Dysrhythmias Chapter

Transcription

1 Dysrhythmias Chapter Copyright 2014 by Mosby, an imprint of Elsevier Inc.

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

3 Properties of Cardiac Cells Automaticity Excitability Conductivity Contractility

4 Conduction System of the Heart

5 Autonomic Nervous System Sympathetic Nervous System [Adrenergic] Parasympathetic Nervous System [Vagal] Increases SA node rate Increases force of contraction Increases impulse conduction of AV node Decreases SA node rate Slows AV impulse conduction Decreases force of contraction

6 Dysrhythmias Disorder of impulse formation, conduction or both Primary pacemaker SA node( beats/minute) Secondary pacemakers AV node (40 60 beats/minute) His-Purkinje fibers (20 40 beats/minute)

7 Electrocardiogram Monitoring

8

9 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)

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

11 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- 1 st negative deflection(-), below the baseline R wave 1 st positive deflection, above baseline S wave 1 st negative deflection after R wave

12 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

13 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?

14 12-Lead ECG 6 leads frontal plane (leads I, II, III, avr, avl, and avf) 6 leads (V 1 V 6 ) horizontal plane (precordial leads) Common monitoring leads: II, V1, MCL-1

15 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

16 Case Study istockphoto/thinkstock Demonstrate the appropriate location to apply the leads for : 5-lead cardiac monitor 12- lead ECG.

17 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 PracPce Alert - ST Segment Monitoring 17

18 Lead Placement Right Arm (RA) infraclavicular fossa close to right shoulder Left Arm (LA) infraclavicular fossa close to left shoulder Left Leg (LL) below rib cage on left side of abdomen Ground (RL)

19 Lead Placement Limb leads (I,II,III) place to decrease muscle artifact during limb movement Precordial Leads - depends on patient s needs

20 ECG Time and Voltage

21 Calculating HR Rate= # QRS complexes in 1 minute R-R intervals in 6 seconds strip, X /# 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

22 EKG Interpretation Normal rate <60 bpm - bradycardia >100 bpm tachycardia Basic pacing rates: Atria 80 bpm Junctional bpm Ventricular bpm

23 Assessment of Cardiac Rhythm

24 Artifact

25 Assessment Steps of Cardiac Rhythm Interpret the rhythm Patient hemodynamically stable? Determine cause of dysrhythmia Treat the patient, not the monitor!

26 Case Study istockphoto/thinkstock 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?

27 Normal Sinus Rhythm Sinus node ( beats/minute) normal conduction pattern

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29 Sinus Bradycardia

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31 Sinus Bradycardia aerobically trained athletes and during sleep=normal Response to parasympathetic nerve stimulation and certain drugs Disease states

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

33 Sinus Bradycardia Treatment Atropine Pacemaker Stop offending drugs

34 Audience Response Ques4on 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 exhibit a. Palpitations. b. Hypertension. c. Warm, flushed skin. d. Shortness of breath.

35 Sinus Tachycardia

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37 Sinus Tachycardia Vagal inhibition or sympathetic stimulation Physiologic and psychologic stressors Drugs can

38 Sinus Tachycardia Manifestations Dizziness Dyspnea Hypotension Angina in patients with CAD

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

40 Premature Atrial Contraction

41 Premature Atrial Contraction 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

42 Premature Atrial Contraction Causes Stress Fatigue Caffeine Tobacco Alcohol Hypoxia Electrolyte imbalance Disease states

43 Premature Atrial Contraction Manifestations Palpitations Heart skips a beat Treatment Monitor for more serious dysrhythmias Withhold sources of stimulation β-adrenergic blockers

44 Paroxysmal Supraventricular Tachycardia (PSVT)

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46 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

47 Paroxysmal Supraventricular Manifestations Tachycardia (PSVT) HR is beats/minute HR > 180 leads to decreased cardiac output and stroke volume Hypotension Dyspnea Angina

48 Paroxysmal Supraventricular Tachycardia (PSVT) Treatment Vagal stimulation IV adenosine IV β-adrenergic blockers Calcium channel blockers Amiodarone DC cardioversion

49 Atrial Flutter

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51 Atrial Flutter Associated w/disease ventricular rate>100 and loss of atrial kick decreased CO heart failure Increases risk of stroke

52 Atrial Flutter Treatment Pharmacologic agent Electrical cardioversion Radiofrequency ablation

53 Case Study S.D. s ECG reveals atrial fibrillation with a rapid ventricular response (HR = 168). istockphoto/thinkstock Describe what S.D. s rhythm would look like. What might be the cause of this dysrhythmia for S.D.?

