Dysrhythmias Identification and Pharmacologic Treatment - Exam 6 Flashcards
Which comes first: mechanical activity of the heart or electrical activity of the heart?
Electrical activity comes first.
What is automaticity?
The unique ability of the cardiac muscle cells to generate and conduct electrical activity
What is the main pacemaker of the heart?
The SA node
What is the rate of discharge of the SA node?
60-100 bpm
What is the SA node’s backup?
The AV node
What is the rate of discharge of the AV node?
If the SA node fails to fire:
40-60 bpm
What is the back up if both of the natural pacemakers of the heart fail to discharge?
Purkinje fibers
What is the rate of discharge of the perkinje fibers?
20-40 bpm
Depolarization of what takes place during the P-wave?
atrial depolarization
Depolarization of what takes place during QRS?
ventricular depolarization
What is dysrhythmia?
The absence of a rhythmic pattern. A term also commonly used to refer to any deviation from the normal pattern of the heartbeat, or dysrhythmia. May also be called arrhythmia.
What is ectopic focus?
Any cell other than the sinus node which is initiating impulses and causing myocardial depolarization
What is excitability?
Ability of cardiac cells to be electrically stimulated
What is refractory period?
Repolarization of the cardiac muscle of which the cardiac muscle is resistant to stimulation. This refractory period consists of two stages: the absolute and relative refractory period. If a stimulus is strong enough during the relative refractory period, it can cause depolarization that could lead to a lethal cardiac rhythm.
What are common causes of dysrhythmias?
- Hypovolemia
- Hypoxia
- Hydrogen ion (acidosis)
- Hypo-Hyperkalemia (Ca, Mg)
- Hypoglycemia
- Hypothermia
- Toxins (caffeine, cocaine, drugs)
- Tamponade (cardiac)
- Tension pneumothorax
- Thrombus (coronary, pulmonary)
- Trauma (hypovolemia, SNS, increase ICP)
- Thyroid disorder
In the name of a rhythm, what does the first part refer to?
The first part tells the location of the impulse
“sinus bradycardia”
sinus = impulse originates from SA node
What is normal sinus rhythm?
Sinus rhythm is the normal heart rhythm in which the electrical impulse originates from the SA node
What is the ECG criteria for normal sinus rhythm?
- 60-100 bpm
- P-P interval regular and R-R interval regular
- P wave upright, uniform and 1 P wave for every QRS complex
- PRI 0.12-0.20 second
- QRS less than or equal to 0.12 seconds. Complex is uniform
What is sinus bradycardia?
Just like sinus rhythm, sinus bradycardia the electrical impulse originates from the SA node but at a slower rate, less than 60/minute
What is the ECG criteria for sinus bradycardia?
- This may be a “normal” rhythm for an individual
- Increased vagal tone due to valsalva or vomiting
- Hypothermia
- Hypothyroidism
- Acute MI
- Increase ICP
- Result of medications
- Beta blockers
- calcium channel blockers
- Digoxin
What is the clinical assessment for SB?
- SB may not result in any changes in a patient’s hemodynamic status
- SB may cause decrease cardiac output and thus hypotension
- Orthostasis
- Mental status changes, dizziness, or syncope due to low cerebral blood flow
- SB may cause symptoms of angina or shortness of breath
What are the nursing interventions for SB?
- If no symptoms, nothing is done
- ABCs
- HOB flat
- Assess hemodynamic response and associated symptoms
- O2 possibly
- IV access
- Atropine to increase HR (IVP for symptomatic patient)
- Pacemaker
What is sinus tachycardia?
Just like sinus rhythm, in sinus tachycardia the electrical impulse originates from the SA node but at a faster rate
What is the ECG crtieria for sinus tachycarida (ST)?
- More than 100bpm
- P-P interval regular and R-R interval regular
- P wave upright, uniform, and 1 P wave for every QRS complex
- PRI 0.12-0.20 seconds
- QRS less than or equal to 0.12 seconds. Complex is uniform
What are the possible causes of sinus tachycardia?
- Exertion
- Pain
- Fever
- Increased sympathetic stimuation: caffeine, tobacco, stress
- Hypovolemia
- Anemia
- Hypoxia
- Hyperthyroidism
What is the clinical assessment for ST?
