BASIC
DYSHYTHMIA INTERPRETATION
Objectives: At the conclusion of this class, the student will be able to:
Describe the cardiac conduction system
SA node sets rhythm, lives in upper RA, it likes a rate of 60-100—doesn’t
like going over 150, so higher tachs are either drugs or another pacer. It
conducts to the AV node, which goes to bundle of His, the L and R bundle
branches, and the purkinje fibers.
And a normal ECG complex
has a Reg R-R, P before each QRS, and T after. A normal pr= 0.12-0.2. A
normal QRS is < 0.12.
P means atrial depol
p-r is the codxn from SA to AV
QRS is depol of vents, also repol of atria but you can't see it
T is repol of vents

Electrical transmission connected with mechanical events, but conditions such
as prolonged hypoxia or acidosis can cause depolarization w/o contraction
And state nursing responsibilities for a patient requiring cardiac
monitoring;
skin prep, put the leads in the right place. Don't throw away the wrong cord.
check it if its alarming, don't trust the machine, always confirm a rhythm.
Make sure the pt isn't playing w/ the leads.
All pts on ekg’s: you always need to know their rythym.
Assess when: vs, things change, prn, after giving sensitive meds, etc.
IF a pt is at risk for arrhythmis, you need to advocate that they get on EKG
leads.
Identify a system for interpreting ECG patterns;
Rate: count it
Rate: reg or irreg?
p waves present. If not: altered or absent= other than SA node are firing
pr interval: 0.12-0.20 sec; longer possible conduction delay of AV node or heart block;
present but not consistently followed by QRS complex= 2nd or 3rd degree heart block
QRS complex: is 0.10 or less; prolonged= abnormal conduction thru ventricles,
Identify factors that place a person at risk for developing
dysrhythmias;
fluid vol def/overload. MI's. hypothermia. drugs. coffee.
Tachydysrhythmias noted in pt. w/ fluid volume deficits- HR incr. in response to
diminished stroke volume
Fluid volume overload= ventricular enlargement & decreased contractility=
premature beats, conduction block, & abnormal HR
Myocardial factors: CAD. Alteration in myocardial perfusion & potential
ischemia; ventricles do not depolarize effectively (QRS complex) & repolarization is
inefficient (T wave)= abnormal ventricular beats or blocks in conduction
Fluid volume abnormalities/shock, esp hypovolemia
Electrolyte abnormalities: esp K high or lo, Mag, Ca+, these affect the
heart.
hypokalemia- ↓+ions needed to depolarize, becoming more difficult & repolarization
is extended- PR interval is longer & T wave is flat, QT lengthens, extra wave follow
T= bradydysrhythmias & conduction bloc; hyperkalemia- easier depolarization &
short repolarization; tall T waves, QT shortens, PR interval lengthens & QRS complex
widens, cell becomes too positive & can’t depolarize= asystole (no heartbeat);
Hypercalcemia strengthen contractility & shorten ventricular repolarization,
shortening QT interval; Hypocalcemia prolongs QT interval; Hypomagnesmia
increases irritability of nervous system= dysrhythmias- prominent U wave &
flattening of T wave, & prolonged QT interval; Hypermagnesmia- prolonged PR
interval, wide QRS complex, bradycardia, & tall, peaked T wave; Hypothermia
↓electrical activity of heart- bradycardia (<60), prolonged of PR & QT intervals, &
wide QRS complex.
Summary those at risk have an alteration in tissue perfusion, imbalanced fluid
volume, or electrolytes or decreased body temp..
Hypothermia
Shock: big time at risk.
Medications: brady [dig, beta block, Ca channel block]; cocaine, too much
K+. Diuretics lead to volume and lyte problems. Acid-Base Imbalances.
Identify and describe treatment of the following common dysrhythmias:
sinus rhythm: nothing
sinus bradycardia, atropine, or isoproteronol [isoprenaline]
sinus tachycardia, relax the pt, give pain meds, antioxylytics, O2, Ca
Channel blockers and beta-blockers
PACs, do nothing if not a problem, less caffeine and ETOH, betablockers
[pg 282]
Atrial fibrillation, handle the high rate first [pg 277] with dig, beta block,
Ca Channel Block. Then the fib: amiodarone, adenosine, verapamil [ati], .
