1. Normal ECG:

o   P wave- atrial depolarization, stimulated by SA node

o   PR interval-atrial conduction through AV node

o   QRS complex- ventricular depolarization & atrial repolarization

o   ST segment- ventricular conduction & complete repolarization

o   QT interval- ventricular depolarization & repolarization (beginning of QRS complex to end of T wave

2. Identify a system for interpreting ECG patterns:

  • Rate- count # of complexes in 6 sec. x by 10
  • Examine R-R for regularity, if not = dysrhythmias
  • P wave- precedes each QRS; 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 segment is 0.10 or less; prolonged= abnormal conduction thru ventricles, delay thru bundle branches, or early activation of ventricles thru bypass route
  • ST segment s.b. isoelectric (deflections = muscle injury)
  • QT interval less than 0.40 sec (depends on HR). ↑HR=QT shortens

3. Identify factors that place a person at risk for developing dysrhythmias:

  • 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
  • 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
  • Electrolyte abnormalities ↑risk; 
  • 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..

4. Identify and describe treatment of the following common dysrhythmias:

sinus rhythm, sinus bradycardia, sinus tachycardia, PACs, atrial fibrillation, ventricular tachycardia, ventricular fibrillation, PVC, and paced rhythm:

  • Sinus dysrhythmias – regular rates, harmless until CO compromised; nurse assess for ↓LOC, hypotension, angina
  • Sinus bradycardia– HR <60, PR- 0.20sec; atropine (blocks parasympathetic innervations to SA node=normal sympathetic innervation controlling SA firing
  • Sinus tachycardia– HR>100<150, PR– 0.12-0.14; sympathetic nervous system stimulation from fear, fever, pain, ↓CO from hypovolemia or ventricular failure; imagery, distraction, calm environment, sedatives, tranquillizers, anitanxiety meds, analgesics, antipyretics, oxygen, calcium channel blockers, beta blockers
  • Atrial fibrillation (p276)- most common, atria contracting too fast & unable to refill=ventricles are inadequately filled & SV diminished; remaining blood tends to form clots ↑risk of thrombotic stroke

o   Irregular ventricular response- QRS regularly irregular- noted in difference btwn apical pulse & peripheral pulse

o   Absent P waves & irregular QRS intervals; meds: digoxin, beta blockers, & calcium channel blockers

o   Conversion from a-fib to normal sinus rhythm improves hemodynamics, by direct cardioversion or class 1A, 1C, and III antiarrhythmics

  • Premature Atrial Contraction (PAC p280)- originates from one or more ectopic pacemakers in atria

o   P wave is visible unless hidden by T wave, & may look different to norm

o   Underlying rhythm is regular with brief PAC irregularity

  • Premature Ventricular Contractions (PVC)- originates from one or more ectopic pacemakers in the ventricles

o   Outside of atria= no P wave;

o   PVC wave form is large (higher voltage & > 0.12 sec) & bizarre, & usually in opposite direction to pt. norm

o   Ventricular diastole is ineffective as is cardiac output

o   Close observation req’d b/c it may become ventricular tach or fib:

§  Look for > 6 PVC’s per min

§  PVC’s occurring together

§  Multifocal- from more than 1 ectopic focus

§  Run of v.tach (>3 PVC’s in a row)

§  R-on-T phenom (PVC occurs on down stroke of the T wave preceding PVC

§  Nurse assess for underlying cardiac rhythm- type of PVC (uniform vs. multiform); timing (repeatable pattern)

o   Lidocaine administered if PVC’s are of ischemia or infarct origin; Amiodarone or procainamide if PVC’s are refractory to lidocaine.

o   Harmless unless > 6 or more/min.; life threatening if indicating ventricular irritability

  • Ventricular dysrhythmias (p282) more life threatening & require immediate treatment

o   Recognizable by absent P waves, or not associated with QRS, regular wide QRS complex; chaotic waveforms

  • Ventricular tachycardia (VT)- 3 or more consecutive PVC >100 bpm; ectopic pacemakers in ventricles fire spontaneously;

o   P waves buried in QRS

o   QRS > 0.12 sec.

o   Short runs (<30 sec.) OK, not OK if it goes into v.tach

  • Ventricular fibrillation– most common cause of sudden death;

o   ECG pattern chaotic

o   Impossible to identify PQRST waves & rhythm is grossly irregular

o   Pt. unresponsive & no pulse needs resuscitations- Defibrillation, bolus of vasopressin or epinephrine, amiodarone, lidocaine, magnesium & procainamide; once resuscitated, last med given is initiated into IV

5. Discuss nursing responsibilities with cardioversion and defibrillation:

  • Monitors pt. ECG strips prior, during, & after procedure & responses
  • Informed consent  & IV access
  • Check electrolytes for any imbalances esp. Ca, Mg, K

6. Discuss indications for and nursing implications with pacemaker and implantable cardioverter/defibrillator therapy:

  • Preparing pt. for procedure; monitoring ECG pattern; assess threshold (minimum amt of output to initiate depolarization)
  • Pt. teaching & education regarding device- literature, ECG strips, medicalert bracelets, know device- manuftr, model #

