Exam 1 ECG Fundamentals Questions With Complete Solutions

Automaticity correct answer: Ability to initiate an impulse at a regular interval; "pacemaker" Excitability correct answer: Ability of the heart to respond to a stimulus Conductivity correct answer: Ability of the heart to transmit an electrical impulse from one cell membrane to another Contractility correct answer: The ability of the heart muscle cells to shorten in response to an electrical stimulus Refractoriness correct answer: "Resistant to"; cannot respond to a stimulus Absolute refractory period correct answer: Absolutely no stimulus can cause depolarization or accept a stimulus at this point; between the Q to the beginning portion of the T wave Relative refractory period correct answer: Vulnerable period when a strong stimulus may result in depolarization; during the T wave Polarized cell correct answer: "Resting and ready"; Calcium and sodium extracellular, potassium intracellular Depolarized cell correct answer: "Active state"; Calcium and sodium shift into the cell, potassium shifts into the extracellular fluid Repolarized cell correct answer: "Recovering and relaxing"; Calcium and sodium shift out of the cell, potassium shifts back into the cell Cardiac conduction system route correct answer: SA node- intra atrial pathways- AV node- junctional tissue- His bundle- left and right bundle branch- Purkinje fibers SA node correct answer: Pacemaker of the heart; fastest rate of automaticity (60-100) Junctional tissue correct answer: Backup pacemaker; intrinsic rate of 40-60 Purkinje fibers correct answer: Last fibers to transmit impulses to the right and left ventricles, causing them to contract Electrocardiography correct answer: The graphic representation of the heart's electrical activity; remember to ASSESS patient ECG demonstrates correct answer: -Anatomical orientation of the heart -Disturbance of rhythm and conduction -Ischemia or infarct (STEMI) -Drug toxicity Cardiac monitor correct answer: Anything that will show the electrical signals of the heart on a screen Telemetry monitoring system correct answer: -Uses three to six electrodes -Transmits to a central location where multiple patients may be monitored -Cell phones do not interfere with monitoring (check with your agency) Electrodes correct answer: -Transmits electrical signals from the patient to the monitor -Disposable Electrode application correct answer: -Avoid bones, joins and folds in skin -Shave or clip excess hair -Prep skin with clean, dry gauze or per policy -Change electrodes per policy Depression vs elevation correct answer: Physician uses for dx of ischemia or MI Depression- lack of oxygen Elevation- infarction, injury ECG leads correct answer: Allows different views or angles of the heart; always attached to a positive (recording), negative and a grounding electrode 3 lead correct answer: Minimum requirement for cardiac monitoring (telemetry) 5 and 6 lead correct answer: Allow you to view any of the 12 ECG leads (2-4 at the same time); the computer selects what lead depending on the one that you program 12 lead correct answer: Uses 10 electrodes, but 12 different views of the heart can be obtained -One time snapshot, must lie still -Used to diagnostics P wave correct answer: Atrial depolarization Q wave correct answer: Initial negative deflection produced by ventricular depolarization PR interval correct answer: Represents atrial contraction and ventricular filling; 0.12s-0.20s (normal) QRS complex correct answer: Ventricular depolarization; <0.12s (normal) ST segment correct answer: Ventricular systole or contraction T wave correct answer: Ventricular depolarization; note: depolarization could occur if the stimulus is strong enough during the vulnerable period (relative refractory period) of the T wave Graph paper measurements correct answer: 1mm or 1 small box= 0.04s 5mm or 1 big box= 0.2s Each notch in the graph paper=3s Steps to reading an ECG strip correct answer: 1. Check the rhythm (regular or irregular?) 2. Calculate the rate (1500, 10x, sequence method) 3. Examine the P wave (present for each QRS complex? Identical?) 4. Measure the PR interval (normal width? Consistent throughout the strip?) 