Module 2: Dysrthymias

Question 1

Properties of Heart Cells

Answer 1

 Automaticity
 Excitability
 Conductivity
 Contractility

Question 2

Nervous System Control of Heart

Answer 2

Autonomic nervous system controls
 Parasympathetic nervous system - vagus nerve
* Decreases firing of SA node
* Slows impulse conduction of AV node
 Sympathetic nervous system
* Increases SA node firing
* Increases impulse conduction of AV node
* Increases cardiac contractility

Question 3

Calculating HR from ECG

Answer 3

Count
 Number of QRS complexes in 1 minute
 Number of QRS complexes in 6 seconds and multiply by 10
 Number of small squares between one R-R interval, and divide this number into 1500
 Number of large squares between one R-R interval, and divide this number into 300

Question 4

ECG Monitoring

Answer 4

Graphic tracing of electrical impulses of heart
*Waveforms represent electrical activity produced by movement of charged ions across membranes of heart cells

Question 5

Telemetry Monitoring: 2 Types

Answer 5

Two types
Assessing heart rhythm off site
 Centralized monitoring system
 Advanced alarm system alerts provides different
levels of detection of dysrhythmias, ischemia, or
infarction

Question 6

Normal Sinus Rhythm

Answer 6

SA node fires 60 to100 beats/min
 Follows normal conduction pattern
 P wave is normal and precedes QRS
 QRS has normal shape and duration
 PR interval is normal

Question 7

Sinus Bradycardia

Answer 7

SA nodes fires at less than 60 beats/min
 Normal rhythm in aerobically trained athletes
and during sleep
 Can occur in response to parasympathetic nerve
stimulation and certain drugs
 Also associated with some disease states

Question 8

Sinus Brady Manifestations

Answer 8

Manifestations
 Hypotension
 Pale, cool skin
 Weakness
 Angina
 Dizziness or syncope
 Confusion or disorientation
 Shortness of breath

Question 9

Sinus Brady Treatment

Answer 9

Stop offending drugs
 IV Atropine
 Pacemaker
 Dopamine or epinephrine infusion

Question 10

Sinus Tachycardia

Answer 10

Sinus rate is 101 to 180 beats/min.
 Caused by vagal inhibition or sympathetic
stimulation
 Associated with physiologic and psychologic
stressors
 Drugs can increase rate

Question 11

Sinus Tachy Manifestations

Answer 11

Manifestations
 Dizziness
 Dyspnea
 Hypotension
 Angina in patients with CAD

Question 12

Sinus Tachy Treatment

Answer 12

Treatment
 Guided by cause (e.g., treat pain)
 Vagal maneuvers
 β-blockers, adenosine, or calcium channel blockers
 Synchronized cardioversion

Question 13

Premature Atrial Contraction

Answer 13

Contraction starting from ectopic focus in atrium
in location other than SA node
 Travels across atria by abnormal pathway,
creating distorted P wave
 May be stopped, delayed, or conducted normally
at the AV node

Question 14

Premature Atrial Contraction Causes

Answer 14

Emotional stress
 Fatigue
 Caffeine
 Tobacco
 Alcohol
 Hypoxia
 Electrolyte imbalances
 Disease states

Question 15

Premature Atrial Contractions Manifestations + Treatment

Answer 15

Manifestations
-Palpitations
-Heart “skips a beat”
 Treatment
-Monitor for more serious dysrhythmias
-Withhold sources of stimulation
-β-blockers

Question 16

Paroxysmal Supraventricular
Tachycardia

Answer 16

Reentrant phenomenon: PAC triggers a run of
repeated premature beats
 Paroxysmal refers to an abrupt onset and
ending
 May occur with overexertion, stress, deep
inspiration, stimulants, disease, digitalis toxicity

Question 17

Paroxysmal Supraventricular
Tachycardia - Manifestations

Answer 17

Manifestations
 HR is 151 to 220 beats/min
 HR greater than 180 leads to decreased cardiac
output and stroke volume
* Hypotension
* Palpitations
* Dyspnea
* Angina

