Chapter 35: Dysrhythmias | Questions, Answers and Rationales
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Chapter 35: Dysrhythmias
Institution
Chapter 35: Dysrhythmias
Chapter 35: Dysrhythmias | Questions, Answers and Rationales A patient admitted with syncope has continuous ECG monitoring. An examination of the rhythm strip reveals the following: atrial rate 74 beats/min and regular; ventricular rate 62 beats/min and irregular; P wave normal shape; PR interva...
A patient admitted with syncope has continuous ECG monitoring. An examination of the
rhythm strip reveals the following: atrial rate 74 beats/min and regular; ventricular rate
62 beats/min and irregular; P wave normal shape; PR interval lengthens progressively
until a P wave is not conducted; QRS normal shape. The priority nursing intervention
would be to
a. give epinephrine 1 mg IV push.
b. prepare for synchronized cardioversion.
c. observe for symptoms of hypotension or angina.
d. apply transcutaneous pacemaker pads on the patient.
Rationale: The rhythm is a second-degree atrioventricular (AV) block, type I (i.e., Mobitz
I or Wenckebach heart block). It is characterized by a gradual lengthening of the PR
interval. Type I AV block is usually a result of myocardial ischemia or infarction. It is
typically transient and well tolerated. The nurse should assess for bradycardia,
hypotension, and angina. The symptomatic patient may need atropine or a temporary
pacemaker.
The ECG monitor of a patient in the cardiac care unit after an MI shows ventricular
bigeminy with a rate of 50 beats/min. The nurse would
a. perform defibrillation.
b. administer IV amiodarone.
c. prepare for temporary pacemaker insertion.
d. assess the patient's response to the dysrhythmia.
Rationale: A premature ventricular contraction (PVC) is a contraction originating in an
ectopic focus in the ventricles. When every other beat is a PVC, the rhythm is called
ventricular bigeminy. PVCs are usually a benign finding in patients with a normal heart.
In patients with heart disease, PVCs may reduce the cardiac output and precipitate
angina and heart failure, depending on the frequency. Because PVCs in coronary artery
disease (CAD) or acute myocardial infarction indicate ventricular irritability, the patient's
physiologic response to PVCs must be monitored. Assessing the patient's
hemodynamic status is important for deciding the need for drug therapy.
,In the patient with supraventricular tachycardia, which assessment indicates decreased
cardiac output?
a. Hypertension and dyspnea
b. Chest pain and palpitations
c. Abdominal distention and tachypnea
d. Bounding pulses and a systolic murmur
Rationale: Manifestations of decreased cardiac output in the patient with
supraventricular tachycardia include hypotension, angina, palpitations, and dyspnea.
The nurse prepares a patient for synchronized cardioversion knowing that cardioversion
differs from defibrillation in that
a. defibrillation delivers a lower dose of electrical energy.
b. cardioversion is a treatment for atrial bradydysrhythmias.
c. defibrillation is synchronized to deliver a shock during the QRS complex.
d. patients should be sedated if cardioversion is done on a nonemergency basis.
Rationale: Synchronized cardioversion is the therapy of choice for patients with
hemodynamically unstable ventricular or supraventricular tachydysrhythmias. A
synchronized circuit in the defibrillator delivers a countershock that is programmed to
occur on the R wave of the QRS complex of the electrocardiogram. The synchronizer
switch must be turned on when cardioversion is planned. The procedure for
synchronized cardioversion is the same as for defibrillation with a few exceptions: If
synchronized cardioversion is done on a nonemergency basis, the patient is sedated
before the procedure, and the initial energy needed for synchronized cardioversion is
less than the energy needed for defibrillation.
Which patient teaching points should the nurse include when providing discharge
instructions to a patient with a new permanent pacemaker and the caregiver? (select all
that apply)
a. Avoid or limit air travel.
b. Take and record a daily pulse rate.
c. Obtain and wear a Medic Alert ID device at all times.
,d. Avoid lifting arm on the side of the pacemaker above shoulder.
e. Do not use a microwave oven because it interferes with pacemaker function.
Rationale: Pacemaker discharge teaching should include: Air travel is not restricted.
The patient should tell airport security of the presence of a pacemaker because it may
set off the metal detector. A hand-held screening wand should not pass directly over the
pacemaker. Manufacturer information varies about the effect of metal detectors on
pacemaker function. The patient should monitor the pulse and tell the HCP if it drops
below a predetermined rate. The patient should have and wear a Medic Alert ID device
at all times. The patient must avoid lifting the arm on the pacemaker side above the
shoulder until approved by the HCP. Microwave ovens are safe to use. They do not
interfere with pacemaker function.
Important teaching for the patient scheduled for a radiofrequency catheter ablation
procedure includes explaining that
a. ventricular bradycardia may be induced and treated during the procedure.
b. catheter will be placed in both femoral arteries to allow double-catheter use.
c. the procedure will destroy areas of the conduction system that are causing rapid
heart rhythms.
d. general anesthetic will be given to prevent the awareness of any "sudden cardiac
death" experiences.
Rationale: Radiofrequency catheter ablation therapy involves the use of electrical
energy to "burn" or ablate areas of the conduction system as definitive treatment of
tachydysrhythmias.
What should the nurse measure to determine whether there is a delay in impulse
conduction through the patient's ventricles?
a. P wave
b. Q wave
c. PR interval
d. QRS complex
The QRS complex represents ventricular depolarization. The P wave represents the
depolarization of the atria. The PR interval represents depolarization of the atria,
atrioventricular node, bundle of His, bundle branches, and the Purkinje fibers. The Q
wave is the first negative deflection following the P wave and should be narrow and
short.
, The nurse needs to quickly estimate the heart rate for a patient with a regular heart
rhythm. Which method will be fastest to use?
a. Count the number of large squares in the R-R interval and divide by 300.
b. Print a 1-minute electrocardiogram (ECG) strip and count the number of QRS
complexes.
c. Use the 3-second markers to count the number of QRS complexes in 6 seconds and
multiply by 10.
d. Calculate the number of small squares between one QRS complex and the next and
divide into 1500.
Using the 3-second markers to count the number of QRS complexes in 6 seconds and
multiplying by 10 is the quickest way to determine the ventricular rate for a patient with a
regular rhythm. The other methods are accurate but take longer.
A patient has a junctional escape rhythm on the monitor. What heart rate should the
nurse expect the patient to have?
a. 15 to 20
b. 20 to 40
c. 40 to 60
d. 60 to 100
If the sinoatrial (SA) node does not discharge, the atrioventricular (AV) node will
automatically discharge at the normal rate of 40 to 60 beats/min. The slower rates are
typical of the bundle of His and Purkinje system and may be seen with failure of both
the SA and AV node to discharge. The normal SA node rate is 60 to 100 beats/min.
The nurse obtains a rhythm strip on a patient who has had a myocardial infarction and
makes the following analysis: no visible P waves, PR interval not measurable,
ventricular rate of 162, R-R interval regular, QRS complex wide and distorted, and QRS
duration of 0.18 second. How should the nurse interpret this cardiac rhythm?
a. Atrial flutter
b. Sinus tachycardia
c. Ventricular fibrillation
d. Ventricular tachycardia
The absence of P waves, wide QRS, rate greater than 150 beats/min, and the regularity
of the rhythm indicate ventricular tachycardia. Atrial flutter is usually regular, has a
narrow QRS configuration, and has flutter waves present representing atrial activity.
Sinus tachycardia has P waves. Ventricular fibrillation is irregular and does not have a
consistent QRS duration.
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