- Hemodynamic changes may result from decrease in CO related to a decrease in the stroke volume
- Symptoms depend on the rate and the overall cardiac status
- Hypotension
- Orthostasis
- Dizziness or syncope
- Dyspnea
- Development of angina due to increase workload of the heart
What are the nursing interventions for ST?
- ABCs
- Treats underlying cause
- Control pain
- Treat fever
- Decrease stress and anxiety
- Limit intake of caffeine or tabacco products
- Treatments of hypovolemia or anemia
- Meds (goal is to slow HR)
- Beta blocers
- Calcium chennel blockers
What is supraventricular tachycardia (SVT)?
The electrical impulse originates outside the SA node in an ectopic site in either atrium. The rate for SVT is between 200-300 BPM
What is the ECG criteria for SVT?
- More than 200-300 bpm
- R-R interval regular, unable to identify P-P interval
- P wave not discernible
- QRS less than or equal to 0.12 second, complexes are uniform
What are the possible causes of supraventricular tachycardia?
- Most common dysrhythmia found in children
- Over exertion
- Fever
- Pain
- Increase sympathetic stimulation due to : caffeine, tabacco, stress
- Dehydration or hypovolemia
What is the clinical assessment of SVT?
- Clinical signs in infants and children:
- Poor feeding
- Extreme irritability
- Pallor
- Weak pulses
- Hypotension
- Palpitations
- Dizziness or syncope
- Dyspnea
- Development of angina due to increase cardaic workload
What are the nursing interventions for SVT?
- Treatment of SVT depends on HR and defree of cardiac compromise. May require oxygen
- In some cases, a vagostimulation is used:
- Applying ice to face
- Carotid massage
- Having the patient bear and exhale against a closed glottis
- Medication used in the termination of the dysrhythmia includes adenosine or amiodarone
- If patient becomes hemodynacmically compromised, cardioversion may also be considered
What is the ECG criteria for premature atrial contraction?
- Rate is dependent on the underlying rhythm
- R-R interval regular, except for ectopy. P-P interval is regular due to one premature beat
- Not every P wave is uniform but there is 1 P wave to every QRS complex
- PRI 0.12-0.20 seconds
- QRS less than or equal to 0.12 seconds, complexes are uniform
What is premature atrial contraction (PAC)?
The electrical impulse originates in an irritable focus outside of the SA node. This focus electrically discharges prematurely, thus producing an ectopic beat that occurs early in the cardiac cycle.
What are the possible causes of premature atrial contraction (PAC)?
- May be benign
- Increase sympathetic stimulation due to: caffeine, tobacco, stress
- CAD
- Hypoxia
- COPD
- Valvular heart disease
What is the clinical assessment of premature atrial contractions?
- In people withh normal heart, rare PAC, are not significant
- If PAC occur in a disease heart, then PACs may be a warning sign to the development of other dysrhythmia such as Atrial Fibrillation
What are the nursing interventions for premature atrial contractions?
- Anticoagulant (coumadin)
- Beta blockers
- Control ventricular rate (slow HR)
- amiodarone
- Digoxin
What is atrial fibrillation?
The atria are so irritable that multiple foci are depolarized between 400-600 times a minute. These electrical discharges produce fibrillatory waves instead of P waves. The AV node will only allow so many impulses through to the ventricles, thus producing an irregular rhythm
What is the ECG criteria for atrial fibrillation?
- Variable rate. From 50-180 bpm. Atrial rate does not match ventricular rate
- R-R interval irregular. Irregular rhythm
- No distinct P wave seen, what is seen is a fibrillatory wave
- No PRI
- QRS less than or equal to 0.12 seconds, complexes are usually uniform
- Effect of cardiac output: uncontrolle drate greater than 100
What are the possible causes of atrial fibrillation?
- Usually occurs in patients with underlying heart disease
- Cardiomyopathy
- Heart failure
- Rheumatic heart disease
- Hypertension
- Hyperthyroidism/Grave’s Disease
- Chronic alcohol ingestion
What is the clinical assessment of atrial fibrillation?
- A fib can result in a decrease in cardiac output due to the loss of the atrial kick.The atriums are quivering and thus do not contract and this decreases the stroke volume of the ventricle.
