NURS 310 Chapter 36 Dysrhythmias

Paroxysmal Supraventricular Tachycardia: treatment

-Vagal stimulation -IV adenosine -IV β-blockers -Calcium channel blockers -Amiodarone -DC cardioversion if no other effective therapy

Sinus tachycardia

-caused by vagal inhibition or sympathetic stimulation -Associated with physiologic and psychologic stressors -drugs can increase rate - 100 to 200 bpm

Telemetry Monitoring: two types

-centralized monitoring system -advanced alarm system alerts when it detects dysrhythmias, ischemia or infarction

Premature atrial contraction

-contraction originating from ectopic focus in atrium in location other that SA node -travels across atria by abnormal pathway, creating distorted P wave -May be stopped or delayed, or conducted normally at the AV node

Premature Ventricular contractions: treatment

-correct causu-e -antidysrhythmics

Sinus tachycardia: manifestations

-dizziness -dyspnea -hypotension -angina in pt with CAD

Electrocardiogram Monitoring (ECG)

-graphic tracing of electrical impulses -waveforms of ECG represents activity of charged ions across membranes of myocardial cells

Sinus tachycardia: treatment

-guided by cause (treat pain) -vagal maneuver - B-blockers

sinus bradycardia: manifestations

-hypotension -pale, cool skin -angina -dizziness or syncope -confusion -SOB

Sinus bradycardia

-normal rhythm in aerobically trained athletes and during sleep -can occur in response to parasympathetic nerve stimulation

Calculating HR

-number of QRS complexes in 1 minute -R-R intervals in 6 seconds, and multiply by 10

premature atrial contraction: manifestations

-palpitations -heart "skips a beat"

premature atrial contraction: treatment

-patient with healthy hearts (not serious): monitor for more serious dysrhythmias; withhold sources of stimulation; B-blockers

Paroxysmal Supraventricular tachycardia (PSVT)

-reentrant phenomenon: PAC triggers a run of repeated premature beats -paroxysmal refers to an abrupt onset and termination -Associated with overexertion, stress, deep inspiration, stimulants, disease, digitalis toxicity

Secondary pacemakers

-AV node (40-60 beats/minute) -His-purkinje fibers (20-40 beats/minute)

Ventricular Fibrillation

-Associated with MI, ischemia, disease states, procedures -Unresponsive, pulseless, and apneic -If not treated rapidly, death will result -Treat with immediate CPR and ACLS: Defibrillation Drug therapy (epinephrine, vasopressin)

First-degree AV block

-Associated with disease states and certain drugs -Typically not serious -Patients asymptomatic -No treatment -Monitor for changes in heart rhythm PR > .20

Second-Degree AV Block, Type 2 (Mobitz II)

-Associated with heart disease and drug toxicity -Often progressive and results in decreased CO -Treat with pacemaker

Third-Degree AV Heart Block (Complete Heart Block)

-Associated with severe heart disease, some systemic diseases, certain drugs -Usually results in decreased CO -Can lead to syncope, HF, shock -Treat with pacemaker -Drugs to increase heart rate if needed while awaiting pacing

Premature Ventricular Contractions

-Associated with stimulants, electrolyte imbalances, hypoxia, heart disease -Not harmful with normal heart but CO reduction, angina, and HF in diseased heart -Assess apical-radial pulse deficit

sinus bradycardia: treatment

-Atropine -Pacemaker -Stop offending drugs (narcotics)

Pulseless Electrical Activity: Treatment

-CPR followed by intubation and IV epinephrine -Treatment is directed toward correction of the underlying cause

Implantable Cardioverter-Defibrillator (ICD)

-Consists of a lead system placed via subclavian vein to the endocardium -Sensing system monitors HR and rhythm - delivering 25 joules or less to heart when detects lethal dysrhythmia

Sudden Cardiac Death (SCD)

-Death from a cardiac cause -Majority of SCDs result from ventricular dysrhythmias

Accelerated Idioventricular Rhythm (AIVR)

-Develops when the intrinsic pacemaker rate (SA node or AV node) becomes less than that of ventricular ectopic pacemaker -Rate is between 40 and 100 beats/minute -Atropine if patient symptomatic -Temporary pacing -Do not suppress rhythm

Atrial fibrillation: treatment

-Drugs to control ventricular rate and/or convert to sinus rhythm (amiodarone and ibutilide most common) -Electrical cardioversion -Anticoagulation -Radiofrequency ablation -Maze procedure with cryoablation

Junctional dysrhythmias

-Dysrhythmias that originate in the AV junction -SA node has failed to fire, or impulse has been blocked at the AV node -AV node becomes pacer—retrograde transmission of impulse to atria -Abnormal P wave; normal QRS -Associated with disease, certain drugs

