ECG Assessment/Dysrhythmias Questions With Complete Solutions

Normal cardiac impulse correct answer: Begins in the sinoatrial (SA) node in the upper right atrium and spreads over the atrial myocardium via Bachmann's bundle and internodal pathways, causing atrial contraction; then the impulse travels to the atrioventricular (AV) node through the bundle of His and down the left and right bundle branches; ends in the Purkinje fibers Purkinje fibers correct answer: Transmit the impulse to the ventricles Electrocardiogram Monitoring correct answer: Graphic tracing of electrical impulses produced by the heart Wave forms of ECG represent activity of charged ions across membranes of myocardial cels 12 Leads of ECG correct answer: 12 recording leads: - 6 leads (leads I, II, III, aVR, aVL, and aVF) measure electrical forces in the frontal plane - 6 leads (V1-V6) measure electrical forces in the horizontal plane (precordial leads) 12-Lead ECG correct answer: May show changes suggesting structural changes or damage such as ischemia, infarction, enlarges cardiac chambers, electrolyte imbalance, or drug toxicity; helpful in the assessment of dysrhythmias ECG paper correct answer: Rhythm strip provides documentation of patient's rhythm Allows for measurement of complexes and intervals P wave correct answer: Atrial contraction QRS wave correct answer: Contraction of the ventricles T wave correct answer: Relaxation of the ventricles ST depression correct answer: Ischemia (NSTEMI) ST elevation correct answer: Necrosis/infarction (STEMI) Calculating HR correct answer: Count: the R-R intervals in 6 seconds, and multiply by 10 Artifact correct answer: Muscle tremor Loose electrodes Each tiny box correct answer: .04 seconds PR interval normal limits correct answer: .12-.20 QRS interval normal limits correct answer: .12 seconds .12 indicates a bundle branch block (AV node not getting enough flow) QT interval normal limits correct answer: .4 seconds .4 may result in Torsades de Points Normal Sinus Rhythm correct answer: Rate: 60-100 P wave for every QRS P waves have consistent shape PR: .12-.20 QRS: .12 Sinus Bradycardia correct answer: Sinus node fires 60 bpm Normal rhythm in aerobically trained athletes and during sleep Common in patients taking beta-blockers for CAD P wave precedes each QRS and has a normal shape and duration PR interval is normal, and the QRS complex has normal shape/duration Sinus Tachycardia correct answer: Discharge rate from the sinus node is increased as a result of vagal inhibition and is 100 bpm Common in patients experiencing pain, fevers, dehydration, or shock Conduction pathway is the same in sinus tachycardia as that in normal sinus P wave normal, precedes each QRS complex and has a normal shape and duration PR interval is normal, QRS complex normal shape/duration Atrial Flutter correct answer: Atrial tachydysrhythmia identified by recurring, regular, sawtooth-shaped flutter waves Originates from a siingle ectopic focus Atrial rate is 200-350 bpm Ventricular rate approximately 150 bpm Atrial rhythm regular PR interval variable and not measurable AV block usually seen in a fixed ratio of flutter waves A Flutter waves represent correct answer: Atrial depolarization followed by repolarization A Flutter clinical significance correct answer: Risk for stroke due to risk of thrombus formation in the atria Treatment of choice for asymptomatic patient - warfarin Atrial Fibrillation correct answer: Total disorganization of atrial electrical activity due to multiple ectopic foci, resulting in loss of effective atrial contraction Most common dysrhythmia Prevalence increases with age A Fib ECG correct answer: Atrial rate may be as high as 350-600 bpm P waves are replaced by chaotic, fibrillatory waves PR interval not measurable QRS complex usually normal shape/duration A Fib with controlled ventricular response correct answer: Ventricular rate of 60-100 A Fib with rapid ventricular response correct answer: Ventricular rate of 100 A Fib with slow ventricular response correct answer: Ventricular rate of 60 A Fib and A Flutter may be... correct answer: Coexistent Atrial Fibrillation clinical significance correct answer: Can results in decrease in CO due to ineffective atrial contractions (loss of atrial kick) and rapid ventricular response Thrombi may form in the atria as a result of blood stasis Embolus may develop and travel to the brain, causing a stroke A Fib treatment correct answer: If patient has been in A Fib for 48 hours, anticoagulation therapy with warfarin is recommended for 3-4 weeks before cardioversion, and for 4-6 weeks after successful cardioveresion Premature Ventricular Contractions correct answer: HR varies according to intrinsic rate and number of PVC's Rhythm irregular P wave barely visible PR interval not measurable QRS complex wide and distorted, lasting longer than .12 second T wave large opposite direction