mechanisms:
Automaticity
Triggered activity
Recently
31
Atrial dysrhythmias can affect _______ and ____________, leading to ________
Ventricular filling time
Diminish the strength of the atrial contraction
Decreased CO and ultimately decreased tissue perfusion
32
Key characteristics of Atrial dysrhythmias
P waves that differ in appearance from normal sinus P waves (P’ waves)
Abnormal, shortened, or prolonged PR intervals
QRS complexes that appear narrow and normal
33
What is wandering atrial pacemaker?
Pacemaker site shifts between the SA node, atria, and/or AV junction
34
Most characteristic feature of Wandering Atrial Pacemaker
P waves that change in appearance (3 or more)
35
Describe Wandering atrial pacemaker
Rate normal (60-100bpm)
Slightly irregular rhythm
P waves differ continually****
QRS complexes normal/consistent
PR intervals vary (can be normal, short, long)
QT interval WNL
36
Wandering atrial pacemaker is generally caused by ...
The inhibitory vagal effect of respiration on the SA node and AV junction
37
Wandering atrial pacemaker can be a normal finding in...
Children
Older adults
Well-conditioned athletes
No usually of any clinical significance, but may be related to some types of organic heart disease, esp DIGITALIS
38
Early ectopic beats that originate outside the SA node
Premature Atrial Complexes (PACs)
Produce an irregularity in the rhythm
39
Describe Premature Atrial Complexes
Have P waves that are upright (in lead II), preceding each QRS complex but have a different morphology than the normal P waves of the underlying rhythm
Followed by a non-compensatory pause
40
What is a non-compensatory pause?
A pause where there are less than two full R-R intervals between the R wave of the normal beat which precedes the PAC and the R wave of the first normal beat which follows it
The PAC inhibits and “resets” the SA node
41
Characteristics of PACs
Rate depends on underlying rhythm
Irregular rhythm due to the early beat
P waves may be upright or inverted, will appear different than those of the underlying rhythm
Normal QRS
PR interval varies
QT WNL or possibly shortened
42
Possible causes of PACs
Cardiac disease (Coronary or valvular heart disease, pulmonary disease)
Use of certain drugs (DIGITALIS****)
Acute resp failure, hypoxia, electrolyte imbalances, fever, alcohol, cigarettes, anxiety, fatigue, ID
43
If someone has taken too much digitalis, expect...
Premature Atrial Complexes (PACs)
44
When are PACs considered significant?
Isolated PACs in patients with healthy hearts
45
PACs may predispose a patient with heart disease to more serious dysrhythmias such as...
Atrial tachycardia
Atrial flutter
Atrial fibrillation
46
PACs can serve as an early indicator of ________ or _________ in patients experiencing an acute MI
Electrolyte Imbalance
CHF
47
What are the three categories of PACs?
Bigeminal (Normal, PAC, Normal, PAC, Normal, PAC)
Trigeminal (Normal, Normal, PAC, Normal, Normal, PAC)
Quadrigeminal (Normal, Normal, Normal, PAC)
48
PACs may have wide QRS complexes when seen with...
Abnormal ventricular conduction
They can therefore be easily confused with PVCs (PACs with aberrant ventricular conduction)
49
What helps distinguish PACs from PVCs?
PACs usually do not have a compensatory pause
50
What is Atrial Tachycardia?
Rapid dysrhythmia (rate of 150-250bpm) that arises from the atria
Rate is so fast it overrides the SA node
51
Characteristics of atrial tachycardia
Rate 150-250bpm
Regular rhythm unless the onset is witnessed
P waves may be upright or inverted, but will appear different than those of the underlying rhythm (can also be hidden in preceding T wave)
QRS normal
PR intervals can be normal, shorter than normal or immeasurable if the P waves are hidden
QT WNL
52
Possible causes of atrial tachycardia
Sinus node disease (ie Sick Sinus)
Cardiac disorders (MI, CM, congenital anomalies, Wolff-Parkinson-White syndrome, valvular heart disease, systemic HTN, cor pulmonale)
Use of certain drugs (digitalis*****)
Hyperthyroidism
53
What is the most common cause of atrial tachycardia?
DIGITALIS TOXICITY
54
Atrial tachycardia may occur in ______ or may be ________
Short bursts (Paroxysmal atrial tachycardia) or may be sustained
Short bursts are well tolerated in otherwise normally healthy people
55
What can occur with sustained atrial tachycardia?
