While caring for a client with a temporary pacemaker, your instructor asks you to explain the concept of "capture." Which of the following statements accurately defines "capture" and its significance in cardiac pacing?
Capture is the electrical stimulus delivered by a pacemaker's pulse generator resulting in a vertical line on the ECG."
Capture is the phenomenon where the pacemaker fails to stimulate the heart, leading to a complete absence of cardiac activity and requiring immediate intervention.
Capture describes the rate at which the pacemaker fires, which should always be set higher than the patient's intrinsic heart rate to prevent bradycardia.
Capture is the ability of a pacing stimulus to successfully depolarize the cardiac chamber being paced, indicating effective pacing and coordination with the heart's electrical system.
The Correct Answer is D
A. The vertical spike seen on the ECG represents the pacemaker's electrical stimulus, but capture specifically refers to the heart’s response—not just the spike itself.
B. Failure to capture occurs when the pacemaker delivers a stimulus without causing depolarization, but this is the opposite of capture.
C. The pacemaker rate is the pacing rate, not capture. While it is often set above the intrinsic rate, this does not define capture.
D. Capture occurs when the pacemaker’s electrical stimulus successfully depolarizes the myocardium, producing a corresponding P wave (atrial pacing) or QRS complex (ventricular pacing) on the ECG. Effective capture confirms the pacemaker is working and coordinating appropriately with the heart’s electrical system.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. Amiodarone is used to treat arrhythmias and does not address hypotension caused by nitroglycerin.
B. Increasing the tPA infusion rate could worsen bleeding risks and does not correct hypotension.
C. Nitroglycerin is a vasodilator that can lower blood pressure; decreasing the infusion rate is the immediate priority to stabilize the client’s hemodynamics.
D. Obtaining a chest x-ray may be useful for other assessments but does not address the acute hypotensive event.
Correct Answer is B
Explanation
A. This describes first-degree AV block, where every P wave is conducted to the ventricles, but the PR interval is prolonged.
B. Second-degree type 1 AV block (Wenckebach/Mobitz I) is characterized by a progressive lengthening of the PR interval until a QRS complex is dropped, resulting in more P waves than QRS complexes. This pattern then repeats cyclically.
C. This describes second-degree type 2 AV block (Mobitz II), where some P waves are not conducted but the PR interval of conducted beats remains constant.
D. There are never more QRS complexes than P waves in AV block; this pattern is inconsistent with the physiology of AV conduction.
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