Question 18

Paroxysmal Supraventricular
Tachycardia - Treatment

Answer 18

Treatment
 Vagal stimulation
 IV adenosine
 IV β-blockers
 Calcium channel blockers
 Synchronized cardioversion

Question 19

Atrial Flutter

Answer 19

Typically associated with disease
 Symptoms result from high ventricular rate and
loss of atrial “kick” associated with atrial flutter
decrease CO; can cause heart failure
 Atrial rate 200 to 350 beats/min
 Increases risk of stroke

Question 20

Atrial Flutter Treatment

Answer 20

Treatment
 Pharmacologic agent
 Electrical cardioversion
 Radiofrequency ablation

Question 21

Atrial Fibrillation

Answer 21

Paroxysmal or persistent
 Most common dysrhythmia
 Prevalence increases with age
 Usually in patients with underlying heart disease
 Can occur with other disease states

As with atrial flutter—causes a decrease in CO
and an increased risk of stroke
 Atrial rate may be as high as 350 to 600
beats/min. with chaotic, fibrillatory waves
replacing P waves

Question 22

AFib Treatment

Answer 22

Drugs to control ventricular response, prevent stroke, and/or convert to sinus rhythm (amiodarone most common)
 Electrical cardioversion
 Anticoagulation
 Radiofrequency ablation
 Maze procedure with cryoablation

Question 23

Left Atrial Appendage Occlusion
(LAA)

Answer 23

Pouch that extends off left atrium
 Common source of blood clots with atrial
fibrillation
 LAA occlusion done to prevent blood clots,
decrease risk of stroke
 Alternative treatment is oral anticoagulation

Question 24

Junctional Dysrythmias

Answer 24

Dysrhythmias that start in the AV junction
 SA node does not fire, or impulse is blocked at
the AV node
 AV node becomes pacer—retrograde
transmission of impulse to atria
 Abnormal P wave; normal QRS
 Associated with disease, certain drugs

Serves as safety mechanism—do not suppress
 If rhythms are rapid, may result in reduction of CO
 Treat if patient is symptomatic
 Atropine for escape rhythm
 Correct cause
 Drugs to reduce rate if tachycardia

Question 25

First Degree AV Block

Answer 25

Associated with increasing age, disease states,
and certain drugs
 Usually not serious
 Patients asymptomatic
 No treatment
 Monitor for changes in heart rhythm

Question 26

Second-Degree AV Block,
Type 1 (Mobitz I, Wenckebach)

Answer 26

May result from drugs or CAD
 Typically associated with ischemia
 Usually transient and well tolerated
 Treat if symptomatic
 Atropine
 Pacemaker
 If asymptomatic, observe closely

Question 27

Second-Degree AV Block,
Type 2 (Mobitz II)

Answer 27

Associated with heart disease and drug toxicity
 Often progressive and results in decreased CO
 Treat with pacemaker
 Treatment
 Transcutaneous pacing or temporary pacemaker

Question 28

Third-Degree AV Heart Block
(Complete Heart Block)

Answer 28

Associated with severe heart disease, some
systemic diseases, certain drugs
 Usually results in decreased CO, ischemia, HF,
and shock
 Can lead to syncope
 Treat with pacemaker
 Drugs to increase heart rate if needed while
awaiting pacing

Question 29

Premature Ventricular Contractions

Answer 29

Associated with stimulants, electrolyte
imbalances, hypoxia, heart disease
 Not harmful with normal heart but may reduce
CO, lead to angina and HF in diseased heart
 Assess hemodynamic status

Treatment
 Correct cause
 β-blockers, lidocaine, or amiodarone

Question 30

Accelerated Idioventricular Rhythm
(AIVR)

Answer 30

Develops when the intrinsic pacemaker rate (SA
node or AV node) becomes less than that of
ventricular ectopic pacemaker
 Rate is between 40 and 100 beats/min
 Atropine if patient symptomatic
 Temporary pacing
 Do not suppress rhythm

Question 31

Ventricular Tachycardia

Answer 31

Ectopic foci take over as pacemaker
-Normally, the heart’s rhythm is controlled by the sinus node, located in the right atrium. In VT, ectopic foci (abnormal pacemaker sites within the ventricles) take over the role of the pacemaker.
This results in rapid and often inefficient contractions of the ventricles.

