ACLS EKG Rhythms and Interpretation
Each link
below will take you to a page for the Respective ACLS EKG. These pages cover
all of the basic ACLS EKG’s from Ventricular Fibrillation to Complete Heart
Block. After each article is a short video that simulates the ACLS EKG on a
defibrillator monitor.
Pulseless Rhythms
Pulseless
Ventricular Tachycardia
The
pulseless ventricular tachycardia rhythm is primarily identified by several
criteria. First, the rate is usually greater than 180 beats per minute and the
rhythm generally has a very wide QRS complex.
Second,
the patient will be pulseless and third, the rhythm originates in the
ventricles or AV node. This is in contrast to other types of tachycardias which
have origination above the ventricular tissue (in the atria).
Not all
ventricular tachycardias are pulseless and therefore, pulselessness must be
established prior to beginning an algorithm. This is accomplished simply by
checking a carotid or femoral pulse.
Pulselessness
with a tachyarrhythmia occurs because the ventricles are not effectively moving
blood out of the heart and there is therefor no cardiac output. Many
tachyarrhythmias of a rate >150 will deteriorate into pulselessness if
timely treatment is not given
Play the
video below to see what a Pulseless Ventricular Tachycardia will generally look
like on a defibrillator monitor.
Ventricular Fibrillation
Ventricular
fibrillation or VF occurs when there are uncoordinated contractions within the
ventricles of the heart. The primary cause of VF is hypoxia (lack of oxygen) to
the heart muscle which causes hyperirritability in the cardiac muscle tissue.
As a result,
multiple muscles cells within the ventricles simultaneously fire as pacemakers
causing a quivering or fibrillation that is ineffective for adequate cardiac
output.
The two
images above show what ventricular fibrillation will look like on a EKG rhythm
strip.
VF can
rapidly lead to heart muscle ischemia and there is a high likelihood that it
will deteriorate into asystole.
VF should
be treated per the pulseless arrest algorithm which is also used for pulseless
ventricular tachycardia.
Pulseless Electrical Activity (PEA)
Rhythm
PEA
rhythm occurs when any heart rhythm that is observed on the electrocardiogram
(ECG) does not produce a pulse. PEA can come in many different forms. Sinus
Rhythm, tachycardia, and bradycardia can all be seen with PEA.
Performing
a pulse check after a rhythm/monitor check will ensure that you identify PEA in
every situation.
Pulseless
electrical activity usually has an underlying treatable cause. The most common
cause in emergency situations is hypovolemia.
PEA is
treated by assessing and correcting the underlying cause. These causes can be
summed up in the 6 H’s and 6 T’s of ACLS. Use the link to review
the H’s and T’s.
When an
underlying cause for pulseless electrical activity cannot be determined, PEA
should be treated in the same fashion as asystole
Pop-Quiz:
Question
#1: If you saw the rhythm below after defibrillation, how would you determine
if it is pulseless electrical activity?
click here for answer» You should check for a carotid or femoral pulsePowered by Hackadelic Sliding Notes 1.6.5
Question #2: What is the most common cause of PEA?
click here for answer» HypovolemiaPowered by Hackadelic Sliding Notes 1.6.5
click here for answer» You should check for a carotid or femoral pulsePowered by Hackadelic Sliding Notes 1.6.5
Question #2: What is the most common cause of PEA?
click here for answer» HypovolemiaPowered by Hackadelic Sliding Notes 1.6.5
Bradyarrhythmias
First-Degree Heart Block
Also
called first-degree AV block is a disease of the electrical conduction system
of the heart in which the PR interval is lengthened beyond 0.20 seconds.
This
lengthening of the PR interval is caused by a delay in the electrical impulse
from the atria to the ventricles through the AV node
Normally
and in the case of ACLS, first-degree heart block is of no consequence unless
it involves myocardial infarction or an electrolyte imbalance.
Although
first-degree heart block is not clinically significant for ACLS, recognition of
the major AV blocks is important because treatment decisions are based on the type
of block present.
Below is
a short video which will help you quickly identify first-degree AV block
Second-Degree Heart Block (Type 1)
Also
called Mobitz 1 or Wenckebach is a disease of the electrical conduction system
of the heart in which the PR interval» Powered by Hackadelic Sliding Notes
1.6.5 has
progressive prolongation until finally the atrial impulse is completely blocked
and does not produce a QRS electrical impulse.
