Choice A rationale

Slow repolarization of ventricular Purkinje fibers is not associated with the P wave. The P wave represents atrial depolarization, which is the electrical activation of the atria.

Choice B rationale

Early ventricular repolarization is represented by the T wave, not the P wave. The P wave specifically reflects atrial depolarization.

Choice C rationale

Atrial depolarization is the correct role of the P wave. It represents the electrical activity that leads to atrial contraction. Normal duration is 0.06 to 0.12 seconds.

Choice D rationale

Ventricular depolarization is represented by the QRS complex. The P wave precedes this and is related to atrial depolarization, not ventricular events.

Choice A rationale

Storing nitroglycerin in the bathroom medicine cabinet is incorrect. The bathroom’s humidity and heat can degrade the medication, reducing its effectiveness.

Choice B rationale

Nitroglycerin dilates cardiac blood vessels to deliver more oxygen to the heart. This action helps relieve the chest pain associated with angina by increasing blood flow.

Choice C rationale

Placing one tablet under the tongue every 5 minutes for 30 minutes is incorrect. The correct protocol is one tablet every 5 minutes for up to 15 minutes (total of 3 tablets).

Choice D rationale

Nitroglycerin does not decrease chest pain by dissolving blood clots. It works by dilating blood vessels and increasing oxygen supply to the heart muscle.

Choice A rationale

A QRS duration of 0.30 seconds is abnormally long. The normal QRS duration is 0.06 to 0.12 seconds, indicating this is not normal sinus rhythm.

Choice B rationale

An inverted T wave is not a characteristic of normal sinus rhythm. It may indicate ischemia or other cardiac abnormalities.

Choice C rationale

A P-R interval of 0.32 seconds is prolonged. The normal P-R interval is 0.12 to 0.20 seconds, thus indicating an abnormal rhythm.

Choice D rationale

The P wave falling before the QRS complex is a key characteristic of normal sinus rhythm, representing the orderly conduction of electrical impulses from atria to ventricles. .

Choice A rationale

Ibuprofen is not indicated for chest pain that may suggest myocardial infarction (MI). NSAIDs like ibuprofen can increase cardiovascular risk, thus inappropriate for suspected cardiac events. Administering ibuprofen could mask symptoms.

Choice B rationale

Enteric-coated acetaminophen is not suitable for acute chest pain related to suspected MI. It offers pain relief but does not address underlying ischemic heart disease. Immediate cardiac evaluation and intervention are required in such cases.

Choice C rationale

While maintaining oxygen saturation is essential, it does not address the need for immediate cardiac evaluation in suspected MI. Adequate oxygenation supports tissue perfusion, but it is not the definitive diagnostic or therapeutic intervention.

Choice D rationale

Obtaining an EKG is crucial for diagnosing myocardial infarction by assessing electrical activity of the heart. It helps identify ischemia or infarction. Early detection of abnormalities ensures prompt treatment and reduces complications.

Choice A rationale

The first upward deflection in an ECG represents the P wave, indicating atrial depolarization. It precedes the QRS complex and corresponds to the electrical activity associated with atrial contraction, initiating the cardiac cycle.

Choice B rationale

The peak of the first wave corresponds to the R wave, not the P wave. The R wave is a part of the QRS complex, representing ventricular depolarization, and is not associated with atrial depolarization.

Choice C rationale

The downward deflection following the peak is the S wave, part of the QRS complex, indicating ventricular depolarization. It is not related to the P wave, which specifically represents atrial depolarization.

Choice D rationale

The second upward deflection is the T wave, which represents ventricular repolarization. It follows the QRS complex and is not associated with atrial depolarization or the P wave.

Choice A rationale

The first upward deflection in an ECG represents the P wave, indicating atrial depolarization. It precedes the QRS complex and corresponds to the electrical activity associated with atrial contraction, initiating the cardiac cycle.

Choice B rationale

The peak of the first wave corresponds to the R wave, not the P wave. The R wave is a part of the QRS complex, representing ventricular depolarization, and is not associated with atrial depolarization.

Choice C rationale

The downward deflection following the peak is the S wave, part of the QRS complex, indicating ventricular depolarization. It is not related to the P wave, which specifically represents atrial depolarization.

Choice D rationale

The second upward deflection is the T wave, which represents ventricular repolarization. It follows the QRS complex and is not associated with atrial depolarization or the P wave. .

Choice A rationale

Nitroglycerin causes vasodilation, leading to headaches as a common adverse effect. These headaches are due to the increased blood flow and dilation of cerebral blood vessels.

Choice B rationale

Headaches do not indicate tolerance to nitroglycerin. Tolerance typically presents with a diminished therapeutic effect, not adverse effects like headaches.

Choice C rationale

Anxiety-induced headaches are unlikely since nitroglycerin-induced headaches are a physiological response to vasodilation, not psychological factors.

Choice D rationale

An allergic reaction to nitroglycerin would present with symptoms like rash or itching, not headaches. Headaches are a known and expected adverse effect.

Choice A rationale

Administering 0.9% normal saline IV at 50 mL/hr continuously in acute heart failure can exacerbate fluid overload, worsening symptoms like pulmonary edema.

Choice B rationale

Serum potassium testing is essential in heart failure management due to potential electrolyte imbalances from medications like diuretics.

Choice C rationale

Bumetanide, a loop diuretic, is used to manage fluid overload in acute heart failure by promoting diuresis and reducing volume overload.

Choice D rationale

Morphine sulfate can help alleviate pain and anxiety in heart failure patients, reducing oxygen demand and improving symptoms.

Choice A rationale

An MRI of the chest is contraindicated in clients with a permanent pacemaker due to the strong magnetic fields, which can interfere with pacemaker function.

Choice B rationale

Serum cardiac enzyme levels are useful in monitoring cardiac function and detecting myocardial injury, important for post-pacemaker insertion care.

Choice C rationale

Physical therapy is beneficial for recovery and rehabilitation after pacemaker insertion, aiding in mobility and overall cardiovascular health.

Choice D rationale

A sodium diet is not contraindicated. In fact, a low-sodium diet is recommended for patients with cardiac issues to manage fluid retention. .

Choice A rationale

Antiembolic stockings compress superficial veins, which may further limit blood flow to the already compromised peripheral arteries, exacerbating symptoms of peripheral arterial disease rather than alleviating them.

Choice B rationale

Elevating the legs above heart level reduces arterial perfusion to the extremities. In peripheral arterial disease, maintaining a position that allows gravity to assist arterial flow is beneficial, not restricting it.

Choice C rationale

Applying heat can dilate blood vessels and increase blood flow; however, it can also increase the risk of burns due to decreased sensation and poor skin integrity commonly seen in peripheral arterial disease patients.

Choice D rationale

A warm environment helps to prevent vasoconstriction. Cold temperatures can cause the arteries to constrict, reducing blood flow to the extremities. A consistent warm environment supports improved blood circulation.