Types of VTach:

Monomorphic VT: This is the most common type. “Monomorphic” means the heartbeats look similar to each other on an ECG. It occurs due to a single ectopic focus in the ventricles.

Polymorphic VT: In this type, the ECG appearance of the heartbeats varies, indicating multiple ectopic foci within the ventricles. A subtype of this is Torsades de Pointes, which is often related to prolonged QT interval on ECG and can be very dangerous.

Sustained VT: This refers to VT that lasts for more than 30 seconds. It is a medical emergency that requires immediate treatment, as it can lead to hemodynamic instability and progress to more serious conditions like ventricular fibrillation.

Nonsustained VT: This form of VT lasts for less than 30 seconds and stops on its own. While it may not be immediately life-threatening, it often requires evaluation to assess the risk of more serious arrhythmias or underlying heart disease.

 Considered life-threatening because of
decreased CO and the possibility of
development to ventricular fibrillation

Question 32

Ventricular Tachycardia
Torsades de Pointes

Answer 32

Question 33

VTach Causes

Answer 33

Associated with heart disease, long QT
syndrome, electrolyte imbalances, drug toxicity,
CNS disorders
 Can be stable (patient has a pulse) or unstable
(pulseless)
 Sustained VT causes severe decrease in CO
 Hypotension, pulmonary edema, decreased cerebral blood flow, cardiopulmonary arrest

Precipitating causes must be identified and
treated (e.g., hypoxia)
 VT with pulse (stable) treated with
antidysrhythmics or cardioversion
 Treatment for polymorphic VT with prolonged
baseline QT interval includes IV magnesium,
isoproterenol, phenytoin, or antitachycardia pacing
 Pulseless VT treated with CPR and rapid
defibrillation

Question 34

Ventricular Fibrillation

Answer 34

Associated with acute MI, ischemia, chronic disease
states, cardiac procedures
 Unresponsive, pulseless, and apneic
 If not treated rapidly, death will result
 Treat with immediate CPR and ACLS
 Rapid defibrillation
 Drug therapy (epinephrine, amiodarone)

Question 35

Asystole

Answer 35

Total absence of ventricular electrical activity
 No ventricular contraction
 Patient unresponsive, pulseless, apneic
 Must assess in more than one lead

Usually result of advanced cardiac disease, severe
conduction system problem, or end-stage HF
 Treat with immediate CPR and ACLS measures
 Epinephrine
 Intubation
 Poor prognosis

Question 36

Pulseless Electrical Activity

Answer 36

Electrical activity can be observed on the ECG,
but no mechanical activity of the heart is evident,
and the patient has no pulse
 Prognosis is poor unless underlying cause
quickly identified and treated

H’s and T’s Mnemonic
 Hypovolemia
 Hypoxia
 Hydrogen ion
(acidosis)
 Hyper-/hypokalemia
 Hypoglycemia
 Hypothermia
 Toxins
 Tamponade (cardiac)
 Thrombosis (MI and
pulmonary)
 Tension
pneumothorax
 Trauma

Treatment
 CPR followed by intubation and IV epinephrine
 Treatment is directed toward correction of the
underlying cause

Question 37

SCD (sudden cardiac death)

Answer 37

Death from a cardiac cause
 Most SCDs result from ventricular dysrhythmias
 Ventricular tachycardia
 Ventricular fibrillation

Question 38

Prodysrhythmia

Answer 38

 Life-threatening dysrhythmias caused by
antidysrhythmia drugs
 Severe LV dysfunction increases risk
 Digoxin and class IA, IC, and III antidysrhythmic
drugs
 Most susceptible first few days of drug therapy