Once the
p-wave is blocked and no QRS is generated, the cycle begins again with the
prolongation of the PR interval.
One of
the main identifying characteristics of second degree heart block type 1 is
that the atrial rhythm will be regular.
In the
above image, notice that the p-waves are regular, the PR-interval progressively
gets longer until a QRS is dropped and only the p-wave is present.
Although
first-degree heart block is not clinically significant for ACLS, recognition of
the major AV blocks is important because treatment decisions are based on the
type of block present.
Below is
a short video which will help you quickly identify second-degree AV bloc
Second-Degree (AV) Heart Block (Type 2)
Also
called Mobitz II or Hay is a disease of the electrical conduction system of the
heart. Second-degree AV block (Type 2) is almost always a disease of the distal
conduction system located in the ventricular portion of the myocardium.
- no conducted p-waves
(electrical impulse conducts through the AV node but complete conduction
through the ventricles is blocked, thus no QRS)
- P-waves are not preceded by
PR prolongation as with second-degree AV block (Type 1)
- fixed PR interval
- The QRS complex will likely
be wide click here to see
why» The
QRS on an ECG will most likely be wide because the block occurs in the His
bundle or bundle branches and conduction through the ventricles is slowedPowered by Hackadelic Sliding Notes
1.6.5
Second-degree
AV block (Type 2) is clinically significant for ACLS because this rhythm can
rapidly progress to complete heart block
Secocnd-degree
AV block (Type 2) should be treated with immediate transcutaneous pacing or
transvenous pacing because there is risk that electrical impulses will not be
able to reach the ventricles and produce ventricular contraction.
Complete Heart Block
Third-degree
AV block or complete heart block is the most clinically significant AV block
associated with ACLS. Complete heart block occurs when the electrical impulse
generated in the SA node in the atrium is not conducted to the ventricles.
When the
atrial impulse is blocked, an accessory pacemaker in the ventricles will
typically activate a ventricular contraction. This accessory pacemaker impulse
is called an escape rhythm.
Because
two independent electrical impulses occur (SA node impulse & accessory
pacemaker impulse), there is no apparent relationship between the P waves and
QRS complexes on an ECG.
Characteristics
that can be seen on an ECG include:
- P waves with a regular P to
P interval
- QRS complexes with a regular
R to R interval
- The PR interval will appear
variable because there is no relationship between the P waves and the QRS
Complexes
Common
Causes: The most common cause of complete
block is coronary ischemia and myocardial infarction. Reduced blood flow or
complete loss of blood flow to the myocardium damages the conduction system of
the heart, and this results in an inability to conduct impulses from the atrium
to the ventricles.
Those
with third-degree AV block typically experience bradycardia, hypotension, and
in some cases hemodynamic instability.
The
treatment for unstable third-degree AV block in ACLS is transcutaneous pacing.
Tachyarrhythmias
Supraventricular Tachycardia (SVT)
SVT is a
broad term for a number of tachyarrhythmias that originate above the
ventricular tissue and pass through the AV node causing a ventricular contraction
for every atrial impulse.
Supraventricular
tachycardia is sometimes referred to as atrial tachycardia since the the
impulse originates in the atria.
Most
SVT’s have a narrow QRS complex. P-waves will be present unless the rate is so
rapid that the p-waves are buried in the QRS complexes.
The rapid
beating of the heart will often times make the heart have a less-effective
pump, which can decrease cardiac output and blood pressure.
A patient
may experience the following symptoms which are typical with a rapid pulse of
150–251 or more beats per minute:
- Shortness of air (S)
- Palpitation feeling in chest
(S)
- Ongoing chest pain (U)
- Dizziness (S)
- Rapid breathing (S)
- Loss of consciousness (U)
- Numbness of body parts (S)
The
pathway of choice for SVT in the tachycardia algorithm is based on wheter the
patient is stable or unstable. The symptoms listed above that would indicate
the patient is unstable are noted with the letter (U). Stable but serious
symptoms are indicated with the letter (S).
Unstable
patients with SVT and a pulse are always treated with cardioversion
Atrial
Fibrillation
The most
common cardiac arrhythmia, atrial fibrillation, occurs when the normal
electrical impulses that are generated by the SA node are overwhelmed by
disorganized electrical impulses in the atria.
These
disorganized impulses cause the muscles of the upper chambers of the heart to
quiver (fibrillate) and this leads to the conduction of irregular
impulses to the ventricles.
