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68wm6 p2 Car. Dys.

Cardiac Dysrhythmias

QuestionAnswer
How does the sympathetic nervous system affect the heart rate? Speeds it up.
How does the parasympathetic nervous system affect the heart rate? Slows it down.
Define cardiac automaticity: inherent (intrinsic) ability to contract in a rhythmic pattern. Abiity of the heart to sustain its own impulses.
Define cardiac irritability: ability to respond to a stimulus.
At what rate does the SA node generate impulses? 60-100 a minute
When the impulse leaves the SA node, how does it travel through the atria? Through the bachmans bundle and internodal pathways.
At what rate can the AV node generate impulses if not recieved from the SA node? 40-60 per minute (the back-up pacemaker of the heart)
Define purkenje fibers A diffuse network of muscle fibers located just beneath the endocardium, resulting in contraction and emptying of the ventricles.
At what rate can the purkenje fibers generate impulses if not recieved from the SA and AV nodes? 20-40 per minute
The electrocardiogram gives how many views of the hearts electrical activity with how many electrodes? 12 leads(views) from 10 electrodes
What is the cardiac cycle composed of? Electrical activity caused by automaticity and the mechanical response of contraction.
What are the two phases of the ELECTRICAL activity of the heart? Depolorization and Repolarization.
What are the two phases of the MECHANICAL activity of the heart? Systole and Diastole
a 1mm square (small box) on an EKJ sheet represents how many seconds? 0.04 seconds
a 5mm section (large box) of and EKG sheet represents how many seconds? 0.20 seconds
What does the vertical axis of the EKG represent? Voltage
A 1 mm grid interval on the verticle axis represents what? 0.1 mV (one millivolt)
What is the most exact method to determin a regular rhythm using an EKG? 1500 method
What is the Positive (upward) Complex? Heart’s current flows towards the positive electrode
What is the Biphasic Complex? Heart’s current flows perpendicular to the positive electrode
What is the Negative (Downward) Complex Heart’s current flows away from the positive electrode
What are the augmented leads? Why are they called 'augmented'? aVR, aVL, and aVF. Because the ECG machine increase the voltage
Are unipolar leads positive or negative? Positive.
How many large boxes on an EKG are required to equal a full second? Five
What is the isoelectric line? The flat baseline of an EKG reading
What does the horizontal axis of an EKG represent? Time
What is the first positive deflection? The P-wave
What does the P-wave normally indicate? that the SA node initiated the impulse that depolarized the atrium
What does the PR interval measure? the time it takes for the impulse to depolarize the atria, travel to the AV node, and then dwell there briefly before entering the Bundle of His
What is the normal PR interval? 0.12 to 0.20 seconds (3-5 small boxes)
Where is the P-wave measured? from beginning of the P wave to where the QRS complex begins
What is the first negative deflection after the P-wave? The Q-wave.
True or False: If the Q-wave isnt present, it indicates a serious heart condition. False. May or may not be present
What Q-wave readings indicate a pathological condition? Pathologic if > 0.04 seconds or more than ¼ height of R wave (Seen in patients who have had MI)
What is the first positive deflection after the P-wave? The R-wave
True or False: The S-wave MUST go below the isoelectric line True.
