basic dysrhythmia interpretation rev.02

Basic Dysrhythmia Interpretation Rev.02.20

This Photo by Unknown Author is licensed under CC BY-NC

http://anestesiar.org/2013/sqtl-sindrome-qt-largo-y-anestesia/

https://creativecommons.org/licenses/by-nc/3.0/

Properties of Cardiac Cells

• Automaticity• Excitability• Conductivity• Contractility

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Conduction System of the Heart


Autonomic Nervous SystemSympathetic Nervous System [Adrenergic]

• Increases SA node rate• Increases force of

contraction• Increases impulse

conduction of AV node

Parasympathetic Nervous System [Vagal]

• Decreases SA node rate

• Slows AV impulse conduction

• Decreases force of contraction

Dysrhythmias

• Disorder of impulse formation, conduction or both

• Primary pacemaker • SA node(60–100 beats/minute)

• Secondary pacemakers• AV node (40–60 beats/minute)• His-Purkinje fibers (20–40 beats/minute)


Case Study

• S.D. is a 45-year-old woman who comes to the ED c/o:• sudden onset of palpitations • shortness of breath

• Standard protocol:• obtain a 12-lead ECG and attach S.D. to

the cardiac monitor for continuous monitoring.

iStockphoto/Thinkstock


Case Study

• Demonstrate the correct placement for :

• 5 or 3 lead system• 12- lead ECG.• MCL-1 and Lead II



Practice Alert - ST Segment Monitoring 8

Skin Preparation

• Clip excessive hair before

• Clean skin with alcohol, washcloth, or dry gauze to remove skin oils and/or debris

• Mark locations with indelible ink

Lead Placement


• Right Arm (RA) infra-clavicular fossa close to right shoulder

• Left Arm (LA) infra-clavicular fossa close to left shoulder

• Left Leg (LL) below rib cage on left side of abdomen

• Ground (RL)

Lead Placement


• Limb leads (I,II,III) place to decrease muscle artifact during limb movement

• Precordial Leads - depends on patient’s needs

12-Lead ECG


6 leads frontal plane (leads I, II, III, aVR, aVL, and aVF) 6 leads (V1–V6) horizontal plane

(precordial leads)

Common monitoring leads: II, V1, MCL-1

Electrocardiogram Monitoring


EKG Waveforms

• P wave=• Atrial depolarization• Normally small positive (+) deflection, can be

negative (-)

• QRS Complex=• Ventricular depolarization (stimulation)

• ST segment, T wave, U wave=• Ventricular repolarization (recovery)

EKG Waveforms

• P-R interval• Time from initial stimulation of the atria to initial

stimulation of the ventricles

• Measured from the beginning of the P wave to the beginning of the QRS complex

• Normal 0.12-0.20

• Prolonged when delay through AV junction >0.20 sec = 1st degree AV block

EKG Waveforms

• QRS Complex• Spread of stimulus through the ventricles

• Normal ≤ 0.12 seconds

• If conduction slowed through the ventricles, the QRS is prolonged

• Q wave- 1st negative deflection(-), below the baseline• R wave – 1st positive deflection, above baseline• S wave – 1st negative deflection after R wave

EKG Waveforms

• T Wave• Recovery period after stimulation

• Absolute- occurs when excitability is zero and heart tissue cannot be stimulated

• Relative- occurs slightly later & excitability is possible

EKG Waveforms

• QT Interval• Measured from beginning of QRS complex to end of T

wave

• Return to the resting state

• Normal values depend on the heart rate:• éHR (R-R interval shortens) → QT normally shortens

• ê HR (R-R interval lengthens) QT interval lengthens

• Normally ≤ 0.44sec• prolonged by drugs ex?

