[Exam 2/NO] Chapter 26 - Management of Patients with Dysrhythmias and Conduction Problems Flashcards
Dysrhythmias: What is this
Disorders of the formation or conduction (or both) of the electrical impulse within the heart. Can be disturbance of heart rate, rhythm, or both
Dysrhythmias: How are they initially evidenced?
By hemodynamic effect they cause (change in conduction may change pumping action and decrease BP)
Dysrhythmias: How are they diagnosed?
By analyzing the electrocardiogram (ECG) waveform
Dysrhythmias: Treatment is usually based on what
the frequency and severity of symptoms produced
Dysrhythmias: How are they named?
According to their site of origin of electrical impulse and mechanism of formation involved.
Normal Electrical Conduction: What is the SA Node?
`The electrical impulse that stimulates and paces the cardiac muscle normally originates here.
Normal Electrical Conduction: Normal rate of an electrical impulse?
60-100 times a minute
Normal Electrical Conduction: What is the process of conduction?
When the electrical impulse travels from the SA node through atria to the AV node.
Normal Electrical Conduction: What does the structure of the AV node do?
Slows the electrical impulse, giving atria time to contract and fill ventricles with blood
Normal Electrical Conduction: Name for Electrical Stimulation / Mechanical Contraction?
Depolarization
Systole
Normal Electrical Conduction: Name for Electrical Relaxation / Mechanical RElaxation?
Repolarization
Diastole
Influences on HR and Contractility: Heart rate is stimulated by what?
Autonomic nervous system
Influences on HR and Contractility: What does stimulation of the sympathetic system do?
Increases HR and constricts peripheral blood vessels , therefore increasing blood pressure
Influences on HR and Contractility: What does the parasympathetic system do?
Reduces the heart rate. Results in dilation of arteries, lowering blood pressure
Influences on HR and Contractility: What may cause an increase in sympathetic stimulation?
Exercise, anxiety, fever, or dopamine
Influences on HR and Contractility: What may cause a decrease in sympathetic sitmulation?
Rest, anxiety reduction methods, and beta-adrenergic blocking agents
Obtaining an Electrocardiogram: All ECGs have what two components?
1, Adhesive substance that attaches to skin
- Substance that reduces the skins electrical impedance, enhancing conductivity
Obtaining an Electrocardiogram: What helps reduce skin impedance?
Abrading skin with clean dry gauze pad to exposed inner layer of epidermis
Obtaining an Electrocardiogram: Poor electrode adhesion will cause significant what
artifact (distorted, irrelevant ECG waveforms)
Obtaining an Electrocardiogram: Electrodes create an imaginary line called a lead which serves as what?
As a reference point form which the electrical activity is viewed.
Obtaining an Electrocardiogram: How does hardwire monitoring work?
Cardiac monitor at the patient’s beside for continuous reading, like ICU
Obtaining an Electrocardiogram: How does telemetry work?
Small box that patient carries and continuously transmits the ECG to central monitor
Obtaining an Electrocardiogram: What is an electrophysiology study?
Electrodes are placed inside the heart in order to obtain an intracardiac ECG
Obtaining an Electrocardiogram: What may be done during open heart surgery to obtain this?
Temporary pacemaker wires may be lightly sutured to the epicardium and brought to chest wall.
Obtaining an Electrocardiogram: What is included in the standard 12-lead ECG?
10 electrodes (6 on the chest, and 4 on the limbs).
Obtaining an Electrocardiogram: Where are limb electrodes placed?
On areas that are not bony and do not have significant movement.
Obtaining an Electrocardiogram: Limb electrodes provide the first what?
Six leads. Leads include I, II, III, aVR, aVL, and aVF
Obtaining an Electrocardiogram: How do you locate V1?
Locate the fourth intercostal space, and then place at sternal angle
Obtaining an Electrocardiogram: What are the locations of the five leads?
V1 is below the fourth intercostal. V2 crossed the sternum. V3 flows down and the rest go around the bottom of the breast.
Obtaining an Electrocardiogram: Standard 12-lead ECG reflects electrical activity of what
the left ventricle
Components of ECG: Offers important information abut what
electrical activity of the heart and is useful in diagosing dysrhythmias
Components of ECG: What is measured on horizontal and vertical axis?
Horizontal: Time and rate
Vertical: Amplitude or voltage.
