Download Dysrhythmia Basic Test Answers: A Comprehensive Guide to Cardiac Rhythms - Prof. purdul and more Exams Nursing in PDF only on Docsity!
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dysrhythmia aka arrhythmia - Correct answer - abnormal cardiac rhythms which can cause disturbances of: rate, rhythm, or both rate and rhythm how are dysrhythmias identified? - Correct answer Electrographic Waveform Analysis (ECG) what controls the rate and rhythm of the heartbeat? - Correct answer the heart's electrical system explain the heart's electrical system - Correct answer Each electrical signal (impulse) begins in a group of cells called the sinus node or sinoatrial (SA) node. The SA node is located in the right atrium. In a healthy adult heart at rest, the SA node sends an electrical signal to begin a new heartbeat 60 to 100 times a minute. (This rate may be slower in very fit athletes.) From the SA node, the electrical signal travels through the right and left atria. It causes the atria to contract and pump blood into the ventricles. The electrical signal then moves down to a group of cells called the atrioventricular (AV) node, located between the atria and the ventricles. Here, the signal slows down slightly, allowing the ventricles time to finish filling with blood. The electrical signal then leaves the AV node and travels to the ventricles. It causes the ventricles to contract and pump blood to the lungs and the rest of the body. The ventricles then relax, and the heartbeat process starts all over again in the SA node. normal sinus rhythm (characteristics) - Correct answer 1. Rate:60-100 beats/min Rhythm: regular
- P wave: upright .06-.12 sec
- PR interval: .12-.20 sec
- QRS complex: <.03 sec Sinus Bradycardia - Correct answer in sinus bradycardia, the conduction pathway is the same but the impulse generates in the SA node slower than usual causing a slowed heart rate > -symptomatic sinus bradycardia refers to a HR >60 and is inadequate for the patients condition causing symptoms sinus bradycardia (ECG characteristics) - Correct answer 1. Rate: < 60 beats/min
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Rhythm: regular
- P wave: Normal
- PR interval: Normal
- QRS complex: Normal sinus bradycardia clinical associations - Correct answer 1. may be a normal in ATHLETES and during SLEEP
- occurs in response to: carotid sinus massage Valsalva maneuver hypothermia increased intraocular pressure vagal stimulation and certain drugs ( Bblockers, Ca channel blockers)
- disease states associated with it: hypothyroidism increased intracranial pressure hypoglycemia inferior MI Sinus Bradycardia: Clinical Significance - Correct answer clinical significance of sinus bradycardia depends on how the pt tolerates it. S&S of symptomatic sinus bradycardia include: pale, cool skin hypotension weakness angina dizziness/syncope confusion/disorientation shortness of breath treatment for symptomatic sinus bradycardia - Correct answer atropine (anticholinergic) transcutaneous pacing dopamine/epinephrine infusion permanent pacemaker
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-HR varies with underlying rate and frequencies of the PAC, and the rhythm is irregular. P wave has a different shape from the P wave that originates from SA node, or it may be hidden in the preceding T wave. PR interval may be shorter or longer but its within normal limits. QRS is usually normal. If the QRS is .12 sec or more, abnormal conduction through the ventricles occurs
- treatment: no stimulants such as caffeine, maybe a Bblocker Premature Atrial Contraction (ECG characteristics) - Correct answer 1. Rate:60- beats/min Rhythm: Irregular
- P wave: Abnormal shape
- PR interval: Normal
- QRS complex: Normal (usually) --> can be longer causing abnormal conduction through ventricles but when the impulse moves through the AV node it is in most cases conducted normally through the ventricles ** main thing to know is that Rate is normal -P wave is abnormal and rhythm is irregular **premature contraction shows a whole new impulse graph which occurs too soon. PAC: clinical associations - Correct answer a) emotional stress or fatigue or b) from use of: caffeine tobacco or alcohol c) also can result from: hypoxia electrolyte imbalances disease states (ex: hyperthyroidism, COPD, heart disease) PAC: clinical significance - Correct answer --> in persons with healthy hearts, isolated PACs are not significant -pts may report palpations or that their hearts "skipped a beat" --> in persons with heart disease, frequent PACs may indicate enhanced automaticity of the atria or a reentry mechanism. Such PACs may warn of or start more serious dysrhythmias