- Patients may experience symptoms of low cardiac output, hypotension and decrease cerebral perfusion
- Irregular HR
- Palpitations
- Patients with A fib are at increased risk of developing atrial thrombi and embolic stroke
*****What are the nursing interventions for atrial fibrillation?
Goal is to control ventricular rate (less than 100) Medication includes:
Why is rate control essential even if the patient remains in atrial fibrillation (AF)?
Speaks to ability to maintain adequate CO/BP
What is premature ventricular contractions (PVC)?
The electrical impulse originates in an irritable focus within the ventricle. The irritable focus discharges prematurely and causes an early ectopic beat.
What is the ECG criteria for premature ventricular contraction?
- Rate is dependent on underlying rhythm
- R-R interval irregular, P-P interval irregular
- P waves uniform, upright, and 1 p wave for every QRS complex except for premature beat
- PRI is 0.12-0.20 seconds
- QRS less than or equal to 0.12 seconds. The premature ventricular beat is usually greater than 0.12 seconds and described as wide and bizarre and generally has a compensatory pause.
What are the possible causes of ventricular contraction?
- Electrolyte abnormalities
- Myocardial ischemia or infarction
- Heart Failure
- Increase sympathetic stimuation: caffeine, tabacco, stress
- Fever
- Hypoxia
What is the clinical assessment for premature ventricular contractions?
- Occasional PVCs are considered benign in a patient with normal heart function
- PVCs may indicate increase irritability of the heart and can possible lead to development of life threatening dysrythmias
- In patients with cardiac disease, frequent PVCs may decrease cardiac output. This may be reflective in an apical-radial pulse deficit and hypotension
- Assess for angina or chest pain symptoms
What are the nursing interventions for premature ventricular contraction?
- ABCs
- Oxygen if hypoxic
- Treat underlying cause
- Meds
- Amiodarone
- Lidocaine
lidocaine
Classficiation: antiarrhythmic
Mechanism of action: Decreased automaticity in HIs-purkinje system, increases electrical stimulation threshold of ventricles
Use: Ventricular arrythmias
Side/Adverse Effects: Resp. depression/arrest, cardiovascular collpase/arrest, conduction disorders, parasthsias, confusion
Nursing Implications:
- Monitor LOC, VS, EKG
- Stop infusion in PRI/QRS prolongation
- Watch for neurotoxic effects
- May cause heart block
amiodarone (Cordarone)
Classfication: antiarrhythmic
Mechanism of Action: Acts directly on all cardiac tissues/smooth muscles. Prolongs duration of action potential and refractory period. Decreased peripheral vascular resistance, increased coronary blood flow
Use: ventricular Dysrhythmias, Supra ventricular dysrhythmias, atrial fibrilation.
Side/Adverse Effects:
- Peripheral Neuropathy
- Sinus arrest
- Cardiogenic shock
- Heptotoxicity
- CHF
- Prolongs Pr and QT intervals
Nursing Implications:
- IV:
- Monitor VS/EKG during infusion
- Monitor resp status
- PO
- Check pulse daily
- Take drug same time daily
- Do not take with grapefruit juice
- Monitor for bradycardia if administered with beta blockers or calcium channel blockers
*
adenosine (Adenocard)
Classifcation: antiarrhythmic
Mechanism of action: slows conduction through SA/AV nodes, can interrupt re-entry pathways
Use: supraventricular tachycardia converts to NSR
Action/Adverse Effects: transient facial flushing, dyspnea, chest pain
Nursing Implications:
- Administer by rapid IV push
- Continually monitor patient’s VS/EKG during and after administration as drug causes brief period of asystole
- Emergency equipment must be at bedside
- Very short half life, administer at hub of intracatheter
atropine sulfate
Classification: antidysrhythmic, anticholinergic
Mechanism of action: blocks responses to acetylcholine, blocks vagal impulse to heart. Increases AV condustion, increases heart rate, increases PRI
Use: symptomatic sinus bradycardia
Side/adverse effects: dysrhythmias, urinary retention, blurred vision, other anticholinergic side effects
Nursing Implications:
- Monitor cardiac rhythm
- VS, I/O, CNS status
- Be prepared with emergency cart/external pacer
diltiazem (Cardizem)
Classficiation: calcium channel blocker, negative intotrope
Mechanism of action: inhibits calicum influx across myocardial and arterial smooth muscle membrane, slows SA/AV conduction
Use: IV form, rapid atrial fibrillation and SVT angina due to coronary artery spasm, HTN
Side/adverse effects: HA, edema, CHF, hypotension
Nursing Implications:
- Check BP, HR before initiating drug therapy
- Change positions slowly
- Monitor for signs symptoms of CHF peripheral edema, weight gain, I/O - monitor for rash, facial flushing
- Teach patient to avoid grapefruit
digoxin (Lanoxin)
Classficiation: cardiac glycoside, antiarrhythmic, positive inotrope
Mechanism of action: increases cardiac force of contraction while slowing conduction through AV n ode (positive inotropic effects)
Use: CHF, atrial fibrillation
Side/Adverse effects: visual disturbances (yellow/green halos around lights), narrow therapeutic index, AV block
Nursing Implications:
- Monitor VS especially HR - take apical pulse X 1 minute before dose. Hold less than 60 bpm in adults
- Baseline and periodic serum digoxin/electrolyte levels
- Monitor for toxicity (anorexia, N/V/D, visual)
What is meant by the concept of an underlying rhythm?