7. Discuss pertinent antiarrhythmic agents in terms of indications for use and action.

  • Adenosine             blocks ventricular impulse                   SVDysrhythmia
  • Amiodarone          blocks K+ , delays repolarization        V. tach/fib
  • Lidocaine              ↓refractory period                               PVC; v. tach/fib
  • Propranolol-beta blocker (metopropolol)
  • Diltiazem (Cardiazem)-calcium channel blocker tachy/dysrhthmias
  • Nifedipine (procardia)
  • Digoxin                 ↓conduction thru AV node                 tachy/dysrhythmias

Case Scenarios

  1. 85 yo female complaining of chest pain. Monitor shows sinus tachycardia. What interventions are indicated?
  2. 66 yo male admitted with syncope, takes digoxin and lasix for CHF. Monitor shows sinus bradycardia, 45, BP 78/40. What interventions are indicated?
  3. 58 yo male admitted with AMI, complaining of 8/10 cp. Monitor shows sinus rhythm with frequent PVCs. What interventions are indicated?
  4. 57 yo nurse who faints at her yoga class. In ED, monitor shows sinus bradycardia, rate 44. What interventions are indicated?

I. Cardiac Conduction

A.    Components

  • SA node
  • AV node
  • BB, purkinje fibers

B.     Intervals

  • Rate
  • PR interval
  • QRS duration
  • ST segment
  • QT interval

II. Nursing Responsibilities

C.     Accurate waveform

  • skin prep
  • accurate lead placement

D.    Alarms

E.     Patient education

F.      What does this dysrhythmia mean to this patient?

III. Lead Systems

A. 12-lead EKG: 12 pictures of electrical activity of the heart

B. Common Monitoring Leads:

  • Lead II:  negative electrode under right clavicle, positive electrode                      left midaxillary line, 5th ICS
  • MCL1: negative electrode below left clavicle, positive electrode                          4th ICS, right  sternum border
  • 3 lead cables: positive, negative, ground
  • 5 lead cables: right and left leg, right and left arm and chest lead

IV. Characteristics of Cardiac Monitoring

A. ECG recording:

  • horizontally:
  • *small box=0.04 sec.
  • *large box=.20 seconds
  • vertically: mm/small box

B. Electrical Events: NEED TO KNOW

  • P wave:
  • PR Interval: normal:=/<0.20 seconds
  • QRS complex: normal:=/< 0.10 seconds
  • ST segment:
  • T wave:
  • QT interval:

V. Rhythm Interpretation

A. System for strip interpretation:

  • Measure heart rate.
  • Examine the R-R interval.
  • Examine the P wave.
  • 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

  1. Myocardial factors: CAD
  2. Fluid volume abnormalities
  3. Electrolyte abnormalities
  4. Hypothermia
  5. Medications

VII. Common Arrhythmias

A. Normal Sinus rhythm: 60-100; regular; P before every QRS; normal intervals

B. Sinus bradycardia: SR with rate <60

C. Sinus tachycardia: SR with rate >100

D. Atrial fibrillation: irregularly irregular; irregular ventricular rate; wavy baseline; narrow QRS

E. PACs: early, before QRS, P looks different from sinus P

F. PVCs: early, wide and bizarre, no P before it

G. Ventricular tachycardia: wide and bizarre, regular, rate very fast, no P

H. Ventricular fibrillation: no QRS, wavy baseline

  1. Paced rhythm: ventricular, atrial or both

VIII. Antiarrhythmic Agents: goal to suppress dysrhythmia

  1. Class I: fast sodium channel blockers
    1. Class IA: procainamide
    2. Class IB: lidocaine
    3. Class IC: flecainide
  2. Class II: block effects of catecholamines: slow AV conduction; beta blockers
  3. Class III: block potassium channels; amiodarone
  4. Class IV: calcium channel blockers; verapamil
  5. Nursing action before giving these drugs:
    1. assess vital signs
    2. assess ECG
    3. physical assessment
    4. infusion pump with IV drugs
    5. patient education: reason for drug; report any dizziness, palpitations

IX. Cardioversion, Defibrillation, and Pacemakers

  1. Cardioversion:
    1. Def: delivery of electrical shock synchronized with patient’s heart rhythm;
    2. Indications: treat SVT, atrial fibrillation, & ventricular tachycardia in an unstable patient; sx hypotension, chest pain, diaphoresis, SOB, CHF, MI
    3. Nursing Actions: ECG strip before, during, and after procedure, VS, informed consent, IV access, conscious sedation, oxygen pad placement, assess for complications
  2. Defibrillation:
    1. Def: emergency procedure to treat ventricular tachycardia in unresponsive patient and ventricular fibrillation; unsynchronized
    2. Indications: cardiac arrest
    3. Nursing Actions: ECG strip cont, Pad placement, correct procedure by ACLS staff, ACLS algorithms
  3. Pacemakers
    1. Def: pulse generator used to provide electrical stimulus to the heart when it fails to conduct or generate heart rate that maintains cardiac output
    2. Types: temporary-external and percutaneous, permanent, atrial, ventricular, dual
  4. ICDs
    1. Def: implanted cardioverter/defibrillator
    2. Indications: patients with life threatening arrhythmias that does not respond to medication
    3. Nursing Action: monitor ECG, patient education

see also :

  1. 12 Lead EKG Explained: Part #1
  2. 12 Lead EKG Interpretation Part #2

About rabiah65

dedicated n humble person..

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