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ectopic focus - Correct answer pacemaker location other the SA node vagal stimulation - Correct answer response caused by stimulation of right vagus nerve. After transmission excitation of the Parasympathetic ganglia ACh is released in the SA node which causes slowing or stopping of the heart. -rate of depolarization is decreased vagal maneuvers: -Valsalva maneuver -carotid massage -coughing ganglia - Correct answer An anatomically distinct collection of sensory or motor neuron cell bodies within the Peripheral NS vagus nerve - Correct answer 10th cranial nerve -interfaces with autonomic parasympathetic control of the heart and the GI tract PSVT - Correct answer -dysrhythmia starting at in ectopic focus anywhere above the bifurcation of the bundle of His -In PSVT, abnormal conduction of that electricity causes the atrium, and secondarily the ventricles, to beat very rapidly. -It is referred to as paroxysmal, because the rapid rate can occur sporadically and without warning and may also stop on its own -The rapid heartbeat may last a few seconds or many hours. Often the PSVT resolves before the patient reaches a health care professional. -In many patients with PSVT, there is a "wiring" problem in the AV node and instead of having just one pathway for electricity to travel to the ventricle, there are two. This allows electricity to circle back and cause the atrium to beat more quickly than it should normally. -PSVT is one of many electrical abnormalities that cause the atrium to beat too quickly. -termination may result in systole for a brief period PSVT: clinical associations - Correct answer --> in normal heart PSVT is associated with: overexertion emotional stress deep inspiration and stimulants --> also associated with rheumatic heart disease, digitalis toxicity, CAD and or cor pulmonale
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-in AFL, the atria (upper chambers) of the heart beat too fast, which results in atrial muscle contractions that are faster than and out of sync with the lower chambers (ventricles) -the impulse travels in the atria in an organized circular motion or "circuit" in the atria, causing the atria to beat faster than the ventricles -AV node can delay signals to ventricles, so there is usually some AV blocks in a fixed ratio of flutter waves to QRS complexes Atrial Flutter clinical associations - Correct answer -->rarely occurs in a healthy heart associated with: CAD, HTN, mitral valve disorders, pulmonary embolus, chorine lung disease, hyperthyroidism, cardiomyopathy, corpulmonale, and use of drugs such as digoxin, quinidine, and epinephrine Atrial Flutter characteristics - Correct answer -atrial rate is 200- 350. -ventricular rate is based on conduction ratio. --> In 2:1 conduction, the ventricular rate is typically ~ 150. -Atrial rhythm is regular, and ventricular rhythm is usually regular. -The atrial flutter waves represent atrial depolarization followed by repolarization. -The PR interval is variable and not measurable. The QRS complex is usually normal. -Bc the AV node can delay signals from the atria, there is usually some AV block in a fixed ratio of flutter waves to QRS complexes. supraventricular - Correct answer means above the ventricles so afib and a flutter are these as well Atrial Flutter vs Atrial Fibrillation - Correct answer similar but -in AFib, the heart beats fast and in no regular pattern or rhythm. -with AFL, the heart beats fast, but in a regular pattern. The fast but regular pattern of AFL is what makes it special. makes a very distance sawtooth pattern on ECG -at times, atrial flutter and Afib may coesxit -both include reentry of the impulse in the atria but atrial flutter is a systematic circuit and Afib is a chaotic reentry pathway
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reentry rhythm - Correct answer Re-entrant arrhythmias occur when an electrical impulse recurrently travels in a tight circle within the heart, rather than moving from one end of the heart to the other and then stopping classifying arrhythmias - Correct answer -by rate (normal sinus rhythm, tachycardia, bradycardia) or mechanism (automaticity, reentry, junctional, fibrillation) -During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. what is atrial flutter caused by? - Correct answer -caused by a reentrant rhythm in either the right or left atrium. -For each cycle around the loop, there results an electric impulse that propagates through the atria. Atrial Flutter clinical significance - Correct answer the higher ventricular rates (>100) and loss of atrial "kick" (contraction) that are associated with AFL decreases CO (cardiac output) -this can cause serious consequences such as HF -patients with AFL have an increased risk of stroke bc of the risk or thrombus formation in the atria from the stasis blood -warfarin is given to prevent stroke in patients with AFL cardiac output - Correct answer (mL blood/min) -The volume of blood the heart (ventricles) pump through the circulatory system in a minute. -The amount of blood put out by the LEFT VENTRICLE of the heart in one contraction is called the STROKE VOLUME. -The stroke volume and the heart rate determine the cardiac output. A normal adult has a cardiac output of 4.7 liters (5 quarts) of blood per minute. CO= stroke volume X HR Since the heart is a 'demand pump', that pumps out whatever blood comes back into it from the venous system, it is effectively the amount of blood returning to the heart that determines how much blood the heart pumps out (CO). Atrial Flutter Treatment - Correct answer primary goal: slow the ventricular response by increasing AV block. -drugs used to control ventricular rate include: calcium channel blockers and Beta-adrenergic blockers