54 Atrial Fibrillation

55 Atrial Fibrillation Paroxysmal or persistent Most common dysrhythmia Prevalence increases with age underlying heart disease other disease states

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57 Case Study istockphoto/thinkstock 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?

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59 Atrial Fibrillation As with atrial flutter causes a decrease in CO and an increased risk of stroke

60 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

61 Junctional Dysrhythmias

62 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

63 First-Degree AV Block

64 First-Degree AV Block Disease states and certain drugs Typically not serious Patients asymptomatic No treatment Monitor for changes in heart rhythm

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66 Premature Ventricular Contractions Copyright 2014 by Mosby, an imprint of Elsevier Inc.

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69 Premature Ventricular Contractions Causes: stimulants electrolyte imbalances hypoxia heart disease Treatment Correct cause Antidysrhythmics

70 Audience Response Ques4on 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.

71 Ventricular Tachycardia

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73 Ventricular Tachycardia Ectopic foci take over as pacemaker Monomorphic, polymorphic, sustained, and non-sustained life-threatening low CO ventricular fibrillation

74 Ventricular Tachycardia Torsades de Pointes

75 Ventricular Tachycardia Associated with: heart disease electrolyte imbalances Drugs CNS disorder Assess: stable (pulse) vs. unstable (pulseless) Sustained VT vs. Non-sustain cause

76 Ventricular Tachycardia VT with pulse (stable) VT Pulseless Tx: Antidysrhythmics cardioversion Tx: CPR ACLS protocol defibrillation < 3min (AHA, 2015 updates) handout Copyright 2014 by Mosby, an imprint of Elsevier Inc.

77 C-A-B- A-B-C 2015 updates Copyright 2014 by Mosby, an imprint of Elsevier Inc.

78 Accelerated Idioventricular Rhythm (AIVR) intrinsic pacemaker rate (SA node or AV node) becomes less than that of ventricular ectopic pacemaker Rate beats/minute Cause: reperfusion or dig tox Treatment: Atropine if symptomatic Temporary pacing Do not suppress rhythm

79 Ventricular Fibrillation

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81 Ventricular Fibrillation Associated : MI ischemia disease states Procedures Findings: Unresponsive, pulseless, and apneic Tx : CPR and ACLS Defibrillation Drug therapy (epinephrine*)

82 Audience Response Ques4on 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.

83 Asystole Total absence of ventricular electrical activity No ventricular contraction Causes: advanced cardiac disease severe conduction disturbance end-stage HF Findings: unresponsive, pulseless, apneic

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85 Asystole Tx: Assess rhythm in more than one lead CPR and ACLS measures Epinephrine Intubation Poor prognosis

86 Pulseless Electrical Activity Electrical activity on the ECG monitor, but no mechanical activity of the ventricles = no pulse Prognosis is poor What are underlying causes?

87 Pulseless Electrical Activity Treatment CPR Intubation IV epinephrine Correct the underlying cause

88 Sudden Cardiac Death (SCD) Death from a cardiac cause Ventricular tachycardia Ventricular fibrillation TX: ICD

89 Prodysrhythmia Life-threatening dysrhythmias Causes: antidysrhythmia drugs (Digoxin and class IA, IC, and III ) Risk: Severe LV dysfunction Most susceptible first few days of drug therapy

90 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

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

92 Defibrillation

93 Defibrillation 1. Start CPR while setting up defibrillator 2. Turn on 3. select energy 4. Make sure sync button is turned off 5. Apply gel pads 6. Charge 7. Position paddles firmly on chest 8. Ensure All clear!!!!! 9. Deliver charge

94 Case Study S.D. was admitted to the telemetry unit and an IV amiodarone drip was started. istockphoto/thinkstock The purpose of the drug was to convert her atrial fibrillation to normal sinus rhythm.