Question 39

Defibrillation

Answer 39

 Treatment of choice for VF and pulseless VT
 Most effective when completed within 2 minutes
of dysrhythmia onset
 Passage of electrical shock through the heart to
depolarize myocardial cells
 Allows SA node to resume pacemaker role

 Monophasic defibrillators deliver energy in one
direction
 Biphasic defibrillators deliver energy in two
directions
 Use lower energies
 Fewer post shock ECG dysrhythmias

 Output is measured in joules or watts per second
 Recommended energy for initial shocks in
defibrillation
 Biphasic: 120 to 200 J
 Monophasic: 360 J
 Immediate CPR after first shock

Question 40

Synchronized Cardioversion

Answer 40

 Therapy of choice for ventricular or
supraventricular tachydysrhythmias (VT with a
pulse)
 Synchronized circuit delivers a shock on the R
wave of the QRS complex of the ECG

 Procedure similar to defibrillation except sync button turned ON
 If patient stable, sedate prior
 Initial energy lower
 50 to 100 J (biphasic)
 100 J (monophasic)
 If patient becomes pulseless, turn sync button off
and defibrillate

Question 41

Implantable Cardioverter-
Defibrillator

Answer 41

Appropriate for patients who
 Have survived SCD
 Have spontaneous sustained VT
 Have syncope with inducible ventricular
tachycardia/fibrillation during EPS
 Are at high risk for future life-threatening
dysrhythmias

Decreases mortality

Question 42

Implantable Cardioverter-
Defibrillator Set Up

Answer 42

Consists of a lead system placed via subclavian
vein to the endocardium
 Battery-powered pulse generator is implanted
subcutaneously
 Sensing system monitors HR and rhythm—
delivering 25 J or less to heart when detects
lethal dysrhythmia

 Includes antitachycardia and antibradycardia
pacemakers
 Overdrive pacing for tachycardias
 Backup pacing for bradycardias
 Pre-procedure and postprocedure care same as
pacemaker
 S-ICD

Question 43

Pacemakers

Answer 43

Used to pace the heart when the normal conduction
pathway is damaged
 Pacing circuit consists of
 Power source *battery-powered pulse generator)
 Programmable circuitry

Question 44

Pacemaker Mechanism

Answer 44

Pace atrium and/or one or both of ventricles
 Most pace on demand, firing only when HR drops
below preset rate
 Sensing device inhibits pacemaker when HR
adequate
 Pacing device triggers when no QRS complexes
within set time frame
Antitachycardia pacing: delivery of a stimulus to
the ventricle to end tachydysrhythmias
 Overdrive pacing: pacing the atrium at rates of
200 to 500 impulses/min to try to stop atrial
tachycardias
Cardiac resynchronization therapy (CRT)
 Resynchronizes the heart cycle by pacing both
ventricles
* Biventricular pacing
 Used to treat patients with heart failure
 Can be combined with ICD for maximum therapy

Question 45

Transcutaneous Pacing

Answer 45

For emergency pacing needs
 Noninvasive
 Bridge until transvenous pacer can be inserted
 Use lowest current that will “capture”
 Patient may need analgesia/sedation

Question 46

Epicardial Pacing

Answer 46

Leads placed on epicardium during heart
surgery
 Passed through chest wall and attached to
external power source
 Leads placed prophylactically to treat
dysrhythmias postoperatively

Question 47

Radiofrequency Catheter
Ablation Therapy

Answer 47

Electrode-tipped ablation catheter “burns”
accessory pathways or ectopic sites in the atria,
AV node, and ventricles
 Nonpharmacologic treatment of choice for
several atrial dysrhythmias
 Postcare similar to cardiac catheterization

Question 48

Syncope

Answer 48

Brief lapse in consciousness accompanied by a loss
in postural tone (fainting)
 Noncardiovascular causes
 Stress
 Hypoglycemia
 Dehydration
 Stroke
 Seizure

Cardiovascular causes
 Cardioneurogenic or “vasovagal” syncope
* Carotid sinus sensitivity
 Dysrhythmias (tachycardias, bradycardias)
 Prosthetic valve malfunction
 Pulmonary emboli
 HF