ECG Time and Voltage


Calculating HR

• Rate=• # QRS complexes in 1 minute • R-R intervals in 6 seconds strip, X 10• 300/# of large boxes between R-waves• 1500/# small boxes between R waves• Memorize:

• 300, 150, 100, 75, 60, 50, 43, 37• Count at each large box after first R


EKG Interpretation

• Normal rate 60-100• <60 bpm - bradycardia• >100 bpm – tachycardia

• Basic pacing rates: • Atria 80 bpm• Junctional 40-60 bpm• Ventricular 20-40 bpm

Assessment of Cardiac Rhythm


Artifact


Assessment Steps of Cardiac Rhythm

• Interpret the rhythm • Patient hemodynamically stable?• Determine cause of dysrhythmia• Treat the patient, not the monitor!


Case Study

• The UAP obtains the 12-lead ECG recording for S.D. while you print out a rhythm strip from the cardiac monitor.

• Describe the method you would use to assess S.D.’s rhythm strip?



Normal Sinus Rhythm

• Sinus node (60–100 beats/minute)• normal conduction pattern


Sinus Bradycardia


Sinus Bradycardia

• aerobically trained athletes and during sleep=normal

• Response to parasympathetic nerve stimulation and certain drugs

• Disease states


Sinus Bradycardia

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


Sinus Bradycardia

• Treatment• Atropine• Pacemaker• Stop offending drugs


A patient’s cardiac rhythm is sinus bradycardia with a heart rate of 34 beats/minute. If the bradycardia is symptomatic, the nurse would expect the patient to exhibita. Palpitations. b. Hypertension.c. Warm, flushed skin.d. Shortness of breath.

Audience Response Question


Sinus Tachycardia


Sinus Tachycardia

• Vagal inhibition or sympathetic stimulation

• Physiologic and psychologic stressors

• Drugs


Sinus Tachycardia

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


Sinus Tachycardia

• Treatment• Guided by cause (e.g., treat pain)• Vagal maneuver• β-adrenergic blockers


Premature Atrial Contraction (PAC)



• Contraction originating from ectopic focus in atrium

• Travels across atria by abnormal pathway = distorted P wave

• stopped, delayed, or conducted normally at the AV node



• Causes• Stress• Fatigue• Caffeine• Tobacco• Alcohol• Hypoxia• Electrolyte imbalance• Disease states


Premature Atrial Contraction

• Manifestations• Palpitations• Heart “skips a beat”

• Treatment• Monitor for more serious dysrhythmias• Withhold sources of stimulation• β-adrenergic blockers


Paroxysmal Supraventricular Tachycardia (PSVT)



• Reentrant phenomenon: PAC triggers a run of repeated premature beats

• Paroxysmal = abrupt onset and termination

• Causes:• Overexertion• Stress• deep inspiration• Stimulants• Disease• digitalis toxicity




• Manifestations• HR is 150–220 beats/minute • HR > 180 leads to decreased cardiac

output and stroke volume• Hypotension• Dyspnea• Angina


• Treatment• Vagal stimulation• IV adenosine• IV β-adrenergic blockers • Calcium channel blockers• Amiodarone• DC cardioversion


Atrial Flutter


Atrial Flutter

• Associated w/disease• ventricular rate>100 and loss of atrial

“kick” → decreased CO → heart failure• Increases risk of stroke


Atrial Flutter

• Treatment • Pharmacologic agent• Electrical cardioversion• Radiofrequency ablation


Case Study

• S.D.’s ECG reveals atrial fibrillation with a rapid ventricular response (HR = 168).

• Describe what S.D.’s rhythm would look like.

• What might be the cause of this dysrhythmia for S.D.?



Atrial Fibrillation


Atrial Fibrillation

• Paroxysmal or persistent• Most common dysrhythmia• Prevalence increases with age• underlying heart disease • other disease states


Case Study

• S.D.’s blood pressure is 94/58 with HR of 168.

• What treatment might you expect the health care provider to initially order for S.D.’s atrial fibrillation?



