After the nurse gives IV atropine to a patient with symptomatic type 1. second-degree atrioventricular (AV) block, which finding indicates that the drug has been effective?
A.
Increase in the patient’s heart rate.
B.
Decrease in premature ventricular contractions.
C.
Increase in strength of peripheral pulses.
D.
Decrease in premature atrial contractions
The Correct Answer and Explanation is:
The correct answer is:
A. Increase in the patient’s heart rate.
Explanation:
Atropine is a medication commonly used to treat symptomatic bradycardia, which is often seen in patients with various types of atrioventricular (AV) block. Specifically, for a patient with symptomatic Type 1 second-degree AV block (also known as Mobitz I or Wenckebach block), atropine can be effective in increasing the heart rate and improving cardiac output.
Type 1 second-degree AV block is characterized by a progressive delay in the conduction through the AV node until a beat is dropped (i.e., a QRS complex is missed). This condition can result in bradycardia (slow heart rate) and symptoms such as dizziness, fatigue, or syncope. The primary goal of treatment is to increase the heart rate to alleviate these symptoms and ensure adequate cardiac output.
Atropine works by blocking the parasympathetic influences on the heart, which are mediated by the vagus nerve. The vagus nerve normally slows the heart rate by releasing acetylcholine, which decreases the rate of sinus node firing and prolongs AV node conduction. By inhibiting this action, atropine effectively increases the heart rate by reducing the parasympathetic tone.
Increase in the patient’s heart rate indicates that atropine has been effective. After administration, a typical response would be a noticeable increase in heart rate, which helps improve the blood flow and oxygen delivery to tissues, thus resolving symptoms associated with bradycardia. This response is a direct indication that the medication has had its intended pharmacological effect.
Other options explained:
- B. Decrease in premature ventricular contractions (PVCs): Atropine’s primary use in this context is to address bradycardia, not PVCs. While atropine may have some impact on ventricular ectopy, it is not specifically indicated for managing PVCs.
- C. Increase in strength of peripheral pulses: While an increased heart rate may improve the strength of peripheral pulses, this is an indirect effect. The primary measure of atropine’s effectiveness is the increase in heart rate.
- D. Decrease in premature atrial contractions (PACs): Similar to PVCs, PACs are not the target of atropine therapy for AV block. The primary purpose is to address bradycardia.
In summary, the most direct and relevant indicator of atropine’s effectiveness in treating symptomatic Type 1 second-degree AV block is an increase in the patient’s heart rate.