What is the term for the waveforms that indicated ventricular depolarization QRS complex
What is the normal QRS interval? 0.06-0.12 seconds (1.5-3 small boxes)
What represents ventriculare repolarization on the EKG? The T-wave
The T-wave should be upright no greater than what? 5mm high (5 small boxes or one big box)
Changes in T wave amplitude can indicate what? electrical disturbances resulting from ELECTROLYTE IMBALANCE or MI
What can cause tall, peaked T-waves? Hyperkalemia
What can cause inverted T-waves? Ischemia or an old MI
What connects the QRS complex to the T-wave? The ST segment
True or False: The ST segment is usually isoelectric True
What can ST depression indicate? Ischemia
What can ST elevation idicate? Injury or Infarct
How is the QT interval measured? From the beginning of the QRS complex to the end of the T-wave
What does the QT interval measure? the time taken for the ventricular depolarization and repolarization
What is the normal time for a QT interval? 0.32-0.50 seconds
True or False: A fast heart rate has a long QT interval False. The slower the HR, the longer the normal QT .The faster the HR, the shorter the normal QT
What represents refractory periods of the ventricles QT interval
Systemic analysis of dysrhythmias focuses attention on what following areas *Rhythm Regularity (Rhythmicity) *Rate *Waveform Configuration and Location *Intervals
What are measured to establish atrial regularity? P-waves
What are measured to establish ventricular regularity? R-waves
What is used to calculate the APPROXIMATE rate of regular/irregular rhythms? Rule of 10
Any cardiac rhythm that deviates from normal sinus rhythm (normal conduction and intervals) is a what? Dysrhythmia
S&S and treatment of a dysrhythmia depends on what? Type and Severity
Define SupraVentricular Tachycardia (SVT): SUDDEN onset of a rapid rhythm originating above the AV node (usually in the atria)characterized by a regular rythm and a RATE of 150 - 250 bpm
What is the medical management of SVT? *Eliminate the underlying cause *Vagal maneuvers (carotid massage, increase intrathoracic pressure) *Pharmicologic cardioversion such as Adinosine *Electrical Cardioversion *radiofrequency catheter ablation
Define Atrial Fibrillation: Electrical activity in the atria is disorganized, causing the atria to fibrillate or quiver rather than contract as a unit (irregular, irregular). P-waves and PR interval not measurable, but QRS usually normal.
What leads to atrial fibrilation Widespread irritability and increased automaticity
What is the goal of therapy for atrial fibrillation? To prevent atrial thrombi from becoming embolisms.
Define atrial flutter A dysrhythmias that arises from a single irritable focus in the atria. P-waves replaced wiht multiple flutters and PR not measurable.
True or False: F-waves associated with atrial flutter are highly irregular. False. Flutter waves usually occur continually and with perfect regularity
What is the atrial rate of atrial flutters? 250-350
Are T-waves present in atrial fibrillation or in atrial flutter, or both? T-waves are found in atrial fibrillation, NOT atrial flutter.
What wave form has the appearance of 'teeth of a saw blade' and usually occur continually and with perfect regularity F-waves from atrial flutter
Who is atrial flutter most commonly seen in? patients with heart (valvular) disease
What is the treatments for atrial flutter? *Electrical cardioversion via SYNCRONIZED ELECTRIC SHOCK *Pharmacological cardioversion *Anti-coagulants/blood thinners to prevent thrombi formation in the atria.
Define AV block: Defect in the AV Node (Junction) impairs conduction of impulses from the SA node to the ventricles
What is a 1st degree AV block? Delayed conduction through the AV junction
How is a 1st degree AV block shown on an EKG? As a prolong PR interval greater than 0.20 seconds
What is the impulse rate on an EKG for a 1st degree AV block? Regular to bradycardic
Who are 1st degree AV blocks common in? the elderly and in patients with cardiac disease (Atherosclerosis, CHF)
What kind of AV block is a Wenckebach? 2nd degree: Type 1
How is a 2nd degree Type 2 block illustrated? a steadily lengthening of PR interval until the AV Node is unable to conduct one or more electrical impulses to the ventricles.
What is the rythm of a Wenckebach block? Regularly (P-P) Irregular (QRS-QRS)
What is the impulse rate of a wenckebach block? Normal (Often Sinus Bradycardia with Pause); P wave > QRS
What is the PR interval of a Wenckebach block? Progressive lengthening until QRS complex is dropped
True or False: Type 2 2nd degree AV block is the same severity as Type 2 1st degree AV block False. Mobitz II is a more severe form of AV Block
Whats another name for 2nd Degree type 1 and 2 AV blocks? Mobitz I, Mobitz II
How does the conduction delay vary between Mobitz I (wenckebach) and Mobitz II? Mobitz I (winckebach) the delay occurs ABOVE the AV node, while Mobitz II occurs BELOW (often at the bundle branches)
How does the QRS count differ between Mobitz I (wenckbach) and Mobitz II? Mobitz I (winckebach) has a regularly irregular PR lengthening and predictable QRS disappearance. Mobitz II has random QRS disappearances and PR lengthenings.
True or False: Both Mobitz I and Mobitz II have more P-waves than QRS complexes True.
What constitutes a 3rd degree AV block? Complete Heart Block, AV Dissociation
Whats the rythm of a 3rd degree AV block? P-P is regular, R-R is irregular
Whats the impulse rhythm of 3rd degree AV blocks Atrial normal, Ventrical 20-40 bpm
True or False: The T-wave is inverted in 3rd degree AV block like it is in PVC True
Medical management of a 3rd degree AV block Pacing. 1st transcutaneous, 2nd transvenous, and most likely placement of a permanent pace maker.