Radiofrequency Catheter Ablation Therapy

• Burn or ablate• Non-pharmacologic

treatment of choice

• Post-care • similar to cardiac

catheterization


Junctional Dysrhythmias

• originate in area of AV node• SA node has failed, or impulse blocked • AV node becomes pacer—retrograde

transmission of impulse to atria• Abnormal P wave; normal QRS• Causes: disease, certain drugs


Junctional Dysrhythmias


Junctional Dysrhythmia

• Serves as safety mechanism—do not suppress

• rapid= reduction of CO • Tx symptomatic:

• Atropine for escape rhythm• Correct cause• Drugs to reduce rate


First-Degree AV Block


First-Degree AV Block

• Disease states and certain drugs• Typically not serious• Patients asymptomatic• No treatment• Monitor for changes in heart rhythm


Premature Ventricular Contractions


Premature Ventricular Contractions

Causes: • stimulants• electrolyte imbalances• hypoxia• heart disease

• Treatment• Correct cause• Antidysrhythmics


A patient has a diagnosis of acute myocardial infarction, and his cardiac rhythm is sinus bradycardia with 6 to 8 premature ventricular contractions (PVCs) per minute. The pattern that the nurse recognizes as the most characteristic of PVCs is

a. An irregular rhythm.b. An inverted T wave.c. A wide, distorted QRS complex.d. An increasingly long P-R interval.



Ventricular Tachycardia


Ventricular Tachycardia

• Ectopic foci take over as pacemaker• Monomorphic, polymorphic,

sustained, and non-sustained• life-threatening low CO

ventricular fibrillation


Ventricular TachycardiaTorsades de Pointes


Ventricular TachycardiaAssociated with:• heart disease• electrolyte imbalances• Drugs• CNS disorder

Assess: • stable (pulse) vs. unstable (pulseless)• Sustained VT vs. Non-sustain • cause


Ventricular TachycardiaVT with pulse (stable)

Tx: • Antidysrhythmics• cardioversion

VT Pulseless

Tx: • CPR • ACLS protocol

defibrillation < 3min

(AHA, 2015 updates) handout



2015 updates

C-A-B- A-B-C

Ventricular Fibrillation


Ventricular Fibrillation

• Associated :• MI• ischemia• disease states• Procedures

Findings: Unresponsive, pulseless, and apneic

• Tx : CPR and ACLS• Defibrillation• Drug therapy (epinephrine*)


A patient in the coronary care unit develops ventricular fibrillation. The first action the nurse should take is to

a. Perform defibrillation. b. Initiate cardiopulmonary resuscitation.c. Prepare for synchronized cardioversion.d. Administer IV antidysrhythmic drugs per protocol.



Asystole

• Total absence of ventricular electrical activity • No ventricular contraction

Causes: • advanced cardiac disease• severe conduction disturbance• end-stage HF

• Findings: unresponsive, pulseless, apneic


Asystole

• Tx:• Assess rhythm in more than one lead• CPR and ACLS measures

• Epinephrine • Intubation

• Poor prognosis


Pulseless Electrical Activity

• Electrical activity on the ECG monitor, but no mechanical activity of the ventricles = no pulse

• Prognosis is poor

• What underlying causes should the nurse analyze?


Pulseless Electrical Activity

• Treatment• CPR • Intubation • IV epinephrine• Correct the underlying cause


Sudden Cardiac Death (SCD)

• Death from a cardiac cause• Ventricular tachycardia• Ventricular fibrillation

• TX: ICD


Defibrillation

• Passage of DC electrical shock through the heart to depolarize cells of myocardium

• SA node resumes pacemaker • Treatment of choice for VF and

pulseless VT• Onset 2 min


Defibrillation

A. Monophasic

• deliver energy in one direction

• Monophasic: 360 joules• Immediate CPR after

first shock•

B. Biphasic

• deliver energy in two directions• Use lower energies • Fewer postshock

ECG abnormalities• Biphasic: 120 to

200 joules • Immediate CPR

after first shock


Defibrillation


Defibrillation

1. Start CPR while setting up defibrillator2. Turn on 3. Apply defib patches4. Make sure sync button is turned off5. Select energy6. Charge7. Ensure “All clear”!!!!!8. Deliver charge9. Continue CPR


Case Study

• S.D. was admitted to the telemetry unit and an IV amiodarone drip was started.