If cardioverting, give anticoag and do a transesophageal echo. [ati]
ventricular tachycardia, amiodarone, adenosine, verapamil
ventricular fibrillation, Defibrillation soon. Amiodarone, lidocaine, and
epinephrine. PVC, do nothing if not a problem, less caffeine, lidocaine [pg
282]
Lidocaine administered if PVC’s are of ischemia or infarct origin;
Amiodarone or procainamide if PVC’s are refractory to lidocaine.
Harmless unless > 6 or more/min.; life threatening if indicating ventricular
irritability
and paced rhythm; uhmm...leave it alone?
Discuss nursing responsibilities with cardioversion
get EKG strip before during and after. informed consent, IV access,
sedatives, pain killers, O2 and all metallic objects off the pt. assess for
complications [emboli, resp depres, dysrhthmias]. Check electrolytes for any
imbalances esp. Ca, Mg, K
and defibrillation;
Defib Nursing Actions: ECG strip cont, Pad placement, correct
procedure by ACLS staff, ACLS algorithms
Discuss indications for and nursing implications with pacemaker
Pacemakers: if the electrode is in the atria, that elicits a p wave. If
there’s trouble in both atria and vents, theres a second [dual chamber]
signal that carries it to the vents.
Pt. teaching & education regarding device- literature, ECG strips, medicalert
bracelets, know device- manuftr, model #
Margi say: Nursing Action: monitor ECG, patient education
Def: pulse generator used to provide electrical stimulus to the heart
when it fails to conduct or generate heart rate that maintains cardiac
output
Types: temporary-external and percutaneous, permanent, atrial,
ventricular, dual
ICDs
Def: implanted cardioverter/defibrillator
Indications: patients with life threatening arrhythmias that does not
respond to medication
Nursing Action: monitor ECG, patient education
Discuss indications for pacemaker
Def: pulse generator used to provide electrical stimulus to the heart
when it fails to conduct or generate heart rate that maintains cardiac
output
Types: temporary-external and percutaneous, permanent, atrial,
ventricular, dual
and implantable cardioverter/defibrillator (ICD) therapy;
Def: implanted cardioverter/defibrillator
Indications: patients with life threatening arrhythmias that does not
respond to medication
Discuss pertinent antiarrhythmic agents in terms of indications for use
and action.
ADENOSINE (ADENOCARD): PSVT
AMIODARONE (CORDARONE): ventricular arrhythmias and supraventricular
arrhythmias, particularly with atrial fibrillation
DILTIAZEM (CARDIZEM): Atrial fibrillation, atrial flutter, supraventricular tachycardia,
and Prevention of reinfarction in non-Q-wave MI.
ATROPINE SULFATE: For sinus bradycardia or asystole
LIDOCAINE: Rapid control of ventricular arrhythmias occurring during acute MI, cardiac
surgery, and cardiac catheterization and those caused by digitalis intoxication
Adenosine
blocks ventricular impulse
Amiodarone
blocks K+ , delays repolarization
Lidocaine
↓refractory period
Propranolol-beta blocker (metopropolol)
Diltiazem (Cardiazem)-calcium channel blocker
Nifedipine (procardia)
Digoxin
↓conduction thru AV node
SVDysrhythmia
V. tach/fib
PVC; v. tach/fib
tachy/dysrhthmias
tachy/dysrhythmias
Case Scenarios
85 yo female complaining of chest pain.
Could be: Vasoconst, spasm, angina, indigestion, lung something. Her
organs are old. We do: chest pain, r/o MI.
Monitor shows sinus tachycardia. What interventions are
indicated?
Means heart’s ok, run by the sinus node, it’s just too fast.
Intervene: O2. Why? Angina is always a lack of O2 to heart. How much
O2? 2 L by n/c, and then up to 4—why? b/c a mask at 100% is big time
overdose, she’s probably already anxious. SaO2: cont. Next: run an EKG
strip. In fact, get her on a 12-lead EKG. Chest pain; give her some morphine
[sometimes ER will withhold meds so that they can diagnose]. Assess her
head to toe. Find why she’s in tach: pain, low O2, temp, etc. If her tach is
too high: amidarone or cardizem. Her heart can’t handle this for long—get
that HR down. Get her on an NTG drip.
66 yo male admitted with syncope, takes digoxin and lasix for CHF.
