Management of Supraventricular Tachycardia with Hypotension
Synchronized cardioversion should be performed immediately for this hemodynamically unstable patient with SVT. 1, 2
Initial Assessment
This 31-year-old woman presents with:
- Narrow QRS complex tachycardia (HR 190)
- Hypotension (BP 64/40)
- Respiratory distress (RR 28, O2 sat 89%)
- Diaphoresis and acute distress
These findings clearly indicate hemodynamic instability in the setting of SVT, which requires immediate intervention.
Management Algorithm
1. Immediate Management for Hemodynamically Unstable SVT
- Synchronized electrical cardioversion is the first-line treatment for hemodynamically unstable SVT 1, 2
- This is a Class I recommendation with Level B-NR evidence according to ACC/AHA/HRS guidelines 1
- The patient's hypotension (64/40), tachycardia (HR 190), and respiratory distress make her unstable and unsuitable for initial pharmacological management
2. If Cardioversion Fails or Is Delayed
- Ensure IV access is established
- Consider adenosine 6 mg rapid IV push followed by saline flush if there's any delay in preparing for cardioversion 1, 2
- Prepare for possible intubation if respiratory status worsens
3. Post-Cardioversion Management
- Monitor vital signs closely
- Obtain 12-lead ECG after conversion to sinus rhythm
- Consider initiating rate control medications once stable
Rationale for Immediate Cardioversion
The 2015 ACC/AHA/HRS guidelines clearly state that "synchronized cardioversion should be performed for acute treatment in hemodynamically unstable patients with AVRT if vagal maneuvers or adenosine are ineffective or not feasible" 1. In this case, the patient's severe hypotension makes vagal maneuvers and adenosine not feasible as first-line treatments.
Important Considerations
- Do not attempt vagal maneuvers in this hypotensive patient as they may worsen hemodynamic status
- Do not delay cardioversion to administer medications in a hemodynamically unstable patient
- Avoid verapamil/diltiazem in this hypotensive patient as they can worsen hypotension 3
- Monitor for post-cardioversion complications including bradycardia, hypotension, or recurrence of arrhythmia
Pitfalls to Avoid
- Delaying cardioversion for pharmacological management in an unstable patient
- Misidentifying the rhythm - ensure it is truly SVT and not ventricular tachycardia with aberrancy
- Using calcium channel blockers like verapamil in a hypotensive patient, which could cause cardiovascular collapse 3
- Forgetting to look for underlying causes of SVT after stabilization (e.g., electrolyte abnormalities, thyroid disease, stimulant use)
After successful cardioversion and stabilization, the patient should be referred to cardiology for consideration of long-term management options, including possible electrophysiology study and catheter ablation, which has a success rate of 94-98% for recurrent SVT 2.