EKG Flashcards
What is an EKG?
A graphic representation of the electrical impulses of the heart
EKG are used to
identify irregularities in heart rhythm
How is EKG recorded from the body surface?
Electrodes
Where do impulses in the heart start?
SA node (pacemaker of the heart )
Flow of conduction in the heart
SA Node –> AV (junctional) node –> Bundle of His –> Left and Right bundle branches –> purkinje fibers
what part of the heart delays conduction?
AV node
AV Node allows for
mechanical contraction of the atria to eject blood into ventricles
what are the bundle of his branches responsible for?
depolarizing respective ventricles
What do the purkinje fibers do?
Penetrate myocardium and stimulate muscle contraction from the bottom the heart upwards…. VENTRICLE CONTRACTION
P wave represents
atrial depolarization
P-R interval
represents the slowing of conduction through the AV node
QRS complex
ventricular depolarization and normally followed closely by ventricle contraction
when does depolarization begins
ventricular contraction ends
ST segment
- isoelectric (straight line) pause.
- ventricle is initiating depolarization
When is repolarization complete?
end of the T-wave
single-lead EKG can help practictitoners determine what?
- safety of pursing interventions in the light of abnormalities
- good indicator to stop treatment or continue
most common practice in step-downs, ICUs, and CPPT rehab programs
Single-lead monitoring via telemetry
Single-lead monitoring via telemetry are used to
detect rate and rhythm disturbances
what can Single-lead monitoring via telemetry NOT detect
ischemia
Ischemia
decreased blood flow to cardiac tissue
Ischemia can lead to
disturbance in heart rhythm or infraction
Infarction
interruption of blood flow that leads to death of cardiac muscle tissue
Twelve- lead EKG is used to determine
ischemia or infarction
when is a 12 lead EKG ordered
with change in patient condition or when ischemia is suspected
important info from a 12 lead EKG
- Ventricular hypertrophy
- myocardial ischemia
- Myocadial infarction
Ventricular hypertrophy
indicated by increased height (R wave) and depth (S wave) in QRS complex
Myocardial ischemia
indicated by ST segment depression or T-wave inversion when present with angina
Myocardial infarction
ST segment elevation
ST elevation is seen on EKG in conjunction with acute onset chest pain is what?
MEDICAL EMERGENCY
What is another term for ST segment elevation ?
tombstone Ts
Besides myocardial ischemia what are other causes for ST depression?
- Digitalis toxicity
- Ischemic response to exercise if happens with activity
voltage or amplitude is measure where on the graph paper?
y-axis
Time is measured on where on the graph paper?
x-axis
how many seconds are 1 tick?
3 seconds
Square counting method is ideal for
regular rhythms
during a normal sinus rhythm rate is
60-100 bpm
During normal sinus rhythm QRST should be followed by what?
P
During normal sinus rhythm, P is followed by ?
QRST
During normal sinus rhythm, PR interval is constant at?
0.12 -0.20 seconds
Q waves are a sign of what?
Previous MI (absence in electrical activity)
do Q waves go away?
usually there to stay
Widened QT interval/ syndrome ?
inherited or medication induced
Widened QT interval/ syndrome are often misdiagnosed as what?
seizure
what type of drug is a patient on for a Widened QT interval/ syndrome?
Methadone
why can Widened QT interval/ syndrome be dangerous ?
they can lead to ventricular arrhythmias
U Waves represent repolarization if what?
purkinje fibers or papillary muscles
Patient who may present with U waves ?
hypokalemia or hypercalcemia, digitalis toxicity, and is a possible indicator for myocardial ischemia
dysrhythmia or arrhythmia
any rhythm other than NSR Arrhythmias
Tachyarrythmia
rhythm with a rate >100 bpm
Bradyarrythmia
rhythm with a rate < 60 bpm
Ectopy
electrical activity outside of the normal pathways
Junctional
premature impulses that arise from AV node or junctional tissue
Ventricular
Very dangerous and can alter cardiac output
ectopic focus
activity is originating or from a spot it is not supposed to
causes of sinus tachycardia
increase in sympathetic stimulation (exercise, emotions(fear, anxiety), stimulants (caffeine, atropine, nicotine, amphetamines), increase in O2 demands)
What do we do for tachycardia?
- Attempt to eliminate the cause
- Initiation of beta-blocker therapy
Causes of sinus bradycardia
- super fit folks
- Beta blockers
- Increased vagal stimulation
symptoms of bradycardia
syncope, dizziness, angina or diaphoresis
what do we do for bradycardia?
Nothing, unless patients are sypmtomic
-atropine, temp pacemaker
Sinus Arrhythmia
Quickening and slowing of impulse formation
Most common cause for Sinus Arrhythmia
respiratory cycle
Sinus Arrhythmia during expiration? & Inspiration ?
Expiration: slowing
Inspiration: speeding
What is it called when there is no true P wave, but flutters
Atrial flutter (flutter waves)
Is the ventricular rate effected during atrial flutter?
Not typically
Causes for atrial flutter?