Ventricular filling may not be complete during diastole —> compromised CO in patients with underlying heart disease
May increase myocardial ischemia —> MI
56
Pathological condition that presents with changing P wave morphology and heart rates of 120-150 bpm
Multifocal Atrial Tachycardia (MAT)
The rhythm is irregular due to the multiple Fock
57
Multifocal Atrial Tachycardia has the same features as _________ but faster rate
Wandering atrial pacemaker
May be confused with atrial fibrillation as well
58
Supraventricular Tachycardia (SVT) arises from...
Above the ventricles but cannot be definitely identified as atrial or junctional tachycardia because the P waves cannot be seen sufficiently
Includes Paroxysmal SVT, Nonparoxysmal atrial tachycardia, and multifocal atrial tachycardia
59
Rapid depolarization re-entry circuit in the atria with a rate of 250-350bpm
Atrial Flutter
60
What dysrhythmia produces p waves that have a characteristic saw-tooth appearance?
Atrial flutter (“F waves”)
61
Characteristics of Atrial Flutter
Ventricular rate may be slow, normal, or fast but atrial rate is between 250-350bpm
Regularity - may be reg or irregular
P waves - absent, instead there are F waves
QRS normal
PR immeasurable
QT immeasurable
62
Possible causes of atrial flutter
Conditions that enlarge atrial tissue and elevate atrial pressures
COPD, hypoxia, digitalis, hyperthyroidism, infection, catecholamines
May occur in healthy people who use coffee, alcohol, or cigarettes or who are fatigued/under stress
63
Chaotic, asynchronous firing of multiple areas within the atria (>350bpm)
Atrial fibrillation
64
Characteristics of atrial fibrillation
Totally irregular rhythm with no discernible p waves - instead there is a chaotic baseline of fibrillatory f waves representing atrial activity
65
Atrial fibrillation leads to loss of ....
Atrial kick —> decreased CO by up to 25%
Patients may develop intra-atrial emboli as the atria are not contracting and blood stagnates in the atrial chambers forming a thrombus
66
Why are patients with a fib more predisposed to stroke?
Patients can develop intra-atrial emboli as the atria are not contracting and blood stagnates in the atrial chambers —> thrombus
67
Where do junctional dysrhythmias originate?
In the AV junction (area around AV node and bundle of His)
68
Key characteristics of junctional dysrhythmias
P waves may be inverted with a short PR interval, they may be absent (buried in QRS complex) or they may follow QRS complexes
QRS complexes are usually normal (unless there is an intraventricular conduction defect, aberrancy, or pre-excitation)
69
Single early electrical impulse that arises from the AV junction
Premature Junctional Complex (PJC)
70
Characteristics of Premature Junctional Complexes
Rate depends on underlying rhythm
Irregular rhythm due to early beat
P waves will be INVERTED - may precede, be buried in, or follow the QRS complex
QRS complex is normal
PR interval short
QT WNL
PJCs are followed by a non-compensatory pause
71
Possible causes of PJCs
Cardiac disorders (Ischemia, acute MI, damage to AV junction, CHF, valvular disease, rheumatic heart disease, swelling of AV junction after surgery)
Certain drugs (digitalis, cardiac meds, sympathomimetic drugs)
Excessive caffeine, tobacco, or alcohol, increased vagal tone, hypoxia, electrolyte imbalance (particularly Mg and K), exercise
72
What is junctional escape rhythm?
Arises from AV junction at a rate of 40-60 bpm
Regular rhythm
P waves are inverted and may be before, during, or after QRS
QRS normal
If present, PR intervals shorter than normal
QT normal
73
Possible causes of junctional escape rhythm
Increased vagal tone, sick sinus syndrome, inferior wall MI, rheumatic heart disease, valvular disease
Certain drugs (digitalis, quinidine, beta blockers, CCBs)
Post cardiac surgery, hypoxia
74
Accelerated junctional rhythms arise from...
