17.3: Class II- Beta Adrenergic Blockers
By the end of this section, you should be able to:
- 17.3.1 Identify the characteristics of the beta-adrenergic blocker drugs used to treat dysrhythmias.
- 17.3.2 Explain the indications, actions, adverse reactions, and interactions of beta-adrenergic blocker drugs used to treat dysrhythmias.
- 17.3.3 Describe the nursing implications of beta-adrenergic blocker drugs used to treat dysrhythmias.
- 17.3.4 Explain the client education related to beta-adrenergic blocker drugs used to treat dysrhythmias.
Beta-adrenergic blockers (informally called beta blocker s ) are known by their generic names, which end with “olol.” They can be used for many disease states, including heart failure, myocardial infarction, angina, and hypertension. Beta-adrenergic blockers block adrenergic beta-1 receptors in the heart (among other actions, depending on the drug), which leads to decreased heart rate from the SA node. It also leads to a decreased rate of conduction through the AV node and decreased cardiac contractility. There are other types of beta-adrenergic receptors, such as beta-2 receptors in the lungs that mediate bronchoconstriction. Some beta-adrenergic blockers can also affect alpha receptors in the vasculature, causing vasodilation and decreased blood pressure. Many beta-adrenergic blockers are used in practice; however, it is most common to use the ones that are cardioselective for treatment of arrhythmias. Clients should avoid stopping beta-adrenergic blockers abruptly because sudden discontinuation can exacerbate arrhythmias.
Safety Alert
Beta-Adrenergic Blockers
Beta-adrenergic blockers can cause bradycardia. The nurse should monitor the client’s heart rate before administration and not give the drug to bradycardic clients who do not have a functioning pacemaker.
Many beta-adrenergic blockers are available, and several can be used as antidysrhythmic drugs. This chapter discusses two of the most common beta-adrenergic blockers: esmolol and metoprolol.
Esmolol
Esmolol is an intravenous beta-adrenergic blocker that is selective for the beta-1 receptors in the heart. Esmolol is very fast acting and slows the heart rate within 2–10 min of administration. It also has a short duration; the half-life of esmolol in adults is only 9 min. For this reason, esmolol is often administered as a short-term treatment (used less than 48 hours) via continuous infusion when acute control is needed or for ease of titration. It is approved for sinus tachycardia, supraventricular tachycardia, atrial fibrillation/flutter, and intraoperative and postoperative tachycardia and hypertension. It is used off-label for ventricular tachycardia. Frequent blood pressure monitoring is required. An arterial line provides the best method for continuous monitoring of blood pressure, although it is an invasive procedure and not always done (Pevtsov & Fredlund, 2023).
Clinical Tip
Administration of Esmolol
Esmolol is a vesicant, and extravasation can lead to skin necrosis and sloughing. The nurse should ensure proper needle/catheter placement. If extravasation occurs, the infusion should be stopped, the line aspirated, and the limb elevated.
Metoprolol
Metoprolol is a beta-adrenergic blocker with selective activity at beta-1 receptors in the heart. It is available as an immediate-release tablet (metoprolol tartrate) and an extended-release tablet (metoprolol succinate). It is also available in an intravenous form. It is approved for various cardiac conditions, including heart failure, angina, hypertension, and myocardial infarction. It is used off-label for treating atrial fibrillation/flutter, other supraventricular arrhythmias, and ventricular arrhythmias.
Table 17.4 lists common cardioselective beta-adrenergic blockers and typical routes and dosing for adult clients.
| Drug | Routes and Dosage Ranges |
|---|---|
|
Esmolol
( Brevibloc ) |
Rate control of atrial fibrillation: 500 mcg/kg IV bolus over 1 minute, then 50–300 mcg/kg/minute IV. |
|
Metoprolol
( Lopressor , Toprol XL ) |
Rate control of atrial fibrillation:
Metoprolol tartrate (immediate release): IV: 2.5–5 mg IV over 2 minutes, up to 3 doses. Oral: 25–100 mg orally twice daily. Metoprolol succinate (extended release): 50–400 mg orally daily. |
|
Atenolol
( Tenormin ) |
Rate control of atrial fibrillation: 25–100 mg orally daily. |
|
Propranolol
( Inderal ) |
Rate control of atrial fibrillation:
IV: 1 mg IV over 1 minute, up to 3 doses at 2-minute intervals. Oral: 10–40 mg orally 3–4 times daily. |
| Bisoprolol | Rate control of atrial fibrillation: 2.5–10 mg orally daily. |
Adverse Effects and Contraindications
Cardioselective beta-adrenergic blockers do not have direct hypotensive effects on the vasculature but can still cause hypotension through decreased cardiac output. Beta-adrenergic blockers can mask hypoglycemia due to their effects on heart rate, so clients with diabetes should be aware that they will not necessarily experience their typical hypoglycemic symptoms. Beta-adrenergic blockers can cause central nervous system adverse effects, especially fatigue. They also can be associated with bronchospasm; however, cardioselective beta-adrenergic blockers have a lower risk for this. Sexual side effects are also common.