Components of ECG: What is a positive deflection?
When the waveform moves toward the top of the paper
Components of ECG: What is a negative deflection?
When the waveform moves toward the bottom of the paper.
Components of ECG: ECG is composed of what waveforms?
P Wave
QRS Complex
T Wave
Possible U Wave
Components of ECG: ECG is composed of what segments and intervals?
PR Interval
ST Segment
QT Interval
Components of ECG: P Wave represents what?
Impulse starting in SA node and spreading through atria. Is atrial depolarization
Components of ECG: How long does P Wave last and how high?
0.11 seconds or less, and is 2.5 mm or less in height
Components of ECG: What does the QRS complex represent?
Ventricular depolarization.
Components of ECG: Information to know about Q wave?
First negative deflaction after P. Less than 0.04 seconds, and less than 25% of R amplitude
Components of ECG: Information to know about R wave?
First positive deflection after P wave.
Components of ECG: Informaiton to know about S wavE?
First negative deflection after the R wave.
Components of ECG: What to do when QRS wave is less than 5 mm?
Use small letters of qrs
Components of ECG: What to do when QRS wave is greater than 5 mm?
Use capital letters , QRS
Components of ECG: How long is the QRS wave usually?
< 0.12 seconds
Components of ECG: What to know about T waave?
Ventricular repolarization (cells regain negative charge, resting state). Follows QRS.
Components of ECG: Why is atrial repolarization not visible?
Not visible during T wave because occurs at same time as ventricular depolarization
Components of ECG: What to know about U wave?
Represents repolarization of Purkinje fibers. Appears with hypokalemia, hypertension, or heart disease. Follows T wave, smaller than P wave.
Components of ECG: What is the PR interval?
Measured from beginning of P wave to beginning of QRS. Represents time needed for sinus node stimulation, atrial depolarizations.
Components of ECG: Normal PR time length?
0.12 to 0.20 seconds
Components of ECG: What does the ST segment represent?
Early ventricular repolarizations, lasting from end of QRS to beginning of T wave.
Components of ECG: Beginning of ST segment identified by what?
Change in thickness or terminal portion of QRS complex.
Components of ECG: Why is the ST segment normally analyzed?
To identify whether it is above or below the isoelectric line, which is a sign of cardiac ischemia
Components of ECG: What is the QT interval?
Total time for ventricular depolarization and repolarization. Lasts 0.32 - 0.40 seconds if heart between 65 - 95 bpm.
Components of ECG: What may happen if meds prolong the QT interval?
Place the patient at risk for a leth ventricular dysrhythmias called torsades de pointes.
Components of ECG: What happens when theres no electrical activity in TP interval?
Isoelectric line, graph remains flat.
Components of ECG: PP interval is used to determine what?
Atrial rate and rhythm.
Components of ECG: RR interval is measures from what?
From one QRS complex to the next. Determine ventricular rate and rhythm
Analyzng ECG Rhythm Strip: This must be analyzed to determine what?
Patients cardiac rate and rhythm, and to detect dysrhythmias and conduction disorders.
Determining HR from ECG: East and accurate way to determine this?
Count number of small boxes within an RR interval,and divide 1500 by that number. Determines beats per minute.
Determine Heart Rhythm from ECG: What is used to identify ventricular and atrial rhythm?
Ventricular: RR Interval
Atrial: PP Interval
Determine Heart Rhythm from ECG: What is used to determine whether rhythm is regular or irregular?
If difference between them is less than or greater than 0.8 seconds
Normal Sinus Rhythm: This has what characteristics?
Rate Rhythm QRS Shape P Wave PR Interval P:QRS Ratio
RatE: 60-100 Rhythm: Regular QRS Shape: Normal P Wave: Normal Shape, in front of QRS PR Interval: 0.12-0.20 seconds P:QRS Ratio - 1:1
Sinus Node Dysrhythmias - Sinus Bradycardia: When does this occur?
When the SA node creates an impulse at a slower-than-normal rate
Sinus Node Dysrhythmias - Sinus Bradycardia: Causes of this?
Lower metabolic needs, vagal stimulation, medications, and increased intracranial pressure.
Sinus Node Dysrhythmias - Sinus Bradycardia: Unstable and symptomatic bradycardai due to what
Hypoxemia, AMS, and acute decompensated heart failure
Sinus Node Dysrhythmias - Sinus Bradycardia: Characteristics of this?
