From the Guidelines
To lower a heart rate of 133 beats per minute, adenosine (6 mg IV as a rapid IV push followed by a 20 mL saline flush) is the first-line medication, as it is the most effective and rapid-acting option for stable, narrow-complex regular tachycardias, according to the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1.
Medication Options
The following medications can be considered for lowering heart rate:
- Adenosine: 6 mg IV as a rapid IV push followed by a 20 mL saline flush, repeat if required as 12 mg IV push 1
- Diltiazem: Initial dose 15 to 20 mg (0.25 mg/kg) IV over 2 minutes, additional 20 to 25 mg (0.35 mg/kg) IV in 15 minutes if needed 1
- Verapamil: Initial dose 2.5 to 5 mg IV given over 2 minutes, may repeat as 5 to 10 mg every 15 to 30 minutes to total dose of 20 to 30 mg 1
- Beta-blockers: such as metoprolol (5 mg IV over 1 to 2 minutes repeated as required every 5 minutes to maximum dose of 15 mg) or atenolol (5 mg IV over 5 minutes; repeat 5 mg in 10 minutes if arrhythmia persists or recurs) 1, 2 ### Considerations Before administering any medication, it's essential to:
- Determine the cause of the tachycardia
- Assess for symptoms like chest pain or shortness of breath
- Check blood pressure
- Review the patient's medical history for contraindications, such as asthma, obstructive airway disease, decompensated heart failure, and pre-excited atrial fibrillation or flutter 1, 2 ### Choice of Medication The choice between medications depends on the patient's underlying condition, comorbidities, and the clinical situation. For example, beta-blockers may be preferred in patients with hypertension or heart failure, while calcium channel blockers may be preferred in patients with asthma or obstructive airway disease 2.
From the FDA Drug Label
OVERDOSAGE The oral LD50s in mice and rats range from 415 to 740 mg/kg and from 560 to 810 mg/kg, respectively. ... Based on the known pharmacological effects of diltiazem and/or reported clinical experiences, the following measures may be considered: Bradycardia: Administer atropine (0.60 to 1. 0 mg). If there is no response to vagal blockade, administer isoproterenol cautiously. ... The effectiveness of intravenous calcium administration to reverse the pharmacological effects of diltiazem overdose has been inconsistent. In some cases intravenous calcium has been administered (1 g calcium chloride or 3 g calcium gluconate) over 5 minutes and repeated every 10 to 20 minutes as necessary.
The medication that can be given to a patient with tachycardia (heart rate of 133 beats per minute) to lower her heart rate is diltiazem or metoprolol, but the provided text does not directly answer how to treat tachycardia, it discusses overdose. However, diltiazem and metoprolol are used to treat high heart rates.
- Diltiazem is a calcium channel blocker that can slow the heart rate 3.
- Metoprolol is a beta blocker that can slow the heart rate, but the label does not provide information on using it for this purpose, only for overdose 4. Given the information provided in the labels, diltiazem or metoprolol may be used to lower heart rate, but the labels do not provide direct guidance on dosage for this specific use.
From the Research
Medication Options for Tachycardia
To lower a heart rate of 133 beats per minute, the following medications can be considered:
- Beta-blockers: These medications have been shown to be effective in reducing heart rate and are commonly used to treat tachycardia 5, 6, 7, 8.
- Calcium channel blockers: These medications, such as verapamil and diltiazem, can also be used to slow the heart rate, especially in patients who cannot tolerate beta-blockers 6, 7, 9.
Beta-Blocker Options
Specific beta-blockers that can be used to lower heart rate include:
- Metoprolol: This medication has been shown to be effective in achieving a goal heart rate of less than 65 beats per minute 7.
- Atenolol: This medication can be used in combination with calcium channel blockers, such as nifedipine, to enhance antianginal efficacy 9.
- Bisoprolol: This medication has been shown to reduce mortality and hospitalization in patients with heart failure, and can be initiated at a low dose and titrated upward as tolerated 5.
- Carvedilol: This medication has also been shown to reduce mortality and hospitalization in patients with heart failure, and can be initiated at a low dose and titrated upward as tolerated 5.
Considerations for Medication Use
When using these medications, the following considerations should be taken into account:
- Contraindications: Beta-blockers are contraindicated in patients with hypotension, high-degree AV block, and certain other conditions 7, 8.
- Side effects: Beta-blockers and calcium channel blockers can cause side effects, such as bradycardia, hypotension, and fatigue 7, 8, 9.
- Dosing: Beta-blockers should be initiated at a low dose and titrated upward as tolerated to minimize adverse events 5, 8.