The AV junction at a rate of 60-100 bpm but with inverted P waves
75
Characteristics of accelerated junctional rhythms
60-100bpm
Regular rhythm
Inverted p waves
Normal QRS
PR intervals short if present
QT normal
76
Fast ectopic rhythm that arises from bundle of His at rate of 100-180 bpm
Junctional tachycardia
77
Characteristics of junctional tachycardia
100-180 bpm
Regular rhythm
Inverted P waves
Normal QRS
Short PR interval if present
QT WNL
78
Why are ventricular dysrhythmias potentially life threatening?
The ventricles are ultimately responsible for cardiac output
79
Ventricular dysrhythmias occur when...
The atria, AV junction, or both are unable to initiate an electrical impulse
There is enhanced automaticity of the ventricular myocardium
80
Key features of ventricular dysrhythmias
Wide (>0.12s), bizarre QRS complexes
T waves in the opposite direction of the R wave
Absence of P waves
81
What are the different types of ventricular dysrhythmias?
Premature Ventricular Complexes (PVC)
Idioventricular rhythm
Accelerated idioventricular rhythm
Ventricular Tachycardia
Ventricular fibrillation
Asystole
82
Early ectopic beats that interrupt the normal rhythm, originating from an irritable focus in the ventricular conduction system or muscle tissue
Premature Ventricular Complexes (PVCs)
83
In PCVs, _______ inhibits conduction of a normally fired SA node impulse
Retrograde impulse
84
Characteristics of PVCs
Rate depends on underlying rhythm
Irregular rhythm
P waves not related to QRS (if present at all)
Wide, bizarre QRS complexes with T waves in the opposite direction of the R wave
Absent PR intervals
Usually prolonged QT
85
What are some possible causes of PVCs
MI and ischemia, enlargement of the ventricles, CHF, myocarditis
Use of certain drugs, particularly cocaine, amphetamines, TCAs, stimulants, PCP
Hypoxia, electrolyte imbalance, metabolic acidosis
86
PVCs that look the same are called _______ and PVCs that look different from each other are called
Unifocal (uniform)
Multifocal (multiform)
87
Like PACs, PVCs can be...
Bigeminal
Trigeminal
Quadrigeminal
88
Two PVCs in a row are called...
A couplet
Indicate extremely irritable ventricles
89
PVCs that fall between two regular complexes and do not disrupt the normal cardiac cycle are called...
Interpolated PVCs
90
PVCs occurring on or near the previous T wave are called ______ and may precipitate __________
R-on-T PVCs
Ventricular tachycardia or fibrillation
91
Slow dysrhythmia (20-40bpm) with wide QRS complexes that arise from the ventricles
Idioventricular rhythm
92
Characteristics of idioventricular rhythm
20-40bpm
Regular rhythm
If present, p waves no related to QRS complex
Wide, bizarre QRS complex with T waves in the opposite direction of the R wave
Absent PR intervals
Prolonged QT
93
Idioventricular rhythm that exceeds the inherent rate of the ventricles (40-100bpm)
Accelerated idioventricular rhythm
94
Characteristics of accelerated idioventricular rhythm
40-100bpm
Regular
If present, p waves not related to QRS
Wide, bizarre QRS with T waves in the opposite direction of R wave
Absent PR interval
Prolonged QT
95
Fast dysrhythmia (100-250bpm) that arises from the ventricles
Ventricular Tachycardia
96
Ventricular Tachycardia is considered present when there are ...
3 or more PVCs in a row
A brief episode may be called a “run” or “burst” or “salvo” of v. tach
May come in bursts of 6-10 complexes or may persist (sustained VT)
97
Characteristics of Ventricular Tachycardia
100-250bpm
Regular rhythm
If present, p waves not related to QRS
Wide, bizarre QRS with T waves in the opposite direction of the R wave
Absent PR
Immeasurable QT
98
Ventricular Tachycardia can occur with or without ______
Pulses
99
_______ VT appears with each QRS complex similar in appearance
_______ VT appears with considerably variable QRS complexes
Monomorphic
Polymorphic
100
What is Torsades de Pointes (TdP)?
A unique variant of polymorphic ventricular tachycardia
May be associated with prolonged QT interval
May be drug-induced or associated with electrolyte abnormalities
101
How is Torsades de Pointes managed?
If in cardiac arrest - defibrillation
If patient not in cardiac arrest - infusion of MAGNESIUM SULFATE
Avoid bradycardia (worsens QT prolongation)
102
Ventricular fibrillation results from....
