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Med-Surg · chapter 12 · Cardiovascular System

Dysrhythmia

The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.

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Key points

  1. ECG wave meanings

    The P wave represents electrical depolarization, or the channeled travel of electricity, in the atria, whereas the QRS complex, a jagged triangular shape, represents electrical current traveling through the ventricle.

  2. Telemetry box timing

    It is important to note that in each large box are five small boxes. Each small box represents 0.04 seconds, and each large box represents 0.20 seconds.

  3. Rhythm regularity assessment

    A 6-second strip is required to determine these features. The nurse must “march out” with calipers or by tracing the P-to-P waves to evaluate regularity, or whether beats are occurring at regular intervals.

  4. Six-second heart rate estimate

    The fastest method to obtain heart rate is to count the number of QRS complexes in a 6-second strip and multiply that number by ten. For instance, if the nurse counts seven QRS complexes in a 6-second strip, the ventricular rate is approximately 70 beats a minute.

  5. Symptomatic bradycardia care

    Nursing interventions for symptomatic patients include holding cardiac medications if pulse is less than 60 bpm (alert the provider), having the patient stay in bed as the patient may be lightheaded or dizzy, and continuing to monitor the patient.

  6. Tachycardia triggers and interventions

    Factors contributing to tachycardia may include stress, dehydration, fever, exercise, caffeine, or illegal substances such as cocaine or stimulants. Clinical manifestations may include shortness of breath, anxiety, fluttering, flushed face, or dizziness, but the patient may also be asymptomatic.

  7. PAC and PVC recognition

    Atrial ectopic beats will cause an early, irregular occurrence of P and QRS waves; this is called a premature atrial contraction (PAC). In contrast, a premature ventricular contraction (PVC) is when a ventricular ectopic beat appears without a P wave and widens the appearance of the QRS.

  8. Ectopic beat nursing actions

    Nursing interventions include having the patient remain calm and do some deep breathing, administering cardiac medications/electrolyte replacement as ordered, and monitoring the patient’s vital signs.

  9. Heart block categories

    Another commonly occurring dysrhythmia is heart block, in which there is an impulse interruption between the atria and ventricles, called an atrioventricular (AV) block, or heart block. There are three types of heart block: first-degree heart block; second-degree, further broken down into Type I and Type II; and third-degree heart block.

  10. Mobitz pattern differences

    With Mobitz I second-degree heart block, the classic features are a PR interval that gets longer with each beat until a QRS is dropped, and the pattern repeats. In contrast, in Mobitz II second-degree heart block, the PR interval is constant, and some of the QRSs are blocked.

  11. Third-degree block urgent care

    Third-degree heart block requires quick intervention. Nurses must apply telemetry to the patient and prepare for transcutaneous pacing, assess oxygenation, check labs to alert the provider if there are any electrolyte shifts (potassium or magnesium), maintain bed rest, and hold antiarrhythmics/beta blockers.

  12. Atrial symptom severity

    Patients will report fluttering sensations, chest pain, palpitations, and dizziness, and may experience hypotension. The faster the tachycardia, the more severe the patient’s symptoms will be.

  13. Ventricular rhythm criteria

    A ventricular tachycardia is when the ventricle beats rapidly at 150 to 200 bpm with wide QRS complexes (greater than 0.12 seconds) and no discernible PRs or P waves. A ventricular fibrillation is slightly faster than ventricular tachycardia with rates over 200 bpm.

  14. Ventricular arrest risk

    In severe cases, they can lose perfusion and have syncope. Ventricular fibrillation is considered a cardiac arrest as patients will lose consciousness and require advanced cardiac life support.

Terms to know

normal sinus rhythm
The normal sinus rhythm, or the rhythm that originates from the sinus node and describes the characteristic rhythm in the healthy human heart, includes several features.
transcutaneous pacing
The provider may also order medications to raise the heart rate (such as atropine) or initiate transcutaneous pacing, a noninvasive procedure that uses electrical impulses to temporarily pace a patient’s heart.
ectopic beat
An occasional, singular, irregular beat, also known as an ectopic beat, may originate from the atria or the ventricles.
premature ventricular contraction (PVC)
In contrast, a premature ventricular contraction (PVC) is when a ventricular ectopic beat appears without a P wave and widens the appearance of the QRS.
heart block
Another commonly occurring dysrhythmia is heart block, in which there is an impulse interruption between the atria and ventricles, called an atrioventricular (AV) block, or heart block.
pacemaker
The patient may require transcutaneous pacing and be prepared for surgery for a pacemaker, a small implantable machine with a battery life of approximately ten years that recognizes when the heart rate is too fast or too slow and will pace the rhythm to a preset range (e.g., a heart rate of 60 to 70 bpm) to meet perfusion needs.
AFib
AFib is an irregular, fast rhythm originating from the atria due to multiple impulses being fired.
cardioversion
In events where the patient’s atrial dysrhythmia is non-responsive to pharmacological therapies, cardioversion is a procedure in which electricity is utilized to shock the atrial circuitry back to normal sinus rhythm.

