Week 2 – Cardiac Rhythms Flashcards
When computing a heart rate from the ECG tracing, the nurse counts 15 of the small blocks between the R waves of a patient whose rhythm is regular. From these data, the nurse calculates the patient’s heart rate to be which of the following?
a. 60 beats/min b. 75 beats/min c. 100 beats/min d. 150 beats/min
c. 100 beats/min
Since each small block on the ECG paper represents 0.04 seconds, 1500 of these blocks represents 1 minute. By dividing the number of small blocks (15 in this case) into 1500, the nurse can calculate the heart rate in a patient whose rhythm is regular (in this case, 100).
Which of the following statements best describes the electrical activity of the heart represented by measuring the PR interval on the ECG?
a. The length of time it takes to depolarize the atrium b. The length of time it takes for the atria to depolarize and repolarize c. The length of time for the electrical impulse to travel from the SA node to the Purkinje fibres d. The length of time it takes for the electrical impulse to travel from the SA node to the AV node
c. The length of time for the electrical impulse to travel from the SA node to the Purkinje fibres
The electrical impulse in the heart must travel from the SA node through the AV node and into the Purkinje fibres in order for synchronous atrial and ventricular contraction to occur. The P wave represents atrial contraction and the R wave is part of the QRS complex that represents ventricular contraction. Therefore, when measuring the time from the beginning of the P wave to the beginning of the QRS (PR interval), the nurse is identifying the length of time it takes for the electrical impulse to travel from the SA node to the Purkinje fibres.
The nurse obtains a six-second rhythm strip and charts the following analysis: atrial rate 70, regular; ventricular rate 40, regular; QRS 0.04 sec; no relationship between P waves and QRS complexes; atria and ventricles beating independently of each other. Which of the following would be a correct interpretation of this rhythm strip?
a. Sinus dysrhythmias b. Third-degree heart block c. Wenckebach phenomenon d. Premature ventricular contractions
b. Third-degree heart block
Third-degree heart block represents a loss of communication between the atrium and ventricles. This is depicted on the rhythm strip as no relationship between the P waves, representing atrial contraction, and QRS complexes, representing ventricular contraction. The atria are beating totally on their own at 70 beats/min, whereas the ventricles are pacing themselves at 40 beats/min
The nurse is caring for a patient who is 24 hours postpacemaker insertion. Which of the following nursing interventions is most appropriate at this time?
a. Reinforcing the pressure dressing as needed b. Encouraging range-of-motion exercises of the involved arm c. Assessing the incision for any redness, swelling, or discharge d. Applying wet-to-dry dressings every four hours to the insertion site
c. Assessing the incision for any redness, swelling, or discharge
After pacemaker insertion, it is important for the patient to limit activity of the involved arm to minimize pacemaker lead displacement. The nonpressure dressing is kept dry until removed, usually 24 hours postoperatively. It is important for the nurse to observe for signs of infection by assessing for any redness, swelling, or discharge from the incision site.
The nurse is watching the cardiac monitor, and a patient’s rhythm suddenly changes. There are no P waves. Instead there are fine, wavy lines between the QRS complexes. The QRS complexes measure 0.08 sec (narrow), but they occur irregularly with a rate of 120 beats/min. The nurse correctly interprets that this rhythm is which of the following?
a. Sinus tachycardia b. Atrial fibrillation c. Ventricular fibrillation d. Ventricular tachycardia
Atrial fibrillation
Atrial fibrillation is represented on the cardiac monitor by irregular R-R intervals and small fibrillatory (f) waves. There are no normal P waves because the atria are not truly contracting, just fibrillating.
A patient has sought care following a syncopal episode of unknown etiology. Which of the following nursing actions should the nurse prioritize in the patient’s subsequent diagnostic workup?
a. Preparing to assist with a head-upright tilt-table test b. Assessing the patient’s knowledge of pacemakers c. Preparing an intravenous dose of a ß-adrenergic blocker d. Teaching the patient about the role of antiplatelet aggregators
a. Preparing to assist with a head-upright tilt-table test
A head-upright tilt-table test is a common component of the diagnostic workup following episodes of syncope. IV â-blockers are not indicated, and addressing pacemakers is premature and inappropriate at this stage of diagnosis. Patient education surrounding antiplatelet aggregators is not directly relevant to the patient’s syncope.
For which of the following dysrhythmias is defibrillation primarily indicated?
a. Ventricular fibrillation b. Third-degree AV block c. Uncontrolled atrial fibrillation d. Ventricular tachycardia with a pulse
a. Ventricular fibrillation
Defibrillation is always indicated in the treatment of ventricular fibrillation. Drug treatments are normally used in the treatment of uncontrolled atrial fibrillation and for ventricular tachycardia with a pulse (if the patient is stable). Otherwise, synchronized cardioversion is used (as long as the patient has a pulse). Pacemakers are the treatment of choice for third-degree heart block.
A patient in asystole is likely to receive which of the following drug treatments?
a. Atropine (Atro-Pen) and epinephrine (Epi-Pen) b. Lidocaine (Xylocaine) and amiodarone (Cordarone) c. Digoxin (Lanoxin) and procainamide (Pronestyl) d. â-Adrenergic blockers and dopamine
a. Atropine (Atro-Pen) and epinephrine (Epi-Pen)
Normally the patient in asystole cannot be successfully resuscitated. However, administration of atropine (Atro-Pen) and epinephrine (Epi-Pen) may prompt the return of depolarization and ventricular contraction.
Which of the following ECG characteristics is consistent with a diagnosis of ventricular tachycardia (VT)?
a. Unmeasurable rate and rhythm b. Rate 150 beats/min; inverted P wave c. Rate 200 beats/min; P wave not visible d. Rate 125 beats/min; normal QRS complex
c. Rate 200 beats/min; P wave not visible
Ventricular tachycardia (VT) is associated with a rate of 150 to 250 beats/min; the P wave is not normally visible. P wave inversion and a normal QRS complex are not associated with VT. Rate and rhythm are not measurable in ventricular fibrillation