Chaotic firing of multiple sites in the ventricles —> heart muscle quivers rather than contracting efficiently —> no effective muscular contraction —> no CO
103
Patients with ventricular fibrillation will be ...
In full cardiac arrest
Unresponsive
Pulseless
104
Characteristics of ventricular fibrillation on ECG
300-500 ventricular unsynchronized impulses per minute
Totally chaotic rhythm
Absent P waves, PR interval, QT interval
QRS - wavy, chaotic line without any logic
105
Most common cause of prehospital cardiac arrest in adults
Ventricular Fibrillation
106
What happens if you don’t defibrillate a patient with ventricular fibrillation?
They fucking die
107
Absence of any cardiac activity
Asystole
Appears as a flat (or nearly flat line)
Complete cessation of CO
108
What is the prognosis for asystole?
😂😂😂😂
It’s a fucking terminal rhythm, dumbass
Chances of recovery are extremely low
Poor response to attempts at resuscitation
109
Condition that has an organized electrical rhythm on the ECG monitor but patient is pulseless and apneic
Pulseless Electrical Activity (PEA)
Usually associated with severe underlying heart disease
110
What are some reversible causes of PEA?
```
Hypovolemia
Pericardial tamponade
Tension pneumothorax
Massive acute MI
Drug overdose
```
111
Partial delays or complete interruptions in teh cardiac conduction pathway between the atria and ventricles
Heart block
Disrupts ventricular filling
112
Common causes of heart blocks
```
Ischemia
Myocardial necrosis
Degenerative disease of the conduction system
Congenital anomalies
Drugs (esp digitalis)
```
113
What is a 1st-degree AV heart block?
Not a true block, but a consistent DELAY of conduction at teh level of the AV node
114
Is a 1st degree AV heart block important?
Often of little or no clinical significance b/c all impulses are conducted to the ventricles
But can progress to higher degree block, esp in the presence of inferior wall MI
115
Characteristics of 1st degree AV heart block
Underlying rate may be slow, normal, or reg
Underlying rhythm usually regular
P waves present and normal, precede QRS
QRS complexes normal
***PR Interval >0.20 seconds and CONSTANT***
QT WNL
116
Intermittent block at the level of the AV node
2nd-Degree AV heart block Type I
Aka - “Wenckebach” or “Mobitz I”
117
Characteristics of 2nd degree AV heart block
More P waves than QRS complexes and rhythm has patterned irregularity
***PR interval progressively INCREASES until a QRS is dropped***
After dropped beat, the next PR interval is shorter
As each subsequent impulse is generated, there is a progressively longer PR interval again until another QRS is dropped
CYCLE REPEATS!
118
2nd-degree AV heart block Type I are usually ...
Transient and reversible
May occur in otherwise health persons
May progress to more serious blocks (esp if it occurs in early MI)
119
Intermittent block at the level of the bundle of His or bundle branches resulting in atrial impulses that are not conducted to the ventricles
2nd degree AV heart block Type II (“Mobitz II”)
120
Characteristics of 2nd Degree AV heart block Type II
More P waves than QRS complexes
PR interval is PROLONGED and the duration remains CONSTANT
Intermittently, a P wave occurs and is not followed by a QRS complex (conduction is block)
121
2nd-degree AV heart blocks type II more often progress to...
3rd degree (complete) heart block
122
In 2nd degree av heart block type II, what type of rhythm will you observe?
If the conduction ratio remains the same, a regular rhythm
EXCEPT - if every other P wave is conducted, it is not possible to differentiate Mobitz I from Mobitz II (this is called a 2:1 AV Block****)
123
A 2nd degree AV heart block type II is usually considered...
A serious dysrhythmia - “malignant”
Can result in decreased CO and may produce SSx of hypoperfusion
May progress to a more severe heart block or ventricular asystole
124
Complete block of conduction at or below the AV node
3rd degree AV heart block
Impulses from atria cannot reach ventricles
AKA - complete heart block
125
Characteristics of 3rd degree AV heart block
Upright and round P waves seem to “march right through the QRS complexes”
No associate between the P waves and QRS complexes
126
Clinical significance of 3rd degree av heart blocks
Well tolerated as long as the escape rhythm is fast enough to generate a sufficient cardiac output to maintain adequate perfusion
Can result in decreased CO b/c of the asynchronous action of the atria/ventricles if the ventricular rate is slow