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HF
pericarditis --> often develops acutely with thyrotoxicosis, alcohol intoxication, caffeine use, electrolyte imbalance, stress, cardiac surgery AFIB: ECG characteristics - Correct answer -during fibrillation, atrial rate may be as high as 350-600 beats/min -P waves are replaced by chaotic fibrillary (f) waves -ventricular rate varies and the rhythm is usually irregular -when ventricular rate is between 60-100 it is atrial fibrillation with a "controlled ventricular response" -atrial fibrillation with ventricular rate >100 is AFib with a "rapid (or uncontrolled, ) ventricular response. -The PR interval is not measurable A) Rate/Rhythm: Atrial: 350-600 / Regular Ventricular: > or < 100 / may be regular or irregular B) P wave : Fibrillatory (f) waves C) PR interval: not measurable D) QRS complex: normal (usually ) Afib (AHA) - Correct answer -multiple ectopic foci -may be paroxysmal (beginning and ending spontaneously, or persistent ( >7 days) -in Afib the atria beat irregularly (quiver) instead of beating effectively to move blood into the ventricles -In AF, the normal regular electrical impulses generated by the sinoatrial node in the right atrium of the heart are overwhelmed by disorganized electrical impulses usually originating in the roots of the pulmonary veins (left atrium), ectopic foci -This leads to irregular conduction of ventricular impulses that generate the heartbeat. AF may occur in episodes lasting from minutes to days (paroxysmal AF) or may be permanent in nature (persistent). -Many medical conditions increase the risk of AF, in particular mitral stenosis (narrowing of the mitral valve of the heart). --> -In AF, the heart's electrical signals don't begin in the SA node. Instead, they begin in another part of the atria or in the nearby pulmonary veins. The signals don't travel normally. They may spread throughout the atria in a rapid, disorganized way. This can cause the atria to fibrillate. Signal re circulates through atrium but in a chaotic path
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-The faulty signals flood the AV node with electrical impulses. As a result, the ventricles also begin to beat very fast. However, the AV node can't send the signals to the ventricles as fast as they arrive. So, even though the ventricles are beating faster than normal, they aren't beating as fast as the atria. [controlled or uncontrolled ventricular response ] -controlled ventricular response: ventricular contraction is 60-100 /min -uncontrolled ventricular response: ventricles contract more than 100 beats/ min -Thus, the atria and ventricles no longer beat in a coordinated way. This creates a fast and irregular heart rhythm. when does Afib occur? - Correct answer AF occurs if rapid, disorganized electrical signals cause the heart's two upper chambers—called the atria- to fibrillate fibrillate - Correct answer The term "fibrillate" means to contract very fast and irregularly Atrial Fibrillation: Clinical significance - Correct answer Fib results in a decrease in CO bc of ineffective atrial contractions (loss of atrial kick) and/or a rapid ventricular response. -Thrombi (clots) form in the atria bc of blood stasis. an emboli zed clot may develop and move to the brain, causing a stroke. -Afib accounts for as many as 17% of all strokes Afib: treatment - Correct answer -->goals:
- a decrease in ventricular response (to <100), -ventricular rate control is a priority for its with Afib, drugs for rate control include Ca channel blockers, Bblockers, digoxin
- prevention of stroke long term anticoagulants (warfarin) if rhythm can't be restored
- and conversion to sinus rhythm, if possible. (pharmacologic = amiodarone and ibutilide) or electrical conversion of Afib.. this mat convert Afib to a normal sinus rhythm radiofrequency catheter ablation Maze Procedure sinus rhythm: 5 criteria - Correct answer Sinus rhythm, commonly referred to as 'normal sinus rhythm", is designated as the normal rhythm of the heart. Several requirements must be met for an ECG to be classified as normal sinus rhythm. Criteria for a normal sinus rhythm include:
- A heart rate of 60-100 beats per minute.