Rate Rhythm QRS Shape P Wave Pr Interval P:QRS
Rate: < 60 bpm Rhythm: Regular QRS Shape: Usually normal P Wave: Normal, always in front of QRS PR Interval: 0.12-0.20 P:QRS Ratio - 1:1
Sinus Node Dysrhythmias - Sinus Bradycardia: What to do HR decrease caused by vagus nerve?
Try to prevent bearing down during defecation, and other attempts to prevent this
Sinus Node Dysrhythmias - Sinus Bradycardia: What risk factors does sick sinus syndrome include?
Age, white race, obesity, hypertension, lower hr
Sinus Node Dysrhythmias - Sinus Bradycardia: What is tachy-brady syndrome?
When bradycardia alternates with tachycardia
Sinus Node Dysrhythmias - Sinus Bradycardia Med Mx: What may be given if bradycardia produces signs of clinical instability?
0.5 mg of atropine via IV bolus every 3-5 mins until max dosage of 3 mg given.
Sinus Node Dysrhythmias - Sinus Tachycardia: When does this happen?
When the sinus node creates an impulse at a faster-than-normal rate
Sinus Node Dysrhythmias - Sinus Tachycardia: What are some physiologic causes?
Acute blood loss, anemia, shock, hypervolemia, hypovolemia, heart failure, pain, fever, exercise
Sinus Node Dysrhythmias - Sinus Tachycardia: What are some meds that can cause this?
Sitmulats and illicit drugs
Sinus Node Dysrhythmias - Sinus Tachycardia: What is inapprorpiate sinus tachycardia?
Enhanced use of SA node or excessive sympathetic tone with reduced parasympathetic tone out of proprortion to demands
Sinus Node Dysrhythmias - Sinus Tachycardia: What is an autonomic dysfunction?
Type of sinus tachycardia known as postural orthostatic tachycardia syndrome, which is tachycardia without hypotension until they stand.
Sinus Node Dysrhythmias - Sinus Tachycardia: Characteristics of this?
Rate Rhythm Shape P Wave PR Interval P:QRS Ratio
Rate: > 100 but < 120 Rhythm: Regular QRS: Normal, but regularly abnormal P Wave: In front of QRS, but may be buried in preceding T Wave PR Interval: Between 0.12-0.20 P:QRS Ratio: 1:1
Sinus Node Dysrhythmias - Sinus Tachycardia: What happens to the heart as heart rate increases?
Diastolic filling time decreases, reducing CO and producing symptoms of low blood pressure . Acute pulmonary edema may develop .
Sinus Node Dysrhythmias - Sinus Tachycardia Med Mx: Treatment of choice if persistent and causing hemodynamic instability?
Synchronized cardioversion.
Sinus Node Dysrhythmias - Sinus Tachycardia Med Mx: What can help interrupt tachycardia?
Vagal maneuvers like carotid sinus massage, gagging, bearing down, forceful coughing, or applying cold stimulus to face or admin of Adenosine.
Sinus Node Dysrhythmias - Sinus Tachycardia Med Mx: What is given for narrow QRS?
Beta blockers and calcium channel blockers.
Sinus Node Dysrhythmias - Sinus Tachycardia Med Mx: What is given for wide QRS?
Adenosine.
Sinus Node Dysrhythmias - Sinus Arrhythmia: When does this occur?
When the sinus node creates an impulse at an irregular rhythm, increasing with inspiration and decreasing with expiration.
Sinus Node Dysrhythmias - Sinus Arrhythmia: Nonrespiratory causes include what?
Heart disease and valcular disease.
Sinus Node Dysrhythmias - Sinus Arrhythmia: Characteristics of this?
Rate, Rhythm Duration P WAve PR Interval P:QRS Ration
Rate: 60-100 bpm Rhythm: Irregular QRS Shape: Regularly abnormal P Wave: Always in front of QRS PR Interval: 0.12-0.20 P:QRS Ratio: 1:1
Sinus Node Dysrhythmias - Sinus Arrhythmia Med Mx: What is done to treat?
Does not cause any significant hemodynamic effect and therefore not typically treated
Atrial Dysrhythmias: These originate from where?
Foci within the atria and not the SA node.
Atrial Dysrhythmias - Premature Atrial Complex: What is this?