Baseline, usualcardiac rhythm originating from SA node. Ectopic beats superimposed on this rhythm
If your patient is having increasing numbers of PVCs, what does that tell you about the degree or irritability within the myocardium
More frequent PVCs or multifocal in nature, more irritable and more at risk for progression to VT/VF
What is the expected treatment for a patient who has ventricular tachycardia (VT) but still has a pulse?
- Treat underlying cause
- amiodarone, adenosine, lidocaine
- Cardioversion
What are the expected priority nursing interventions for a patient that has VT without a pulse or VF?
- Defibrillation
- CODE - start CPR
- Quick assessment
- Identify causes and correct
- Epinephrine or amiodarone
What is the ECG criteria for asystole?
- Life threatening rhythm that indicates there is no atrial or ventricular electrical activity
- Leads to loss of cardiac output, shock and death
- Should be seen in two cardiac leads to verify that this is not fine VF or a loose lead
What is asystole?
Total absence of electrical activity of the heart
What are the nursing interventions for asystole?
- CODE
- Initiate CPR/BLS
- Anticipate administering epinephrine IV
- It is futile to defibrillate patients in asystole as there is no electrical activity
What is pulseless electrical activity (PEA)?
- Situation in which electrical activity is observed on the cardiac monitor but there is no mechanical activity of the ventricles and the patient has no pulse
- Prognosis is poor unless the underlying cause is identified and quickly corrected
What are the nursing interventions for pulseless electrical activity (PEA)?
- CPR
- epinephrine
- CODE
- Atropine if heart starts again
What is the desired action for atrial fibrilliation, medication, and anticipated effects?
Increase the force and velocity of myocardial contraction. Slow the heart rate.
Digoxin
Decrease ventricular rate
What is the desired action for ventricular dysrhythmias, medication, and anticipated effects?
- Suppress automaticity (reduce electrical response to stiumulation of ventricles)
- Lidocaine
- Decrease ventricular ectopy
What is the desired action of ventricular dysrhythmias, SVT, atrial fibrillation?
- Acts directly on all cardiac tissues. Blocks effects of sympathetic stimulation.
- amiodarone
- Decrease ventricular and atrial ectopy
What is the desired action for SVT, medication, and anticipated effects?
- Slow conduction through the SA node and AV node. Can interrupt the reentry pathway
- adenosine
- convert tachy rhythm to SR
What is the desired action for atrial fibrillation?
- Slows SA node and AV node conduction by blocking calcium ions
- diltiazem
- decrease ventricular rate
What is the desired action for sinus bradycardia, medication, and anticipated effects?
- Blocks vagal impulses to the heart resulting in decreased AV conduction time. Increases heart rate and cardiac output.
- atropine
- Increase HR
If a regular rhthm has similar QRS complexes of normal width, you can expect that it may originate in what?
- SA node
- Atria
- AV node
What are rhythms with similar QRS complexes of normal widht?
- Normal sinus rhythm
- Sinus bradycardia
- Sinus tachycardia
- SVT
- Atrial fibrillation
- PAC
Which dysrhythmias is amiodarone used to treat?
- SVT
- Atrial fibrillation
- Prematrue ventricular tachycardia
- V. tach
- V. fib