95 Case Study istockphoto/thinkstock 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.

96 Case Study istockphoto/thinkstock What would you teach S.D. about the scheduled procedure? What are three differences between defibrillation and cardioversion?

97 Synchronized Cardioversion Procedure Consent patient patient stable, sedate prior Place Pads sync button turned ON Initial energy lower joules (biphasic) 100 joules (monophasic) If patient becomes pulseless, turn sync button OFF and defibrillate

98 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

99 Implantable Cardioverter- Defibrillator (ICD)

100 Implantable Cardioverter- Defibrillator (ICD) Variety of emotions are possible Fear of body image change Fear of recurrent dysrhythmias Expectation of pain with ICD discharge Anxiety about going home Nsg care: support group

101 Implantable Cardioverter- Defibrillator (ICD) Pa4ent and Caregiver Teaching (T-36-10) 1. Follow-up appointments 2. Incision care 3. Arm restrictions 4. Sexual activity 5. Driving 6. Avoid direct blows 7. Avoid large magnets, MRI

102 8. Air travel Implantable Cardioverter- Defibrillator (ICD) Pa4ent and Caregiver Teaching 9. Avoid antitheft devices 10. What to do if ICD fires 11. Medic Alert ID 12. ICD identification card 13. Caregivers to learn CPR

103 Pacemaker

104 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

105 Pacemaker Spike

106 Pacemakers Antitachycardia pacing: stimulus to the ventricle to terminate tachydysrhythmias Overdrive pacing: pacing the atrium at rates of impulses/minute to terminate atrial tachycardias

107 Pacemakers Cardiac resynchronization therapy (CRT) Resynchronizes the cardiac cycle by pacing both ventricles Biventricular pacing TX: heart failure ICD maximum therapy

108 Temporary Pacemakers Power source outside the body Transvenous Epicardial Transcutaneous

109 Temporary Transvenous Pacemaker

110 Epicardial Pacing Leads placed on epicardium during heart surgery Passed through chest wall and attached to external power source as needed

111 Transcutaneous Pacing Emergent pacing needs Non-invasive Bridge until transvenous pacer can be inserted Use lowest current that will capture analgesia/sedation

112 Transcutaneous Pacing Fig Anterioposterior placement of adhesive electrode pads for defibrillapon or transcutaneous pacing. From: Sole et al. Introduc)on to Cri)cal Care Nursing, 5th Edi)on. W.B. Saunders

113 Temporary Pacemaker

114 Pacemakers ECG monitoring for malfunction Failure to sense Causes inappropriate firing Failure to capture Lack of pacing

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

116 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

117 Pacemakers Pa4ent and Caregiver Teaching Follow-up appointments for pacemaker function checks Incision care Arm restrictions Avoid direct blows Avoid high-output generator No MRIs unless pacer approved Microwaves OK Avoid antitheft devices Air travel Monitor pulse Pacemaker ID card Medic Alert ID

118 Radiofrequency Catheter Ablation Therapy Electrode-tipped ablation catheter burns accessory pathways or ectopic sites in the atria, AV node, and ventricles Non-pharmacologic treatment of choice for several atrial dysrhythmias Post-care similar to cardiac catheterization

119 Case Study S.D. s electrical cardioversion was successful. istockphoto/thinkstock 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.

120 Case Study istockphoto/thinkstock 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?

121 Changes Associated With Myocardial Ischemia

122 Changes Associated With Injury

123 Changes Associated With Infarction

124 ECG Changes Associated With Acute Coronary Syndrome (ACS)

125 ECG Finding With Anterolateral Wall MI

126 Syncope Brief lapse in consciousness accompanied by a loss in postural tone (fainting) Cause: Cardiovascular vs non- Cardioneurogenic or vasovagal Carotid sinus sensitivity

127 Syncope Diagnostic studies Echocardiography Stress test EPS Head-up, tilt test assess cardioneurogenic syncope + results = paradoxic vasodilation and bradycardia (vasovagal response)