A nurse is describing the process by which blood is ejected into circulation as the chambers of the heart become smaller.
How does the nurse categorize this action of the heart?
Repolarization
Systole
Diastole
Ejection fraction
The Correct Answer is B
Choice A Rationale:
Repolarization is a phase in the cardiac cycle that involves the restoration of electrical charges in heart muscle cells, enabling them to prepare for the next contraction. It does not directly refer to the physical contraction and ejection of blood from the chambers.
During repolarization, the heart muscle cells regain their negative electrical charge after depolarization, which triggered the contraction.
Repolarization is essential for maintaining the heart's rhythmic electrical activity and ensuring coordinated contractions.
It does not, however, cause the chambers to become smaller and eject blood, which is the defining feature of systole.
Choice C Rationale:
Diastole is the phase of the cardiac cycle when the heart chambers relax and fill with blood. It is the opposite of systole.
During diastole, the heart muscle relaxes, allowing the chambers to passively expand and collect blood from the veins.
The atrioventricular valves (mitral and tricuspid valves) open during diastole, allowing blood to flow from the atria into the ventricles.
While diastole is crucial for ensuring adequate blood supply to the heart, it does not involve the forceful ejection of blood into circulation that characterizes systole.
Choice D Rationale:
Ejection fraction is a measurement of the heart's pumping efficiency. It represents the percentage of blood that is ejected from the left ventricle with each contraction.
A normal ejection fraction is typically between 55% and 70%.
While ejection fraction is related to systole, it is not a synonym for it. Ejection fraction is a quantitative measure of how well the heart is pumping, while systole refers to the specific phase of the cardiac cycle when contraction and ejection occur.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A rationale:
While it's important to assess for potential causative factors of premature ventricular contractions (PVCs), such as caffeine intake, it's not the immediate priority in this scenario.
The nurse's primary focus should be on assessing the patient's hemodynamic stability and oxygenation status, as frequent PVCs can compromise cardiac function and lead to serious complications.
Assessment of causative factors can be done subsequently, once the patient's immediate physiological needs have been addressed.
Choice B rationale:
The patient's subjective experience of palpitations or fluttering is valuable information, but it doesn't provide objective data about their cardiovascular status.
The nurse needs to prioritize objective assessment of vital signs, such as blood pressure and oxygen saturation, to evaluate the patient's hemodynamic stability and oxygenation.
Subjective symptoms can be further explored after obtaining objective data.
Choice D rationale:
Precipitating factors, such as infection, can contribute to PVCs, but they are not the immediate priority in this case.
The nurse's focus should be on assessing the patient's current cardiovascular status and ensuring their stability.
Investigation of potential precipitating factors can be done later, as part of a comprehensive assessment and management plan.
Choice C rationale:
Blood pressure and oxygen saturation are the most crucial parameters to assess in a patient with frequent PVCs.
Here's why:
Blood pressure: PVCs can disrupt the normal rhythm of the heart, potentially leading to a decrease in cardiac output and hypotension.
Hypotension can compromise perfusion to vital organs, such as the brain and kidneys, and can be a sign of hemodynamic instability.
Therefore, it's essential to monitor the patient's blood pressure closely.
Oxygen saturation: PVCs can also impair the heart's ability to pump blood effectively, which can lead to decreased oxygen delivery to the tissues.
This can result in hypoxemia, which can further worsen cardiac function and cause other complications.
Monitoring oxygen saturation using pulse oximetry is crucial to ensure adequate oxygenation.
Correct Answer is D
Explanation
Choice A rationale:
Assessing lung sounds is important for evaluating respiratory status, but it is not the priority assessment before administering digoxin. Digoxin does not have a direct effect on the respiratory system, and changes in lung sounds would not necessarily indicate a contraindication to its administration.
However, in patients with heart failure, which is a common indication for digoxin, auscultating lung sounds can provide valuable information about fluid status and the effectiveness of treatment. Therefore, while not the priority assessment, lung auscultation remains a relevant part of the overall assessment of a patient receiving digoxin.
Choice B rationale:
Assessing systolic blood pressure is important for monitoring hemodynamic status, but it is not the most critical assessment before administering digoxin. Digoxin does not directly affect blood pressure, and changes in blood pressure would not necessarily indicate a contraindication to its administration.
However, in patients with hypertension, which can be a factor in heart failure, monitoring blood pressure is essential for managing overall cardiovascular health. Therefore, while not the priority assessment, blood pressure measurement remains an important aspect of care for patients receiving digoxin.
Choice C rationale:
Assessing the brachial pulse for 30 seconds can provide a general assessment of heart rate and rhythm, but it is not as accurate as assessing the apical pulse for a full minute.
The apical pulse is the most reliable way to assess heart rate and rhythm, especially in patients with irregular heartbeats or those taking medications that can affect heart rate, such as digoxin.
Therefore, assessing the apical pulse for a full minute is essential to ensure accurate assessment of the patient's cardiac status before administering digoxin.
Choice D rationale:
Assessing the apical pulse for 60 seconds is the priority assessment before administering digoxin. This is because digoxin is a cardiac glycoside that affects the heart's electrical conduction system and can slow the heart rate. It is essential to assess the patient's heart rate and rhythm before administering digoxin to ensure that it is safe to do so.
A slow heart rate (bradycardia), irregular heart rhythms (such as atrial fibrillation), or certain heart block conditions can be contraindications to digoxin administration or require dosage adjustments.
By accurately assessing the apical pulse for a full minute, the nurse can identify any potential contraindications or concerns and ensure the safe administration of digoxin.
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