5. Measure the QRS complex 6. Check for early or late beats Calculating the rhythm correct answer: Paper and pencil method; regular or irregular? Calculating the rate correct answer: 1500 method, 10-times method or sequence method 1500 method correct answer: Count small boxes between waveforms, divide 1500 by time; most precise method, only for regular rhythms 10-times method correct answer: Need a 6s strip (2 notches), count each waveform in a 6s period and multiply by 10; fastest method, can be used for irregular rhythms Sequence method correct answer: Must start when "R" lands on a heavy line, count 50 43 from each large box from one "R" to the next; requires memorization Sequence method numbers correct answer: 50 43 Examining the P waves correct answer: Is there one P wave for every QRS complex? If yes, conducting as it should. If no, there's probably a block Do they all look the same? If yes, originates from AV node. If no, originates from elsewhere. Measuring the PR interval correct answer: Is the PR interval of normal width? Is the PR interval consistent throughout the strip? Measuring QRS complex correct answer: Is there a QRS complex for every P wave? Is the QRS complex of normal width? (<.12s) Checking for early or late beats correct answer: Look at the overall strip Is the abnormal beat a one time occurrence or does it repeat itself in a pattern? Nomenclature of dysrhythmias correct answer: By origin (sinus, atrial, junctional or ventricular) By mechanism (tachycardia, bradycardia, premature, late or escape, flutter, fibrillation, conduction blocks) Normal sinus rhythm correct answer: SA node (normal pacemaker of the heart) is in control 1. Rhythm: regular 2. Rate: 60-100 3. P waves: Precedes every QRS, normal 4. PR interval: 0.12-0.20s 5. QRS duration: <.12s Sinus tachycardia correct answer: SA node fires faster than 100 times/minute 1. Rhythm: regular 2. Rate: 101-160 3. P waves: Precedes every QRS, normal 4. PR interval: 0.12-0.20s 5. QRS duration: <.12s Causes of sinus tachycardia correct answer: Infants and small children Physiological response (anxiety) Drug related (epinephrine, nicotine, cocaine, atropine, alcohol, caffeine) Compensatory mechanism (anemia, hypoxia, hypovolemia, hypotension) Disease states (early signs of CHF, hyperthyroidism) Significance of sinus tachycardia correct answer: Lowers filling time in the heart chambers which leads to decreased SV and CO which can in turn lead to ischemia depending on the fragility of the patient Sinus tachycardia interventions correct answer: Assess the patient and treat underlying cause first Oxygen Drugs (beta blockers, calcium channel blockers, etc) Sinus bradycardia correct answer: SA node fires slower than 60 times per minute 1. Rhythm: regular 2. Rate: Less than 60 3. P waves: Precedes every QRS, normal 4. PR interval: 0.12-0.20s 5. QRS duration: <.12s Causes of sinus bradycardia correct answer: Normal heart (healthy adults, sleep) Drug related (beta blockers, calcium channel blockers, digitalis) Vagal stimulation (vomiting, straining at stool, suctioning) Disease states (acute MI, increased ICP, hypothyroidism) Significance of sinus bradycardia correct answer: Depends on the patient If too slow, inadequate cardiac output Risk of ectopic beats from elsewhere that takes over as the pacemaker Interventions for sinus bradycardia correct answer: Assess the patient and treat the underlying cause first (suctioning, meds, bearing down, etc) Oxygen Drugs (atropine, dopamine) Pacemaker Sinus dysrhythmia correct answer: Heart rate varies with the respiratory cycle, increasing with inspiration and slowing with expiration 1. Rhythm: Irregular 2. Rate: 60-100 3. P waves: Precedes every QRS, normal 4. PR interval: 0.12-0.20s 5. QRS duration: <.12s Calculating sinus dysrhythmia correct answer: Take longest R to R interval minus the shortest R to R interval; if >.12s=dysrhythmia Causes of sinus dysrhythmia correct answer: Normal heart (children, teens, young adults) Vagal stimulation (vomiting, bearing down, suctioning) Disease states (COPD) Significance of sinus dysrhythmia correct answer: Depends on the patient; usually none Interventions for sinus dysrhythmia correct answer: Usually none Minimize vagal stimulation Rule out a more serious arrhythmia Premature atrial complexes (PAC) correct answer: Electrical impulses originate outside the SA node, but within the atria that may or may not be conducted via the AV note 1. Rhythm: regular, except premature impulses 2. Rate: Usually 60-100 3. P waves: Various shapes 4. PR interval: Usually 0.12-0.20s 5. QRS duration: <.12s Causes of premature atrial complexes correct