- Regularity—Regular
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-these dysrhythmias are treated according to the pts tolerance of the rhythm and the pts clinical condition Junctional Dysrhythmias: Clinical association - Correct answer associated with: CAD HR Cardiomyopathy electrolyte imbalance inferior MI rheumatic heart disease
- certain drugs (stimulants) can also cause junctional dysrhythmias rheumatic heart disease - Correct answer characterized by repeated inflammation with fibrinous repair Junctional Dysrhythmias: clinical significance - Correct answer -Junctional Escape Rhythms serve as a back up when SA node has not been effective. should not be suppressed. -Accelerated Junctional Rhythm is due to sympathetic stimulation to improve CO
- Junctional Tachycardia indicates a more serious problem. This rhythm may reduce CO, causing the pt to become hemodynamically unstable (ex: hypotension) Junctional Dysrhythmias: ECG - Correct answer A) Rate:
- Junctional Escape Rhythm Rate: 40-
- Accelerated Junctional Rhythm Rate: 61-
- Junctional Tachycardia Rate: 101- B) Rhythm is regular C) P wave: abnormal in shape and inverted, or may be hidden in QRS D) PR Interval: <.12 when P wave precedes QRS E) QRS complex: usually normal precede - Correct answer (verb) to come before Junctional Dysrhymia's: treatment - Correct answer varies according to type of junctional dysrhythmia -if a pt has symptoms with a junctional escape rhythm, atropine can be used
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-accelerated junctional rhythm/ junctional tachycardia caused by drug toxicity, the drug is stopped. In absence of digitalis toxicity, B Blockers, Ca channel blockers, and amiodarone are used for rate control. Cardioversion should NOT be used First degree AV block - Correct answer every impulse is conducted to the ventricles but the time of AV conduction is prolonged (This causes the prolonged PR interval). -After impulse moves through AV node, the ventricles usually respond normally. First degree AV block: clinical associations - Correct answer MI CAD rheumatic fever hyperthyroidism electrolyte imbalance vagal stimulation drugs (ex: digoxin, Bblockers, Ca channel blockers) First degree AV block: clinical significance - Correct answer -not usually serious but can be a sign of higher degrees of AV block. -pts are Asymptomatic -no treatment First degree AV block: ECG - Correct answer PR prolonged (>.20) bc of prolonged conduction of AV node Second degree AV block - Correct answer type 1: Mobitz or Wenkeback heart block (SVT) and type 2: Mobits II heart block third degree AV block - Correct answer complete heart block -no impulses from atria are conducted to the ventricles
- the atria are stimulated and contract independently of ventricles -the ventricle rhythm is an escape rhythm and the ectopic pacemaker may be above or below the bifurcation of the budge of His -atrial rate and rhythm: regular but may appear irregular due to p waves hidden in QRS complexes -ventricular rate/rhythm: 20-60 beats/min and regular -PR variable -QRS: normal (if an escape rhythm is initiated at the bundle of his or above) or widened (if initiated below bundle of his
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-treatment: atropine to increase HR, temporary pacemaker nonconductive - Correct answer not able to conduct heat or electricity or sound Second Degree AV block type I (Mobitz II) - Correct answer -almost always a disease of the distal conduction system (His-Purkinje System). -characterized on a surface ECG by intermittently nonconducted P waves not preceded by PR prolongation and not followed by PR shortening Secondary AV block type II - Correct answer -P wave is non conducted w/o progressive PR lengthening. This usually occurs in a block in one of the bundle branches is present -PR interval normal or prolonged but fixed
- more serious than type I -a certain number of impulses from SA node are not conducted to ventricles impulse, this occurs in fixed ratios of 2:1, 3:1 and so on) [there is usually a fixed number of non-conducted P waves for every successfully conducted QRS complex] -variable blocked QRS complexes -so more P waves than QRS (ex 2:1, 3:1, etc) -QRS complex is usually greater than .12 bc of bundle branch block -QRS on ECG: Widened QRS complex, preceded by 2 or more P waves, with non conducted (blocked) QRS complex -Atrial rhythm is regular but ventricle rhythm may be irregular Premature Ventricular Contraction (PVC) - Correct answer -a PVC is a contraction originating from an ectopic focus in the ventricles
- it is the premature (early) occurrence of a QRS complex.
- a PVC (QRS) is wide and distorted in shape (lasting more that .12 sec) -QRS wide and distorted bc impulse is generated from an ectopic foci or focus -PVC Rate/Rhythm: HR varies according to intrinsic rate and number of PVCs. Rhythm is irregular bc of premature beats -P wave is rarely visible and is usually lost in QRS complex -retrograde conduction may occur and the P wave may be seen after the ectopic beat -PR interval not measurable -T wave is generally large and opposite in direction to the major direction of QRS complex types od PVCs - Correct answer -->Types of PVCs
- Multifocal PVCs: PVCs that arise from different foci appear different in shape from each other and are called "multifocal PVCs"
- Unifocal PVCs: PVC's that have the same shape are called "unifocal PVCs".