Although beta-adrenergic blockers are indicated to treat heart failure long term, starting beta-adrenergic blockers too quickly or at too high a dose can lead to heart failure exacerbations because of their effect on cardiac contractility.
Beta-adrenergic blockers can cause bradycardia and are contraindicated in clients who have severe bradycardia unless they have a pacemaker and in clients in cardiogenic shock. They should also be used cautiously in clients with acute exacerbations of heart failure.
Table 17.5 is a drug prototype table for beta-adrenergic blockers featuring metoprolol. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
|
Drug Class
Beta-adrenergic blocker Mechanism of Action Acts as a beta-1 receptor antagonist in cardiac tissue, slowing pacing from the sinoatrial node and conduction through the atrioventricular node |
Drug Dosage
Rate control of atrial fibrillation: Metoprolol tartrate (immediate release): IV: 2.5–5 mg IV over 2 minutes, up to 3 doses. Oral: 25–100 mg orally twice daily. Metoprolol succinate (extended release): 50–400 mg orally daily. |
|
Indications
Rate control of atrial fibrillation/flutter Angina Heart failure Hypertension Myocardial infarction Therapeutic Effects Decreases heart rate and conduction Decreases cardiac contractility (not related to antiarrhythmic effects) |
Drug Interactions
Reserpine Digoxin Calcium channel blockers CYP2D6 inhibitors Alpha-adrenergic blockers Ergot alkaloids Food Interactions No significant interactions |
|
Adverse Effects
Fatigue Dizziness Bradycardia Bronchospasm Hypotension Heart failure Heart blocks |
Contraindications
Sinus bradycardia Heart blocks Cardiogenic shock Overt cardiac failure Sick sinus syndrome Severe peripheral arterial circulatory disorders Acute myocardial infarction, especially with hemodynamic instability Hypotension (systolic blood pressure less than 100 mm Hg) Caution: Bronchospastic disease |
Nursing Implications
The nurse should do the following for clients who are taking beta-adrenergic blockers:
- If the baseline heart rate is less than 60 beats per minute, consider checking with the health care provider before giving the drug.
- Monitor the client’s blood pressure.
- Recognize differences in dosing regimens between IV and oral forms of the drugs.
- Take care to avoid and recognize extravasation of esmolol.
- Be careful not to confuse the different forms of metoprolol.
- Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.
Client Teaching Guidelines
The client taking a beta-adrenergic blocker should:
- Avoid orthostatic hypotension by moving slowly when standing up from a sitting or lying position. Extra caution is advised after dose increases.
- Not stop their medication abruptly because this can cause arrhythmias and produce withdrawal effects.
- Alert their health care provider if they feel very dizzy.
- Understand that beta-adrenergic blockers can worsen respiratory symptoms of asthma and chronic obstructive pulmonary disease (COPD).
- Be aware that beta-adrenergic blockers can mask symptoms of hypoglycemia. (This is particularly important for clients with diabetes.)
FDA Black Box Warning
Beta-Adrenergic Blockers
Metoprolol: Following abrupt cessation of therapy with certain beta-blocking agents, myocardial infarction and exacerbations of angina pectoris have occurred.
Atenolol: Advise clients with coronary artery disease who are being treated with atenolol against abruptly stopping the medication. Severe exacerbation of angina and the occurrence of myocardial infarction and ventricular arrhythmias have been reported in clients with angina following the abrupt discontinuation of therapy with beta-adrenergic blockers.
Case Study
Read the following clinical scenario to answer the questions that follow.
Mike Smith is a 73-year-old client who presents to the emergency department with symptoms of a racing heart. The nurse checks his ECG and notices no discernable P waves and narrow QRS (ventricular depolarization) complexes.
History
This client has a past medical history of type 2 diabetes and hypercholesterolemia.
Current Medications
Omeprazole 20 mg daily
| Vital Signs | Physical Examination | |
|---|---|---|
| Temperature: | 98.4°F |
|
| Blood pressure: | 100/72 mm Hg | |
| Heart rate: | 132 beats/min | |
| Respiratory rate: | 17 breaths/min | |
| Oxygen saturation: | 99% on room air | |
| Height: | 5'10" | |
| Weight: | 202 lb |
Based on the information above, the nurse anticipates which diagnosis by the health care provider?
- Answer
-
Atrial fibrillation with rapid ventricular response
Which medication may be given to treat the client’s diagnosis?
- Answer
-
Metoprolol