answer: Normal heart (aging, cigarettes, anxiety, fatigue, fever, infection) Drug related (digitalis, sympathomimetics, anesthetics) Disease states (CHF, COPD, mitral stenosis, electrolyte imbalance, hypoxia) Significance of premature atrial complexes correct answer: Often asymptomatic In patient's with heart disease, more serious Interventions for premature atrial complexes correct answer: Assess the patient and eliminate underlying cause first Infrequent PACs: no treatment Frequent PACs: monitor the patient Supraventricular tachycardia correct answer: A rapid discharge of impulses from an ectopic source above the ventricles 1. Rhythm: regular 2. Rate: 161-240 3. P waves: Precedes every QRS, normal 4. PR interval: 0.12-0.20s 5. QRS duration: <.12s Note: P waves buried in the T waves Causes of supraventricular tachycardia correct answer: Normal heart (caffeine or other stimulants, electrolyte imbalances, physical or psychological stress, hypoxia) Associated cardiac problems (MI, cardiomyopathy, valvular heart disease) Other disease states (digitalis toxicity, hyperthyroidism, COPD) Significance of supraventricular tachycardia correct answer: The rapid rate shortens diastole (decreased ventricular filling time) resulting in loss of atrial kick, reduced cardiac output, reduced coronary perfusion and ischemia myocardial changes Interventions for supraventricular tachycardia correct answer: Assess patient and treat underlying cause Oxygen Valsalva maneuver; carotid sinus massage (provider) Adenosine Cardioversion Unstable SVT symptoms correct answer: Hypotension, chest pain, diaphoresis, palpitations, hypoxia, confusion Adenosine for SVT correct answer: Slows down rhythm to find origin Flush with saline bolus immediately after administration and raise arm while printing ECG strip Can stop HR for up to 6 seconds Drug of choice for SVT correct answer: Adenosine Cardioversion correct answer: Delivery of an electrical stimulus during depolarization- depolarizes all cells simultaneously, allowing the SA node to resume the pacemaker role What wave is electricity in an cardioversion synchronized with? correct answer: R wave What must be present to do a cardioversion? correct answer: QRS complex Differences between ST and SVT correct answer: ST does not exceed a heart rate of 160 bpm, SVT does ST cannot be stopped by vagal maneuvers, SVT can (sometimes) Atrial flutter correct answer: Result of a single reentry circuit within the right atrium 1. Rhythm: Atrial: regular; Ventricular: regular or irregular 2. Rate: Atrial: 250-350 Ventricular: Depends on conduction ratio 3. P waves: F waves or flutter waves (picket fence) 4. PR interval: Replaced by FR interval 5. QRS duration: <.12s Atrial flutter causes correct answer: Disease states (Valvular heart disease, rheumatic heart disease, CHF, pericardial disease, CAD, acute MI, pulmonary embolism, hyperthyroidism, hypoxia, electrolyte abnormalities) Atrial flutter significance correct answer: Decreases cardiac output Loss of atrial kick; thrombus formation Interventions for atrial flutter correct answer: Assess patient- vitals and symptoms HR normal and asymptomatic- monitor Anticoagulants or factor Xa inhibitors Drugs for stable patient with RVR- anti dysrhythmic (amiodarone), beta blockers or calcium channel blockers Cardioversion (electricity first if patient unstable) Risk of cardioversion in atrial flutter correct answer: Embolism Atrial fibrillation hallmark sign correct answer: Pulse defecit Atrial fibrillation correct answer: Result of finding a number of ectopic impulses within the atria 1. Rhythm: Irregular 2. Rate: Atrial >350 impulses per minute 3. P waves: Chaotic F waves 4. PR interval: None 5. QRS duration: <.12s Causes of atrial fibrillation correct answer: Normal heart (heavy smoking, excessive alcohol use, excessive caffeine use, aging) Disease states (rheumatic heart disease, atrial septal defect, HTN, mitral stenosis, CAD, acute MI, COPD, hyperthyroidism) Significance of atrial fibrillation correct answer: Loss of atrial kick Risk of clot formation Lightheadedness, edema, palpitations, chest pain Atrial fibrillation interventions correct answer: Assess patient Oxygen Anticoagulants or factor Xa inhibitors Drugs for pt with RVR-anti dysrhythmic (amiodarone), beta blockers or calcium channel blockers Cardioversion Ablation therapy- cauterize irritable sites Premature ventricular complex cause correct answer: An irritable focus within the ventricles that fire prematurely with QRS intervals >0.12s Unifocal vs multifocal PVCs correct answer: Unifocal: one sit or irritability; complexes look similar Multifocal: more than one site Bigeminy correct answer: Every other beat is a PVC R on T phenomenon correct answer: PVC occurs during vulnerable period of the T wave (relative refractory period) which can put patient into lethal arrhythmia Causes of PVCs correct answer: Ischemia, acute MI, electrolyte imbalance, dig toxicity, COPD, CHF, hypoxia, sympathomimetics, mechanical stimulation, chamber enlargement Significance of PVCs correct answer: Loss of atrial kick If frequent, drop in CO can occur Risk of lethal dysrhythmia (R on T) Interventions for PVCs correct answer: Assess Monitor vitals and frequency Administer antidysrhythmic if frequent PVCs Ventricular tachycardia correct answer: Three or more consecutive PVCs Irritable focus in the ventricles fires at a rate of >100bpm Patient MAY NOT have a pulse Significance of ventricular tachycardia correct answer: Loss of atrial kick Drop in CO May deteriorate to ventricular fibrillation Interventions for ventricular tachycardia correct answer: Assess patient (may or may not have pulse) Monitor vitals and frequency of PVCs Pulseless- defibrillate Stable- amiodarone Unstable- cardioversion Ventricular fibrillation correct answer: Multiple ectopic, uncoordinated and rapid impulses cause the heart to fibrillate rather than contract Ventricular fibrillation significance correct answer: Clinical death Interventions for ventricular fibrillation correct answer: Immediate defibrillation Epinephrine or vasopressin May attempt anti dysrhythmics V fib think... correct answer: Defib Asystole correct answer: No electrical activity is present in the myocardium Clinical death DO NOT defibrillate, no electricity to grab onto AV block correct answer: Delay or block in the AV node Bundle branch block correct answer: Delays within the left or right bundle branches causing the ventricles to depolarize separately How AV block effects ECG strip? correct answer: Abnormal PR interval Classifications of AV blocks correct answer: Delay: 1st degree Partial blockage: 2nd degree (type 1 and 2) Complete blockage: 3rd degree 1st degree AV block correct answer: Originates in the sinus node, but there is a consistent prolonged delay in the AV node PR interval >0.2s 2nd degree AV block (Mobitz I or Wenchebach) correct answer: Atrial impulses encounter longer and longer delay thought the AV node until one impulse is completely blocked PR interval lengthens progressively until a P wave occurs without a QRS 2nd degree AV block type 2 (Mobitz II) correct answer: The block is within or below the bundle of HIS P-QRS ratio 2:1 or 3:1 3rd degree AV block correct answer: Atrial impulse does not conduct though the ventricles; Complete block occurring at the AV junction, HIS bundle or bundle branches Atria and ventricles beat independently Causes of blocks correct answer: Normal in elderly and athletes (Type 1 and Mobitz type 1) MI Myocarditis CAD Hypokalemia Medications (dig and beta blockers) Hypoxia Cardiomyopathy Electrolyte imbalance Rheumatic heart disease Usually bradycardic rhythms Interventions for heart blocks correct answer: Observe- notify MD if symptomatic or new Monitor Increase heart rate to maintain CO Eliminate identifiable causes Atropine Pacemaker if persists Bundle brach block correct answer: Delay in the impulse conduction from the bundle of HIS to the right or left bundle branch which causes one ventricle to contract before the other Bundle brach block appearance on ECG strip correct answer: Wide QRS >0.12s Bunny ear appearance Cause of bundle branch blocks correct answer: May be normal CAD MI Hypertrophy Valve disease HTN Interventions for bundle branch block correct answer: Observe, usually asymptomatic Assess 12 lead ECG Junctional rhythms correct answer: Junctional area takes over as the pacemaker of the heart due to slow or absent heart rate Junctional tissue rate correct answer: 40-60 bpm Junctional rhythm appearance on ECG strip correct answer: Abnormal P waves (inverted, immediately precedes QRS or buried in QRS) If P waves are present, <0.12s Causes of junctional rhythms correct answer: Digoxin Vagal stimulation Hyperkalemia Hypoxia Interventions for junctional rhythms correct answer: Assess patient Eliminate cause Atropine Pacemaker