Digoxin (Lanoxin) is a cardiac glycoside that is among the oldest medications used for heart failure.
What are its two primary actions?
Positive chronotropy and negative inotropy.
Negative inotropy and negative chronotropy.
Positive inotropy and negative chronotropy.
Positive inotropy and positive chronotropy.
The Correct Answer is C
Digoxin is a cardiac glycoside that increases the force of heart contractions (positive inotropy) and decreases the heart rate (negative chronotropy) by inhibiting the sodium-potassium ATPase pump in the cardiac cell membranes and affecting the autonomic tone. This helps to improve the symptoms of heart failure and to control the ventricular rate in atrial fibrillation.
Choice A is wrong because positive chronotropy means increasing the heart rate, which is the opposite of what digoxin does.
Choice B is wrong because negative inotropy means decreasing the force of heart contractions, which is also the opposite of what digoxin does.
Choice D is wrong because positive inotropy and positive chronotropy would both increase the workload of the heart, which is not desirable in heart failure or atrial fibrillation.
Normal ranges for digoxin are 0.5 to 2 ng/mL for heart failure and 0.8 to 2 ng/mL for atrial fibrillation. Digoxin has a narrow therapeutic window and can cause serious side effects if overdosed or underdosed.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
This is because low potassium levels (hypokalemia) increase the sensitivity of the heart to digoxin and can lead to toxicity even with normal serum digoxin levels. Digoxin inhibits the sodium-potassium pump on the cardiac cells, which causes potassium to accumulate outside the cells.Low potassium levels in the blood create a larger gradient for potassium to move out of the cells, which enhances the effect of digoxin and can cause arrhythmias.
Choice B is wrong because calcium 9.2 mg/dL is within the normal range (8.5 to 10.2 mg/dL) and does not increase the risk of digoxin toxicity.However, high calcium levels (hypercalcemia) can potentiate the effects of digoxin and cause toxicity.
Choice C is wrong because sodium 140 mEq/L is within the normal range (135 to 145 mEq/L) and does not increase the risk of digoxin toxicity.However, high sodium levels (hypernatremia) can reduce the binding of digoxin to the sodium-potassium pump and decrease its efficacy.
Choice D is wrong because magnesium 2.2 mg/dL is within the normal range (1.7 to 2.4 mg/dL) and does not increase the risk of digoxin toxicity.However, low magnesium levels (hypomagnesemia) can increase the sensitivity of the heart to digoxin and cause toxicity.
Correct Answer is A
Explanation
Intermittent claudication is a condition in which leg pain is produced upon increased activity and ischemia to tissues, but then the pain is reduced with rest. This is because the blood flow to the leg muscles is insufficient to meet the increased demand during exercise, but adequate at rest.Intermittent claudication is a common symptom of peripheral artery disease (PAD), which is a narrowing of the arteries that supply blood to the legs.
Choice B, sporadic ischemia, is wrong because it is not a specific medical term for a condition that causes leg pain.
Ischemia means reduced blood flow to a part of the body, which can cause pain, but it can be caused by various factors and affect different organs.
Choice C, angina, is wrong because it is a term for chest pain caused by reduced blood flow to the heart, not the legs.
Angina can also be triggered by physical activity and relieved by rest, but it is not related to PAD or leg ischemia.
Choice D, restless leg syndrome, is wrong because it is a condition that causes an uncomfortable urge to move the legs, usually at night or when lying down.
Restless leg syndrome does not cause pain or ischemia in the legs, and it is not improved by rest.It is thought to be related to a problem with the nervous system or iron deficiency.
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