Monitor shows sinus bradycardia, 45, BP 78/40. What interventions are
indicated?
58 yo male admitted with AMI, complaining of 8/10 cp. Monitor shows
sinus rhythm with frequent PVCs. What interventions are indicated?
57 yo nurse who faints at her yoga class. In ED, monitor shows sinus
bradycardia, rate 44. What interventions are indicated?
Where EKG: during procedures, ER, tele, ICU, etc. Dysrrythmia means
abn. Arrhythmia: no rhythym.
I. Cardiac Conduction
Components
SA node: usually the pacemaker, RA, why? Because it beats faster than all
the other pacemaker cells—the fastest pacer always manages the overall
conduit. Automaticity: beats on its own without any extra signals. Beats 60100 bpm. Doesn’t like to go over 150—so if you’ve got a higher tach, think
drugs or supravent-tach.
AV node: next stop. Sends impulse to bundle of His, R/L bundle brances,
purkinje’s.
Right after the depolarization, there’s a contraction.
BB, purkinje fibers
Intervals
Rate: Margi says usually getting the rate is silly b/c it’s a machine,
but….it’s a machine, so do it anyway.
P wave means: atrial depolarizing
PR interval: beginning of P to beginning of Q: too slow means blocked at
AV node. Normal less than 0.20
QRS duration: vents depol, artia repol but you don’t see it. Q is 1st neg
deflection. R is first pos deflection, etc. QRS’s look different but it doesn’t
mean they are bad—has to do with the leads. 0.04-0.12. Margi says: 0.08 to
0.12 is normal in practice. Book says less than 0.10. Whatever.
ST segment
T: vents repol
QT interval
II. Nursing Responsibilities if your pt is on a monitor
Means you better have a ‘clean strip’ to put in the record—don’t want one
with ‘artifact’ from the cables moving around.
Accurate waveform
skin prep: Sometimes you have to make the pt hold perfectly still so you
can have a good strip. Shave hairy men, dry sweaty people.
accurate lead placement
Alarms: go off all the time for no good reason, and if you don’t play with
the cable it will not make so much noise.
Patient education: about alarms, what leads do, that you have to move
slow, don’t play with them.
What does this dysrhythmia mean to this patient?
III. Lead Systems
A. 12-lead EKG: 12 pictures of electrical activity of the heart: gets all
over the chest and the limbs.
B. Common Monitoring Leads:
1. Lead II: negative electrode under right clavicle, positive
electrode
left midaxillary line, 5th ICS
2. MCL1: negative electrode below left clavicle, positive electrode
4th ICS, right sternum border
3. 3 lead cables: positive, negative, ground
4. 5 lead cables: right and left leg, right and left arm and chest
lead
IV. Characteristics of Cardiac Monitoring
A. ECG recording:
1. horizontally:
*small box=0.04 sec.
*large box=.20 seconds
2. vertically: mm/small box
B. Electrical Events: NEED TO KNOW
1. P wave:
2. PR Interval: normal:=/<0.20 seconds
3. QRS complex: normal:=/< 0.10 seconds
4.ST segment:
5. T wave:
QT interval:
V. Rhythm Interpretation
A. System for strip interpretation:
1.Measure heart rate.
2. Examine the R-R interval.
3. Examine the P wave.
4. Measure the PR interval.
Determine if each P wave is followed by a QRS complex.
Examine the QRS complex.
B. Rate determination techniques:
VI. Risk Factors for Development of Dysrhythmias
All pts on ekg’s: you always need to know their rythym.
Assess when: vs, things change, prn, after giving sensitive meds, etc.
IF a pt is at risk for arrhythmis, you need to advocate that they get on EKG
leads.
Myocardial factors: CAD
Fluid volume abnormalities/shock, esp hypovolemia
Electrolyte abnormalities: esp K high or lo, Mag, Ca+, these affect the
heart.
Hypothermia
Shock: big time at risk.
Medications: brady [dig, beta block, Ca channel block]; cocaine, too much
K+. Diuretics lead to volume and lyte problems. Acid-Base Imbalances.