Ventricular tachycardia

-Ectopic foci take over as pacemaker -Monomorphic, polymorphic, sustained, and nonsustained -Considered life-threatening because of decreased CO and the possibility of deterioration to ventricular fibrillation

Pulseless Electrical Activity

-Electrical activity can be observed on the ECG, but no mechanical activity of the heart is evident, and the patient has no pulse -Prognosis is poor unless underlying cause quickly identified and treated

Radiofrequency Catheter Ablation Therapy

-Electrode-tipped ablation catheter "burns" accessory pathways or ectopic sites in the atria, AV node, and ventricles -Nonpharmacologic treatment of choice for several atrial dysrhythmias -Postcare similar to cardiac catheterization

Paroxysmal Supraventricular Tachycardia: manifestations

-HR is 150-220 beats/minute -Originates from ectopic focus above Bundle of HIS -HR > 180 leads to decreased cardiac output and stroke volume -Hypotension -Dyspnea -Angina

Implantable Cardioverter-Defibrillator (ICD): appropriate for what patients

-Have survived SCD -Have spontaneous sustained VT -Have syncope with inducible ventricular tachycardia/fibrillation during EPS -Are at high risk for future life-threatening dysrhythmias

Second-Degree AV Block, Type 1 (Mobitz I, Wenckebach)

-May result from drugs or CAD -Typically associated with ischemia -Usually transient and well tolerated -Treat if symptomatic: Atropine Pacemaker -If asymptomatic, monitor closely

Atrial fibrillation

-Paroxysmal or persistent -Most common dysrhythmia -Prevalence increases with age -Usually occurs in patients with underlying heart disease -Can also occur with other disease states

Atrial flutter: treatment

-Pharmacologic agent -Electrical cardioversion -Radiofrequency ablation

Asystole

-Represents total absence of ventricular electrical activity -No ventricular contraction -Patient unresponsive, pulseless, apneic -Must assess in more than one lead -Usually result of advanced cardiac disease, severe conduction disturbance, or end-stage HF -poor prognosis

Ischemia

-ST-segment depression and/or T wave inversion -ST-segment depression is significant if it is at least 1 mm (one small box) below the isoelectric line -Changes reverse when adequate blood flow is restored to myocardium

Premature atrial contraction: causes

-Stress -Fatigue -Caffeine -Tobacco -Alcohol -Hypoxia -Electrolyte imbalance -Disease states

Synchronized Cardioversion

-Synchronized circuit delivers a countershock on the R wave of the QRS complex of the ECG -Choice of therapy for ventricular ( VT with a pulse) or supraventricular tachydysrhythmias

systole: treatment

-Treat with immediate CPR and ACLS measures: Epinephrine and/or vasopressin Intubation -DO NOT SHOCK THEM!!!

Defibrillation

-Treatment of choice for VF and pulseless VTAllows -SA node to resume pacemaker role -immediate CPR after first shock

Atrial flutter

-Typically associated with disease -Symptoms result from high ventricular rate and loss of atrial "kick" → decreased CO → heart failure -Increases risk of stroke (???) -Atrial rate 200-350 bpm - Ventricular 2:1, 3:1, 4:1

Pacemakers

-Used to pace the heart when the normal conduction pathway is damaged -Pace atrium and/or one or both of ventricles -Most pace on demand, firing only when HR drops below preset rate

A patient in the coronary care unit develops ventricular fibrillation. The first action the nurse should take is to A. Perform defibrillation. (this would be the second step because this is not usually in the room) B. Initiate cardiopulmonary resuscitation. C. Prepare for synchronized cardioversion. D. Administer IV antidysrhythmic drugs per protocol.

B. Initiate cardiopulmonary resuscitation

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 PR interval.

C. a wide, distorted QRS complex

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. (in this situation it would be hypotension) C. Warm, flushed skin. (skin would be pale in this situation) D. Shortness of breath.

D. Shortness of breath

SA node

Normal pacemaker of heart (60-100 beats/minute)

infarction

Physiologic Q wave is the first negative deflection following the P wave

Temporary Pacemakers

Power source outside the body: transvenous; epicardial; transcutaneous

Junctional dysrhythmias: Treatment

Treat if patient is symptomatic: Atropine for escape rhythm, Correct cause, Drugs to reduce rate if tachycardia

Pacemakers: Antitachycardia pacing

delivery of a stimulus to the ventricle to terminate tachydysrhythmias

Dysrhythmias

disorder of impulse formation, conduction of impulses, or both

Telemetry Monitoring

observation of HR and rhythms at a distant site

Pacemakers: Overdrive pacing

pacing the atrium at rates of 200-500 impulses/minute to terminate atrial tachycardias