Practice questions

Stuck on select-all-that-apply? How to take them one option at a time.

The graded version needs JavaScript. Every question is below anyway, with the answer and why.

Every question here, with the answer

  1. At 1900 you are documenting the ventricular rate from a 6-second telemetry strip. You counted 7 QRS complexes. Which entry is most accurate?

    1. Heart rate cannot be estimated from a 6-second strip.
    2. Ventricular rate exactly 75 beats/min based on R-to-R boxes.
    3. Ventricular rate approximately 70 beats/min.
    4. Ventricular rate approximately 42 beats/min.

    Answer: Ventricular rate approximately 70 beats/min.

    The section states that the fastest method is to count QRS complexes in a 6-second strip and multiply by ten, so 7 complexes is approximately 70 beats/min. The other entries either use the wrong calculation, imply a precision not supported by the scenario, or incorrectly state that the rate cannot be estimated.

  2. At 0215 a telemetry alarm sounds while you are covering several patients. Which actions should be reflected in safe telemetry-monitoring documentation according to the section? Select all that apply.

    1. Keep a pager or device with you to receive telemetry alerts.
    2. Rely only on the monitor value without an apical heart-rate assessment.
    3. Physically assess the patient's status and apical heart rate after the alert.
    4. Document the strip later if the patient reports no symptoms.
    5. Remove telemetry for transportation when alarms are inconvenient.

    Answer: Keep a pager or device with you to receive telemetry alerts., Physically assess the patient's status and apical heart rate after the alert.

    The telemetry safety section includes carrying a device to receive alerts and physically assessing the patient’s status and apical heart rate in response. Delaying assessment, removing monitoring for convenience, or relying only on the monitor value does not match the listed safe practices.

  3. At 0900, telemetry shows sinus bradycardia with a pulse of 54 bpm. The patient reports dizziness and has a scheduled cardiac medication due. Which charted nursing response best matches the section?

    1. Cardiac medication held for pulse less than 60 bpm; provider alerted; patient kept in bed and monitored.
    2. Patient instructed to drink caffeine; no provider notification needed unless chest pain occurs.
    3. Cardiac medication given because the PR and QRS intervals are regular; patient encouraged to ambulate.
    4. Telemetry discontinued because sinus bradycardia is always normal during relaxation.

    Answer: Cardiac medication held for pulse less than 60 bpm; provider alerted; patient kept in bed and monitored.

    For symptomatic bradycardia with pulse less than 60 bpm, the section lists holding cardiac medications, alerting the provider, keeping the patient in bed if dizzy, and monitoring. The other entries ignore symptoms, add interventions not supported by the section, or treat bradycardia as automatically normal.

  4. At 1530 you are completing a rhythm note for a strip interpreted as sinus tachycardia. Which elements are consistent with the textbook description and should be included if seen? Select all that apply.

    1. Early wide QRS complexes without P waves.
    2. Rate greater than 100 bpm.
    3. Regular QRS intervals.
    4. Rate less than 60 bpm.
    5. Regular PR intervals.

    Answer: Rate greater than 100 bpm., Regular QRS intervals., Regular PR intervals.

    The section defines sinus tachycardia as a rate greater than 100 bpm with regular PR and QRS intervals. A rate less than 60 bpm describes bradycardia, and an early wide QRS without a P wave is consistent with a PVC rather than sinus tachycardia.

  5. At 1110 you review a strip showing one early wide-appearing QRS complex with no preceding P wave, followed by a pause. Which documentation is most accurate?

    1. Premature atrial contraction (PAC) with a non-compensatory pause.
    2. Mobitz I second-degree heart block with progressive PR lengthening.
    3. Premature ventricular contraction (PVC) with a compensatory pause.
    4. Sinus tachycardia with regular PR and QRS intervals.

    Answer: Premature ventricular contraction (PVC) with a compensatory pause.

    The described finding matches the section’s description of a PVC: an early, wide QRS without a P wave followed by a compensatory pause. A PAC has an early P and QRS, Mobitz I involves progressive PR lengthening, and sinus tachycardia has regular PR and QRS intervals.

  6. At 0600 your preceptor identifies a strip as Mobitz II second-degree heart block and asks you to update the telemetry note. Which rhythm details match that diagnosis in this section? Select all that apply.

    1. The PR interval is constant.
    2. The pattern repeats like Mobitz I.
    3. Some of the QRSs are blocked.
    4. The PR interval gets longer with each beat until a QRS is dropped.
    5. The PR interval is consistently greater than 0.20 seconds while QRS is normal and regular.

    Answer: The PR interval is constant., Some of the QRSs are blocked.

    For Mobitz II, the section states that the PR interval is constant and some QRSs are blocked. Progressive PR lengthening with a repeating dropped QRS pattern describes Mobitz I, while a consistently prolonged PR interval with normal regular QRS describes first-degree heart block.

Where every quote comes from

Section 12.2 Dysrhythmia of Medical-Surgical Nursing by Christy Bowen, Bridget Carey, Jessica Palozie, Maren Reinholdt, OpenStax, 2024. Read the whole section free at openstax.org.

The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.