How to manage sustained supraventricular tachycardia (SVT) with tachycardia and hypotension?

From the Guidelines

Synchronized cardioversion is the first-line treatment for hemodynamically unstable supraventricular tachycardia (SVT) with hypotension, as it quickly restores normal sinus rhythm. This approach is supported by the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.

Key Considerations

• The patient's condition, with a heart rate in the 150s and systolic blood pressure in the 90s, indicates hemodynamic instability, necessitating immediate intervention.
• Synchronized cardioversion at 50-100 joules is recommended for acute treatment in patients with hemodynamically unstable SVT when vagal maneuvers or adenosine are ineffective or not feasible 1.
• If the patient is conscious, consider brief sedation before cardioversion to minimize discomfort and anxiety.
• After cardioversion, if the patient remains stable, adenosine can be administered as 6 mg rapid IV push followed by a saline flush; if ineffective, give 12 mg, and a second 12 mg dose if needed, as adenosine is beneficial for acute treatment in patients with orthodromic AVRT 1.

Ongoing Management

• For ongoing management, consider calcium channel blockers like diltiazem (0.25 mg/kg IV over 2 minutes) or beta-blockers such as metoprolol (5 mg IV over 2-5 minutes, repeatable up to 3 doses) to control the heart rate and prevent recurrence of SVT.
• Amiodarone (150 mg IV over 10 minutes, then 1 mg/min infusion) may be used for refractory cases, as it can help in converting SVT to sinus rhythm and preventing its recurrence.
• These medications work by slowing conduction through the AV node, interrupting the reentry circuit that typically causes SVT.

Monitoring and Follow-Up

• Maintain continuous cardiac monitoring throughout treatment to quickly identify any recurrence of SVT or other arrhythmias.
• Be prepared to provide airway support if sedation is used for cardioversion.
• After acute management, patients should be evaluated for underlying causes of SVT and may require long-term oral medications or catheter ablation to prevent recurrence, as suggested by the guidelines for the management of adult patients with supraventricular tachycardia 1.

From the FDA Drug Label

WARNINGS Heart failure: Verapamil has a negative inotropic effect, which in most patients is compensated by its afterload reduction (decreased systemic vascular resistance) properties without a net impairment of ventricular performance. Hypotension: Occasionally, the pharmacologic action of verapamil may produce a decrease in blood pressure below normal levels, which may result in dizziness or symptomatic hypotension.

For managing sustained SVTs with heart rate in the 150s and low blood pressure (systolic 90s), verapamil may not be the best initial choice due to its potential to worsen hypotension.

• The primary concern in this scenario is the patient's hemodynamic instability, indicated by low blood pressure.
• Verapamil can cause a decrease in blood pressure, which may exacerbate the patient's condition.
• Given the potential risks, alternative treatments for SVT that do not involve verapamil should be considered, especially in patients with hypotension 2.

From the Research

Management of Sustained SVTs with Tachycardia and Hypotension

• The management of sustained supraventricular tachycardia (SVT) with tachycardia and hypotension involves several approaches, including vagal maneuvers, pharmacological treatment, and direct current cardioversion 3, 4, 5, 6.
• Vagal maneuvers are recommended as the first-line treatment for SVT, with the modified Valsalva maneuver being the most effective technique 5.
• Adenosine is recommended as the first-line pharmacological treatment for stable SVT, with a high success rate in converting SVT to a normal sinus rhythm (NSR) 3, 4, 7.
• In cases of hemodynamically unstable SVT, adenosine can still be effective, but the patient should be closely monitored for potential adverse effects 4.
• Telemedicine can be a useful tool in the management of in-flight SVTs, allowing for remote diagnosis and guidance of treatment 6.

Pharmacological Treatment

• Adenosine is the preferred pharmacological treatment for SVT, with an initial dose of 6 mg, followed by two 12 mg doses as needed 7.
• Verapamil can also be used to treat SVT, but it may have a higher risk of adverse effects, such as hypotension and ventricular tachycardia 4.
• The choice of pharmacological treatment should be based on the patient's clinical condition and medical history.

Special Considerations

• In pregnant women, adenosine can be safely used to treat SVT, with no reported adverse effects on the mother or fetus 7.
• In cases of in-flight SVTs, telemedicine can be used to guide treatment and prevent unnecessary flight diversions 6.