For ACLS,
atrial fibrillation becomes a problem when the fibrillation produces a rapid
heart rate which reduces cardiac output and causes symptoms or an unstable
condition.
When
atrial fibrillation occurs with a (RVR) rapid ventricular rate (rate > 100
beats/min), this is called a tachyarrhythmia. This tachyarrhythmia may or may
not produce symptoms. Significant symptoms that occur are due to a reduction in
cardiac output.
The
following is a list of the most common symptoms.
- palpitations or chest
discomfort
- shortness of air and
possibly respiratory distress
- hypotension,
light-headedness and possibly loss of consciousness
- peripheral edema, jugular
vein distention, and possibly pulmonary edema
For the
purpose of ACLS, it is important to be able to recognize atrial fibrillation
when the patient is symptomatic. On an ECG monitor, there are two major
characteristics that will help you identify atrial fibrillation.
- No p-waves before the QRS on
the ECG. This is because there are no coordinated atrial contractions.
- The heart rate will be
irregular.
Irregular impulses that the ventricles are receiving cause the irregular
heart rate.
When the
heart rate is extremely rapid, it may be difficult to determine if the rate is
irregular, and the absence of p-waves will be the best indicator of atrial
fibrillation.
ACLS Treatments:
For the
purposes of ACLS atrial fibrillation is treated when the
arrhythmia/tachyarrhythmia produces hemodynamic instability and serious signs
and symptoms.
For the
patient with unstable tachycardia due to a tachyarrhythmia, immediate
cardioversion is recommended. Drugs are not used to manage unstable
tachycardia.
Atrial Flutter
This
abnormal heart rhythm technically falls under the category of supra-ventricular
tachycardias. Atrial flutter is typically not a stable rhythm and will
frequently degenerate into ventricular fibrillation.
Atrial
Flutter will usually present with atrial rates between 240-350 beats per
minute. These rapid atrial rates are caused by electrical activity that moves
in a self-perpetuating loop within the atria.
The
impact and symptoms of atrial flutter depend upon the ventricular rate of the
patient (i.e. cardiac output). Usually, with atrial flutter, not all of the
atrial impulses will be conducted to the ventricles, and the more atrial
impulses that are conducted, the greater the negative effect.
Symptoms
Symptoms
of atrial flutter are similar to those of atrial fibrillation and may include
the following:
- palpitations, chest pain or
discomfort
- shortness of air
- lightheadedness or dizziness
- nausea
- nervousness and feelings of
impending doom
- symptoms of heart failure
such as activity intolerance and swelling of the legs occur with prolonged
fast flutter)
Complications
As with
its symptoms, atrial flutter shares the same complications as atrial
fibrillation. These complications are usually due to ineffective atrial
contractions and rapid ventricular rates. Ineffective atrial contractions can
lead to thrombus formation in the atria and rapid ventricular rates can cause
decompensation and heart failure.
Atrial
Flutter which produces rapid ventricular rates can degenerate into ventricular
fibrillation, causing hemodynamic collapse and death.
Treatment:
For the
purposes of ACLS, atrial flutter is treated the same as atrial fibrillation.
When atrial flutter produces hemodynamic instability and serious signs and
symptoms, it is treated using ACLS protocol. For the patient with unstable
tachycardia due to this tachyarrhythmia (atrial flutter), immediate
cardioversion is recommended. Drugs are not used to manage unstable
tachycardia.
Cardioversion
Atrial
flutter is considerably more sensitive to electrical direct-current
cardioversion than atrial fibrillation, and usually requires a lower energy
shock. 20-50J is commonly enough to revert to sinus rhythm.
ACLS
Drugs
Each of
the ACLS Algorithms utilizes a number of drugs which we will classify as
“primary drugs”. The “primary drugs” are the medications that are used
directly in an ACLS Algorithm. Here are the Primary ACLS drugs
broken down by ACLS Algorithm.
Each is a
link to its respective page which covers, in detail, all aspects of the
medication and it use in
each ACLS algorithm and in post resuscitation efforts.
