What are the pre-operative considerations for a patient with a history of Supraventricular Tachycardia (SVT) undergoing surgery?

Pre-operative Considerations for Patients with SVT History

Patients with a history of supraventricular tachycardia (SVT) undergoing surgery require comprehensive pre-operative assessment and management to minimize perioperative arrhythmia risk and optimize outcomes. Proper management can significantly reduce morbidity and mortality associated with perioperative arrhythmic events.

Pre-operative Evaluation

Arrhythmia Assessment

• Document the specific SVT mechanism (AVNRT, AVRT, AT) through review of previous ECGs and electrophysiology studies 1
• Assess frequency, severity, and triggers of SVT episodes
• Determine hemodynamic impact of previous episodes (syncope, heart failure symptoms)
• Evaluate for presence of accessory pathways, especially Wolff-Parkinson-White syndrome, which requires special consideration 2

Cardiac Assessment

• Echocardiography to assess for structural heart disease, ventricular function, and valvular abnormalities
• Exercise testing may be appropriate to evaluate functional capacity and provoke arrhythmias 2
• Ambulatory monitoring (24-hour Holter) if progression of arrhythmia is suspected 2
• Assess for underlying hemodynamic abnormalities that may trigger SVT, especially in patients with congenital heart disease 2

Pre-operative Management

Medication Management

• Continue antiarrhythmic medications through the perioperative period
  • Beta-blockers are particularly useful for prevention of recurrent AT or atrial flutter 2
  • Calcium channel blockers (diltiazem, verapamil) should be continued if effective 2
  • Sotalol may be beneficial in selected patients, but requires inpatient monitoring for 48-72 hours when initiated due to proarrhythmia risk 2
  • Flecainide should be used cautiously in patients with structural heart disease due to proarrhythmic risk 3

Special Considerations for Congenital Heart Disease

• Patients with adult congenital heart disease (ACHD) and SVT require specialized evaluation
• Preoperative catheter ablation should be considered in patients with Ebstein anomaly undergoing cardiac surgery 2
• Combined surgical approach (arrhythmia surgery with repair) is effective in 94% of cases versus 76% with catheter ablation alone in Ebstein anomaly 2
• Assess for hemodynamic abnormalities that may contribute to arrhythmias 2

Perioperative Management

Immediate Pre-operative Period

• Ensure adequate anticoagulation if indicated (particularly for patients with atrial flutter or fibrillation) 2
• Optimize electrolyte balance (particularly potassium and magnesium) to minimize arrhythmia risk
• Consider temporary pacing capability for patients with history of significant bradyarrhythmias 2

Intraoperative Considerations

• Have resuscitation equipment readily available, including defibrillator
• Place defibrillator pads preemptively for high-risk patients
• Avoid triggering factors for SVT:
  • Maintain adequate anesthesia depth
  • Minimize sympathetic stimulation
  • Maintain normothermia
  • Avoid electrolyte disturbances

Acute Management of Perioperative SVT

If SVT occurs during the perioperative period:

1. For hemodynamically stable patients:

   • Vagal maneuvers (first-line) 1
   • IV adenosine (second-line) - highly effective with 91% success rate 1
   • IV beta-blockers or calcium channel blockers (third-line) 2

2. For hemodynamically unstable patients:

   • Immediate synchronized cardioversion 2

Post-operative Considerations

• Monitor for recurrent arrhythmias in the post-operative period
• Maintain antiarrhythmic medications as soon as oral intake is possible
• Consider electrophysiology referral for patients with recurrent or poorly controlled SVT for definitive treatment (catheter ablation) 1
• Catheter ablation is highly effective with success rates of 94-98.5% and should be considered for definitive treatment in patients with recurrent SVT 4

Common Pitfalls to Avoid

• Discontinuing antiarrhythmic medications abruptly before surgery
• Using verapamil or diltiazem in patients with pre-excited AF (can lead to ventricular fibrillation) 1
• Failing to recognize that surgical stress, anesthetics, and electrolyte disturbances can trigger SVT
• Overlooking tachycardia-mediated cardiomyopathy in patients with frequent SVT episodes 4
• Inadequate rate control leading to hemodynamic compromise during surgery

By following these pre-operative considerations, the risk of perioperative SVT can be minimized, and appropriate management strategies can be implemented if arrhythmias occur during the perioperative period.