• The purpose of the drug was to convert her atrial fibrillation to normal sinus rhythm.



Case Study

• Although her heart rate has decreased to 108 beats/minute, she remains in atrial fibrillation 24 hours later.

• A cardiologist was consulted and electrical cardioversion is planned.



Case Study

• What would you teach S.D. about the scheduled procedure?

• What are three differences between defibrillation and cardioversion?



Synchronized CardioversionProcedure

• Consent patient• Sedation if stable• Place Pads• sync button turned ON• Initial energy lower

• 50-100 joules (biphasic)• 100 joules (monophasic)

• If patient becomes pulseless, turn sync button OFF and defibrillate


Implantable Cardioverter-Defibrillator (ICD)

• Appropriate for patients who• survived SCD• spontaneous sustained VT• syncope with inducible ventricular

tachycardia/fibrillation during EPS• high risk for future life-threatening dysrhythmias

• Decreases mortality rate• Pre/post –procedure care same as pacemaker



• Variety of emotions• Fear of body image change• Fear of recurrent dysrhythmias• Expectation of pain with ICD discharge • Anxiety about going home

• Nsg care: support group Teaching patient and caregiver


Pacemaker


Pacemakers

• Pace atrium and/or one or both of ventricles

• 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


Pacemaker Spike


Pacemakers

• Cardiac resynchronization therapy (CRT)• Resynchronizes the cardiac cycle by

pacing both ventricles• Biventricular pacing• TX: heart failure• ICD maximum therapy


Temporary Pacemakers

• Power source outside the body • Transvenous • Epicardial • Transcutaneous


Temporary Transvenous Pacemaker


Epicardial Pacing

• Leads placed on epicardium during heart surgery

• Passed through chest wall and attached to external power source as needed


Transcutaneous Pacing

• Emergent pacing needs • Non-invasive• Bridge until transvenous pacer can be

inserted• Use lowest current that will “capture”• analgesia/sedation


Transcutaneous Pacing

Fig 10-9. Anterioposterior placement of adhesive electrode pads for defibrillation or transcutaneous pacing. From: Sole et al. Introduction to Critical Care Nursing, 5th Edition. W.B. Saunders


Pacemakers Malfunction • Failure to sense

• Causes inappropriate firing

• Failure to capture • Lack of pacing

Pacemakers

• Monitor for other complications• Infection• Hematoma formation• Pneumothorax• Atrial or ventricular septum perforation• Lead misplacement


Pacemakers

• Post-procedure care• OOB once stable• Limit arm and shoulder activity• Ice and Sandbag x 4hrs• Monitor insertion site (bleeding ,

swelling, infection)• Patient teaching important


Case Study

• S.D.’s electrical cardioversion was successful.

• S.D.’s sinus rhythm has remained stable for 24 hours and she is ready to go home.

• As you enter her room to provide discharge teaching, she tells you she is experiencing some chest “heaviness and tightness right under her breast bone.”



Case Study

• You ask the UAP to obtain a 12-lead ECG while you notify S.D.’s health care provider.

• What specific ECG change will you be looking for to determine if S.D.’s chest pain is related to cardiac:

• ischemia? • Injury?• Infarction?



Changes Associated With Myocardial Ischemia


Changes Associated With Injury


Changes Associated With Infarction


ECG Changes Associated With Acute Coronary Syndrome (ACS)


ECG Finding With Anterolateral Wall MI


Syncope

• Brief lapse in consciousness accompanied by a loss in postural tone (fainting)

• Cause: Cardiovascular vs non-• Cardioneurogenic or “vasovagal”

• Carotid sinus sensitivity


Syncope

• Diagnostic studies• Echocardiography• Stress test• EPS• Head-up, tilt test

• assess cardioneurogenic syncope• + results = paradoxic vasodilation and

bradycardia (vasovagal response)


Diagnostic Studies- CXR

Fig. 32-12

Diagnostic Studies-Echo


basic dysrhythmia interpretation rev.02

Documents