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- Ventricular bigeminy: when every other beat is a PVC the rhythm is called Ventricular bigeminy
- Ventricular trigeminy: when every 3rd beat is a PVC
- Couplet: two consecutive PVCs
- Ventricular tachycardia (VT): occurs when there are 3 or more consecutive PVCs. --> R-on-T phenomenon: occurs when a PVC falls on the T wave of a preceding beat. Dangerous bc the PVC is firing during the relative refractory phase of the ventricular repolarization. Excitability of the cardiac cells increases during this time, and the risk for the PVC to start VT or ventricular fibrillation (VF) is great bigeminy - Correct answer -(Latin: bi-two, gemini-twins) is a descriptor for a heart arrhythmia in which there is a continuous alternation of long and short heart beats. Most -Most often this is due to ectopic heart beats occurring so frequently that there is one after each sinus beat, typically premature ventricular contractions (PVCs). For example, a sinus beat is shortly followed by a PVC, then followed by a pause. The normal beat then returns, only to be followed by another PVC PVC: clinical Associations - Correct answer -associated with: stimulants electrolyte imbalance hypoxia fever exercise emotional distress -disease states associated with PVCs are: MI Mitral valve prolapse HF CAD PVC: clinical significance - Correct answer -usually not harmful in a pt with a normal heart. -in disease hearts, PVCs may reduce CO and lead to angina and HF -- Bc PVCs in CAD or acute MI indicate ventricular irritability, the patients physiological response to PVC should be assessed
- -obtain patients apical-radial pulse rate, since PVCs often do not generate a sufficient ventricular contraction to result in peripheral pulse. This can lead to a pulse deficit.
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-rhythm irregular or regular -AV dissociation may be present, with P waves occurring independently of QRS complex -atria may be polarized in a retrograde fashion by ventricles -P wave usually buried in QRS complex -PR not measurable -QRS distorted and wide (>.12) -T wave in opposite direction of QRS complex Forms of VT - Correct answer -depend on QRS configuration
- monomorphic VT
- Polymorphic VT
- Torsades de pointes VT monomorphic VT - Correct answer has QRS complexes that are the same in size, shape, and direction Polymorphic VT - Correct answer occurs when the QRS complexes gradually change back and forth from one shape, size, and direction to another over a series of beats Torsades De Pointes VT - Correct answer -french for "twisting of the points"
- a polymorphic VT associated with a prolonged QT interval of the underlying rhythm VT characteristics - Correct answer -may be sustained (longer than 30 seconds) or non sustained (less than 30 seconds)
- the development of VT is an ominous sign, its life threatening bc of decreased CO and the possibility of the development of VF, which is lethal VT: clinical associations - Correct answer --> associated with: MI CAD significant electrolyte imbalances cardiomyopathy mitral valve prolapse long QT syndrome drug toxicity CNS disorders VT: ECG - Correct answer -Ventricular rate is 150- 250 -rhythm can be regular or irregular
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-AV dissociation may be present, with p waves occurring independently of the QRS complex -The atria may be depolarized by the ventricles in retrograde fashion -the P wave is usually buried in the QRS complex -PR interval is not measurable -QRS complex is distorted in appearance and wide (>.12) -T wave is in the opposite direction of the QRS complex VT: ECG Chart - Correct answer A) Heart Rate: 150- B) Rhythm: regular or irregular C) P wave: not visible D) PR interval: not measurable E) QRS complex: wide and distorted Ventricular Fibrillation (VF) - Correct answer -->condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly -a severe derangement of the heart rhythm characterized on ECG by irregular waveforms of varying shapes and amplitudes. -This represents the firing of multiple ectopic foci in the ventricle. -mechanically the ventricle is simply "quivering", with no effective contraction, and consequently no CO occurs. -VF is lethal
- HR not measurable -Rhythm irregular and chaotic -P wave not visible -PR and QRS not measurable VF: Clinical associations - Correct answer -Ventricular fibrillation is the most commonly identified arrhythmia in cardiac arrest patients. -occurs in acute MI and myocardial ischemia and in chronic diseases such as HF and cardiomyopathy
- it may occur during cardiac pacing or cardiac catheter stimulation of the ventricle
- may also occur with coronary reperfusion after thrombolytic therapy -other clinical associations: electric shock hyperkalemia hypoxemia acidosis drug toxicity