A Single ECG complex that occurs when an electrical impulse starts in the atrium before the next normal impulse of the sinus node
Atrial Dysrhythmias - Premature Atrial Complex: This may be caused by what?
Caffeine, alcohol, nicotine, stretched atrial myocardium , anxiety, hypokalemia or infarction
Atrial Dysrhythmias - Premature Atrial Complex: Characteristics of this?
Rate Rhythm QRS Shape P Wave PR Interval P:QRS Ratio
Rate: Depends on underlying rhythm (sinus tachycardia)
Rate: Irregular due to early P waves, creating short PP Interval
QRS Shape: Follows teh early P Wave
P Wave: May be early or hidden in T Wave
Pr Interval: 0.12-0.20 seconds, but early P wave has shorter PR interval
P:QRS Ratio: 1:1
Atrial Dysrhythmias - Premature Atrial Complex: What may the patient complain of?
My heart skipped a beat, which there being a pulse deficit
Atrial Dysrhythmias - Premature Atrial Complex Medical Mx: What to do if they are frequent?
This may be a sign of worsening disease state or onset of more serious dysrhythmias, liek atrial fibrillation. Treat underlying cause.
Atrial Dysrhythmias - Atrial Fibrillation: What does this result from?
Abnormal impulse formation that occurs when structural or electrophysiological abnormalities alter atrial tissue, cuasing rapid, disorganized, uncoordinated twitching.
Atrial Dysrhythmias - Atrial Fibrillation: What systems play an important role here?
Extrinsic (central) and intrinsic crdiac autonomic nervous sytems (CANS)
Atrial Dysrhythmias - Atrial Fibrillation: What do hyperactive autonomic ganglia in CANS play a role in?
Atrial finrilation, resulting in impulses that are initiated from pulmonary veins.
Atrial Dysrhythmias - Atrial Fibrillation: Characteristics of this?
Rate Rhythm QRS Shape P Wave PR Interval P:QRS Ratio
Rate: Atrial - 300-600 bpm and Ventricular is 120-200
Rhythm - Irrregular QRS Shape: May be abnormal P Wave: No discernible P Waves PR Interval: Can't be measured P:QRS - Many:1
Atrial Dysrhythmias - Atrial Fibrillation: These people are at an increased risk for what?
Heart failure, MI, and Embolic Events like stroke
Atrial Dysrhythmias - Atrial Fibrillation: What does a rapid and irregular ventricular response cause?
Reduces time for ventricular filling, resulting in smaller stroke volume. Some experiernce palpitations and CMs of HF (SOB, hypotension, dyspnea)
Atrial Dysrhythmias - Atrial Fibrillation: These patients may exhibit a pulse deficit, which is what?
Numeric difference between apical and radial pulse rates.
Atrial Dysrhythmias - Atrial Fibrillation: Erratic nature of atrial contraction, alterations in ventricular ejection, and atrial myocardial dysfunction promote formation of what
thrombi, espeically within left atrium.
Atrial Dysrhythmias - Atrial Fibrillation , Assess/Diagnostic Finding: Why is 12-lead ECG performed?
To verify the atrial fibrillation rhythm, and also identify the presence of left ventricular hypertrophy
Atrial Dysrhythmias - Atrial Fibrillation , Assess/Diagnostic Finding: What can a transthoracic echocardiogram (TEE) identify?
Presence of valvular heart disease, provide information about left ventricular (LV) and right ventricaular (RV) size and function
Atrial Dysrhythmias - Atrial Fibrillation , Assess/Diagnostic Finding: Blood tests to screen for diseases that are known to cause atral fibrillation?
Thyroid, renal, and hepatic functions .
Atrial Dysrhythmias - Atrial Fibrillation Med Mx: What may happen if nothing is done for treatment?
Spontaneously converts to sinus rhythm within 24-48 hours and without treatment
Atrial Dysrhythmias - Atrial Fibrillation Med Mx: This revolves around what?
Preventing embolic events such as stroke with antithrombotic drugs , controlling the ventricular rate of response
Atrial Dysrhythmias - Atrial Fibrillation, Antithrombotic Meds: What drugs may this include?
Anticoagulants and antiplatelet drugs.
Atrial Dysrhythmias - Atrial Fibrillation, Antithrombotic Meds: Patients with a low stroke risk may be placed on what med therapy?
Aspirin therapy dosed at 75-325 mg daily