A nurse is interpreting a patient's ECG.
Which of the following findings indicate a normal sinus rhythm? Select all that apply.
P wave precedes each QRS complex.
T wave follows each QRS complex.
QRS complex duration is 0.16 seconds.
Heart rate is 100-120 beats per minute.
PR interval is 0.12-0.20 seconds.
Correct Answer : A,B,E
Choice A rationale:
In normal sinus rhythm, the sinoatrial node initiates each impulse, resulting in a P wave preceding every QRS complex. This indicates proper atrial depolarization followed by ventricular depolarization. The consistent presence of P waves before QRS complexes confirms intact conduction through the AV node and a functioning sinus node.
Choice B rationale
The T wave represents ventricular repolarization and should follow each QRS complex in a normal sinus rhythm. This sequence ensures the ventricles recover electrically before the next depolarization. Abnormal T wave morphology or timing may indicate ischemia, electrolyte imbalance, or other pathology. Normal T wave progression confirms healthy repolarization dynamics.
Choice C rationale
A QRS duration of 0.16 seconds exceeds the normal range of 0.06–0.10 seconds, suggesting intraventricular conduction delay or bundle branch block. Normal sinus rhythm requires a narrow QRS complex, indicating rapid and coordinated ventricular depolarization. Prolonged QRS duration is inconsistent with normal sinus rhythm and may reflect underlying conduction system disease.
Choice D rationale
A heart rate of 100–120 beats per minute is classified as sinus tachycardia, not normal sinus rhythm. Normal adult resting heart rate ranges from 60–100 beats per minute. Rates above 100 may be physiological (e.g., exercise, fever) or pathological (e.g., anemia, hyperthyroidism). Normal sinus rhythm requires a rate within the standard range.
Choice E rationale
The PR interval reflects conduction from the atria to the ventricles and should measure 0.12–0.20 seconds. This interval includes atrial depolarization and AV nodal delay. A normal PR interval confirms intact AV conduction. Shortened or prolonged PR intervals may indicate pre-excitation syndromes or AV block, respectively.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
An asymptomatic bradycardia with a heart rate of 50 beats per minute, which is within the range of 50-60 bpm for normal sinus bradycardia in some individuals, particularly well-conditioned athletes, generally does not require a permanent pacemaker. Pacemaker implantation is typically reserved for symptomatic bradycardia or higher-degree Atrioventricular (AV) blocks.
Choice B rationale
Third-Degree (Complete) Atrioventricular (AV) Block is characterized by a complete failure of electrical conduction between the atria and the ventricles, resulting in independent atrial and ventricular rhythms. The slow, unreliable ventricular escape rhythm often leads to symptoms like syncope, heart failure, or sudden cardiac death, making a permanent pacemaker mandatory.
Choice C rationale
First-degree Atrioventricular (AV) block is a benign condition characterized by a prolonged PR interval (normal range 0.12 - 0.20 seconds) with every impulse conducted. It rarely progresses to higher-degree blocks and is typically asymptomatic, so it does not meet the criteria or indication for permanent pacemaker implantation.
Choice D rationale
Atrial flutter with a controlled ventricular rate means the AV node is effectively regulating the rapid atrial impulses. This rhythm is generally managed with rate-control medications like beta-blockers or calcium channel blockers, and does not warrant a permanent pacemaker, which is primarily for correcting symptomatic bradyarrhythmias. —.
Correct Answer is C
Explanation
Choice A rationale
Young age is typically a factor that favors traditional open-heart surgery for valve replacement. Younger patients have a longer life expectancy, and a surgical valve has historically been considered more durable than TAVR devices, which have uncertain long-term durability and may require future interventions.
Choice B rationale
A low surgical risk profile generally makes the patient a better candidate for traditional open-heart surgery (SAVR). SAVR allows for direct visualization, precise placement, and is associated with very low risk in this patient group, whereas TAVR is typically reserved for those who cannot tolerate the risks of SAVR.
Choice C rationale
A high surgical risk (e.g., due to advanced age, severe comorbidities like renal failure or severe lung disease) is the primary indication making TAVR the more suitable option. TAVR is a minimally invasive procedure performed via a catheter, which significantly reduces the trauma, recovery time, and overall risk of major complications compared to open-heart surgery.
Choice D rationale
TAVR currently only uses bioprosthetic (tissue) valves, which do not require lifelong anticoagulation but have a limited lifespan. Preference for a mechanical valve (which requires anticoagulation but is very durable) would necessitate traditional open-heart surgery, not TAVR. —.
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