Supraventricular Tachycardia (SVT) and Its Pharmacological Treatment

Introduction

Supraventricular tachycardia (SVT) is a condition characterized by an abnormally fast heart rate originating above the ventricles. It is often caused by reentry circuits within the atria or atrioventricular (AV) node. The typical heart rate during an SVT episode ranges from 150 to 250 beats per minute.

Symptoms

• Palpitations (rapid or irregular heartbeat)
• Dizziness or lightheadedness
• Shortness of breath
• Chest discomfort
• Anxiety

Pharmacological Treatment

The choice of medication depends on several factors, including the type of SVT, patient stability, and comorbid conditions. Below are the key pharmacological options:

1. Adenosine (First-Line for Acute SVT)

• Mechanism of Action: Slows conduction through the AV node, interrupting reentry circuits.
• Administration: Given as a rapid IV bolus.
• Side Effects: Brief chest discomfort, flushing, transient asystole.

2. Beta-Blockers (e.g., Metoprolol, Propranolol, Esmolol)

• Mechanism of Action: Decrease sympathetic stimulation, slow AV node conduction.
• Indications: Maintenance therapy, prevention of recurrent SVT.
• Contraindications: Severe asthma, bradycardia.

3. Calcium Channel Blockers (e.g., Verapamil, Diltiazem)

• Mechanism of Action: Block calcium channels in the AV node to slow conduction.
• Indications: Alternative to beta-blockers for rate control.
• Contraindications: Heart failure, hypotension.

4. Antiarrhythmic Drugs (e.g., Flecainide, Propafenone, Amiodarone, Sotalol)

• Class I (Flecainide, Propafenone): Used for atrial arrhythmias in structurally normal hearts.
• Class III (Sotalol, Amiodarone): Used in patients with structural heart disease or refractory cases.
• Amiodarone Risks: Can cause thyroid dysfunction, lung toxicity, liver damage.

5. Digoxin

• Mechanism of Action: Increases vagal tone to slow AV nodal conduction.
• Indications: Used in some cases where beta-blockers or calcium channel blockers are contraindicated.

Special Considerations

• Emergency Management: Adenosine is the drug of choice for acute termination.
• Long-Term Management: Beta-blockers or calcium channel blockers are commonly used.
• Comorbidities: Drug choice should consider conditions like heart failure, asthma, and hypertension.

Conclusion

Pharmacological management of SVT is highly effective when tailored to the patient's specific needs. In cases of refractory SVT or frequent recurrences, catheter ablation may be considered.

References

For further guidance, refer to the following clinical guidelines:

Source recommendations

1. 2020 ESC Guidelines for the management of adult congenital heart disease

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2. https://pubmed.ncbi.nlm.nih.gov/32860028/
3. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Grown-Up-Congenital-Heart-Disease-Management-of
4. https://www.jacc.org/doi/10.1016/j.jacc.2021.09.010
5. https://www.revespcardiol.org/en-2020-esc-guidelines-for-management-articulo-S1885585721001201

2. 2020 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation

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4. https://www.jacc.org/doi/10.1016/j.jacc.2019.01.011
5. https://www.ahajournals.org/doi/10.1161/cir.0000000000000041

3. 2019 ESC Guidelines for the management of supraventricular tachycardia

1. https://academic.oup.com/eurheartj/article/41/5/655/5556821
2. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Supraventricular-Tachycardia
3. https://pubmed.ncbi.nlm.nih.gov/31504425/
4. https://www.acc.org/Latest-in-Cardiology/ten-points-to-remember/2019/09/10/12/36/2019-ESC-Guidelines-for-Supraventricular-Tachycardia
5. https://pubmed.ncbi.nlm.nih.gov/31837143/