Define Premature Ventricular Contraction (PVC): Common ventricular dysrhythmia; the beat can be generate anywhere in the ventricles. P-waves not visible, PR interval not measurable, QRS wide >0.12 sec, T-waves inverted.
What electrolytes do you measure for in the medical management of PVC? K+ and Mg++
Define ventricular tachycardia (VT) VT is a rapid, life-threatening dysrhythmia that originates in the ventricles
What constitutes ventricular tachycardia? Three or more PVCs in a row. VT is sustained PVCs
What is the impulse rate in VT? 140-240 beats per minute
What is the QRS interval of VT? Prolonged; Wide (greater than 0.12 secs) and Bizarre
What drug toxicity can cause VT? Digitalis
Management of stable VT with pulse: Medications leading up to Synchronized Cardioversion
Management of unstable VT with pulse: Cardioversion
Management VT without pulse: Basic Life Support (BLS), DEFIBRILLATION, ACLS ASAP
Define Ventricular Fibrillation (VF): VF is a chaotic, life-threatening dysrhythmia characterized by a quivering of the ventricles that results in total loss of cardiac output (CO)
True or False: Though the heart is still trying to work, VF is still a case of clinical death. True
What drug toxicity can cause VF? Digitalis or Quinidine
Define Ventricular Standstill / Asystole: Complete cessation of all electrical activity, where a flat baseline is seen without any evidence of P, Q, R, S, or T waveforms. Ventricular standstill is also called Asystole because all contraction of the heart muscle stops
What is the treatmeant of Ventricular Standstill/ Asystole? Basic Life Support (BLS) and ACLS ASAP (Medications)
What is the mechanism of action of Adenosine and Digoxen Slows conduction through the AV node. Decreases conduction velocity and prolongs the effective refractory period in the AV node.
What are two major precautions of anti-dysrhythmic agents? *Hepatic or renal insufficiency (dosage reduction recommended if CCr <=40 ml/min). *Geri: appears on Beers list. May induce heart failure in elderly patients.
What pulse do you check before administering anti-dysrythmic medication? Apical pulse
How should PO anti-dysrhythmic medication be taken? administer medication on an empty stomach, 1 hr before or 2 hr after meals
What do you need to instruct the PT to report while taking anti-dysrhythmic medications? Facial flushing, shortness of breath, or dizziness.
If a dose of anti-dysrhythmic medication is missed, when should it be taken? as soon as remembered unless within 4 hr of next dose.
True or False: Since it is not a narcotic, Anti-Dysrhythmic drugs are safe to take while driving. False. Medications may cause dizziness.
How should vials of lidocaine for dysrhythmias read? “lidocaine for dysrhythmias” or “lidocaine without preservatives”
When MUST dysrhythmias be treated When patient has S/Sx of DECREASED CARDIAC OUTPUT.
What are some S/Sx of decreased cardiac output to indicate the need of anti-dysrhythmia drugs chest pain, SOB, decrease LOC, hypotension, pulmonary congestion, heart failure, and shock.
Explain synchronized electrical shock cardioversion. Disrupts the ectopic pacemaker that is causing the dysrhythmia and allow the SA node to take control. Used for Tachydysrhythmias
What is electric cardioversion synchronized to? Ventricular depolarization (R-wave)
Why is electric cardiversion synchronized to the R-wave. to prevent shock from being delivered during repolarization T-wave (R on T phenomenon leads to VF)
True or False: Electrical cardioversion disrupts the rythm by depolarizing the heart. False. Purpose is to disrupt the rhythm rather than completely depolarize the heart
What is the energy used for electrical cardioversion? low energy is used (50J-100J)
What mode must the defibrillator be turned to before electrical cardioversion? synchronous mode
What lead is used for observation of an eletrical cardiogram patient? Lead II
True or False: You dont need to look for any specific waves before shocking, because the purpose of the shock is to set the waves right. False. You must determine that the R-wave is properly detected since shocking on the T-wave can lead to VF.
After a pacemaker is inserted, what should be done with the affected arm? Imobilized for the first few hours after placement and the arm should not be raised above the head for several days.
Created by: Shanejqb on 2011-09-01



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