VII. Common Arrhythmias
all atrial dysrythmias have a lack of P-Waves
A. Normal Sinus rhythm: 60-100; regular; P before every QRS; normal
intervals
B. Sinus bradycardia: SR with rate <60
Atropine is for symptomatic Brady
C. Sinus tachycardia: SR with rate >100
D. Atrial fibrillation: irregularly irregular; irregular ventricular rate;
wavy baseline; narrow QRS. NTK. Very common arrhythmia. Irreg irreg
means goes thru AV node sporadically. Usually looks like you can’t
distinguish a P-Wave, or the p-waves aren’t always there.
unequal R-R= irreg.
atria aren’t getting filled therefore poor CO. These pts are fainty and tired
don’t bother finding P waves, they are not behaving.
QRS is ok—it’s skinny.
Inverted t wave
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
E. PACs: early, before QRS, P looks different from sinus P. need to
know difference btwn this and PVC or a fib. Means the atria are ctx a
little early [premature atrial ctx—just wants to jump right in]. There’s a P
still there, before a extra long R-R—so the rate isn’t perfectly regular in one
spot. Usually r/t coffee, nerves. QRS is normal.
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
F. PVCs: early, wide and bizarre, no P before it. The QRS should look
weird b/c it comes from the ventricle, right?
QRS is wide and bizarre and usually a bit early compared to the other beats.
Sometimes the QRS inverts on these long bizarre QRS’s.
Common in previous MI of some sort. This is irritable tissue.
Chart; “sinus rhythm w/ occasional PVC.”
Don’t freak out or treat it.
QuickTime™ and a
decompressor
are needed to see this picture.
Ventricular badness is the most likely to make you keel over.
Ventricular tachycardia: wide and bizarre, regular, rate very fast, no P
QuickTime™ and a
decompressor
are needed to see this picture.
Atrial Flutter: rare, doubt it’ll be on exam
QuickTime™ and a
decompressor
are needed to see this picture.
H. Ventricular fibrillation: no QRS, wavy baseline: dead person, full
code, the guy on the golf course who dies is usually a v-f arrest. Usually the
cause of cardiac arrest—why we have defibrillators. Defib them, hopefully
the SA node will get back on top of it.
QuickTime™ and a
decompressor
are needed to see this picture.
Rules for Ventricular Fibrillation (V-Fib)
Regularity: There is no regularity to the rhythm because there are no
complexes or waves present that are able to be analyzed.
Rate: There is no measurable rate.
P WAVE: There are no P waves present.
PRI: PRI is unable to be measured due to no P waves being present.
QRS: There are no QRS complexes present.
Paced rhythm: ventricular, atrial or both
QuickTime™ and a
decompressor
are needed to see this picture.
VIII. Antiarrhythmic Agents: goal to suppress dysrhythmia
Class I: fast sodium channel blockers
Class IA: procainamide
Class IB: lidocaine
Class IC: flecainide
Class II: block effects of catecholamines: slow AV conduction; beta
blockers
Class III: block potassium channels; amiodarone
Class IV: calcium channel blockers; verapamil
Nursing action before giving these drugs:
assess vital signs
assess ECG
physical assessment
infusion pump with IV drugs
patient education: reason for drug; report any dizziness, palpitations
IX. Cardioversion, Defibrillation, and Pacemakers
Cardioversion:
Def: delivery of electrical shock synchronized with patient’s heart
rhythm;
Indications: treat SVT, atrial fibrillation, & ventricular tachycardia in
an unstable patient; sx hypotension, chest pain, diaphoresis, SOB, CHF,
MI
Nursing Actions: ECG strip before, during, and after procedure, VS,
informed consent, IV access, conscious sedation, oxygen pad placement,
assess for complications
Defibrillation:
Def: emergency procedure to treat ventricular tachycardia in
unresponsive patient and ventricular fibrillation; unsynchronized
Indications: cardiac arrest
Nursing Actions: ECG strip cont, Pad placement, correct procedure by
ACLS staff, ACLS algorithms
Pacemakers: if the electrode is in the atria, that elicits a p wave. If there’s
trouble in both atria and vents, theres a second [dual chamber] signal that
carries it to the vents.
Def: pulse generator used to provide electrical stimulus to the heart
when it fails to conduct or generate heart rate that maintains cardiac
output
Types: temporary-external and percutaneous, permanent, atrial,
ventricular, dual
ICDs
Def: implanted cardioverter/defibrillator
Indications: patients with life threatening arrhythmias that does not
respond to medication
Nursing Action: monitor ECG, patient education