Tachycardia : adenosine, diltiazem, beta-blockers, amiodarone, digoxin,
verapamil, magnesium
Acute Coronary Syndromes: Oxygen, Aspirin, Nitroglycerin, Morphine,
Fibrinolytic therapy
Heparin, Beta-Blockers
Heparin, Beta-Blockers
Acute Stroke
tPA-tissue
plasminogen activator, Glucose (D50), Labetalol, Nitroprusside, Nicardipine
Aspirin
Aspirin
Review of Respiratory Arrest
Respiratory
Arrest simply means cessation of breathing. In ACLS, respiratory arrest
typically means that a patient’s respirations are completely absent or inadequate
to maintain oxygenation, but a pulse is present.
Management
of respiratory arrest includes the following interventions:
Give oxygen
Open the airway
Provide basic ventilation
Provide respiratory support with the use of artificial airways (OPA and NPA)
Suction to maintain a clear airway
Maintain airway with advanced airways
Give oxygen
Open the airway
Provide basic ventilation
Provide respiratory support with the use of artificial airways (OPA and NPA)
Suction to maintain a clear airway
Maintain airway with advanced airways
During
respiratory arrest, the ACLS provider should avoid hyperventilation of the
patient. Hyperventilation is providing too many breaths per minute or too large
of a volume per breath during ventilation. Hyperventilation may lead to
increased intrathoracic
pressure, decreased venous return to the heart, diminished cardiac output, and increased gastric inflation, all of which can decrease the likelihood of positive outcomes.
pressure, decreased venous return to the heart, diminished cardiac output, and increased gastric inflation, all of which can decrease the likelihood of positive outcomes.
For patients
with a perfusing rhythm deliver 1 breath every 5 to 6 seconds
Opening Airway
The most
common cause of airway obstruction in a patient that is unresponsive is the
loss of tone in the throat muscles. When loss of throat muscle tone occurs the
tongue can fall back and obstruct the airway. This type of obstruction is
easily prevented
with a basic airway opening technique called the head tilt-chin lift. In the case that spinal injury is suspected, the jaw thrust maneuver can be utilized. This jaw thrust maneuver allows the BLS/ACLS provider to maintain a stable cervical spine.
with a basic airway opening technique called the head tilt-chin lift. In the case that spinal injury is suspected, the jaw thrust maneuver can be utilized. This jaw thrust maneuver allows the BLS/ACLS provider to maintain a stable cervical spine.
ACLS Ventilation
There are
5 basic airway skills used to ventilate a patient. Basic ventilation skills are
discussed in the BLS course and will not be
discussed in detail here. The following is a list of the 5 basic airway skills: 1.) Head tilt-chin lift; 2.) Jaw thrust without head
extension for possible cervical spine injury; 3.) Mouth-to-Mouth ventilation; 4.) Mouth-to-Barrier device (using a pocket mask); and 5.) Bag-mask ventilation.
discussed in detail here. The following is a list of the 5 basic airway skills: 1.) Head tilt-chin lift; 2.) Jaw thrust without head
extension for possible cervical spine injury; 3.) Mouth-to-Mouth ventilation; 4.) Mouth-to-Barrier device (using a pocket mask); and 5.) Bag-mask ventilation.
Bag-Mask ventilation
Bag-Mask
ventilation is the most common method of providing positive-pressure
ventilation. Both the oropharyngeal airway and the nasopharyngeal airway may be
used as adjuncts to improve effectiveness of patient ventilation. The oropharyngeal
airway may only be used on the unconscious patient because it can stimulate
gagging and vomiting in a conscious patient. The nasopharyngeal airway may be
used on the unconscious patient or on the semiconscious patient and is also
indicated if a patient has massive trauma around the mouth or wiring of the
jaws.
Suctioning
If the
airway is being maintained with the basic airway skills listed above, blood,
secretions, and vomit become the primary causes of an obstructed airway in the
unconscious patient. Suctioning should be used to clear the airway if it
becomes occluded with these body fluids.
Limit
suctioning to 10 seconds or less to reduce the risks of hypoxemia. Monitor for
changes in heart rate as oropharyngeal suctioning can cause vagal stimulation
resulting in bradycardia.
Advanced Airways
Advanced
Airways used during ACLS include Combitube, LMA (Laryngeal mask airway), and ET
tube (endotracheal tube).
Once an advanced airway is in place, chest compressions are no longer interrupted for ventilations.
1 breath should be given every 6-8 seconds (10-12 breaths per minute).
Once an advanced airway is in place, chest compressions are no longer interrupted for ventilations.
1 breath should be given every 6-8 seconds (10-12 breaths per minute).
You
should be given adequate time to practice with these devices during your ACLS
training before ACLS megacode testing.