The therapeutic effect of Digitalis is to?

SCTIMST Staff Nurse - 2015 (Set-B)

Pharmacology

Easy

Appeared in: SCTIMST Staff Nurse - 2015 (Set-B)

Explanation

Digitalis is classified as a positive inotropic agent, which means its primary function is to increase the force of myocardial (heart muscle) contraction.
This action strengthens the heartbeat, leading to improved cardiac output and more efficient blood circulation.
This effect is the main reason Digitalis is used in the management of heart failure, where the heart's pumping ability is compromised.

Option A: Digitalis does not primarily dilate coronary arteries. This is the main mechanism of action for drugs like nitrates, which are used to treat angina.
Option C: This is misleading. While Digitalis can slow the ventricular response in atrial fibrillation (a type of arrhythmia), it can also cause serious arrhythmias, especially in cases of toxicity. Its primary goal is not to suppress all arrhythmias.
Option D: While Digitalis does decrease electrical conductivity through the AV node (a negative dromotropic effect), this is a secondary effect. The principal therapeutic goal for which it is prescribed, especially in heart failure, is to improve the strength of contraction.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Therapeutic effect of Digitalis (Digoxin) as background academic context rather than a clinical decision trigger.
Digitalis (Digoxin) has a narrow therapeutic index, meaning the dose required for therapeutic effect is very close to the dose that causes toxicity. Nurses must be vigilant in monitoring patients.
A critical nursing responsibility is to check the apical pulse for one full minute before administering digoxin. The medication is typically held if the heart rate is below 60 beats per minute for an adult, and the provider must be notified.
Electrolyte imbalances, particularly hypokalemia (low potassium), significantly increase the risk of digoxin toxicity. Therefore, monitoring potassium levels is crucial.

How to Approach the Question

First, identify the drug in question: Digitalis (also known as Digoxin).
Recall the primary drug class and its main action. Digitalis is a cardiac glycoside, known for being a 'positive inotrope'.
Translate the medical term 'positive inotrope' into a simpler concept: it increases the force or strength of the heart's contraction.
Scan the options to find the one that matches this primary action. 'Strengthen the Heart beat' is a direct description of the positive inotropic effect.
Briefly consider the other options to confirm they are secondary effects or incorrect. Decreasing conductivity is a secondary effect, and dilating arteries is incorrect. While it affects arrhythmias, it's not its primary therapeutic goal and can also cause them.

Concept Tested & Keywords

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E6 Pharmacology KD Tripathi Essentials 9e Part 2 p. 188-190

E6 Pharmacology Katzung 16e pp. 336-338, 337-339