A nurse is assisting with teaching a newly licensed nurse about heart sounds. Which of the following sounds is heard when the aortic and pulmonic valves close?
S1
S2
S3
S4
The Correct Answer is B
Choice A reason : S1 represents the sound made by the closure of the atrioventricular valves (mitral and tricuspid valves) and is not the sound associated with the closure of the aortic and pulmonic valves.
Choice B reason : S2 is the sound heard when the aortic and pulmonic valves close. It is often described as a "dub" and occurs at the end of ventricular systole.
Choice C reason : S3 is a rare extra heart sound that follows S2 and usually indicates an increase in left ventricular filling pressure, which can be found in conditions such as heart failure.
Choice D reason : S4 is another extra heart sound that occurs just before S1. It is typically associated with a stiff or hypertrophic ventricle and is not related to the closure of the aortic and pulmonic valves
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A reason : The statement that warfarin dissolves clots in the bloodstream is incorrect. Warfarin does not dissolve existing clots. Instead, it is an anticoagulant that works by decreasing the production of certain clotting factors in the blood, which helps prevent the formation of new clots.
Choice B reason : This statement is not accurate regarding the action of warfarin. Warfarin does not affect the electrical impulses of the heart. Medications that slow the response of the ventricles to fast atrial impulses are typically antiarrhythmic drugs, not anticoagulants like warfarin.
Choice C reason : This is the correct statement. Warfarin is prescribed for clients with atrial fibrillation to reduce the risk of stroke. Atrial fibrillation increases the risk of forming blood clots in the heart, which can then travel to the brain, causing a stroke. Warfarin's anticoagulant effect helps to prevent these clots from forming.
Choice D reason : Warfarin does not help maintain a normal heart rhythm. It is not an antiarrhythmic drug but an anticoagulant. The purpose of warfarin in atrial fibrillation is to prevent stroke by reducing the risk of clot formation, not to correct the heart rhythm.
Correct Answer is D
Explanation
Choice A reason: The PR interval, which is the time from the onset of atrial depolarization (beginning of the P wave) to the onset of ventricular depolarization (beginning of the QRS complex), normally ranges from 0.12 to 0.20 seconds. A PR interval of 0.15 second is within the normal range and does not indicate an acute myocardial infarction.
Choice B reason: The QT interval represents the total time for ventricular depolarization and repolarization. The normal QT interval varies based on heart rate and gender but is typically less than half of the R-R interval in a normal heart rhythm. Therefore, a QT interval equal to the R-R interval is abnormally prolonged, which may suggest other conditions but is not a specific indicator of acute myocardial infarction.
Choice C reason: The QRS complex reflects ventricular depolarization and normally ranges from 0.06 to 0.10 seconds. A QRS interval of 0.08 second is within the normal range and does not suggest an acute myocardial infarction.
Choice D reason: ST segment elevation is a critical finding in the diagnosis of acute myocardial infarction. The ST segment should be at the isoelectric line; elevation above this line is indicative of myocardial injury and is a key diagnostic criterion for ST-elevation myocardial infarction (STEMI). An elevated ST segment is often seen in the early stages of an acute myocardial infarction and requires immediate medical attention.
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