Rheumatic heart disease, mitral valve disease, hypoxemia
treatment for atrial flutter
meds (digoxin, verapamil, beta-blockers)
Cardioversion
Atrial rate during atrial flutter
250-300 times per minute
what is it called when there is no true Pwave and SA node is no longer the pacemaker?
Atrial fibrillation
during atrial fib there are multiple ectopic foci in where?
atria
During atrial fibrillation, ventricular rate depends on what?
AV node responsiveness
what is a classic sign of a fib?
highly irregular pulse
causes of a fib?
Advanced age, ischemia/infarction, CHF, stress, and renal failure
why is a fib a problem
- Decreased cardiac output
- Becomes very dangerous in the presence of tachycardia
- Stagnant blood…. excess coagulation…. clot formation
when should you terminate/ hold exercises with someone with Afib?
when ventricular rate is > 120-130 bpm at rest
what is the treatment of Afib
Pharmacological control, anticoagulation, radiofrequency ablation
when do heart blocks occur?
when cardiac electrical impulse is either delayed or blocked within the AV node, bundle of HIS, or Purkinje system
Is 1st degree heart block , a block or a delay?
Delay
2st degree heart block/ Moritz I is caused by?
conduction delay at AV node or bundle of his
What will be longer than normal in 2st degree heart block: Moritz I
PR interval
what is almost always a disease of the AV node?
2nd degree heart block : mobitz I
2nd degree heart block can also be known as
Moritz I or wenckebach
what do you see on an ECG during 2nd degree heart block/ mobitz I
progressive elongation of PR interval followed by a “dropped” or missing QRS complex
2nd degree. Moritz II is almost always a conduction disorder involving what?
bundle of his or purkinje system
What do you see during a 2nd degree/ Moritz II
- PR interval stays the same but “dropped” beats will be visible
- Intermirrent non-conducted P waves
Clinical significance of 2nd degree heart block/ mobitz II
- Can rapidly progress to complete heart block
- Can lead to cardiac arrest
Definitive treatment for 2nd degree heart block/ Moritz II
implanted pacemaker
during 3rd degree or complete heart block impulses are generated where? and not conducted where?
- generated in SA node
- NO conducted to ventricles
3rd degree heart block is categorized by?
complete lack of relationship between P waves and QRS complexes
what happens during a 3rd degree heart block?
A new or “accessory” pacemaker will generate “escape rhythms”, usually in the ventricles
what are the two independent rhythms on the ECG?
- P waves with a regular P to P interval (aka normal sinus rhythm)
- The QRS complexes with regular R to R interval. PR interval is variable here.
what causes 3rd degree or complete heart block?
- Coronary ischemia
- inferior wall MI (can damage AV node)
- Anterior wall MI (can cause damage to distal conduction system of heart)
Symptoms of 3rd deg heart block
severe bradycardia, hypotension, hemodynamic instability
Treatment of 3rd degree heart block
- Electrical pacing, either temporary or permanent
- Definitive treatment is dual chamber artificial pacemaker
What are Premature ventricular contractions (PVC)
- Ectopic focus generating an impulse from somewhere in the ventricles
- Can be an individual event or occur in a predictable pattern
- Can be unifocal or multifocal
When should you be concern during PVC?
- 3 PVC in a row
- 6 PVC in a minute
PVC can lead to
Ventricular Tachycardia
causes of PVC?
If isolated, possibly due to stress, caffeine or nicotine sensitivity, electrolyte imbalance
Ischemia, cardiac disease, irritation of myocardium
Symptoms of PVC ?
Feeling of a “skipped beat”, possible feelings of anxiety, SOB, dizziness
treatment of PVC?
Treat underlying cause
In patients with lung disease, PVCs may indicate hypoxemia. Patient should be placed on supplemental O2
Antiarrhythmic medication
Ventricular tachycardia or tech is defined as?
3 or more PVCs in a row
-Rate 100-250 bpm
sustained v-tach
run of v-tach> 30 s, even if it self terminates
non-sustained v-tach
Self-termination in < 30 seconds
v-tach can lead to?
ventricular fibrillation
why does v-tach occur?
rapid firing by a single ventricular focus
causes of v-tach?
- Ischemia or acute infarction, CAD, heart disease
- Medication reactions (digoxin or qunidine toxicity)
- Athletes during exercise due to electrolyte imbalance
Symptoms of v-tach?
- Dizziness and syncope
- Disorientation
- Weak, thready pulse
Treatment of v-tach?
Immediate pharmacological intervention, cardioversion or defibrillation
What is Torsade de pointes
- Unique configuration of v-tach
- “Twisting of the points” around the isoelectric line
- Often associated with prolonged Q-T interval
- Occurs at a rapid rate and terminate spontaneously
Torsade de pointes is a what?
MEDICAL EMERGENCY
Torsade de pointes is treated with?
cardioversion
what is ventricular fibrillation?
erratic quivering of ventricular musculature
V fib is caused by?
multiple ectopic foci firing at the same time ….. no cardiac output
What do you always associate V fib with?
cardiac arrest
